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iii
Highest Velocities
Lowest Velocities
The Dynamic Ether
of Cosmic Space
Correcting a Major Error in Modern Science
James DeMeo, PhD
v
The Dynamic Ether
of Cosmic Space
Correcting a Major Error in Modern Science
by
James DeMeo
2019 Natural Energy Works Ashland, Oregon, USA
www.naturalenergyworks.net
viii
The Dynamic Ether of Cosmic Space
CONTENTS
Page Table of Figures ......................................................... x Table of Tables .......................................................... xii Acknowledgments ..................................................... xiii
Author’s Introduction ................................................ 1
Part I: Cosmic Ether as Theory and Experimentally Confirmed Fact 23
The Matter of Space, Light Waves and Motion ........ 25 Positive Results of Michelson-Morley ...................... 45 FitzGerald, Lorentz and Morley-Miller ..................... 57 Millers Positive Ether Experiments, 1921-1926 ....... 79 Which Way Drifting? Miller’s Mis-Step ................... 115 Sagnac and Michelson-Gale ...................................... 131 Michelson Returns to the Ether ................................. 141 Recent Confirmations of Ether ................................. 167
ix
Page Part II: The Empire Strikes Back: Erasure, Mystification and Falsification of History 191
Einstein Rising ......................................................... 193 The Shankland, et al. Hatchet Job on Miller ........... 213
Part III: Into New Territory: Additional Evidence for a Material, Motional and Dynamic Ether 227
Ether and Cosmic Life-Energy ................................ 229 Direct Evidence for the Dynamic Ether ................... 265 Implications and Consequences of Ether ................. 297 Conclusions .............................................................. 337
Appendix 1. Model to View Earth-Ether Motions ... 347 Appendix 2. Newton’s Letter to Boyle 1687 ........... 349 References ................................................................ 361 Web References ...................................................... 375 Newspaper Clippings ............................................... 376 Glossary ................................................................... 378 Index ........................................................................ 381 About the Author ...................................................... 389
x
The Dynamic Ether of Cosmic Space
Table of Figures Page 1. Newtonian Static Ether “Absolute Space” 11 2. A Static but Dragged Ether 12 3. Competing Theories of a Material Cosmic Ether 14 4. A Motional-Material Dynamic Ether 16 5. Earth’s Net Motion Through the Galaxy? 17 6. The Earth’s Spiral Path Through the Cosmos 18 7. Young’s Double-Slit Experiment 38 8. Fizeau & Foucault’s Experiments 43 9. The Michelson 1881 Interferometer 47 10. Michelson’s Two-Swimmer Analogy 48 11. Light Paths of the M-M 1887 Interferometer 51 12. The Michelson-Morley 1887 Interferometer 52 13. Miller’s Review of the Michelson-Morley Data 55 14. Morley-Miller Magnetic Experiment 62 15. The Morley-Miller Wood Interferometer 65 16. The Morley-Miller 64-meter Steel Interferometer 67 17. Morley-Miller 1905 Error in Computations 70 18. Miller’s 1933 Graph of Ether Drift Measures 75 19. Light Paths of Morley-Miller Steel Interferometer 83 20. Light-Interference Fringes 83 21. The Mt. Wilson Observatory 84 22. Miller's Ether Rocks Interferometer House, Mt. Wilson 85 23. Miller's Rebuilt Interferometer, 1921 Ether Rocks 86 24. Miller’s Concrete Interferometer, 1921 Ether Rocks 87 25. Miller’s Interferometer, 1922 Case School Physics Lab 90 26. Rockefeller Physics Building 91 27 Miller's Interferometer, Grass Knoll, 1924 Mt. Wilson 93 28. Miller's Interferometer House, 1924, Grass Knoll 94 29. Miller’s Calculations of Azimuth vs Velocity 95 30. Miller’s Preliminary Computation 97 31. A Typical Interferometer Data Sheet 102 32: Velocities and Azimuths of Ether-Drift 105 33: Shifting Global Ether-Drift Azimuths 106 34: Average Velocity and Azimuth of Ether Drift 107 35. Miller’s Determination for a Northerly Axis 111 36. Miller’s Interferometer Orientations 112 37. A Conventional View of Solar System Motions 126 38. Northern Orbital Plane Poles of the Planets and Sun 128 39. Sagnac’s Rotating Interferometer 132
xi
40. Sagnac Interferometer & Optical Gyroscope 134 41. The Michelson-Gale Experiment 137 42. Variability in the Michelson-Gale Results 138 43. Dayton Miller and Albert Michelson 141 44. The Michelson-Pease-Pearson Invar Interferometer 143 45. Michelson-Pease-Pearson Mount Wilson Experiment 147 46. Concrete Base of the Mt. Wilson Observatory 148 47. Michelson-Pease-Pearson Experiment at Irvine Ranch 156 48. The Irvine Ranch Experiment 157 49. The Joos-Zeiss Interferometer 160 50. The Kennedy-Thorndike Experiment 163 51. Galaev’s Radiowave Antenna 169 52. Galaev’s Radiowave Experimental Diagram 169 53. Galaev’s Radiolink Interference Variations 170 54. Diagram of Galaev’s Optical Interferometer 172 55. Galaev’s Optical Interferometer 173 56. The Galaev Interferometer on a Rooftop 175 57. Galaev’s Ether-Wind Velocity Determinations 177 58. Galaev’s Sidereal Azimuth Determinations 178 59. Ether-Wind Velocity Versus Altitude 179 60. The Múnera Team’s Stationary Interferometer 181 61. The Múnera Interferometer, in Bogotá 182 62. Ether-Wind Velocity versus Altitude 186 63. Mercury’s Orbital Perihelion Advance 202 64. Eddington’s Eclipse Observations, Principe 204 65. The 1919 Eclipse Expeditions 205 66. Exaggerated Starlight Bending 206 67. The Solar Corona at Larger Distances 207 68. The Orgone Energy Accumulator 233 69. Orgone Accumulator Thermal Anomaly (To-T) 234 70. Biological Effects of the Orgone Accumulator 235 71. Kreiselwelle and Cosmic Superimposition 241 72. The Orgone Anti-Nuclear Radiation Effect 242 73. Planetary Motions and Gravitational Superimposition 245 74. The Kreiselwelle or Spinning Wave 246 75. Kepler Incongruent with Spiral Ether-Wind Velocities 248 76. Miller’s Ether-Drift and Reich’s Spiral Motions 250 77. The Earth’s Spiral Path Through the Cosmos 253 78. Polar Map of Cosmic Vectors, Update 1 254 79. Piccardi’s Helicoidal Earth-Orbit Diagram 259
xii
The Dynamic Ether of Cosmic Space
Table of Tables Page 1. Summary of the Morley-Miller Experiments 72 2. Miller’s 1921 Results at Mount Wilson 88 3. Miller’s 4-Epoch Ether Drift Determinations 102 4. The Epoch-Average Daily Swing of Ether Wind 105 5. Miller’s 1928 versus 1933 Determinations 109 6. Miller’s 1931 Table on the Absolute Motion of the Earth 121 7. Miller’s Ether Velocity “k-Factor” 123 8. Velocities of Post-Miller Ether Drift Experiments 164 9. Summary of Successful Ether-Drift Experiments 187 10. Orbital Properties of the Planets and Solar Surface 203 11. Miller’s 4-Epoch Averages of Ether Wind Velocity 248
80. Piccardi’s Animated Model of Helicoidal Motion 260 81. Sidereal-Hour Variations in Biological Clock 261 82. Seasonal Cosmic Variations in Biological Clocks 262 83. Kuiper Belt Planetoids & “Planet 9” 271 84. Direction of “Planet 9” Gravitational Anomaly 271 85. Andromeda Galaxy: Tilting of the Core Mass 273 86. Satellite Images of Earth’s Plasmasphere 275 87. UV-Glowing Charged Clouds of Interstellar Medium 278 88. The Super-Kamiokande Neutrino Detector 282 89. Galactic Rotation Anomaly for M33 284 90. Seasonal Variations in Dark Matter Wind 286 91. 17 Independent Vectors of Cosmic Motion 289 92. Spectroscopic Changes in ORAC-Charged Water 291 93. The Two LIGO Experiments 299 94. Massive Mirror Ends of the LIGO Light-Paths 301 95. One LIGO Event, 18 August 2017 303 96. Variation in Raw GPS Signal Data 308 97. Unit-Elements of Film Emulsions and CCDs 311 98. Low-Intensity Lightwaves through a Double Slit 311 99. Galaxies in Hubble Extreme Deep Field Image 316 100. Structure of Galaxy Distribution in the Universe 317 101. Close-up Center of the Milky Way Galaxy 325 102. The M87 “Black Hole” Image 328 103. Is This the Unprocessed M87 “Black Hole” Image? 328 104. Superluminal Motion in the M87 Jet 332 105. Vortex-Spiral Motion Yields Apparent Straight Lines 336 106. Apparent Straight Line Motion is Curved in Space 336
xiv
The Dynamic Ether of Cosmic Space
“I believe that I have really found the relationship between gravitation and electricity, assuming that the Miller experiments are based on a fundamental error. Otherwise, the whole relativity theory collapses like a house of cards.” — Albert Einstein, letter to Robert Millikan June 1921
“My opinion about Miller’s experiments is the following. ... Should the positive result be confirmed, then the special theory of relativity and with it the general theory of relativity, in its current form, would be invalid. Experimentum summus judex. Only the equivalence of inertia and gravitation would remain, however, they would have to lead to a significantly different theory.” — Albert Einstein, letter to Edwin Slosson, 8 July 1925, Hebrew Univ. Archive Jerusalem.
“The effect [of ether-drift] has persisted throughout. After considering all the possible sources of error, there always remained a positive effect.” — Dayton Miller, 1928, p.399
“You imagine that I look back on my life’s work with calm satisfaction. But from nearby it looks quite different. There is not a single concept of which I am convinced that it will stand firm, and I feel uncertain whether I am in general on the right track.” — Albert Einstein, on his 70th birthday, letter to Maurice Solovine, 28 March 1949
1
Author’s Introduction
Author’s Introduction
Intergalactic Medium! Interstellar Medium! Interstellar Wind! Neutrino Sea! Neutrino Wind! Dark Matter! Dark Matter Wind! Gravitational Waves! Higgs “God” Field! Cosmic Strings! Cosmic Ray Anisotropy! CMBR Anisotropy! Zero-Point Vacuum Fluctuation! Torsion Fields! Solitons!
Modern astrophysics and astronomy describe the cosmic space between the planets, stars and galaxies as an empty void, a hard vacuum lacking in inherent properties or substance. And yet, scientists working in these disciplines continue to discover “empty space” to be saturated with energy and particles, with turbulence and motion, as with the above concepts. Each is considered, by convention, to be a completely separate phenomenon from all the others, in spite of numerous points of similarities and agreement. Each term stands for its own presumed “soup” of discrete mystery particles. No matter how fantastically abundant, the space between them remains an empty void, save for scatterings of light and other electromagnetic waves. The scientists have identified all these specific “trees”, but deny the existence of any “forest”, whereby their basic nature could be more logically understood. As with the example of 10 blind men in a room with an elephant, each describes in exceedingly precise detail what they have individually grasped – the trunk, tusk, body, tail, legs – but the word “elephant” has become taboo. Like the proverbial naked emperor, nobody dares speak about a possible single ocean of cosmic energy, which offers a more unified and simpler understanding of all the diverse particles and “winds”. In a related manner, a casual look at images of deep space shows us billowing clouds of nebulae, of objects pushing through an unknown fluid and leaving behind a trail within a resisting transparent medium, all frozen in time. They appear more like something seen in the depths of the oceans or lakes. In some areas, a surrounding cosmic substance glows brilliantly with luminating stars, while elsewhere, everything appears darkened and dirty, as if smoke blanketed a patch of space.
23
Part I:
Cosmic Ether as Theory
and Experimentally
Confirmed Fact
25
The Matter of Space, Waves and Motion
The Matter of Space,
Light Waves and Motion
“...when primordia are being carried downwards straight through the void by their own weight, at times quite undetermined and at undetermined spots they push a little from their path, but only just so much as you could call a change of trend. But if they were not used to swerve, all things would fall downwards through the deep void like drops of rain, nor could collision come to be, nor a blow brought to pass for the primordia. So nature would never have brought anything into existence.” – Lucretius, Roman Poet, c.75 BC De Rerum Natura, Book II
Lucretius’ primordial “swerve”, quoted above, was a reference to curved or circular motion in the Great Void of the Cosmic Heavens, an early concept of creation in motion, resting upon ideas that ranged back to Greek philosophers such as Aristotle, and the Roman Epicureans. For those ancient philosophers, creation was a role played out by the gods, but they also put reasoned explanations to the physical world they could touch and see. The nature of cosmic motions, the passage of the Sun, Moon, stars and “wandering” planets, was always a central human interest, but only dimly understood, and set apart from the confined material existence of humankind on the Earth’s surface. Aristotle divided the material world into four elements, of fire, air, water and earth, but the heavens were composed of a fifth element, a
Lucretius (c.75 BC)
45
The Positive Results of Michelson-Morley
The Positive Results of the
Michelson-Morley Experiment
The history of science records the July 8-12, 1887 ether-drift experiment of Albert Michelson and Edward Morley as a pivotal turning point, after which the energetic ether, filling all of cosmic space, was discarded by mainstream physics and astronomy. Thereafter, the postulate of “empty space” devoid of ether was embraced, along with related concepts which demanded constancy of light speed in all directions, in harmony with Albert Einstein's relativity theory. The now famous Michelson-Morley experiment continues to be widely cited today, in nearly every physics textbook, for its claimed “null”, “zero”, or “negative” results. These claims, however, are not true, something easily determined by a careful reading of the original MichelsonMorley paper, which appeared in the American Journal of Science in November 1887. In fact, their experiment reported a slight positive result, later to be independently replicated by others, including by both Michelson and Morley, working separately from each other, with different research associates. Twentieth Century science nevertheless ignored all such positive evidence for the cosmic ether, as if psychologically compelled to make a wrong turn.
Albert Michelson (1852-1931)
Edward Morley (1838-1923)
57
FitzGerald-Lorentz and Morley-Miller
The FitzGerald-Lorentz Theory
and Morley-Miller Experiments
“Strictly speaking, the condensation [of ether] must be still more considerable than the value we have found to be necessary. If the ether be attracted by the earth, it is natural to suppose that it is acted on likewise by the sun; thus the earth will describe its orbit in a space in which the ether is already condensed. In this dense ether, the earth must produce a new condensation.” — Heinrik Lorentz 1899, p.446.
The years before the Michelson-Morley experiment of 1887 were characterized by a scientific discourse on the nature and properties of the ether, and its role in the properties of light and space. Nearly all had accepted the ether theory for most of their professional lives, and also accepted the wave theory of light, which demanded such a medium for light-wave transmission. Disagreements persisted on just what kind of ether might actually exist. Into that discussion came the 1887 result, variously described as “null” or “zero”, but which as pointed out in the last chapter was a substantial quantity. A significant ether-wind velocity was recorded, of up to 5 to 7.5 km/sec by Michelson-Morley’s own statements, or an average of ~8.4 km/sec as their data was later recalculated by Miller in 1933, using a new theory and understanding about Earth’s net motion in space. The Michelson-Morley result was too small to accommodate the static ether of Newton, but it was significant and sufficient enough to warrant further investigation along the lines of a partially entrained ether-drag effect. Such an ether drag would by definition reduce the conventionally (at that time) “expected” velocity close to the surface of the Earth. A trend was also set into motion following a new theory of “matter contraction”, to dismiss the Michelson-Morley result as purely “null”, and to explain away the cosmic ether itself, as if it were a nuisance. And
79
Dayton Miller’s Experiments
Dayton Miller’s Positive
Ether Drift Experiments, 1921-1926
“I believe that I have really found the relationship between gravitation and electricity, assuming that the Miller experiments are based on a fundamental error. Otherwise, the whole relativity theory collapses like a house of cards.” — Albert Einstein, letter to Robert Millikan June 1921 (in Clark 1971, p.328)
In the decades following the MichelsonMorley experiment of 1887, the worlds of physics and astronomy were thrown into confusion, given how the cosmic ether had been a foundational theory for understanding the wave-theory of light, as well as a variety of astronomical and physical phenomena. While the Michelson-Morley experiment obtained a slight positive result, as already discussed, the phrase “null result” and similar misrepresentations came into widespread use when referencing their experiment. Conference lectures and published papers of that period, as by FitzGerald and Lorentz, also previously described, carried forward with an increasingly mystified matter-contraction postulate, as a means to “explain” why the cosmic ether was not, or could never be detected – even though it had already been detected, repeatedly. Astrophysics thereby retreated away from real, tangible results on a critical experiment, in what psychologists might call emotional denial, substituting in its place a new metaphysics, which had its historical foundation in Newton’s metaphysically-demanded static ether concepts.
Dayton Miller (1866-1941)
115
Which Way Ether Drifting?
Which Way Ether Drifting?
Miller’s Mis-Step, and Last Years
Ether Confirmed, Ether Velocity Confirmed, Axis of Ether Drift Determined, but...
In Which Direction Does Earth Move Along That Axis?
The preceding chapter reviewed Dayton Miller’s exceptional work on the ether-drift question, his confirmation of both ether and ether drift or ether wind, with a set of velocities and azimuths determined at four different seasonal epochs atop Mount Wilson. He also plotted the axis of ether drift, finding it close to the axis of the solar system’s ecliptic plane. However, by the time of his comprehensive 1933 paper on the subject, he had reversed his long-standing view on the northerly direction of Earth’s motion along that axis, and instead argued for a southerly direction. I object to his change in direction of motion along the ether-drift axis, but not to the axis itself. My claim requires a clear discussion of the evidence, both pro and contra. As noted by Miller in the preceding chapter, the interferometer could determine the axis of ether drift using the Michelson interferometer, but not the direction of ether motion along that axis. For that determination, one needs to logically compare the axis of ether-drift findings against other astronomical observations related to the Earth’s velocity and movements relative to nearby stars, and other cosmic coordinates and determinations.
After Mount Wilson
By 1926, after Miller concluded his four major seasonal epochs of ether experiments, he began to reveal his thinking as to the larger issues of the Earth’s net velocity through the universe, as well as about an Earth pushing through a dragged ether. His writings on these matters reveal a level of comprehension and skill certainly equal to that of
131
Sagnac and Michelson-Gale
Sagnac and Michelson-Gale:
Ether Detection by Rotation
Another variant of the ether-drift experiments employed a rotating platform which sent two light beams around an irregular “racetrack” path by use of mirrors, one moving clockwise and the other counterclockwise. After completing the circuit, the two beams were recombined back into one beam, whereupon interference fringes would appear for observation. The experiment could evaluate for both the existence of an ether, and for changes in light speed dependent upon direction of rotation. The success of these experiments, reported below but nearly forgotten or obfuscated by the Einstein followers today, provided even more direct proof that light has variable velocities, dependent upon the speed of the emitter and observer, but irrespective of whether the cosmic ether is static, is in motion along one or another preferred direction, or is even fully stagnant as per the Stokes concepts.
1913-1914: George Sagnac Proves Variable Light Speed and Ether
Enter Georges Sagnac, who undertook the original rotating interferometer experiment in 1913, only 8 years after Einstein’s 1905 published papers on the subject of his new relativity theory. In this experiment, Sagnac created a rotating tabletop interferometer, turning at a speed of 2 revolutions per second. On the surface of the rotating table, two light beams were sent to bounce along different mirrors, so as to move either with the direction of the rotating disk, or in opposition to the rotation. The two light beams originated from the same light source, being split into two beams, much as in the Michelson interferometer. After moving around the rotat
Georges Sagnac 1869-1928
141
Michelson and Others Return to the Ether
Figure 43. Dayton Miller (left) and Albert Michelson (right) at a Conference on the Michelson-Morley Experiment held at Mount Wilson Observatory, February 1927.
Michelson and Others Return
to the Ether-Drift Question
1926-1928: Michelson, Pease and Pearson Confirm, but Nevertheless Deny an Ether-Drift
In apparent efforts to replicate Miller’s results as obtained at Mount Wilson in 1925 and 1926, Albert Michelson, with assistance from F.G. Pease and F. Pearson (hereafter “MPP”), undertook a new set of ether experiments. Their results, with the title “Repetition of the MichelsonMorley Experiment”, were published in the January 1929 issue of Nature magazine, followed by a nearly identical article a few months later in the Journal of the Optical Society of America. Unfortunately in both cases only a frustratingly vague and short report was given, exposing shortcomings well below the standards an optical expert such
167
Recent Confirmations of Ether
Recent Confirmations
of an Ether Wind
Yuri Galaev, Kharkiv Ukraine Experiments, 1998-2003
Yuri Galaev is a radio engineer at the Institute for Radiophysics & Electronics, a part of the National Academy of Sciences of Ukraine, in Kharkiv4. His work, using both optical light and radiofrequencies to investigate the cosmic ether produced a confirmation of Dayton Miller’s work, “down to the details”. His methods were unique, employing new designs, including both a radio wave analysis and a simplified Michelson-type apparatus. Like Miller, Galaev was one of the very few who embraced rather than ignored the material nature of the ether and the importance of removing shielding materials in the surroundings of the interferometer. This appears as a major reason for his success, and for the failure of so many others. He summarized the matter succinctly:
“In 1933, Miller has marked the shielding property of metal covers in his work. However the scientific community did not react properly to such peculiarity, shown by him in this work... there was a lot of experiments with zero results obtained with the interferometers screened by metallic chambers by that time. ...proper significance [had not been given] to Miller’s conclusions 1933 about the inapplicability of metal boxes in the experiments with an ethereal wind. Thus, proper checks of Miller’s experiments weren’t conducted yet until nowadays, in spite of numerous physicists’ attempts to repeat his experiments! All his followers carefully screened the devices from an ethereal wind by metal chambers, and, according to A.A.
Yuri Galaev
4. Kharkiv is the Ukranian city once called “Kharkov” during the Soviet era.
191
Part II:
The Empire Strikes Back:
Erasure, Mystification,
and Falsification
of History
193
Einstein Rising
Einstein Rising
“My opinion about Miller’s experiments is the following... Should the positive result be confirmed, then the special theory of relativity and with it the general theory of relativity, in its current form, would be invalid. Experimentum summus judex. Only the equivalence of inertia and gravitation would remain, however, they would have to lead to a significantly different theory.” — Albert Einstein, letter to Edwin Slosson, 8 July 1925 (Hebrew U. Archive)
The Rise of Einstein’s Theory of Relativity
In 1905, Albert Einstein published several research papers that are considered to be cornerstones of modern physics and astronomy. Upon first reading his works decades ago, I found his relativity theory to be deeply mystical, referencing unseen forces such as “curved spacetime”. He ignored measured real-world cosmic motions that affected the velocity of light, and conjured up cosmic motions in a space-time unreality, which still remains as sheer speculation, heavy with maths but never convincingly affirmed by empirical reality. Today I accept him as a humanitarian, and his ideas on energy-mass equivalency (E=mc2) as approximations. However, the proofs of variable light-speed, as from the successful ether-drift experiments, completely destroy a central assumption of Einstein’s relativity theory, that of light-speed constancy. Above that concern, when the evidence claiming to prove the accuracy of his relativity theory is critically examined from the viewpoint of the
Albert Einstein (1879-1955)
213
The Shankland, et al. Hatchet Job
The Shankland, et al.
Hatchet Job on Miller *
Over the years after Miller’s death in 1941, his Mount Wilson etherdrift results continued to trouble Einstein and his followers. A postmortem of Miller’s work was finally undertaken in the early 1950s by a team from Case School, led by Robert Shankland, and with “extensive consultations” with Einstein. As one might anticipate, the new evaluation of Miller’s findings made all the wrong assumptions about the cosmic ether as previously exposed in prior chapters, with a clear bias to “disprove Miller”. Given how Einstein’s supporters continue to place a high value on the Shankland, et al. study, I will go into some detail to expose its serious flaws and biases. Shankland in fact was Miller’s graduate student for many years, and only emerged to become a professional advocate of Einstein’s relativity after the death of Miller in 1941. His early career as a scientist got off to a rocky start, in his first published paper (1936) “An Apparent Failure of the Photon Theory of Scattering”. In that paper, Shankland
Robert S. Shankland, former student of Dayton Miller and later Chairman of the Physics Department at Case Western Reserve University in Cleveland Ohio. Shankland’s academic career soared following publication of several widely read interviews with Einstein, and after he organized a post-mortem on Miller's work in cooperation with Einstein, pronouncing Miller’s work as worthless. Shankland subsequently became a bureaucrat within the Atomic Energy Commission.
* This chapter was originally presented to a meeting of the Natural Philosophy Alliance, in Berkeley, California, May 2000, titled “Critical Review of the Shankland, et al. Analysis of Dayton Miller’s Ether-Drift Experiments”.
227
Part III:
Into New Territory:
Additional Evidence
for a
Material, Motional
and Dynamic Ether
229
Ether as Cosmic Life Energy
Ether as Cosmic Life-Energy
“There is no such thing as ‘empty space’. There exists no ‘vacuum’. Space reveals definite physical qualities [which] can be observed and demonstrated. Some can be reproduced experimentally...” – Wilhelm Reich,
Ether, God and Devil, 1948, p.111
In the years after the historic ether-drift experiments were concluded, and figuratively “driven into exile”, multiple converging lines of evidence from other scientific disciplines indicated the discovery of an interconnecting self-organizing cosmic medium, a cosmic life-energy with ether-like dynamic and plasmatic properties. The discovered lifeenergy functioned within living systems, influencing chemistry and biology, and could change the physical structure of water. It also existed as a background medium filling the atmosphere and vacuum of space. Experimenters such as Jacques Benveniste (memory of water), Frank Brown (external biological clock mechanisms), Harold Burr (electrodynamic fields), Björn Nordenström (bioelectrical circuits), Giorgio Piccardi (physical-chemical fields), Wilhelm Reich (orgone energy) and Viktor Schauberger (living water) independently documented different aspects of this phenomenon. Entire bodies of scientific work and literature have been developed over the years by these and similar scientists, far too large to review here. For some, I can only give a general citation to their work in the References. For those in the 20th Century up to c.1995, an annotated bibliography was developed by John Burns (1997), Cosmic Influences on Humans, Animals and Plants. Science journals such as Cycles and the Interdisciplinary Journal of Cycle Research published numerous papers on these subjects. Today their journals have nearly vanished, their leading scientific luminaries passed away. When alive, most were subjected to public “skeptic” attacks, academic misrepresentations, and unethical erasure.
The Dynamic Ether of Cosmic Space
230
Regrettably, nothing of the most insightful and productive of the above list of life-energy scientists, Wilhelm Reich, is found in Burns annotations, and little of fact about him is found elsewhere in mainstream science, pop-media or internet. This was the result of a deadly 20th Century’s slander and book-burning campaign directed against him in the 1940s and thereafter, as discussed in the Introduction. (WebRef.1) He published his findings in his own institute’s journals and books, which were eventually reprinted in the 1970s, after the book-burning epoch. In this chapter I will survey the facts on Reich’s experimental findings, speak to my own positive replications of his experiments over the last decades, and end with a short discussion on Piccardi and Brown. These latter two scientists identified specific cosmic components in their investigations which, I will show, are agreeable in the details with Reich and Miller. Taken together and merged with the prior findings on cosmic ether under discussion, these studies collectively document a major scientific breakthrough, the discovery of a unitary cosmicatmospheric-biological energy, ignored, suppressed and dismissed prematurely during the 20th Century.
Wilhelm Reich’s Dynamic Ether-Like Orgone Energy
From 1934 to 1957, Wilhelm Reich produced a series of experimental reports documenting the existence of a unique form of energy, called the orgone, or orgone energy. Reich’s line of research began with the clinical and experimental investigation of Freudian libido theory, including a milestone study on the bioelectric nature of emotions, somatic impulses, sexual excitation and sensory perception. Reich’s research proceeded also into microbiology, with a study of motility and impulse-creation within simple microbes such as the ameba, which has no brain, nerves or muscle tissue by which to move its protoplasm towards food or away from irritating influences. His studies (Reich 1934, 1938) identified bioelectric commonalities in the motions of raw protoplasm in ameba, to nervous and muscular impulses in humans. The work by Seifriz (1936) and others on motile slime molds suggests related findings. Slime molds are a large single cell of
Wilhelm Reich 1897-1957
265
Evidence for a Dynamic Ether
Direct Evidence
For a Dynamic Ether
Motional, Dynamic, Spiralling, Luminiferous, Variable Density, Matter-Forming, Substantive
A Review of What We Know
Let’s start this chapter by reviewing the specific nature and properties of the cosmic ether as learned from the different experiments already recounted in this work. From Michelson-Morley 1887, we learned a cosmic ether wind with an upper value of ~5 to 7.5 km/sec was detected, able to partially penetrate through the stone basement building in which the light-beam interferometer experiment was conducted. Their results were a much lower velocity than the ~200-300 km/sec anticipated from Newtonian static ether “absolute space” assumptions. While the 36 turns of their interferometer were minimal, over only a few days, their results were never “null” or “zero”. They stated the experiment would have to be repeated again at a higher altitude over intervals of three months. This repetition was never conducted by them. From Morley-Miller 1898 to 1906, we learned that light speed is not affected by a strong magnetic field. They later constructed a larger and more sensitive light-beam interferometer, used for experiments over several years, with nearly a thousand individual turns of the instrument over different months. They experimentally tested their interferometer for the postulated “matter contraction” of FitzGerald-Lorentz, which was never confirmed. This was accomplished by mounting the interferometer optical components on a base of different density materials, such as wood, concrete or steel, and comparing that to the sandstone base used in the Michelson-Morley experiment. However, in the process, Morley-Miller repeatedly confirmed a real ether drift of ~7.5 to ~9 km/sec. The highest ether velocity was obtained when the
297
Implications of Cosmic Ether
Implications and Consequences of a Material-Motional Cosmic Ether for Modern Astrophysics
The Cosmic Ether Changes Everything!
For more than 100 years, empirical experimental evidence identifying a real material and motional ether has been consistently ignored, overlooked and suppressed, while at the same time, ambiguous and speculative, mystical theories have been promulgated and hungrily devoured. And whenever evidence was asserted to support such mysticisms, it was never so unequivocal that opposing ether theory could not equally or better explain it. Factually, proof for a motional and material cosmic ether changes everything!It upsets the modern applecart, and forces us back to unfinished discussions of the early 1900s. To this we must add the considerable work of Reich, who independently and experimentally confirmed an ether-like life energy, and described how it moved in living tissues, in the atmosphere and in the cosmos, thereby adding additional detail to what is known about cosmic ether. The two objective discoveries, and their respective bodies of evidence – of cosmic ether and cosmic orgone – are at root, functionally identical. And not accidentally, some of the same players, notably Einstein and his followers, worked towards the erasure of both Reich and Miller. In this closing chapter I will review modern cosmological concepts and experiments currently underway, and will challenge their basic foundational assumptions from the viewpoint of a dynamic cosmic energy in space. As a prelude, I would remind the scientific reader of a major fallacy in contemporary physics, where modern theories as from Einstein, the big bang and quantum entanglement, are stretched so thin in efforts to basically “explain everything”, that in the process must resort to increasingly fantastic and unbelievable claims. By contrast, the cosmic ether of space already has considerable independent evidence and equally valid explanatory and predictive power, resting firstly upon the historical proofs of its own existence.
337
Conclusions
Conclusion
Figure 105 on the facing page was first presented in the Introduction. The lower part is Figure 106, also reproduced for emphasis from the chapter on Ether and Cosmic Life Energy. Together with all the other figures in Part III, they present a concluding, though generalized and non-mathematical, ether/life-energetic understanding of cosmic forces ruling celestial motions, gravitation and other aspects of matter and life. Figure 106 depicts Mass 1 moving towards Mass 2 in a straight line, but only if one is standing upon the rotating Earth. It is only an apparent straight-line motion. Standing as an observer out in space, what we call “gravitation” is seen as a curve of motion, with both objects captured in a sweep of merging, negatively entropic and self-attracting cosmic energy, carrying matter with it. Ether/life-energy, orgone energy as Reich described it, superimposes in a curve of energetic attraction which brings the two objects together. This is standard old-fashioned Galilean relativity, which often gets lost in the modern discussions about Einstein’s relativity and imaginary “space-time gravity wells”. The old master Galileo had, in the 1600s, already proven basic properties of gravitation in his famous experiments at the Tower of Pisa, where balls of unequal weight were dropped from a height of around 55 meters, arriving at the ground at the same time. This refuted the older view of Aristotle that different weight objects fell at different velocities. Galileo also wrote several logical premises, today called “thought experiments”. He imagined (and possibly confirmed by experiment) a man on horseback riding in a straight line, who holds a ball off to the side of his direction of motion, and then drops the ball which falls downwards. From the perspective of the horseback rider, the ball moves downwards in a straight line, with a forward motion the same as the horse, until landing directly next to where the horse is galloping. From the perspective of someone standing on the ground, watching the horseman ride by and drop the ball, however, the ball falls downwards in a long curve, not a straight line. This observation led Galileo to go beyond his initial weight-drop experiments at Pisa, to
349
Appendix 2: Newton Letter to Boyle
Isaac Newton's 1679 Letter to Robert Boyle, on the Cosmic Ether of Space
Appendix 2
Newton the Younger (1689) Newton the Elder (1712)
Prefacing Comments
Below is a letter on the question of the cosmic ether of space, written by Isaac Newton in 1679 to Robert Boyle, a fellow scientist about 15 years older than Newton at the time, and who is remembered with a fame nearly equal to that of Newton. This letter first came to my attention when it was reprinted in a relatively-unknown journal edited by the heretic-scientist Wilhelm Reich, his International Journal of Sex-Economy and Orgone Research (vol.3 1944, p.191-194). The original reference from Reich's journal is found in the 1938 volume Isaac Newton: 1642-1727, by J.W.N. Sullivan (Macmillan, NY, p.118124). However, a longer and more complete version of the letter was thereafter found in an 1846 publication of lengthy title by William Vernon Harcourt, cited (as Newton 1679) in the Reference section of this book, containing pertinent information not previously available. The letter below is significant firstly because it is not well-known outside of a few historians. Where it is quoted, significant parts as I have now restored, are often left out.
361
References
References
A chronologically-ordered list of the historical ether-drift citations, with download links, is found at: www.orgonelab.org/energyinspace.htm
Abbot BP (2018) GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs. arXiv:1811.12907v2 Alfven H (1981) Cosmic Plasma, Springer.
Allais M (1997) L’Anisotropie de L’Espace:La nécessaire révision de certains postulats des théories contemporaines, Clément Juglar, Paris.
Allais M (2002) Experiments of Dayton C. Miller (1925-1926) and the Theory of Relativity. Pulse of the Planet #5, p.132-137.
Arp H (1987) Quasars, Redshifts and Controversy, Interstellar Media. Arp H (1997) Seeing Red: Redshifts, Cosmology and Academic Science, Aperion. Canada.
Arp H (2003) Catalogue of Discordant Redshift Associations. Aperion, Montreal. Asimov I (1966) The Neutrino, Ghost particle, Doubleday, NY. Baker CF (pseud. Rosenblum CF) (1972) An Analysis of the United States Food and Drug Administration's Scientific Evidence Against Wilhelm Reich, Part II, the Physical Concepts. J. Orgonomy, 6(2) 222-231. Baker CF (pseud. Rosenblum CF) (1973) An Analysis of the Food and Drug Administration's Scientific Evidence Against Wilhelm Reich, Part III, Physical Evidence. J. Orgonomy, 7(2) 234-245. Baker CF (1980) The Orgone Energy Continuum. J. Orgonomy, 14(1) 37-60. Baker, CF (1982) The Orgone Energy Continuum: the Ether and Relativity. J. Orgonomy, 16(1) 41-67.
Becker RO (1998) The Body Electric: Electromagnetism and the Foundation of Life, Wm. Morrow, NY. Bauer I (1987) Erethrocyte Sedimentation: A New parameter for the measurement of Energetic Vitality. Annals, Inst. Orgonomic Sci.4:49-65. Baumer H (1987) Sferics: Die Entdeckung der Wetterstrahlung. Rowohlt Verlag, Hamburg. Becker RO, Selden G (1985) The Body Electric. Wm. Morrow, NY. Bernabei R (2007) DAMA sheds light on dark-matter particles. Nature 449, 24, 6 September. Bernabei R (2010). Particle Dark Matter in the Galactic Halo: Recent Results from DAMA//LIBRA. CRIS 2010 lecture, September, Catania Italy; see WebRef.10 Beloussov L, Popp FA, Voeikov V, Wijk RV, eds. (2000) Biophotons and Coherent Systems: Proc. 2nd Alexander Gurwitsch Conference. Moscow U. Press; republished by Springer Press 2007.
381
Index
A
aberration, stellar 12, 37-39, 59-60, 74, 82, 116, 119, 208-209, 340 absolute space 10-11, 139, 181,185, 187, 198, 208, 265, 269, 319, 350 Aether 2, 4, 26 Allais, Maurice 9 Andromeda Galaxy 32, 124, 272273 blue halo 287, 292-293 Aristotle 25-26, 337 Arp, Halton 4, 6, 211, 321-322, 334 astrologers 2, 318 atomic clocks 304-307
B
Bell, Alexander Graham 46 Benveniste, J. 229 Bernabei, R. 251, 286-287 Biblical creationism 320 big-bang creationism 2, 4-6, 13, 22, 212, 236, 280-281, 283, 297, 300, 303, 314-324, 335, 341-344 biophotons 293 Biretta, John 331-332 black holes 2, 22, 212, 285, 301303, 324-331, 333-335, 341, 345 as ring of stars 328-330 as ether vortex Sagittarius-A 325 M87 image, problems 326-330 Bode’s Law 341 book-burning 19-21, 230, 319, 343344 Boyle, Robert 32-24, 60, 349-360 Brace, D.B. 63 Bradley, James 37 Brown, Frank 4, 6, 15, 229-230, 252, 254, 261-263, 268, 286, 288-289, 242
Index
Bruno, Giordano 27 Burr, Harold S. 8, 15, 229, 263
C
Cahill, Reginald 184-187, 190, 252, 254, 268, 288-289 Campbell 119, 209 Carnegie 119 Case Western Reserve University 8, 52, 54, 80, 130, 213, 225 Case School of Applied Science, Pierce Hall 50-52, 54, 62, 66-67, 69, 73, 80, 86, 90-91, 101, 118, 122, 130, 161, 213-216, 221, 266 Western Reserve University 50, 73, 80, 130 Catholic Church 5, 26, 33, 314-315, 318-319, 333, 350 Cedarholm 188 Champeney, D.C. 188 Chappell, John xi, 8 cloudbuster 5-6, 236 Copernicus, Nicolaus 3, 13, 27, 335 Cosmic Microwave Background Radiation, CMBR, 1, 5, 118, 323 cosmic strings 1, 335 cosmic superimposition, see Reich, Wilhelm cosmic rays 1, 119, 238, 276, 279280, 283, 285, 288-289, 293-294 winds, anisotropy 279 Courviosier 118
D
dark matter 1, 236, 242, 251, 272, 276, 280, 292-293, 295, 334 MACHOS 285, 294, 334 WIMPS 285-286, 294, 334 wind, anisotropy 283-289
The Dyamic Ether of Cosmic Space
382
DAMA Project, see Bernabei DeMeo findings, theory, graphics Atomic clock variable inertia 307 blue glows 292-295 comet velocities 354 correlations of cosmic motions 111, 128, 254, 288-290 dubious black holes 326-330 ether lens effect 210 ether velocity/altitude 186-187 ether-vortex tornado 325, 330 galactic and solar tilting 272-273 GPS experiment 308 LIGO 302-304 Miller’s ether velocities 248-250 Miller’s data sheets 8, 225 planet nine 270 Reich and Kepler, 248-250 orgone accumulator 233-235, 242 rotation of plasmasphere 274-275 spectroscopical analysis 290-292 spiral-form vortex motions 16, 18, 250, 253, 325, 328 Descartes 15, 19, 29-33, 36, 39, 42, 257 Dewitte, Roland 189-190 dowsing 7
E
Edison, Thomas 344 Einstein, Albert xiv, 5, 8, 15, 22, 61, 193-212, computational error 77 E=mc2 15, 193 Einstein rings 210-211 equivocal nature 200 ether concept 198-199 gravity wells 198, 211, 334, 337, 341, 345, 339, 345 last years 200, 223 mysticism 199, 342 perihelion of Mercury, problems 200-203
relativity theory 5, 8-9, 15, 45, 74, 76-77, 79, 84, 87-88, 98-100, 110, 131, 136, 138, 140, 143, 162-164, 185-187, 190-213, 224, 236, 240, 256, 266-267, 298, 305, 313, 318, 324, 331-334, 337-344 Shankland affair 200, 223-224 space-time distortion 15, 22, 76, 187, 193, 195, 210-211, 236, 304, 326, 330 , 334-335, 342 starlight bending near Sun, problems 203-210 Epicureans 25 epicycles 2, 27, 333, 335 Esclangon 119 Essen, Louis 188, 305 ether, cosmic blocking by materials 54, 63 dielectric 39, 63, 231-232, 293, 295, 305, 346, 197-198, 265, 267 entrained, dragged, static, as cosmic braking force 13-14 ether turbulence in LIGO 303 experimental summary 186-187 luminiferous 2-3, 19, 26, 32, 36, 53, 58, 60-61, 133, 237, 240, 292 magnetism 11, 33, 39, 62-63, 8788, 231, 265, 304 prime mover 13-14, 26, 28, 3233, 35, 42, 113, 236, 257, 268269, 319, 339, 341, 350 properties 178-179, 339-341 static-dragged versus dynamicmotional 10-15, 32-37, 265-295 tornado vortex 325, 330 velocity and altitude 186-187 velocity zero in December 251 water drag experiments 42-43 winds, substitute names for 276 Event Horizon Telescope EHT 326329
383
Index
F
Faraday, Michael 304, 345 Faraday cage 231, 233, 236 Fibonacci 340 Fickinger, William xiii, 8, 225 first order/second order 172 FitzGerald, George 58-76 FitzGerald-Lorentz matter contraction 57, 60-65, 67-68, 70, 73, 76, 79, 117, 129-130, 198, 265, 352 Fizeau, Hippolyte 40-43, 171 Food and Drug Administration, see book burnng Foucault, Léon 41-43, 54, 155, 171 fractals 340 freedom of speech, loss in universities 9-10, 335 Fresnel, August-Jean 38-40, 60-61, 74, 133, 135, 139
G
galactic core and solar rotational tilting 272-273 galactic redshifts 320-322 Galaev, Yuri 9, 49, 167-179, 183189, 252, 254, 260, 267, 269, 288-289, 306, 351 galaxy distribution in universe 317 Galilei, Galileo 3, 5, 13, 21, 27-28, 33, 36, 40, 301, 333, 335, 337338, 350 Galilean relativity 194, 337-338 Gell-Mann, Murray 314 Gerson, Max 344 golden section 340 GPS 307-309 gravitational redshifts 210-211 gravitational waves 1, 298-304 Grusenick, Martin 189-190 Grimaldi, Francesco 29-30 Gurwitsch, Alexander 263
H
Hafele and Keating 306 H-bombs 345 Heisenberg uncertainty 313-314 Helmholtz, Hermann von 46 Hicks, W.M. 70 Higgs “God” particle field 1, 276, 287 Holy Ghost, ether as 28, 33, 37 Hoxsey, Harry 344 Hubble, Edwin 32, 314 Hubble constant 334 Hubble telescope 277, 315-316, 326, 331 deep-field image 316 Huygens, Christiaan 37, 359
I
IMAGE satellite, see plasmasphere intergalactic medium or wind, see interstellar medium International Society for Biometeorology, Piccardi Group 7 interstellar medium or wind 1, 236, 276-278, 280, 283, 288-289, 292293
J
Jaesja 188 Joos, Georg 158-162, 216, 206
K
Kelvin, Lord 64, 77, 224 Kennedy, Roy 149-151, 266 Kennedy-Thorndike 162-163, 266 Kepler, Johannes 28, 33, 37, 39 theory and equations 20, 96, 127, 202, 245, 247-252, 268, 287, 339 Kervran, Louis 263 Kreiselwelle, spinning wave, see Reich, Wilhelm Kuiper Belt planetoids 271
The Dyamic Ether of Cosmic Space
384
L
Lemaitre, George 315 life-energy, see Reich, Wilhelm
light phenomena double-slit experiment 38, 309313 refraction 29-30, 37, 39, 74, 206, 210, 304, 353 corpuscular photons or particles 10, 36-38, 194-195, 199, 208, 210, 213, 238, 309-314 Light Interferometric Gravitational Observatory LIGO/ALIGO 298304 ether turbulence 303 results not unequivocal 301-303 light flashes, visible, background radiation 294 visible orgone energy phenomena, see Reich, Wilhelm Lodge, Oliver 59, 209, 319 Lorentz, Heinrik 57-74, 76, 79, 116-117, 129, 186, 198, 220, 305, 340, 342 Lorentz-FitzGerald matter contraction, see FitzGerald-Lorentz Lucretius, primordial swerve 25 luminiferous ether, see ether, luminiferous Lysenkoism 10
M
mainstream media “fake news” and slander 6, 19-21, 230, 233, 243-244, 343 hysteria, hype, bias 56, 74, 98100, 198, 200, 205, 208-209, 212, 224-225, 230, 233, 318, 326, 335, 343 Marett, David 279 Marinov, Stefan 188
Massive Compact Halo Objects MACHOS, see dark matter Maxwell, James Clerk 39 Mersenne, Martin 29 Messier, Charles, spiral nebulae 32 Michelson, Albert 45-56, 134-140, 141-149, 154-158, 265-267 1881 experiment 46-47 early studies 46 invention of the interferometer 46-50 last years 149, 165 two swimmer example 48 Michelson-Morley experiment 4556, 60-61 absence of null-zero result 53-58 re-calculation by Miller 53-56 Conference on, at Mt. Wilson 103, 108, 117, 141, 220 Michelson-Gale experiment 134140, 196, 266 Michelson-Pease-Pearson experiments 141-149, 154-158, 266 Milian, Viktor 240 Millikan, Robert xiv, 79, 88, 197198 Miller, Dayton 61-77, 79-113 1921 Mt. Wilson experiments 8489 1922-1924 Cleveland control experiments 90-92 1924 Mt. Wilson experiments 9396 1925-1926 Mt. Wilson experiments 96-110 axis of drift closer to Vega 251 early studies 80 error of southerly apex 115-130 Joos, response to 161-162 last years 130 phonodiek 77, 122, 224 rebuilt interferometer 81-83
385
Index
work with Morley 61-77, 265266 Morgan, J.P. 344 Morley, Edward 45-56, 61-77, 80, 265-266 Morley-Miller experiments 4, 80. 61-77, 265-266 absence of null result 68-69, 73 compute error 69-70, 73-74, 76 Euclid Heights 69-76 magnetic experiment 62 new computation by Miller 7072, 75-76 new interferometer 64-67 Morse, P.M. 122, 124-125 Mount Wilson Observatory 84-85, 148 1927 Conference on Ether Drift 103, 108, 117, 141, 220 also see Miller and MichelsonPease-Pearson experiments Müller 189 multiple universes 22, 313, 335 Múnera, Héctor 180-187, 190, 252, 254, 267-268, 288-289
N
Nassau, J.J. 122, 124-125 Nazis 19, 255 neutrinos 1, 236, 242, 276, 285, 288-289, 293-294 wind, anisotropy 280-283 Super-Kamiokande detector 282 Newtonian static ether, see ether, static Newton, Isaac 10-13, 19, 32-38, 42, 57-60, 79, 124, 135, 139, 181, 183, 187, 198-201, 204, 208-211, 245, 265-267, 301, 304, 313, 319, 335, 339 on precession of Mercury 201, 204 on bending of starlight 208-210
letter to Robert Boyle 32-33, 349360 Queries 34-35 Noble, H.R. 63 Nordenström, Björn 229
O
Occam’s Razor 13, 196, 294 Oracles of Delphi 330 Orgone Biophysical Research Laboratory 7 orgone energy, see Reich, Wilhelm orgone energy accumulator, see Reich, Wilhelm
P
Pauli, Wolfgang 280 pendants, pyramids, gizmos 21 Penzias, Arno 5, 318 perihelion of Mercury, problems, see Einstein ether explanation for 200-203 photomultiplier tube detectors PMTs in water or ice, for neutrinos 281283, 285, 293 with NaI(Tl) for dark-matter WIMPs 285, 293 for cosmic ray and gamma ray detection 293 for biophoton detection 293-294 Piccardi, Giorgio 4, 7, 15, 229-230, 251-254, 257-261, 263, 268-269, 288-289, 306, 342, 351 Piccard-Stahl 151-154, 266 Planck, Max 239, 322, 346 Planet 9 gravitational anomaly 270271 plasmasphere 208, 274-275 Pollack, Gerald 263 Pope John Paul II 319
The Dyamic Ether of Cosmic Space
386
prime mover 13-14, 26, 28, 32-35, 42, 113, 236, 240, 252, 257, 268269, 319, 339, 341, 350 Ptolemy, Claudius 29
Q
quantum magic 22, 310, 313-314, 342 quantum vitamin pills 22 quantum flapdoodle 314 quasars 292-293 ejected from Seyfert galaxies 321-322, 292 high redshifts 322, 334 superluminal jets 333-334 water-drenched 294-295
R
Rankine, A.O. 63 Rayleigh, Lord 59-60, 63, 292 redshifts, see galactic, gravitational or quasar redshifts Reich and Miller 20, 258-259 Reich, Wilhelm 4, 19-22, 229-264, 268-269 bions 236, 320 cosmic superimposition 15, 20, 32, 236, 239-247, 255, 257, 336 discovery of orgone energy and accumulator 230-231 effects of orgone energy accumulator 231-235 Einstein, meeting with 256-258 kreiselwelle, spinning wave 236, 239-241, 245-249. observations of orgone energy 235-242 orgone energy, summaries 236, 339-341 orgone lumination 32, 237, 281, 321, 339 orgone pulsation 19, 232, 236, 238, 244, 319, 340
Reichian relativity 336, 338 slander and destruction of 19-22 spiral motions agreeable with Miller 247-250, 258-259 vacor tubes 237, 240, 242 visible fog-like form 238 visible orgone units 238-239, 281, 294 Royal Society (British) 64 Russell, Walter 18
S
Sagnac, Georges 78, 131-134, 139140, 161, 196, 266, 298, 307-308 Sagittarius-A 324-325, 330 Schauberger 229 Seaver, Jay 187 self-organizing principle 19, 33, 36, 229, 268-269, 318-320, 341 Shankland, Robert 8, 92, 186, 200, 213-225 biased study of Miller 213-225 betrayal of Miller 223-224 Shapley, Harlow 343 skeptic clubs 6, 21-22, 225, 229, 294 Silvertooth, E.W. 188 Slosson, Edwin xiv, 99, 193, 197 Shnoll, Simon 263 solitons 1 Solovine, Maurice xiv, 200 solar flares 17, 239 solar extended corona 206-208 solar pulsation 17 spinthariscope, see light flashes spiral vortex motions 13, 15-20, 3132, 39, 42, 61, 70, 96, 107, 112, 127, 133, 171, 201-202, 211, 232, 236-239, 241, 244-260, 268-269, 272-273, 277, 283-287, 324, 326, 328, 330, 339-340 starlight bending near Sun ether explanation for 203-210
387
Index
Stokes, George 39-40, 54, 59-60, 74, 129, 131, 135-138 stratospheric and planetary winds 276 Sun’s Way 113, 116, 120, 125-129, 171, 251, 254, 269, 273, 288-289 superluminal objects 330-334 Swenson, Lloyd 4, 87, 96, 122, 142-143, 149-150, 224
T
Tchijevski, A.I. 263 Tesla, Nikola 344 torsion fields 1 Tromp, Solco 7 Trouton, Fredrick 63
U
University of Kansas 4
V
vacor high-vacuum tubes, see Reich, Wilhelm Velikovsky, Immanuel 343
W
Weakly Interacting Massive Particles WIMPS, see dark matter Wedler, Eric 7 Westinghouse 344 Wheeler, Raymond 263 Wikipedia, disreputable 21
Y
Young, Thomas 37-38
Z
zero-point vacuum fluctuation 1, 4
The Dynamic Ether of Cosmic Space
388
Other Books by James DeMeo
Saharasia: The 4000 BCE Origins of Child Abuse, Sex-Repression, Warfare and Social Violence In the Deserts of the Old World, Revised Second Edition.
The Orgone Accumulator Handbook: Wilhelm Reich’s Life-Energy Discoveries and Healing Tools for the 21st Century, with Construction Plans, Third Revised Edition.
In Defense of Wilhelm Reich: Opposing the 80-Years’ War of Mainstream Defamatory Slander Against One of the 20th Century’s Most Brilliant Physicians and Natural Scientists.
Marx Engels Lenin Trotsky: Genocide Quotes. The Hidden History of Communism’s Founding Tyrants, in their Own Words.
Preliminary Analysis of Changes in Kansas Weather Coincidental to Experimental Operations with a Reich Cloudbuster: From a 1979 Research Project, reprinted 2010.
(as Editor) Heretic’s Notebook: Emotions, Protocells, EtherDrift and Cosmic Life-Energy, with New Research Supporting Wilhelm Reich.
(as Co-Editor) Nach Reich: Neue Forschungen zur Orgonomie: Sexualökonomie, Die Entdeckung der Orgonenergie.
(as Editor) On Wilhelm Reich and Orgonomy.

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General covariance and general relativity 791
General covariance and the foundations of general relativity: eight decades of dispute
John D Norton
Department of History and Philosophy, University of Pittsburgh, Pittsburgh, PA 15260, USA
Abstract
Einstein o ered the principle of general covariance as the fundamental physical principle of his general theory of relativity, and as responsible for extending the principle of relativity to accelerated motion. This view was disputed almost immediately with the counter-claim that the principle was no relativity principle and was physically vacuous. The disagreement persists today. This article reviews the development of Einstein's thought on general covariance, its relation to the foundations of general relativity and the evolution of the continuing debate over his viewpoint.
This review was received in march 1993.
792 J D Norton
Contents
1. Introduction 794
2. The background of special relativity 796 2.1. Lorentz covariance and the relativity of inertial motion 796 2.2. Minkowski's introduction of geometrical methods 796 2.3. Covariance versus invariance in special relativity 797
3. Einstein's development of general relativity 797 3.1. The early years 1907-1912: principle of equivalence and the relativity of inertia 798 3.2. The `Entwurf' theory 1912-1915: general covariance gained and lost 799 3.3. The hole argument: general covariance condemned 801 3.4. Einstein's 1916 account of the foundations of general relativity: general covariance regained 802 3.5. The point-coincidence argument 804 3.6. The Gottingen defense of general covariance 805 3.7. Einstein's three principles of 1918 806 3.8. Mach's principle forsaken 808 3.9. Einstein's objection to absolutes 809
4. The favourable text-book assimilation of Einstein's view: fragmentation and mutation 811 4.1. Einstein's principle of equivalence as a covariance principle and its later misrepresentation 812 4.2. The early years: 1916-1930 814 4.3. The lean years: 1930-1960 815 4.4. Rebirth: 1960-1980 815 4.5. Recent years since 1980 816
5. Is general covariance physically vacuous? 817 5.1. Kretschmann's objection: the point-coincidence argument turned against Einstein 817 5.2. Einstein's reply 819 5.3. Generally covariant formulations of Newtonian mechanics 820 5.4. Automatic general covariance: coordinate free formulation 821 5.5. Later responses to Kretschmann's objection 825
6. Is the requirement of general covariance a relativity principle? 829 6.1. Disanalogies with the principle of relativity of special relativity 829 6.2. Relativity principles as symmetry principles 831 6.3. Coordinate systems versus frames of reference 835 6.4. Relativity principles and the equivalence of frames 837
7. General relativity without principles 841 7.1. General relativity without general relativity 841 7.2. The principle of equivalence as the fundamental principle 842 7.3. Challenges to the principle of equivalence 842
General covariance and general relativity 793
8. Eliminating the absolute 843 8.1. Anderson's absolute and dynamical objects 843 8.2. Responses to Anderson's viewpoint 846 8.3. No gravitational eld-no spacetime points 847 8.4. What are absolute objects and why should we despise them? 847
9. Boundaries and puzzles 849 9.1. Is general covariance too general? Or not general enough? 849 9.2. The Einstein puzzle 850
10. Conclusion 852
794 J D Norton
1. Introduction
In November 1915, Einstein completed his general theory of relativity. Almost eight decades later, we universally acclaim his discovery as one of the most sublime acts of human speculative thought. However, the question of precisely what Einstein discovered remains unanswered, for we have no consensus over the exact nature of the theory's foundations. Is this the theory that extends the relativity of motion from inertial motion to accelerated motion, as Einstein contended? Or is it just a theory that treats gravitation geometrically in the spacetime setting? When Einstein completed his theory, his own account of the foundations of the theory was adopted nearly universally. However, among the voices welcoming the new theory were small murmurs of dissent. Over the brief moments of history that followed, these murmurs grew until they are now some of the loudest voices of the continuing debate. In any logical system, we have great freedom to exchange theorem and axiom without altering the system's content. Thus we need no longer formulate Euclidean geometry with exactly the de nitions and postulates of Euclid or use precisely Newton's three laws of motion as the foundations of classical mechanics. However, some two millennia after Euclid and three centuries after Newton, we still nd their postulates and laws within our systems, now possibly as theorems and sometimes even in a wording remarkably close to the original. The continuing disagreement over the foundations of Einstein's theory extends well beyond such an orderly expansion of our understanding of a theory's foundations. It is far more than a squabble over the most perspicacious way to reorganize postulate and theorem or to clarify brief moments of vagueness. The voices of dissent proclaim that Einstein was mistaken over the fundamental ideas of his own theory and that the basic principles Einstein proposed are simply incompatible with his theory. Many newer texts make no mention of the principles Einstein listed as fundamental to his theory; they appear as neither axiom nor theorem. At best, they are recalled as ideas of purely historical importance in the theory's formation. The very name `general relativity' is now routinely condemned as a misnomer and its use often zealously avoided in favour of, say, \Einstein's theory of gravitation". What has complicated an easy resolution of the debate are the alterations of Einstein's own position on the foundations of his theory. At di erent times of his life, he sought these foundations in three principles and with varying emphasis. They were the principle of equivalence, Mach's principle and the principle of relativity. By his own admission (Einstein 1918), he did not always distinguish clearly between the last two. Again, he lost completely his enthusiasm for Mach's principle, abandoning it unequivocally in his later life. The reception an development of Einstein's account in the literature has been anything but a graceful evolution. It has been more a process of uncontrolled mutation, fragmentation and even disintegration. The principle of equivalence took root in so many variant forms that Anderson and Gautreau (1969, p1656) eventually lamented that there are `almost as many formulations of the principle as there are authors writing about it.' This dissipation is at least partially fuelled by skeptical attacks on the principle such as Synge's (1960, p ix) famous complaint that he has never been able to nd a version of the principle that is not false or trivial. The locus of greatest controversy has been at the core of Einstein's interpretation, the principle of relativity. Does the general theory extend the principle of relativity to accelerated motion and is this extension captured by the general covariance of its laws? It is routinely allowed that the special theory of relativity satis es the principle of relativity of inertial motion simply because it is Lorentz covariant: its laws remain unchanged in form
General covariance and general relativity 795
under a Lorentz transformation of the space and time coordinates. Now Einstein's general theory is generally covariant: its laws remain unchanged under an arbitrary transformation of the spacetime coordinates. Does this formal property allow the theory to extend the relativity of motion to accelerated motion? Until recent decades, the majority of expositions of general relativity answered yes and some still do. As early as 1917, Kretschmann (1917) argued that general covariance has no real physical content and no connection to an extension of the principle of relativity. Rather, the nding a generally covariant formulation of a theory amounts essentially to a challenge to the mathematical ingenuity of the theorist. Skeptical sentiments such as these drove a dissident tradition that has grown from a minority in Kretschmann's time to one of the dominant traditions at present. It had derived further support from the development of more sophisticated mathematical techniques that are now routinely used to give generally covariant formulations of essentially all commonly discussed spacetime theories, including special relativity and Newtonian spacetime theory. Finally, to many, Einstein's statements of his views seemed too simple or abbreviated to stand without further elaboration or repair; whereas their at rejection by the skeptics seemed too easy. Thus much energy has been devoted to nding ways in which the general covariance of Einstein's theory can be seen to be distinctive even in comparison with the generally covariant formulatons of special relativity and Newtonian spacetime theory. The best developed of these attempts is due to Anderson (1967) and is based on the distinction of absolute from dynamical objects. General relativity satis es Anderson's `principle of general invariance' which entails that the theory can employ no non-trivial absolute objects. This principle is o ered as a clearer statement of Einstein's real intentions and as giving a precise interpretation of Einstein's repeated disavowal of the absolutes of Newton's space and time. The purpose of this article is to review the development of Einstein's views on general covariance, their relation to the foundations of general relativity and the evolution of the continuing debate that sprang up around these views. Section 2 and 3 will review the development of Einstein's views. Section 4 will outline the ways in which attempts were made to receive and assimilate Einstein's views in a favourable manner. Section 5 will review Kretschmann's famous objection, Einstein's response and the diverse ways in which both were received in the literature. It includes discussion of modern geometrical methods that ensure automatic general covariance. Section 6 reviews the development of the characterization of a relativity principle as a symmetry principle rather than a covariance principle. Section 7 explores the tradition of exposition of general relativity that simply ignores the entire debate and makes no mention of principles of general relativity and of general covariance. Section 8 develops Anderson's theory of absolute and dynamical objects as it relates to Einstein's views. Section 9 examines Fock's and Arzelies proposals for alterations to the covariance of general relativity and gives an historical explanation of why so many of Einstein's pronouncements on coordinates and covariance are puzzling to modern readers. In the time period covered in this review article, the mathematical methods used in relativity theory evolved from a coordinate based calculus of tensors to a coordinate free, geometric approach. The mathematical language and sensibilities used in various stages of the article will match those of the particular subject under review. The alternative of translating everything into a single language would harmfully distort the subject (see section 9.2).
796 J D Norton
2. The background of special relativity
2.1. Lorentz covariance and the relativity of inertial motion
Einstein's (1905) celebrated paper on special relativity brought the notion of the covariance of a theory to prominence in physics and introduced a theme that would come to dominate Einstein's work in relativity theory. The project of the paper was to restore the principle of relativity of inertial motion to electrodynamics. In its then current state, the theory distinguished a preferred frame of rest, although that frame had eluded all experiment and even failed to appear in the observational consequences of electrodynamics itself. Einstein's renowned solution was not to modify electrodynamics, but the background space and time itself. He devised a theory in which inertial frames of reference were related by the Lorentz transformation. If an inertial frame has Cartesian spatial coordinates (x; y; z) and time t and a second frame moving at velocity v in the x direction has spatial coordinates (; ; ) and time coordinate  , then, under the Lorentz transformation,
 = (x t)  = (t vx=c2)  = y  = z (1)
where = (1 v2=c2) 1=2 and c is the speed of light. Hitherto classical theory had in e ect employed what was shortly called (by, for example, Laue (1911, p3)) the Galileitransformation.
 = x t)  = t  = y  = z
Selecting suitable transformation laws for the eld and other quantities, Einstein was able to show that the laws of electrodynamics remained unchanged under the Lorentz transformation. That is, they were Lorentz covariant. Therefore, within the space and time of special relativity, electrodynamics could no longer pick out any inertial frame of reference as preferred. Each inertial frame was fully equivalent within the laws of the theory. Anything said about one by the laws of electrodynamics must also be said of all the rest. Electrodynamics was now compatible with the relativity of inertial motion. With the example of electrodynamics as its paradigm, the task of constructing a special relativistic version of a physical theory reduced essentially to formulating its laws in such a way that they remained unchanged under Lorentz transformation. Thus Einstein's (1905, section 10) original paper proceeded to formulate a modi ed mechanics for slowly accelerated electrons with this property. Thermodynamics soon also received some of its earliest relativistic reformulations in the same manner (see Einstein 1907, part IV, for example). The lesson of Einstein's 1905 paper was simple and clear. To construct a physical theory that satis ed the principle of relativity of inertial motion, it was sucient to ensure that it had a particular formal property: its laws must be Lorentz covariant. Lorentz covariance became synonymous with satisfaction of the principle of relativity of inertial motion and the whole theory itself, as Einstein (1940,p329) later declared: The content of the restricted relativity theory can accordingly be summarized in one sentence: all natural laws must be so conditioned that they are covariant with respect to Lorentz transformations.
2.2. Minkowski's introduction of geometrical methods
In Einstein's hands, Lorentz covariance was a purely algebraic property. Space and time coordinates were, in e ect, variables that transformed according to certain formulae. Hermann Minkowski (1908, 1909) was responsible for introducing geometric methods and thinking into relativity theory. He explained the background to his approach in his more
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popular (1909) lecture. It amounted to an inspired but essentially straightforward application of then current ideas in geometry. Minkowski's colleague at Gottingen, Felix Klein, had brought a fertile order to the world of 19th century geometry. That world was beginning to fragment after the discovery that geometry did not have to be Euclidean. In his famous Erlangen program, Klein (1872) proposed categorizing the new geometries by their characteristic groups of transformations. Euclidean geometry, for example, was characterized by the group of rotations, translations and re ections. The entities of the geometry were the invariants of these transformations. Minkowski pointed out that geometers had concentrated on the characteristic transformations of space. But they had ignored the groups of transformations associated with mechanics, those that connected various inertial states of motion. Minkowski proceeded to treat these groups in exactly the same way as the geometric groups. In particular he constructed the geometry associated with the Lorentz transformation. To begin, it was not the geometry of a space, but of a spacetime, and the notion of spacetime was introduced into physics almost as a perfunctory by-product of the Erlangen program. Moreover he found the spacetime had the hyperbolic structure now associated with a Minkowski spacetime. From this geometric perspective, the formulation of a theory that satis ed the principle of relativity became trivial. One merely needed to formulate the theory in terms of the geometric entities of the spacetime|in e ect the various types of spacetime vectors Minkowski had de ned|and the theory would be automatically Lorentz covariant. Thus Minkowski (1908, appendix;1908, section V) could write down the principle of relativity, for the theory was constructed purely geometrically. Thus, in his exposition of four-dimensional vector algebra and analysis, Sommerfeld (1910,749) could state: According to Minkowski, as is well known, one can formulate the content of the principle of relativity as: only spacetime vectors may appear in physical equations. . .
2.3. Covariance versus invariance in special relativity
The di erence between Einstein and Minkowski's approach to the same theory and even the same formalism is a polarity that will persist in various manifestations throughout the whole development of relativity theory, both special and general. Einstein's emphasis is on the algebraic properties of the theory, the equations that express its laws and their behaviour under transformation, its covariance. Thus the satisfaction of the principle of relativity is established by often arduous algebraic manipulation. The equations of the theory are transformed under the Lorentz transformation and the resulting equations are shown to have preserved their form. Minkowski's emphasis is on the geometric properties of the theory, on those geometric entities which remain unchanged behind the transformations, its invariance. Thus Minkowski ensures satisfaction of the principle of relativity by quite di erent means. The only structures allowed in constructing a theory are spacetime invariants. This restriction ensures compatibility with the principle of relativity and that its satisfaction can be settled by inspection.
3. Einstein's development of general relativity
While it may have been some years in preparation, the special theory of relativity coalesced into its nal form quite suddenly so that Einstein's rst paper on the theory remains one of its classic expositions. The development of general relativity was far slower and more tangled. Eight years elapsed between the inception and completion of the theory, during which time Einstein published repeated reports on the intermediate phases, false turns and unproven expectations. Even after the completion of the theory Einstein's account of its
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foundations continued to evolve. The modern image of Einstein's view of the foundations of general relativity is drawn fairly haphazardly from pronouncements that were made at di ering times in this evolution. As a result they are not always compatible. Indeed the pronouncements were sometimes as much expressions of results anticipated as demonstrated. For this reason, it would be misleading to construct any single edi ce and proclaim it Einstein's account of the foundations of general relativity. Rather we shall have to trace the evolution of Einstein's views as they were elaborated and modi ed in pace with the development of the theory. In developing general relativity, Einstein sought to satisfy many requirements. However we shall see that his e orts were dominated by a single theme, covariance, and they reduced essentially to an enduring task, expanding the covariance of relativity theory beyond Lorentz covariance.
3.1. The early years 1907{1912: principle of equivalence and the relativity of inertia
Two years after his completion of the special theory, Einstein began developing ideas that would ultimately lead him to the general theory of relativity. In a nal speculative section of a 1907 review article on relativity theory, he raised the question of whether the principle of relativity could be extended to accelerated motion (Einstein 1907, part V). The question was immediately understood as asking whether he could expand the covariance group of relativity theory. Feeling unable to tackle the general question, Einstein considered the simple case of a transformation from an inertial reference frame of special relativity to a reference frame in uniform rectilinear acceleration. In the accelerated frame of reference a homogeneous inertial eld arises. Because of the key empirical fact the the equality of inertial and gravitational mass, Einstein was able to identify this eld as a gravitational eld. He then made the postulate that would dominate the early years of his work on gravitation. In the wording of Einstein (1911, section 1) . . . we assume that the systems K [inertial system in a homogeneous gravitational eld] and K0 [uniformly accelerated system in gravitation free space] are exactly equivalent, that is, . . . we assume that we may just as well regard the system K as being in space free from gravitational elds, if we then regard K as uniformly accelerated. This assumption soon acquired the name `hypothesis of equivalence' (Einstein 1912a, p355) and then `principle of equivalence' (Einstein 1912b, p443). Through it, Einstein generated a novel theory of static gravitational elds (Einstein 1907, part V, 1911,1912a,b). In it, the now variable speed of light played the role of the gravitational potential; light from a heavy body such as the sun would be red shifted; and light grazing a heavy body such as the sun would be de ected. For our purposes, the important point is that Einstein saw in the principle an extension of the principle of relativity. Continuing the above passage he observed: This assumption of exact physical equivalence makes it impossible for us to speak of the absolute acceleration of the system of reference, just as the usual theory of relativity forbids us to talk of the absolute velocity of a system. . . The principle of equivalence formed just one part of Einstein's assault on the problem of extending the principle of relativity. He had also to answer the more general worry that acceleration seemed distinguishable from inertial motion by observable consequences, whereas no such consequences enable us to distinguish inertial motion from rest. Newton had driven home the point in the Scholium to the De nitions of Book 1 of his Principia (1687). He noted that the absolute of rotation of water in a bucket was revealed by the observable curvature of the water's surface. The inertia of the water was responsible for this e ect, leading it to recede from the axis of rotation.
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Einstein found his answer to Newton in his reading of Ernst Mach. Mach (1893,p284) pointed out that all that was revealed in Newton's bucket thought experiment was correlation between the curvature of the water and its rotation with respect to the Earth and other celestial bodies. Thus Einstein (1912c) was delighted to report his 1912 theory entailed certain weak eld e ects that promised to convert this correlation into a physical interaction, with the rotation of the stars with respect to the water directly causing the curvature of its surface. He found that the inertia of a test mass is increased if it is surrounded by a shell of inertial masses and that, if these same masses are accelerated, they tend to drag the test mass with it. These results raised the possibility of an idea which he attributed (p39) directly to Mach: . . . the entire inertia of a point mass is an interaction with the presence of all the remaining masses and based on a kind of interaction with them. Einstein (1913,p1261) soon called this idea the `hypothesis of the relativity of inertia.' Clearly if a theory could be found that implemented this hypothesis, Einstein would have succeeded in generalizing the principle of relativity to acceleration. For, in such a theory, the preferred set of inertial frames would cease to be an absolute feature of the background space and time; the disposition of inertial frames of reference would merely be an accident of the overall distribution of matter in the universe. However, by the middle of 1912, Einstein was still far from such a theory. In concluding his response to a polemical assault by Max Abraham, Einstein (1912d, pp1063{4) described his project in terms of the expansion of the covariance of the current theory of relativity and his hope that `the equations of theory of relativity that also embraced gravitation would be invariant with respect to acceleration (and rotation) transformations.' however he confessed that `it still cannot be foreseen what form the general spacetime transformation equations could have.' The Einstein who wrote these words in July 1912 had not yet foreseen that his name would be irrevocably associated with a generally covariant theory.
3.2. The `Entwurf' theory 1912{1915: general covariance gained and lost
All this changed with Einstein's move to Zurich in August 1912. There he began collaborating with the mathematician Marcel Grossmann, a good friend from his student days. Grossman discovered for Einstein the existence of the `absolute di erential calculus' 1 of Ricci and Levi-Civita (1901) and pointed out that this calculus would enable Einstein to construct a generally covariant theory. The focus of this calculus was the fundamental quadratic di erential form
'=
Xn
r;s=1
arsdxrdxs (2)
which was assumed to remain invariant under arbitrary transformations of the variables x1; : : : ; xn. Of course the modern reader immediately associates this form with the invariant line element of a non-Euclidean surface of variable curvature, such as was introduced by Gauss and developed by Riemann. However, Ricci and Levi-Civita's x1; : : : ; xn were variables and not necessarily geometric coordinates. They were at pains to emphasize that what was then called in nitesimal geometry was just one of many possible applications of their calculus.
1The Ricci-Levi-Civita calculus only later acquired its modern name of `tensor calculus' after Einstein and Grossman (1913) renamed all of Ricci and Levi-Civita's `contravariant and covariant systems' as `tensors' thereby extending the formerly rather restricted compass of the term `tensor.' See Norton (1992, appendix).
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As late as 1912, Einstein had not adopted the four-dimensional methods of Minkowski, even though these methods had already found their rst text book exposition (Laue 1911). Einstein's 1912 static gravitational theory had been developed using essentially the same mathematical techniques as his 1905 special relativity paper. Thus it is an odd quirk of history that, when Einstein did nally immerse himself in the four-dimensional spacetime approach, he turned to exploit a calculus whose creators sought to skirt its geometric interpretation in favour of a broader interpretation. Einstein and Grossmann published the results of their joint research early the following year with Einstein writing the `Physical Part' and Grossmann the `Mathematical part.' The theory of the resulting paper (Einstein and Grossmann 1913) is commonly known as the `Entwurf ' theory for the title of the paper. `Entwurf einer verallgemeinerten Relativitatstheorie und einer Theorie der Gravitation' (`outline of a generalized theory of relativity and a theory of gravitation'). Its central idea involved the introduction of Ricci and Levi-Civita's fundamental form (2). They started with the invariant interval of Minkowski in di erential form
ds2 = c2dt2 dx2 dy2 dz2 (3)
where (x; y; z; t) are the space and time coordinates of an inertial frame of reference in a Minkowski spacetime. Transforming to arbitrary coordinates x for  = 1; : : : ; 4 (3)
becomes 2
ds2 = g dxdx : (4)
Einstein employed his principle of equivalence to interpret the matrix of quantities guv that had arisen with the introduction of arbitrary coordinates. In the special case of the principle, the transformation from (3) to (4) is from an inertial coordinate system to a uniformly accelerated coordinate system. In that case, the matrix of coecients g
reduces to that of (3), except that c now is a function of the coordinates (x0; y0; z0). That is, (4) becomes
ds2 = c2(x0; y0; z0)dt2 dx02 dy02 dz02: (30)
According to the principle of equivalence, the presence of a gravitational eld was the only di erence between the spacetime of (3') and that of special relativity (3). Therefore Einstein interpreted the coordinate dependent c of (3') as representing a gravitational eld and, more generally, the g of (4) as representing a gravitational eld. Einstein and Grossmann proceeded to develop essentially all the major components of the nal general theory of relativity. Just one eluded them. The spacetimes represented by (3), (3') and (4) are all at. To treat the general case of the gravitational eld, non- at metrics must also be admitted and, in the nal theory, the decision of which are admitted is made by the gravitational eld equations. Einstein expected these equations to take the now familiar form
G = T (5)
where T is the stress-energy tensor and G a gravitation tensor constructed solely from the metric tensor g and its derivatives. Einstein and Grossmann considered the Ricci tensor as the gravitation tensor|just a hair's breath away from Einstein's nal choice of the Einstein tensor. However they reported that the resulting eld equations failed to give
2Henceforth summation over repeated indices is implied. Einstein himself did not introduce this summation convention until 1916.
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the Newtonian limit in the case of weak, static gravitational elds. In their place, to the astonishment of modern readers, they o ered a set of gravitational eld equations that was not generally covariant. Einstein then descended into a long struggle with his imperfect theory that lasted almost three intense years before he emerged victoriously with the nal generally covariant theory in hand.3
3.3. The hole argument: general covariance condemned
During these three years, Einstein formulated an argument that would decisively redirect his understanding of general covariance. He and Grossmann had been unable to nd acceptable generally covariant eld equations. The so-called `hole argument' purported to show that this circumstance need not worry them since all generally covariant eld equations would be physically uninteresting. Einstein published the argument four times in 1914, appearing, for example, as a later appendix to the journal printing of Einstein and Grossmann (1913). Its clearest exposition was in a review article (Einstein 1914, pp1066{7).4 The argument was beguilingly simple. Einstein asked us to imagine a region of spacetime devoid of matter|the `hole'|in which the stress energy tensor T vanished. He now assumed that we had generally covariant gravitational eld equations and that g was a solution for this spacetime in a coordinate system x . Einstein transformed to a new coor
dinate system x0 , which agreed with x outside the hole but came smoothly to di er from
it within the hole. In the new coordinate system the metric would be g0 and constructed according to the usual tensor transformation law. That is, the same gravitational eld would be represented by g in coordinate system x , and by g0 in coordinate system x0 . At this point Einstein e ected a subtle manipulation that is the key to the hole argument. One could consider the symmetric matrix g(x ) as a set of ten functions of the
variable x and g0(x0 ) as a set of ten functions of the variable x0 . One can now construct
a new set of ten functions g0(x ). That is, take the ten functions of the new matrix g0 and consider them as functions of the old coordinates x . The original g(x ) and the
construction g0(x ) cannot represent the same gravitational eld in di erent coordinate systems. They are both de ned on the same coordinate system x , yet they have di er
ent components, since g and g0 are di erent functions. That is, g(x ) and g0(x ) represent di erent gravitational elds in the same coordinate system. Now, by their construction, the functions g(x ) and g0(x ) will be the same outside the hole, but they will come smoothly to di er within the hole. Thus the two sets of functions represent distinct gravitational elds. Let us call them g and g0. The elds g and g0 are the same outside the hole but come smoothly to di er within the hole.
3This fascinating episode has been dissected in some detail with some help from his private calculation (see Stachel 1980 and Norton 1984). 4For further discussion see Norton (1987).
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Einstein has presumed the eld equations general covariant. Therefore, if they are solved by the g(x ), then they must be solved by g0(x0 ) and therefore also by the
construction g0(x ). That is, generally covariant gravitational eld equations allow as
solutions the two distinct gravitational elds g and g0. Einstein found this outcome unacceptable. For the one matter distribution outside the hole now clearly fails to determine what the gravitational eld would be within the hole. That is, we could specify the matter distribution and gravitational eld everywhere in spacetime excepting some matter-free hole that could be arbitrarily small in both spatial and temporal extent. Nonetheless generally covariant eld equations would be unable to determine what the gravitational eld would be within this hole. This was a dramatic failure of what he called the law of causality and we might now call determinism. Einstein deemed the failure suciently troublesome to warrant rejection of generally covariant gravitational eld equations as physically interesting.5
3.4. Einstein's 1916 account of the foundations of general relativity: general covariance regained
In November 1915, Einstein's long struggle with his `Entwurf' theory came to a close. His resistance to general covariance nally broke under the accumulating weight of serious problems in his `Entwurf' theory. His return to general covariance and the nal general theory of relativity were reported to the Prussian Academy in a series of hasty communications that chronicle the tense confusions of these last desperate days.6 Early the following year, Einstein (1916) sent Annalen der Physik a review article on the nal theory. The article's account of the theory's foundations was written with a freedom unavailable to Einstein in the dark years of the `Entwurf' theory. Thoughout those years, Einstein had maintained his allegiance to the relativity of inertia. That allegiance had to rest principally on a sincere hope of what might be demonstrable. He had not demonstrated the unconditional relativity of inertia in his `Entwurf' theory; he was still sure only of weak eld e ects compatible with the relativity of inertia (Einstein 1913, section 9) and similar to those he had found in his 1912 theory. More vexing, however, was the very public failure of general covariance, which compromised the claim that he was extending the principle of relativity. Einstein did not report on equally serious problems that had befallen the principle of equivalence. The simple 1907/1911 version of the principle required only equivalence of uniform acceleration and a homogeneous gravitational eld. Yet in the nal version of the 1912 theory, the principle had to be restricted to in nitesimally small regions of space. Einstein found the need for this restriction extremely puzzling since the restriction was not invoked to homogenize an inhomogeneous eld. Worse, in the `Entwurf' theory, even this restriction failed to save this form of the principle, which had to be reported as a result of his earlier 1912 theory (see Norton (1985, section 4.3) for a discussion). By 1916, Einstein's problem with general covariance had evaporated and with them the problems with the principle of equivalence. Thus the 1916 review article could commence with a more con dent account of the theory's foundations which remains today one of
5It was pointed out much later by Stachel (1980), using mathematical notions not available to Einstein in 1913, that the new gravitational eld g0 was generated from g as the carry along g0 = hg under the di eomorphism h induced by the coordinate transformation x , to x0 . The indeterminism that worried Einstein so profoundly is now routinely obliterated as a gauge freedom associated with arbitrary di eomorphism so that, while g and g0 may be mathematically distinct, they are not judged to represent physically distinct gravitational elds (see Wald 1984, p438). 6Einstein 1915. For disscussion of this episode, see Norton (1984, sections 7,8).
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the most widely known of Einstein's accounts. The exposition began with a series of now familiar considerations all of which drove towards general covariance. Both special relativity and classical mechanics, Einstein reported, su ered an epistemological defect. It was illustrated with Einstein's variant of Newton's bucket. Two uid bodies hover in space. They are in an observable state of constant relative rotation about a line that connects them. In spite of the obvious symmetry of this setup, Einstein supposed that one sphere S1 proves to be spherical when surveyed and the other S2 proves to be an ellipsoid of revolution. Classical mechanics and special relativity could explain the di erence by supposing that the rst sphere is at rest in an inertial frame of reference, introduced by Einstein into the argument as a `privileged Galilean space,' and that the second is not. This explanation, Einstein objected, violates the `demand of causality', for these privileged frames are `merely factitious causes' and not an observable thing. The true cause of the di erence must lie outside the system, Einstein continued, immediately identifying the true cause in the disposition of distant masses. In e ect Einstein used his example to conclude that the only theory that could satisfactorily account for this example was one that satis ed the requirement of the relativity of inertia. Any such theory, Einstein continued, cannot single out any inertial frame as preferred. Therefore: The laws of physics must be of such a nature that they apply to systems of reference in any kind of motion. along this road we arrive at an extension of the postulate of relativity. (Einstein's emphasis) Einstein then introduced the principle of equivalence in the form given above in section 3.1 in which it asserts the equivalence of uniform acceleration and a homogeneous gravitational eld. The principle is used to suggest that a theory which implements a generalized principle of relativity will also be a theory of gravitation. Einstein then turns to deal with a complication that arises from using accelerated frames of reference in special relativity. In accelerated frames, in particular in rotating frames, geometry ceases to be Euclidean and clocks are slowed in a position-dependent manner. As a result it turns out that one can no longer easily de ne space and time coordinate systems by the familiar operations of laying out rods and using standard clocks. This apparent complication|and not the need for a generalization of the principle of relativity|leads Einstein to propose general
covariance:7
The method hitherto employed for laying coordinates into the space-time continuum in a de nite manner thus breaks down, and there seems to be no other way which would allow us to adapt systems of coordinates to the four-dimensional universe so that we might expect from their application a particularly simple formulation of the laws of nature. So there is nothing for it but to regard all imaginable systems of coordinates, on principle, as equally suitable for the description of nature. This comes to requiring that: The general laws of nature are to be expressed by equations which hold good for all systems of coordinates, that is, are co-variant with respect to any substitutions whatever (generally covariant). It is clear that a physics theory which satis es this postulate will also be suitable for the general postulate of relativity. For the sum of all substitutions in any case includes the those which correspond to all relative motions of three-dimensional systems of coordinates (Einstein's emphasis)
7A footnote at the word `imaginable' was omitted from the standard Perrett and Je ery English translation. It says: `Here we do not want to discuss certain restrictions which correspond to the requirement of unique coordination and of continuity.' This now essentially unknown footnote shows that Einstein did at least once apologize for his failure to specify precisely which group of transformations was intended by `any substitutions whatever.'
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Why did Einstein not simply insist that the generalization of the principle of relativity to accelerated motion forces general covariance? Following the analogy with Lorentz covariance, the generalized principle of relativity would require an extension of the covariance of the theory to include transformations between frames in arbitrary states of motion. But general covariance extends it even further. It includes transformations that have nothing to do with changes of states of motion, such as the transformation between Cartesian and polar spatial coordinates. But, as Einstein indicates, he feels compelled to go to this larger group since he can see no natural way of restricting the spacetime coordinate system.
3.5. The point-coincidence argument
Immediately following the above statement of the requirement of general covariance, Einstein gave another argument for general covariance which John Stachel has conveniently labelled the `point-coincidence argument'. That this requirement of general co-variance, which takes away from space and time the last remnant of physical objectivity, is a natural one, will be seen from the following re exion. All our space-time veri cations invariably amount to a determination of space-time coincidences. If, for example, events consisted merely in the motion of material points, then ultimately nothing would be observable but the meetings of two or more of these points. Moreover, the results of our measurings are nothing but veri cations of such meetings of the material points of our measuring instruments with other material points, coincidences between the hands of a clock and points on the clock dial, and observed point-events happening at the same place and the same time. The introduction of a system of reference serves no other purpose than to facilitate the description of the totality of such coincidences. We allot to the universe four space-time variables, x1, x2, x3, x4 in such a way that for every point there is a corresponding system of values of the variables x1 . . . x4. To two coincident point events there corresponds one system of values of the variables x1 . . . x4 i.e. coincidence is characterized by the identity of the co-ordinates. If, in the place of the variables x1
. . . x4, we introduce functions of them, x01, x02, x03, x04, as a new system of co-ordinates, so that the system of values are made to correspond to one another without ambiguity, the equality of all four co-ordinates in the new system will also serve as an expression for the space-time coincidence of the two point-events. As all our physical experience can be ultimately reduced to such coincidences, there is no immediate reason for preferring certain systems of co-ordinates to others, that is to say, we arrive at the requirement of general co-variance.
This point-coincidence argument is cited very frequently in the literature since 1916. However its real purpose was essentially completely forgotten until it was rediscovered and revealed by John Stachel (1980). Einstein's 1916 exposition of general relativity contained a very puzzling omission. In the years immediately preceding, by means of the hole argument, Einstein had apparently proved that any generally covariant theory would be physically uninteresting. Yet there was Einstein extolling exactly such a theory without explaining where the hole argument went astray.
That melancholy task of correcting his past error was the real function of the pointcoincidence argument. This was precisely the use to which the argument was put in Einstein's correspondence of December 1915 and January 1916 (see Norton 1987, section 4). According to Einstein's assumption, the physical content of a theory is fully exhausted by a catalogue of the spacetime coincidences it sanctions. Therefore any transformation that preserves these coincidences preserves its physical content. Now the transformation used in the hole argument from the eld g to the mathematically distinct eld g0 is more than a
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mere transformation of coordinates. For g and g0 are mathematically distinct elds in the same coordinate system. However the transformation from g to g0 is one that preserves all coincidences. Therefore g and g0 represent the same physical eld. Whatever indeterminism is revealed in the hole argument is a purely mathematical freedom akin to a gauge freedom and o ers no obstacle to the physical interest of a generally covariant theory. Einstein scarcely ever mentioned the debacle of the hole argument again in print. However it continued to inform his ideas about covariance, spacetime, eld and coordinate systems. For example, in executing the hole argument, in order to e ect the transition from g(x ) to g0(x ), one has to assume, in e ect, that the coordinate system x , has
some real existence, independent of the g or g0. For, guratively speaking, one has to remove the eld g, leaving the bare coordinate system x , and then insert the new
eld g0. In a letter of December 26, 1915, to Paul Ehrenfest, Einstein explained that one defeats the hole argument by assuming among other things that `the reference system signi es nothing real'.8 We hear these echoes of the hole argument when Einstein (1922,p21) proclaims in a May 1920 address in Leiden: There can be no space nor any part of space without gravitational potentials; for these confer upon space its metrical qualities, without which it cannot be imagined at all. These same echoes still reverberate in the 1952 appendix to Einstein's popular text Relativity: the Special and the General Theory, when Einstein (1952,p155) insists . . . a pure gravitational eld might have been described in terms of the gik (as functions of the co-ordinates), by solution of the gravitational equations. If we imagine the gravitational eld, i.e. the functions gik, to be removed, there does not remain a space of the type (1) [Minkowski spacetime], but absolutely nothing, and also no `topological space' (Einstein's emphasis). Most recently, the hole argument has enjoyed a revival in the philosophy of space and time literature where, in variant form, it provides a strong argument against the doctrine of spacetime substantivalism (Earman and Norton 1987). For further discussion of the background an rami cations of the hole and point-coincidence arguments see Howard (1992) and Ryckman (1992).
3.6. The Gottingen defense of general covariance
The most prominent legacy of the hole argument in the literature on general relativity does not arise from Einstein's analysis, however. In 1915 and 1917 David Hilbert (1915, 1917) published a two-part paper on general relativity which proved to be enormously in uential. Citing the hole argument, Hilbert (1917,pp59{63) turned to the question of the `principle of causality'. He observed that his formulation of general relativity employed fourteen independent variables, that is, ten metrical components for the gravitational eld and four potentials for the electromagnetic eld. However in the joint theory of gravitational and electromagnetic elds, four identities reduced the fourteen eld equations to only ten independent equations. These four conditions could, however, be absorbed in four stipulations used to specify a coordinate system. Hilbert insisted that his underdetermination of the eld was not physical. Echoing the geometric themes of his Gottingen colleagues Klein and the late Minkowski, he recalled (p61) `. . . an assertion that does not remain invariant under any arbitrary transformation of the coordinate system is marked as physically meaningless' (Hilbert's emphasis). He then argued that the four degrees of freedom did not leave the invariant content of the theory underdetermined. His example was an electron at rest in some coordinate system. A coordinate transformation leaves the electron unchanged in the past of some instant
8As quoted in Norton (1987,p 169).
806 J D Norton
speci ed by time coordinate x4 = 0, but sets it in motion in the future. The two coordinate descriptions are the same in the past, the electron is at rest, but in the future only one describes the electron as moving. The one past can extend to di erent futures. The di erences, however, have no physical signi cance, since the relevant assertions about the electron's motion are not invariant. One could make the invariant by introducing an invariant coordinate system adapted to the spacetime geometry, such as the Gaussian system Hilbert considered. Coordinate based assertions of the electron's motion would now be invariant, but they would no longer be underdetermined since the introduction of the Gaussian system used up the four remaining degrees of freedom. Hilbert's depiction of the indeterminism of a generally covariant theory was in terms of a count of independent eld variables and independent eld equations. It is the version that rapidly came to appear most often in the literature (e.g. Pauli 1921, section 56). The four identities among the eld equations that allowed the underdeterminism were only later connected with the contracted Bianchi identities (see Mehra 1974, section 7.3). Again Hilbert's discussion and his example of the electron was the rst treatment of the Cauchy problem in general relativity, so that the literature on the Cauchy problem can trace its descent back to Einstein's hole argument (see Stachel 1992).9
3.7. Einstein's three principles of 1918
In March 1918, Einstein (1918) returned to the question of the fundamental principles of general relativity. As he made clear in his introductory remarks, the paper was provoked by Kretschmann's (1917) criticism (see section 5.2 below). However its purpose was to lay out his understanding of the foundations of his theory. This exposition di ered from the 1916 account in at least one major area. In 1916, Einstein assumed that his generally covariant theory would satisfy the relativity of inertia, although no proof had been given. At best Einstein would have been able to point to weak eld e ects compatible with the relativity of inertia. (These weak eld e ects are of the same type as those he reported in the `Entwurf' theory of Einstein (1913, section 9) and are described in his text (Einstein 1922a, p100)). By 1917, Einstein had found that a simple reading of the relativity of inertia was incompatible with his theory. He reported his failure in an introductory section (section 2) to his famous paper on relativistic cosmology (Einstein 1917). On the basis of the relativity of inertia, he expected that the inertia of a body would approach zero if it was moved suciently far from other masses in the universe. This expectation would be realized in the theory if the spacetime metric adopted certain degenerate values at a mass-free spatial in nity. However Einstein found that such degenerate behaviour was inadmissible in his theory. Instead he seemed compelled to postulate some non-degenerate boundary conditions for the metric at a mass-free spatial in nity, such as Minkowskian values. This Minkowskian boundary condition became the embodiment for Einstein of the failure of the relativity of inertia. For this boundary condition made a de nite contribution to the inertia of a test body that could not be traced to other masses. That is, with these boundary condition, the inertia of a body was in uenced by the presence of other masses, in so far as they a ected the metric eld. However its inertia was not fully determined by the other masses. Therefore, if the relativity of inertia was to be satis ed, it was necessary to abolish these arbitrarily postulated boundary conditions. (The question of whether this was also sucient remained unaddressed.) Einstein succeeded in abolishing these boundary
9Howard and Norton (forthcoming) conjecture that there was an encounter in 1915 between the Gottingen resolution of the hole argument and an unreceptive Einstein, still convinced of the correctness of the hole argument.
General covariance and general relativity 807
conditions at spatial in nity by a most ingenious ploy: he abolished spatial in nity itself. He introduced the rst of the modern relativistic cosmologies, the one we now call the `Einstein universe', which is spatially closed and nite. The price Einstein had to pay turned out to be high. In order for his eld equations to admit the Einstein universe as a solution, he needed to introduce the extra `cosmological' term in his eld equations. In his notation and formulation of 1917, with G representing the Ricci tensor and  a constant, this meant that the old eld equations
G =  (T 1
2 g T )
were replaced by
G g =  (T 1
2 g T )
The cosmological term is g and  is the cosmological constant. This development was essential background to understanding the three principles Einstein listed in (Einstein 1918,pp241{2) as those on which his theory rested. (a) Principle of relativity. The laws of nature are only assertions of timespace coincidences; therefore they nd their unique, natural expression in generally covariant equations. (b) Principle of equivalence. Inertia and weight are identical in essence. From this and from the results of the special theory of relativity, it follows necessarily that the symmetric `fundamental tensor' (g) determines the metric properties of space, the inertial relations of bodies in it, as well as gravitational e ects. We will call the condition of space, described by the fundamental tensor, the `G- eld.' (c) Mach's principle. the G- eld is determined without residue by the masses of bodies. Since mass and energy are equivalent according to the results of the special theory of relativity and since energy is described formally by the symmetric energy tensor (T), this means that the G- eld is conditioned and determined by the energy tensor. The separation of the principle of relativity and Mach's principle into two distinct principles was clearly the product of Einstein's experience with the cosmological problem. If the Einstein of 1916 had assumed that the relativity of inertia would be satis ed automatically within a generally covariant theory, then the Einstein of 1918 no longer harboured such delusions. The 1918 version of the principle of relativity seems to assert something less than a fully generalized relativity of the motion of bodies. In e ect it merely asserts the key thesis of the point-coincidence argument: the physical content of a theory is exhausted by its catalogue of allowed spacetime coincidences. General covariance follows from this thesis as a consequence. The principle of relativity (a) is now supplemented by the new Mach's principle (c) and it is only their conjunction that begins to resemble Einstein's original goal of a fully generalized relativity of motion. In e ect Mach's principle (c) was intended to capture in a eld theoretic setting the old, Mach-inspired conditions for the metric eld at spatial in nity, which, Einstein reported in 1917, compromised the relativity of inertia. All this was alluded to by Einstein in a footnote to the title `Mach's principle', which also announced that he was introducing the name for the rst time:
808 J D Norton
Up to now I have not distinguished principles (a) and (c) and that caused confusion. I have chosen the name `Mach's principle' since this principle is a generalization of Mach's requirement that inertia be reducible to an interaction of bodies. Einstein's wording of the principle of equivalence (b) was an interesting departure in so far as it now emphasized that the principle depended on the empirical equality of two quantities, inertial and gravitational mass, and that the e ect of the principle had been to unify them completely. However there was little real change from Einstein's earlier use of the principle, as was shown by the remainder of the paragraph that described the principle. In e ect it gave a synopsis of the transition form the line element (3) to (3') and (4) and the resulting interpretation of the non-constant coecients of (3') and (4) as representing the gravitational eld, as well as the inertial and geometric properties of spacetime.
3.8. Mach's principle forsaken
For all his e orts, Einstein's portrayal of the foundations of general relativity had still not reached its nal form with the 1918 list. Over the years following, the principle of relativity and of equivalence retained their 1918 forms. However Einstein came to abandon Mach's principle. The seeds of Einstein's disenchantment with Mach's principle were becoming apparent as early as 1919. Einstein (1919, section 1) described its o spring, the cosmological term added to his 1915 eld equations, as `gravely detrimental to the formal beauty of the theory'. With the discovery of the expansion of the universe, Einstein formally disowed the cosmological term (Einstein and de Sitter 1932). In any case, the augmentation of his eld equations with the cosmological term had forced neither the relativity of inertia nor Mach's principle into his theory, for it had not eliminated the possibility of essentially matter-free solutions of the eld equations. In such solutions, the inertia of a test body could not be attributed to other masses. These solutions were the subject of an extended exchange in publication an in private between Einstein and de Sitter towards the end of the 1910s (See Kerzberg 1989). Einstein also began to distance himself from the relativity of inertia. Whereas the idea was urged without reservation up to 1916, he soon came to describe it as a very signi cant idea, but one of essentially historical interest only. For example, Einstein (1924, p87) attributed to Mach the idea that inertia arose as an unmediated interaction between masses. But he dismissed it casually as `logically possible, but cannot be considered seriously any more today by us since it is an action-at-a-distance theory'.10 Einstein (1924, p90) did still maintain that the metric is fully determined by ponderable masses in a spatially nite cosmology according to his theory, although the term `Mach's principle' was not used. As time passed, Einstein had fewer and fewer kind words for this Machian approach to inertia. He explained in 1946 for example in his Autobiographical notes (1949, p27) Mach conjectures that, in a truly reasonable theory, inertia would have to depend upon the interaction of the masses, precisely as was true for Newton's other forces, a conception that for a long time I considered in principle the correct one. It presupposes implicitly, however, that the basic theory should be of the general type of Newton's mechanics: masses and their interaction as the original concepts. Such an attempt at a resolution does not t into a consistent eld theory, as will be immediately recognized. His 1918 Mach's Principle had been an attempt to translate this requirement on masses and their interactions into eld theoretic terms, but he soon seemed to lose enthusiasm even for this enterprise. The diculty was that the 1918 principle required that the metric eld g be determined by the masses of bodies as represented by the stress-energy tensor
10The same point is made less forcefully in Einstein (1922, pp17{18) and Einstein (1922a, p56)
General covariance and general relativity 809
T. However this gave a primary determining function to a quantity, T, which Einstein (1949, p71) reported he had always felt was `a formal condensation of all things whose comprehension in the sense of a eld theory is still problematic' and one that was `merely a makeshift'. Einstein gave a nal synopsis of Mach's principle in a letter of February 2, 1954 to Felix Pirani in the year prior to his death. Citing the above diculty with the stress-energy tensor and the fact that this tensor presumes the metric, he labeled his 1918 version of Mach's principle `a ticklish a air' and concluded `In my opinion we ought not to speak about Mach's principle any more.'11
3.9. Einstein's causal objection to absolutes
When Einstein disowed the relativity of inertia and Mach's principle, he actually disowed somewhat less than it rst seemed. Both these principles were introduced to solve a problem in earlier theories of space and time: these theories were defective in the way they used inertial systems as causes. Einstein still clearly maintained that the problem was serious and that his general theory of relativity had solved it. However he had originally thought the solution was best expressed in terms inspired by his reading of Mach; that is, as a generalized relativity of the motion of bodies. As he put it in Einstein (1913, p1260) To talk of the motion and therefore also acceleration of a body A in itself has no meaning. One can only speak of the motion or acceleration of a body relative to other bodies B, C etc. What holds in kinematic relation of acceleration ought also to hold for the inertial resistance, with which bodies oppose acceleration . . . He was led away from this Machian characterization of the solution by his work on Mach's principle and the cosmological problem, as well as his preference for eld rather than body as a primitive notion. We shall see that his mature characterization of the solution was that general relativity allowed space and time to be mutable. They no longer just acted causally, they could also be acted upon and, in this sense, had lost their absolute character. In Einstein's mature view, it is this special causal property that distinguishes general relativity from earlier theories and possibly even justi es the name `general relativity', in so far as it is the eld theoretic translation of Einstein's original notion of the generalized relativity of the motion of bodies. In the early years of Einstein's theory, the causal defect was located most prominently in the mere fact of the older theories' use of an inertial reference system as a cause. Thus in Einstein's 1916 review article, he sought to account for the centrifugal bulges in a rotating uid body (see section 3.4 above). To say that the body bulges because it rotated with respect to an inertial frame of reference is to introduce a `merely factitious cause, and not a thing that can be observed' (1916, p113). This same example is treated similarly in Einstein (1914a,pp344{6), Einstein (1917a) makes clear the sort of cause that he would nd acceptable in his popular exposition of relativity. In ch XXI he asks for the reason for the preferred status of inertial systems. He draws an analogy with two pans of water on a gas range. One is boiling, one is not. The di erence, Einstein insists, only becomes satisfactorily explained when we notice the bluish ame under the boiling pan and none under the other. Einstein soon came to stress a di erent aspect of these earlier theories as causally defective. He identi ed this aspect with their absolute character. In his Meaning of relativity (1922a, p55) he wrote in parody of Newton's Latin
11Translation from Torretti (1983, p202) with `dem Mach'schen Prinzip' rendered as `Mach's principle'.
810 J D Norton
. . . from the standpoint of the special theory of relativity we must say, continuum spatii et temporis est absolutum. In this latter statement absolutum means not only `physically real', but also `independent in its physical properties, having a physical e ect, but not itself in uenced by physical conditions'. And he continued to explain that such absolutes are objectionable since (pp55{6) . . . it is contrary to the mode of thinking in science to conceive of a thing (the spacetime continuum) which acts itself, but which is not acted upon. The text immediately turned to Mach's ideas and, later (pp99{108) to the weak eld e ects compatible with the relativity of inertia and his 1917 eld formulation of this idea in a spatially closed cosmology. Around the same time, Einstein's briefer summaries advertised general relativity as eliminating the absoluteness of space and time (Einstein 1972, p260):12 Space and time were thereby divested not of their reality but of their causal absoluteness|i.e.a ecting but not a ected. In these briefer summaries, Einstein was no longer insisting that the spacetime metric was to be fully determined by the distribution of masses. Space and time had lost their absoluteness simply because they were no longer immutable. By the 1950s, as Einstein explained to Pirani, he no longer endorsed his 1918 Mach's principle. However he did retain the idea that the earlier theories were causally defective in admitting such absolutes (e.g. Einstein 1950, p348) and, as he explained in the `completely revised' (p0) 1954 appendix to his Meaning of relativity (1922, p139{40), general relativity had resolved the problem as its essential achievement: It is the essential achievement of the general theory of relativity that it has freed physics from the necessity of introducing, the `inertial system' (or inertial systems). . . . Thereby [in earlier theories], space as such is assigned a role in the system of physics that distinguishes it from all other elements of physical description. It plays a determining role in all processes, without in its turn being in uenced by them. This view of the de ciency of earlier theories and general relativity's achievement is not one that grew in the wake of Einstein's disenchantment with Mach's principle. Rather, it was present even in his earliest writings beneath the concerns for the relative motion of bodies and the observability of causes. Einstein (1913, pp1260{1) makes the essential point: . . . in [theories current today], the inertial system is introduced; its state of motion, on the one hand, is not conditioned by the status of observable objects (and therefore caused by nothing accessible to perception) but, on the other hand, it is supposed to determine the relations of material points. A footnote earlier in the paragraph also tried to identify what was so unsatisfactory about inertial systems. What is unsatisfactory about this is that it remains unexplained how the inertial system can be singled from other systems. Thus we have here the enduring core of the cluster of ideas that led Einstein to the relativity of inertia and Mach's principle: his concern that, through their introduction of inertial systems, earlier theories allowed absolutes that acted but could not be acted upon. Finally, we may ask whether the `essential achievement' of general relativity, the elimination of the absolute inertial systems, follows automatically from general covariance in Einstein's view, so that general covariance would then truly amount to a generalized principle of relativity in a form adapted to a eld theory. It is hard to nd a clear answer in Einstein's writings. His 1918 catalogue of three principles suggested that the requirement of general covariance (`(a) principle of relativity') needed to be supplemented by something additional (`(c) Mach's principle') to realize fully the general relativity of motion.
12See also Einstein (1922, p18, 1924, p88).
General covariance and general relativity 811
Einstein's text suggests this without clearly stating it, for Einstein (1918, p241) introduces the three principles with the remark that they are `in any case in no way independent from each other'. This it is not clear whether these particular two of the three principles really are independent or, if they are not, whether general covariance somehow leads to Mach's principle. Perhaps the best answer we will nd is Einstein's repeated insistence that general covariance, in conjunction with the requirement of simplicity, leads us directly to general relativity (see, for example, Einstein (1952, pp 152{3, 1949, pp71{3, 1933, p274)). And it is this theory that eliminates the absoluteness of the inertial system.
4. The favourable text-book assimilation of Einstein's view: fragmentation and mutation
Although Einstein had to struggle to gain acceptance of this theory in its earliest years (especially prior to 1916), by 1920 Einstein's new theory was widely celebrated. The extravagant publicity surrounding the success of Eddington's 1919 eclipse expedition had even launched Einstein into the popular press and public eye. During this period, the vast majority of accounts of Einstein's theory merely sought to recapitulate Einstein's own account. Thus began the tradition of writing in what I call the favourable assimilation of Einstein's view and which is to be reviewed in this section. I shall consider an account of the foundations of general relativity favourable to Einstein's view if it names some or all of Einstein's three principles of 1918 as foundations of the theory: principle of relativity/covariance, principle of equivalence and Mach's principle; it must include at least the rst principle. Two things will become clear about the favourable reception of Einstein's account of the foundations of general relativity. First, it is very widespread and still a major tradition today. Second, what is often o ered as a recapitulation of Einstein's account|even if only tacitly|can di er in very signi cant ways from what Einstein really said. Most prominently, the relativity of inertia and Mach's principle is only infrequently reported as part of the foundations of general relativity in more technical expositions. This disfavour is not a response to Einstein's own later disillusionment with Mach's principle. From the earliest moments, the principle failed to nd a place in the majority of accounts within more technical expositions. Rather the favourable accounts rapidly stabilized, most commonly, into locating the foundations of general relativity in the principle of equivalence and the principle of relativity. Even here, these accounts have failed to remain faithful to Einstein's viewpoint. They almost exclusively employ an in nitesimal principle of equivalence, a variant form that Einstein never endorsed and was quite di erent in outlook from Einstein's own form. In order to gauge the magnitude and character of the favourable reception, this section will review the favourable accounts of the foundations of general relativity as they have appeared in the textbooks on general relativity. The review is also limited principally to expositions that either proved a self-contained exposition of tensor calculus or sucient di erential geometry for general relativity or presume such knowledge in the reader and that proceed at least as far as a formulation of the gravitational eld equations. We should note also that the favorable reception extends beyond the realm of relativity theory. Aguirre and Krause (1991, p508) are prepared to label a mechanics as `general relativistic' merely because it is generally covariant. Jean Eisenstaedt (1986, 1989) has described the rising and falling fortunes of general relativity. After an initial period of great interest and activity in the late 1910s and early 1920s, the theory fell into decades of neglect because of many factors: a sense that the theory had only slender con rmation, that its practical utility to physicists was small and
812 J D Norton
that the theory had been eclipsed by the developments in quantum theory. The 1960s saw a new vigour in work on the theory, in part due to a renewed interest in empirical tests of the theory and to the exploitation of new, more sophisticated mathematical tools. In the following, the favourable receptions is divided into periods re ecting these shifts in intensity of work. First, however, I will review the special problem of the principle of equivalence.
4.1 Einstein's principle of equivalence as a covariance principle and its later misrepresentation
There are many instances of later accounts misrepresenting Einstein's ideas. None is as universal and complete as the later treatments of Einstein's principle of equivalence. In his Meaning of Relativity, Einstein gives a statement of the principle typical of all his writing. K is an inertial system in special relativity and K0 a system of coordinates uniformly accelerating with respect to K. Having noted that free masses in K0 are accelerated `just as if a gravitational eld were present and K0 unaccelerated', Einstein (1922a, p57{8) then
writes:
. . . there is nothing to prevent our conceiving this gravitational eld as real, that is, the conception that K0 is `at rest' and a gravitational eld is present we can consider as equivalent to the conception that only K is an `allowable' system of co-ordinates and no gravitational eld is present. The assumption of the complete physical equivalence of the systems of coordinates, K and K0, we call the `principle of equivalence'; . . . [it] signi es an extension of the principle of relativity to co-ordinate systems which are in non-uniform motion relative to each other. In fact, through this conception we arrive at the unity of nature of inertia and gravitation. Einstein however, is nearly universally understood as urging a rather di erent principle, which I shall call the `in nitesimal principle of equivalence'. A canonical formulation is given in Pauli (1921, p145): For every in nitely small world region (i.e. a world region which is so small that the space- and time-variation of gravity can be neglected in it) there always exists a coordinate system K0(X1; X2; X3; X4) in which gravitation has no in uence either on the motion of particles or any other physical process. The key idea here is that in adopting a suciently small region of spacetime, an arbitrary gravitational eld becomes homogenous and can be transformed away by a suitable choice of coordinate system. This principle exists in many variant forms. Sometimes it is strengthened to require that when the gravitational eld is transformed away we recover special relativity locally (for example, Misner et al. 1973, p386) With somewhat di erent quali cations, Pauli's in nitesimal principle corresponds to Dicke's `strong equivalence principle' (Roll et al., 1964, p444). Dicke's `weak equivalence principle', however, requires only the uniqueness of gravitational acceleration, which amounts to requiring that the trajectories of free fall of suitably idealized bodies are independent of their constitutions. Unlike most other writes, Pauli (1921, p145) acknowledged that his in nitesimal version of the principle of equivalence di ered from Einstein's, suggesting that, where Einstein's principle applied only to homogeneous gravitational elds, Pauli's version was for the `general case'. However the di erences ran far deeper than Pauli allowed and pertain to quite fundamental questions of the role of the principle of equivalence in general relativity. These di erences can be summarized in three essential aspects of the principle which remained xed throughout Einstein's writings on general relativity, from the earliest moments in 1907, to his nal years in the 1950s:13
13The case for these di erences betwee Einstein's version and the common in nitesimal version
General covariance and general relativity 813
 Einstein's principle of equivalence was a covariance principle. Special relativity required the complete physical equivalence of all inertial coordinate systems; for Einstein, general relativity required the complete equivalence of all coordinate systems. Einstein's principle of equivalence required the complete equivalence of a set of coordinate systems of intermediate size: inertial systems plus uniformly accelerated coordinate systems. That is, the principle sanctioned the extension of the covariance of special relativity beyond Lorentz covariance but not as far as general covariance. Thus, for Einstein, the principle of equivalence was a relativity principle intermediate in range between the principle of relativity of special relativity and of general relativity. The point is so important for our concerns here that it is helpful to have it in Einstein's own words (1950, p374): This is the gist of the principle of equivalence: In order to account for the equality of inert and gravitational mass within the theory it is necessary to admit non-linear transformations of the four coordinates. That is, the group of Lorentz transformations and hence the set of `permissible' coordinate systems has to be extended. Or, more succinctly, in an article devoted to explicating precisely what he intended with his principle of equivalence, Einstein (1916a, p641) wrote in emphasized text: The requirement of general covariance of equations embraces that of the principle of equivalence as a quite special case. The function of the alternative, in nitesimal principle of equivalence is to stipulate that a spacetime of general relativity with an arbitrary gravitational eld is in some sense locally|that is, in in nitesimal regions|like the spacetime of special relativity. (Einstein objected in correspondence with Schlick to the latter's use of this idea, pointing out to Schlick that the sense in which special relativity holds locally must be so weak that accelerated and unaccelerated particles cannot be distinguished. For details, see Norton (1985, section 9).) As a covariance principle, Einstein's version of the principle served no such function. Therefore it was invariably restricted in the following related ways:  Einstein's principle of equivalence was applied only in special relativity to what we now would call Minkowski space-times. That is, the inertial coordinate system K of Einstein's formulation of the principle is not some kind of free fall coordinate system of general relativity. It is simply an inertial coordinate system of special relativity. Thus the coordinate systems K and K0 are both coordinate systems of a Minkowski spacetime. Because of this, we would now be inclined to picture the entire principle as operating within special relativity. This seems not to have been Einstein's view. He seems to have regarded special relativity supplemented with the principle of equivalence as having more physical content than special relativity alone. The supplemented theory had a wider covariance and it dealt with a new phenomenon, homogeneous gravitational elds.  Einstein's principle of equivalence was not a prescription for transforming away arbitrary gravitational elds; it was just a recipe for creating a special type of gravitational eld. Einstein's principle of equivalence gave a recipe for creating a homogeneous gravitational eld by transforming to a uniformly accelerated coordinate system. The in nitesimal principle gives a recipe for transforming away an arbitrary gravitational eld: one rst homogenizes it by considering an in nitesimal region of spacetime and then transforms it away by the reverse transformation of Einstein's principle. Einstein repeatedly insisted that his principle of equivalence did not allow one to transform away an arbitrary gravitational eld, but only gravitational els of a quite special type, those produced by acceleration
of the principle is laid out is some detail in Norton (1985)
814 J D Norton
of the coordinate system. (Einstein devotes a paragraph of near page length to this point (1916a, pp640{1). See Norton (1985, section 2).)14
4.2. The early years: 1916{1930
Einstein had named Mach's principle as one of the three fundamental principles of general relativity. However, the principle or its precursor, the relativity of inertia, has played the least role in accounts of the foundations of general relativity. Typically the principle does not appear in the discussion of the foundations of the theory. If it appears in an exposition, it arises most commonly later in the context of the cosmological problem and not always in a favourable light, even in expositions otherwise well disposed to Einstein's viewpoint. This pattern was set an the earliest moments. In 1916 and 1917 the Dutch astronomer de Sitter took up the task of allowing the Germans and British to exchange more than artillary shells. He presented a three part report to the Britisch royal Astronomical Society on Einstein's new theory of gravitation ( de Sitter 1916). Whilst otherwise favourable to Einstein, its second part concluded with criticism of Einstein's notion of the relativity of inertia. Development of this criticism continued in the third part. Einstein's 1917 work on the cosmological problem and his 1918 formulation of Mach's principle did not improve the reception of his ideas on the origin of inertia. Laue's (1921,pp179{80) early general relativity text mentions them only in passing as incompatible with Minkowskian boundary conditions at spatial in nity. He nds the whole question physically too unclari ed to warrant further discussion. Pauli (1921) does give the question more coverage, but only in a later, closing section (section 62) Einstein's ideas on the relativity of inertia gured more prominently in more popular expositions of general relativity. For example Freundlich (1919, section 4), Thirring (1922, section XV), Born (1924, ch VII, section 1) and Kop (1923, pp 2{5, 191{5) treat the relativity of inertia. Indeed, the more popular the text, the more likely we are to nd these ideas used to explain the foundations of general relativity. The literature on Mach's principle has become enormous and is ourishing today. However its concerns have come to diverge from the concerns of this article, general covariance and the foundations of general relativity. The interested reader is referred to Reinhart (1973) and Torretti (1983, pp194{202) for further discussion. What is most important for our concerns is that the majority of expositions of relativity theory from this period emphasize the general covariance of general relativity as especially important. Of course this emphasis was justi ed if only for the novelty of general covariance. However the achievement of general covariance was also routinely assumed to ensure automatic satisfaction of a generalized principle of relativity. In some expositions this assumption was discussed in detail, in others it was merely suggested by labelling the requirement of general covariance, a principle of relativity. Accounts that emphasize general covariance and presume an automatic connection to a generalized principle of relativity include: de Sitter (1916, pp700{02), Freundlich (1919, p28), Carmicheal (1920, ch VII), Page (1920, p387), Schlick (1920, pp52{3), Cunningham (1921, ch VII), De Donder (1921, pp10{14), Laue (1921, p21), Pauli (1921, section 52), Weyl (1921, section 27), Becquerel (1922), Kottler (1922, pp188{9), Thirring (1922, p151), Kop (1923), Born (1924, ch VII), Reichenbach (1924, p141), Levi-Civita (1926, p294), Levinson and Zeisler (1929, p70). Some of these accounts explicitly invoke Einstein's point-coincidence argument to
14Einstein himself never employed the trick of homogenizing an arbitrary gravitational eld by considering in nitesimal regions of spacetime. In 1912, when his principle still dealt only with homogenous gravitational elds, he was forced to restrict it to in nitesimal regions of space to overcome certain technical diculties with this theory of static gravitational elds. When they were overcome, the restriction disappeared. See Norton (1985, section 4.3).
General covariance and general relativity 815
establish general covariance. They include de Sitter (1916, pp700{02), Carmicheal (1920, ch VII), Schlick (1920, pp52{3). Many of the expositions also place great emphasis on the principle of equivalence. A few from the very earliest years state the principle in exactly Einstein's fashion: Thirring (1922, p109), Kop (1923, p110) (also Carmichael (1920, p80), although critically). Others employ the now familiar in nitesimal principle of equivalence, other variant formulations of the principles or give vague characterizations of the principle that defy clear classi cation. The following at least name a principle of equivalence in the foundations of general relativity: Freundlich (1922, section 55), Kottler (1922, p 192), Born (1924 ch VII), Reichenbach (1924, pp 141{2).
4.3. The lean years: 1930{1960
During these three lean decades for general relativity, the volume of publication fell to the merest trickle. Within that trickle, Einstein's view of general covariance remained a dominant theme. Accounts of general relativity which emphasized the general covariance of the theory and either explicitly or tacitly took this general covariance to extend the principle of relativity include: Bergmann (1942, ch X), Schrodinger (1950, p2), Moller (1952, ch VII), Jordan (1955, section 14), Kratzer (1956, section 15), Bargmann (1957, p162), Tonnelat (1957, ch XI) All but Schrodinger and Jordan introduce a principle of equivalence by name. Moller (1952, pp219{20) introduces general relativity with a discussion of the relativity of inertia. Tolman (1934, p3 and ch VI) is exceptional in o ering Einstein's three principles of 1918|the principle of covariance, the principle of equivalence and Mach's principle|as the foundations of general relativity. However his version of the principle of equivalence is the in nitesimal version never endorsed by Einstein and he accepts Kretschmann's view of the physical vacuity of the principle of covariance, while insisting with Einstein on its heuristic value.
4.4. Rebirth 1960{1980
The renaissance of general relativity in the 1960s brought clearer divisions in the literature on the foundations of general relativity. As we shall see below, one increasingly important strand either simply ignored Einstein's view of the foundations of the theory or became quite strident in its denunciation of Einstein's view. Another sought to repair Einstein's account in the face of such assaults. A major part of the literature, however, continued in simple assent with Einstein's view, only making smaller adjustment according to taste. Most commonly, accounts in this last category found both an in nitesimal principle of equivalence and the principle of general covariance in the foundations of general relativity. Such accounts include: Weber (1961, sections 1.3, 2.4), Bergmann (1961, 1962), Lawden (1962, ch 6), Rosser (1964, sections 12.1, 12.2), McVittie (1965, ch 4), Yilmaz (1965, ch 15, 16), Skinner (1969, ch 3), Davis (1970, 5.I.2), Prasanna (1971, preface, ch 1), Mavrides (1973, sections III.4, II.5), Papapetrou (1974, Introduction, section 18), Pathria (1974, ch 6,7), Bowler (1976, ch 9), Adler, Bazin and Schi er (1977, p60 and section 5.1), Stephani (1977, section 8.1), Treder et al. (1980, Introduction). Most of these accounts explicitly connected general covariance with a generalized principle of relativity, either in name or by explicit discussion. These include: Bergman (1961, 1962), Lawden (1962, ch 6), Rosser (1964, sections 12.1, 12.2), Yilmaz (1965, ch 15, 16), Prasanna (1971), Mavrides (1973, sections III.4,), Papapetrou (1974, Introduction), Pathria (1974, ch 6,), Bowler (1976, ch 9), Adler, Bazin and Schi er (1977, p60 and section 5.1), Stephani (1977, section 8.1),
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Treder et al. (1980, Introduction). Skinner (1969, section 3.3.1) reported that the principle of general relativity required something beyond the principle of covariance: `the laws of physics must determine the geometry of spacetime appropriate for a particular physical circumstance'. Two accounts portrayed general covariance as a generalized principle of relativity but did not place the principle of equivalence by name in the foundations of general relativity: Charon (1963, lecon 8), Atwater (1974). Mach's principle is mentioned by Lawden (1962, p133). Work on general relativity in this period also gave rise to a variant form of the principle of general covariance. Weinberg (1977, pp91{2) de ned his principle of general covariance as: It states that a physical equation holds in a general gravitational eld, if two conditions are met: 1. The equation holds in the absence of gravitation: that is, it agrees with the laws of special relativity when the metric eld g equals the Minkowski tensor  and when the ane connection vanishes. 2. The equation is generally covariant; that is, it preserves its form under a general coordinate transformation x ! x0. The novelty, of course, is that the second condition alone is usually taken as the principle of general covariance, whereas the rst looks like a form of the in nitesimal principle of equivalence. Indeed Weinberg presents the principle as an alternate form of the in nitesimal principle of equivalence and shows how it follows from the principle of equivalence. He insists that it is not a relativity principle like the Lorents invariance of special relativity. Bose (1980, ch 1) locates the foundations of general relativity in a local principle of equivalence and its re-expression in a two condition principle of general covariance equivalent to Weinberg's. Similarly Foster and Nightingale (1979, ppxi-xiii) locate the foundations of general relativity in an in nitesimal principle of equivalence and a version of the principle of general covariance essentially the same as Weinberg's. They strengthen Weinberg's condition 2. to read [2'.] the equation is a tensor equation (i.e. it preserves its form under general coordinate transformation). The strengthening lies in the fact that not only tensor equations are covariant under arbitrary coordinate transformations. See also Treder et al. (1980)
4.5. Recent years since 1980
The years since 1980 have seen no resolution of the disagreements over the foundations of general relativity. As we shall see later, the literatures that reject Einstein's account or seek major repairs continue to ourish. At the same time, a signi cant literature retains a viewpoint almost as close to Einstein's as the favourable reception in the 1920s. Broadly, in this latter literature, the foundations of general relativity are still located within an in nitesimal principle of equivalence and a principle of general covariance. Two accounts o er essentially Weinberg's view. Both Straumann (1984, ch 2) and Kenyon (1990, ch 1) base general relativity on an in nitesimal principle of equivalence. (Kenyon discusses both Dicke's weak and strong version, with the latter amounting to an in nitesimal principle.) Kenyon (1990, section 6.4) gives a formulation of the principle of general covariance which is essentially Weinberg's as strengthened by Foster and Nightingale (see above). Without explicitly introducing the name, principle of general covariance, Straumann (1984, section 1.3) provides two requirements which are `a mathematical formulation of the principle of equivalence'. The rst is actually the principle of minimal coupling, a version of the principle of equivalence (Trautman 1965, Anderson 1967, p337,
General covariance and general relativity 817
Anderson and Gauteau 1969). The second requirement is essentially Weinberg's version of the principle of general covariance.
De Felice and Clarke (1990, p7{13) locate the foundations of general relativity in the familiar in nitesimal principle of equivalence and principle of general covariance. Cameli (1982, section 1.4, 1.5) locates the foundation of the theory in these same two principles. He does, however, delineate three versions of the principle of general covariance which, he notes, are `not quite equivalent'. 1. All coordinate systems are equally good for stating the laws of physics. Hence all coordinate systems should be treated on the same footing, too. 2. The equations that describe the laws of physics should have tensorial forms and be expressed in a four-dimensional Riemannian spacetime. 3. The equations describing the laws of physics should have the same form in all coordinate systems.
Ellis and Williams (1988, section 5.2) locate the foundations of the theory in an in nitesimal principle of equivalence and what they call an extension of the principle of relativity: `the laws of physics are the same for all observers, no matter what their state of motion'. The term principle of general covariance is not mentioned. Sexl and Urbantke (1983) treat all three of Einstein's principles of 1918. The principle of equivalence (section 1.2) is given most emphasis, although in it in nitesimal form. Mach's principle and the principle of general covariance are mentioned only apparently for historical interest (section 4.5), with the latter o ered as Einstein's attempt to satisfy the former.
Finally, d'Ivorno (1992, ch 9) in a chapter entitled `The Principles of General Relativity', acknowledges that these principles have been a source of much controversy. However, as principles fundamental to general relativity or at least serious candidates for them, he presents Einstein's three principles of 1918, the Anderson and Gautreau principle of minimal coupling and a principle of correspondence (with Newtonian gravitation theory and special relativity in the limiting cases). The in nitesimal principle of eqivalence is presented as the `key principle'. Mach's principle is given three formulations, all closely connected with Einstein's cosmological ideas of 1917 and 1918. d'Ivorno nds the `full import' of the principle of general relativity ('all observers are equivalent') contained in the principle of general covariance (`the equations of physics should have tensorial form'). And, the hole argument, which gured so prominently in Einstein's early thinking about general covariance, is discussed in section 13.6. To my knowledge, this is the rst time the hole argument has been discussed in a general relativity text in over half a century. The hole argument has also recently reappeared in the physics journal literature. See, for example, Rovelli (1991).
5. Is general covariance physically vacuous?
5.1 Kretschmann's objection: the point-coincidence argument turned against Einstein
In the tradition that is skeptical of Einstein's account of the foundations of general relativity, the best known of all objections is due to Kretschmann (1917, pp575{6). He began his paper with the remarks.15
15I have suppressed Kretschmann's footnotes in this passage to other literature. For further discussion see Norton (1982, section 8). See also Howard and Norton (forthcoming) for speculation that these footnotes direct readers to Einstein's unacknowledged source for his point-coincidence argument, Kretschmann (1915)!
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The forms in which di erent authors have expressed the postulate of the LorentzEinstein theory of relativity|and especially the forms in which Einstein has recently expressed his postulate of general relativity|admit the following interpretation (in the case of Einstein, it is required explicitly): A system of physical laws satis es a relativity postulate if the equations by means of which it is represented are covariant with respect to the group of spatio-temporal coordinate transformations associated with that postulate. If one accepts this interpretation and recalls that, in the nal analysis, all physical observations consist in the determination of purely topological relations (`coincidences') between objects of spatio-temporal perception, from which it follows that no coordinate system is privileged by these observations, then one is forced to the following conclusion: By means of a purely mathematical reformulation of the equations representing the theory, and with, at most, mathematical complications connected with that reformulation, any physical theory can be brought into agreement with any, arbitrary relativity postulate, even the most general one, and this without modifying any of its content that can be tested by observation. Kretschmann's point is that there must be something more to a relativity principle than covariance. For he argues that we can take any theory and reformulate it so that it is covariant under any group of transformations we pick; the problem is not physical, it is merely a challenge to our mathematical ingenuity. In brief, general covariance is physically vacuous. This at least, is how Kretschmann's point has been understood almost universally and it is almost what he actually argued. His real objection was a little more subtle. It depended on a non-trivial assumption that virtually all later commentators fail to report16 All physical observations consist in the determination of purely topological relations (`coincidences') between objects and spatio-temporal perception. This assumption is clearly recognizable to us as the basic premise of Einstein's own pointcoincidence argument (see section 3.5 above). There can be no question of the importance of this assumption to Kretschmann's point even though it is buried in the grammar of his statement. A little later, he repeats it (p579). . . . according to the investigations of Ricci and Levi-Civita (1901) it may scarcely be doubted that one can bring any physical system of equations into a generally covariant form without alteration of its observationally testable content. This is obvious from the beginning, if one once again recalls that strictly only purely topological facts of natural phenomena or, according to Einstein, coincidences are observable. Thus, allowing that Kretschmann's mention of `topological facts' alludes to his own version of the point-coincidence argument (see Howard and Norton, forthcoming), we nd that Kretschmann's real objection is this: if we accept the point-coincidence argument, then any theory can be given a formulation of arbitrary covariance. This is a most striking reversal of fortunes. The point-coincidence argument had been Einstein's salvation from the hole argument and permitted his return to general covariance. However, in advocating the point-coincidence argument, Einstein had in e ect already agreed to virtually everything in Kretschmann's objection. To establish the admissibility of general covariance for his own theory, Einstein had allowed that the physical content of a theory resides solely in the observable coincidences it sanctions. Since these coincidences are preserved under arbitrary coordinate transformation, the physical content of a theory is una ected by the adoption of a generally covariant formulation. What Kretschmann noticed was that this argument depended on nothing peculiar to general relativity, so it
16I cannot resist speculating that this misreading is at least in part due to the bewildering complexity of his German prose, which has been disentangled considerably in the above translation. This translation also slightly corrects the translation of Norton (1992, section 8.1).
General covariance and general relativity 819
could equally be used to establish the admissibility of a generally covariant formulation of any theory. Again it did not depend on the fact that the covariance group was the general group, so the same argument established the admissibility of formulations of any theory of arbitrary covariance.
5.2. Einstein's reply
Einstein (1918) responded to Kretschmann's objection. Having laid out the three principles upon which he believed general relativity to be based, he turned to Kretschmann's objection, which he restated correctly with its now lost premise (p 242): Concerning (a) [principle of relativity], Herr Kretschmann observes that a principle of relativity, formulated in this way, makes no assertions over physical reality, i.e. over the content of the laws of nature; rather, it is only a requirement on their mathematical formulation. That is, since all physical experience relates only to coincidences, it must always be possible to represent experiences of the lawful connection of these coincidences by generally covariant equations. Therefore he believes it necessary to connect another requirement with the requirement of relativity. Einstein had little choice but to accept Kretschmann's point. The alternative was to renounce the point-coincidence argument that he had advertised so widely. However he tried to salvage something of the special connection between general covariance and general relativity in the heuristics of theory choice. He continued: I believe Herr Kretschmann's argument to be correct, but the innovation proposed by him not to be commendable. That is, if it is correct that one can bring any empirical law into generally covariant form, the principle (a) still possesses a signi cant heuristic force, which has already proved itself brilliantly in the problem of gravitation and rests on the following. Of two theoretical systems compatible with experience, the one is to be preferred that is the simpler and more transparent from the standpoint of the absolute di erential calculus. Let one bring Newtonian gravitational mechanics into the form of absolutely covariant equations (four dimensional) and one will certainly be convinced that principle (a) excludes this theory, not theoretically, but practically! Thus Einstein seems to accept Kretschmann's objection, begrudgingly, with a quali cation on the role of general covariance in theory choice and with the reservation that general covariance in all theories would be impractical. Indeed it is ironic that the version of the principle of relativity given in this same paper by Einstein (quoted in section 3.7 above) essentially just restates Kretschmann's point.17 Whatever concession Einstein made to Kretschmann seems to have had a lesser e ect on Einstein's later writings. He does occasionally allow that general covariance is `more characteristic of the mathematical form of this theory [of general relativity] than its physical content' (1924, p90{1). Or that the `requirement [of general covariance] (combined with that of the greatest possible logical simplicity of the laws) limits the natural laws concerned incomparably more strongly than the special principle of relativity' (1952, p 153). The heuristic role of simplicity in connection with general covariance was emphasized in his Autobiographical Notes (1949, p65). But this emphasis seemed to be forgotten by p73, where he recalled: `We have already given physical reasons for the fact that in physics invariance under the wider [general] group has to be required'. (Einstein's emphasis) More
17The only di erence is that Kretschmann allows the point-coincidence argument to justify a formulation of any covariance, whereas Einstein sees it forcing a generally covariant formulation as the `unique, natural expression' of the theory. Presumably this is because a generally covariant formulation adds the least to the catalog of coincidences. See Einstein to Besso, January 3, 1916, as quoted in Norton (1992, p298)
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commonly, however, the quali cation over simplicity is simply not mentioned. It does not appear at the relevant point in his text, Einstein (1922a, p61). Again, Einstein (1950, p352) insists, without explicit mention of simplicity considerations that . . . the principle of general relativity imposes exceedingly strong restrictions on the theoretical possibilities. Without this restrictive principle it would be practically impossible for anybody to hit on the gravitational equations . . . How can we reconcile Einstein's concession to Kretschmann and his continuing emphasis on the importance of general covariance? The answer may well lie in Einstein's famous proclamation of his 1933 Herbert Spencer lecture, which revealed a metaphysics not present explicitly in Einstein's writings of 1918: Our experience hitherto justi es us in believing that nature is the realization of the simplest conceivable mathematical ideas. I am convinced that we can discover by means of purely mathematical constructions the concepts and laws connecting them with each other, which furnish the key to understanding the of natural phenomena . . . the creative principle resides in mathematics. When Einstein replied to Kretschmann that one ought to pick of two empirically viable systems the simpler and more transparent within the absolute di erential calculus, he may have been urging something more than merely a matter of practical convenience. It is not just that the simpler is more convenient, so that generally covariant formulations of Newtonian gravitational are (he believed) practical impossibilities. We can recognize the truth of a theory in its mathematical simplicity, And instead of being physically vacuous, general covariance is the right language in which to seek this simplicity. Later writers who endorsed Einstein's 1918 reply to Kretschmann may well have armed a more extreme metaphysics than they realized!
5.3. Generally covariant formulations of Newtonian mechanics
In 1918 Einstein sought to protect the special connection between general covariance and his general theory of relativity by issuing a challenge: nd a generally covariant formulation of Newtonian gravitational mechanics. He had con dently predicted that should anyone try the result would be unworkable practically. Einstein was shortly proved wrong. Cartan (1923) and Friedrichs (1927) found serviceable, generally covariant formulations of Newtonian gravitation theory. Einstein was right in so far as these generally covariant formulations were more complex than general relativity. However Einstein was quite wrong in predicting that such formulations would not be usable practically. Although they are not as attractive a host for routine calculation as the far simpler Galilean covariant formulation, they are of the same order of complexity as other theories routinely examined in physics. However there are certain circumstances in which their use is preferable if not mandatory. In an article comparing Newtonian and relativistic theories of gravitation, Trautman (1966, p413) pointed out such comparison can really only be e ected reliably if the two theories under comparison are formulated in the same mathematical language. Otherwise it is hard to ascertain which di erences are physical and which are accidents of the di erences in formulation. Since general relativity is known only in a generally covariant formulation, this means we ought to compare it only with the generally covariant formulation of Newtonian theory. (For similar sentiments, see also Havas (1964, p939) and Malament (1986, p 181).) For this reason, a few expositions of relativity include a treatment of Newtonian spacetie theory in a generally covariant formulation, although the practice is not common. See for example Trautman (1964, ch 5), and Misner et al (1973, ch 12). In the philosophy of space and time literature, however, the use of the general covariant formulation of Newtonian
General covariance and general relativity 821
theory is becoming standard, even at the introductory level, see Earman and Friedman (1973), Earman (1974, pp276{7), Friedman (1983, ch III), Malament (1986) and Norton (1992a). Although both Cartan and Friedrichs were very much concerned with the relationship between their work and Einstein's general theory of relativity, it is striking that neither made the obvious point that their work had seriously weakened Einstein's 1918 reply to Kretschmann and raised very serious doubts over Einstein's claim to have generalized the principle of relativity to acceleration.18 It is only later that this obvious point about generally covariant formulations of Newtonian theory is made: they provide an instantation of Kretschmann's claim that any theory can be made generally covariant. See Havas (1964, p 939) and Misner et al (1973, p302).
5.4. Automatic general covariance: coordinate free geometric formulation
It did not need the labours of Cartan and Friedrichs to show that theories other than general relativity admitted generally covariant formulations. In a sense this possibility had been known for a long time. As Painleve pointed out as early as 1921 in his discussion of general relativity (1921, p877), Lagrangian mechanics has always been invariant under arbitrary spatial transformation. Again, the moment Einstein applied the absolute di erential calculus of Ricci and Levi-Civita to relativity theory in 1913, it was obvious that special relativity could be given generally covariant formulation. In this form, special relativity is simply the theory of spacetime with line element (4), where g is symmetric with Lorentz signature and whose Riemann-Christo el curvature tensor vanishes. That Einstein never embraced this obvious possibility suggests that his understanding of general covariance was a little more complex than the simple one supposed in Kretschmann's objection.19 Perhaps for this reason or perhaps just for its simplicity, the Lorentz covariant formulation of special relativity remains popular today. The possibility of formulating special relativity in arbitrary coordinates, however, was explicitly recognized in the literature quite early (see for example Kretschmann (1917, p579), De Donder (1925, ch 1), Fock (1959, ch IV, p350). A number of commentators have observed that Ricci and Levi-Civita's calculus vindicates Kretschmann's objection in the sense that it provides the necessary mathematical apparatus for nding generally covariance formulation of `practically any assumed law' (Whittaker 1951, Vol II, p 159) or `almost any law' (North 1965, p58). This possibility has not really been exploited widely in the relativity literature until the 1960s and 1970s with the introduction of what Misner, Thorne and Wheeler (1973) label as the `geometric' or ` coordinate free' approach. This approach is based on Ricci and Levi-Civita's calculus. However, as was pointed out in section 3.2 above, the calculus was created explicitly as an abstract calculus, as independent as possible from geometric notions. The calculus was signi cantly altered to arrive at its modern geometric incarnation. It is now augmented with geometric ideas from topology. The most signi cant augmentations are the modern ideas of a di erential manifold and of a geometric object of Veblen and Whitehead (1932), as well as an abstract, algebraic approach to vectors, tensors and the like, attributed to
18Thus Ho man (1932, p177) makes no mention of Cartan's and Friedrich's work when he remarks that the general principle of relativity `holds in exactly the same words for the Newtonian theory [as for general relativity]. Rather the remark is supported merely by observing that the principle requires only that the mathematical expression of a theory be independent of the coordinates system and does not restrict the theory's content. 19Indeed, as he made clear through his principle of equivalence, he held that an extension of the covariance of special relativity beyond Lorentz covariance was a physical extension of the theory; his principle of equivalence tells us that extending the covariance to uniformly accelerated coordinates now allows the theory to embrace the phenomenon of gravitation in a special case.
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Cartan (Misner et al 1973, ch 8 and 9). These methods became standard in the 1960s and 1970s through such expositions of relativity theory as Trautman (1965), Hawking and Ellis (1973), Misner, Thorne and Wheeler (1973), Sachs and Wu (1977). Following their methods, we would characterize special relativity as a theory of Minkowski spacetimes. That is, the theory has models
hM; gabi
Where M is a connected, four-dimensional, di erentiable manifold and gab is a symmetric second rank tensor of Lorentz signature which is at, so that it satis es the equation
Rabcd = 0
Where Rabcd is the Riemann-Christo el curvature tensor. There are obvious extensions if one wishes to include further elds, such as a Maxwell eld and charge ux. Similarly, general relativity, is the theory with models
hM; gab; Tabi
where now gab need not be at. Tab is the second rank, symmetric stress-energy tensor, which may be required to satisfy further `energy conditions' (Hawking and Ellis, 1973, section 4.3). The metric tensor gab and Tab are related by the gravitational eld equation
Gab = Tab
where Gab is the Einstein tensor and  a constant A typical geometric formulation of Newtonian spacetime theory without absolute rest (after Malament 1986) has models
D
M; ta; hab; ra
E
The theory's temporal metric is ta, is a smooth, non-vanishing co-vector eld. The spatial
metric is second rank, symmetric, smooth non-vanishing contravariant tensor, hab, which is degenerate through its signature (0,1,1,1), ra is a smooth derivative operator, conferring ane structure on the spacetime. These structures satisfy orthogonality and compatibility conditions
habta = 0 ratb = rahbc = 0
Many alternative, further conditions can be imposed upon this basic spacetime structure, for example, according to whether we wish to add gravitation as distinct scalar eld and leave the background spacetime at or whether we wish to incorporate gravitation into the spacetime as curvature after the model of general relativity (see Friedman 1983, ch III). These are all instances of a general, geometric formulation of spacetime theories. All such theories have models
General covariance and general relativity 823
hM; O1; O2; : : : ; Oni (6)
where O1; O2; : : : ; On are now just n geometric object elds subject to certain constraining equations. Virtually all theories of space and time now given serious consideration can be formulated in this way. 20 Such theories are automatically generally covariant in a sense that actually follows from the de nitions of the mathematical structures used in the formulation. Following Standard de nitions (e.g. Bishop and Goldberg 1968, ch 1, Hawking and Ellis 1973, ch 2, Torretti 1983, appendix), an n-dimensional di erentiable manifold is a connected, topological space with a set of coordinate charts, such that every point of the topological space lies in the domain of a coordinate chart, which is a homeomorphism of an open set of the space with Rn. The set of coordinate charts form a maximal or complete atlas in so far as the atlas contains every coordinate chart that can be constructed in the usual way from its coordinate charts by Ck-transformations on Rn. k is some positive integer or, most commonly, in nity. The next step is complicated by the vagueness of the de nition of `geometric object'. It is given by Veblen and Whitehead (1932, p46) as `an invariant which is related to the space [under consideration]' where an invariant is `anything which is unaltered by transformations of coordinates'.21 Thus for our purposes, it is prudent to assume that our geometric object elds, are like Anderson's (1967, p15) `local geometrical objects'. They are represented by a nite set of numbers for each point in the manifold in each coordinate charts and which transform under coodinate transformation in a way that respect transitivity, identity and inversion. These numbers are the geometric object's components in the coordinate charts. Let us say that a geometric object eld O has components Oik::: where the integer valued i; k; : : : represents a suitable set of index labels. Combining, we now arrive at the sense in which any theory with models (6) is generally covariant. If N is any `local coordinate neighbourhood' of M , an open set of N that is the domain of some coordinate chart xi, then the restriction of the model (6) to N will be represented by
hA; (O1)ik:::; : : : ; (On)ik:::i (7)
Where A is the range of xi and the remaining structures are the components of the objects O1; : : : On in the coordinate chart xi. The theory is generally covariant in the sense that if (7) is a coordinate representation of the model (6), then so is any representation derivable from (7) by arbitrary Ck transformation. This is sometimes known as `passive general covariance ' Put more brie y, once we have formulated a theory as having models of the form (6), then, built into the de nitions of the structures used is the possibility of representing the models in coordinate systems that are related by the arbitrary transformations of Einstein's general covariance. (More precisely, they are related by Ck transformations if the manifold has a Ck maximal atlas of coordinate charts.) These coordinate representations behave
20That is not to say that all intelligible theories of space and time must admit such a formulation. With a precise de nition of geometric object in hand, it is just a matter of mathematical patience to construct a spacetime theory without such a formulation. Oe could begin, for example, by considering spacetimes whose event sets are very large but nite and do not admit smooth coordinate charts. 21The still vague `related to space' clause is an attempt to avoid the problem that `. . . strictly speaking, anything, such as a plant or an animal, which is unrelated to the space which we are talking about, is an invariant'.
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exactly like the components of the generally covariance formulation of theories used by Einstein and others in the early years of general relativity. It is to this automatic general covariance that Thirring (1979, p 166) referred when he
wrote At the time of the birth of gravitation theory, the requirement of general covariance provided some relief from the labor pains, but later on it was more often a source of confusion. The concept of a manifold incorporates it automatically when the de nition used equivalence classes of atlases, and hence only chart independent statements are regarded as meaningful. This program is by no means unique to gravitation theory| we have also followed in in classical mechanics and electrodynamics. The big di erence [in general relativity] is that the metric g on M is now not determined a priori. While the use of these geometric methods has become standard in modern work on general relativity, it should be noted that their dominance is not viewed universally with unmixed joy. Weinberg (1972, preface) notes that an emphasis on these methods tends to obscure the importance of the principle of equivalence within the theory and the natural connections to quantum theory. Finally, there is a notion that is loosely dual to the notion of passive general covariance described above. It is the notion of `active general covariance'. The main mathematical di erence is that the active version employs maps on the manifold M of the models (6) rather than transformations between coordinate charts. It can be de ned as follows. Let h be an arbitrary di eomorphism 22 from M to M . Then a theory with models of the form (6) is generally covariant in the active sense if every structure
hhM; hO1; hO2; : : : ; hOni (60)
is a model whenever
hM; O1; O2; : : : ; Oni (6)
is a model. In addition, it is routinely assumed that the structure (6) and (6') represent the same physical circumstance (e.g., in the case of general relativity, see Hawking and Ellis 1973, p56). This assumption has been called `Leibniz equivalence' (Earman and Norton 1987). Many theories are generally covariant in the active sense. A sucient condition for active general covariance is that the object elds O1; O2; : : : ; On that can be included in the models (6) are determined solely by tensor equations. Thus general relativity is covariant in this sense as are versions of special relativity and Newtonian spacetime theory. Passive general covariance involves no physically contingent principles. Once models of the form of (6) are selected, passive general covariance follows as a matter of mathematical de nition, no matter what the physical content of the theory. Passive general covariance involves no physically contingent principles, Once models of the form of (6) are selected, passive general covariance follow as a matter of mathematical de nition, no matter what the physical content of the theory. This is not the case with active general covariance/Leibniz equivalence. Structures (6) and (6') are mathematically independent structures, that they represent the same physical circumstance is an assumption dependent on the properties of the physical circumstance and our methods of coordinating the structures to it. The di erences between such pairs of structures as (6) and (6') are generally of a nature that make it uninteresting to suppose anything other than
22For example, if M is a Ch manifold, then h might be any Ch di eomorphism in the sense of Hawking and Ellis (1973, p 23).
General covariance and general relativity 825
Leibniz equivalence. However, it has been argued (Earman and Norton 1987, Norton 1988) that at least one doctrine, spacetime substantivalism, must deny Leibniz equivalence.23 Since the assumption of active general covariance/Leibniz equivalence is a physical assumption albeit weak, it does require physical arguments to support it. It turns out that Einstein's two celebrated arguments|the point-coincidence argument and the hole argument|can be put in to modern forms that support active general covariance/Leibniz equivalence. According to the modernized point-coincidence argument, the two di eomorphic models (6) and (6') would agree on all observables, for all that is observable are coincidences that are preserved by the di eomorphism. Therefore, if we deny Leibniz equivalence, we would have to insist that the two di eomorphic models represent distinct physical circumstances, even though no possible observation could pick between them. To construct the modernized hole argument, we consider some neighbourhood H of the manifold M in models (6) and (6') and pick a di eomorphism h that is the identity outside H but comes smoothly to di er from it within H. The the two di eomorphic models will be the same outside H but will come smoothly do di er within H. We now have a mathematical indeterminism, in the sense that the fullest speci cation of the model outside H will fail to determine how it is to be extended into H according to the theory. This indeterminism is usually dismissed as a purely mathematical gauge freedom associated with active general covariance. If we deny Leibniz equivalence and insist that the two models represent distinct physical circumstances, then we convert this gauge freedom into a physical indeterminism. The di erences between the models within H must now represent a di erence of physical circumstances. Which will obtain within H cannot be determined by the fullest speci cation of the physical circumstances outside H, no matter how small H is in spatial and temporal extension. For further discussion of the di erences between active and passive general covariance, see Norton (1989, section 2.3).
5.5. Later responses to Kretschmann's objection
Kretschmann's objection is probably the single most frequently mentioned of all objections to Einstein's views on the foundations of general relativity. As I have already indicated above, however, the objection which appears universally under Kretschmann's name in the literature is actually a considerably reduced version of what Kretschmann really said. It is commonly reported as the assertion that general covariance is physically vacuous, since it is merely a challenge to our mathematical ingenuity to bring any theory into generally covariant form. For the purposes of this section, which reviews later responses to the objection, I will take `Kretschmann's objection' to be this reduced version, for that is the one that was responded to. Essentially no one other than Einstein seemed to realize that Kretschmann had based his objection on a contingent assumption, the premise of the pointcoincidence argument. That assumption|that `the laws of nature are only assertions of timespace coincidences'|is so non-trivial that Einstein actually made it the statement of his 1918 version of the principle of relativity. In later literature, Kretschmann's objection is commonly accepted. Instances in which Kretschmann is cited by name include Havas (1964, p939), Rindler (1969, p196), Earman
23At present, however, there is no consensus in the philosophy of space and time literature over the connection between spacetime substantivalism, Leibniz equivalence and the hole argument, with virtually every conceivable position being defended. See Bartels (1993), Butter eld (1987, 1988, 1989), Earman (1989, ch 9), Norton (1992a, section 5.12), Cartwright and Hoefer (forthcoming), Maudlin (1988, 1990), Rynasiewicz (forthcoming (a), (b)), Stachel (forthcoming), Teller (forthcoming), Mundy (1992).
826 J D Norton
(1974, p271), Friedman (1973, p55), Ray (1987, p70). Again Kretschmann's assertion of the physical vacuity of general covariance may be made without naming Kretschmann. Instances include Silberstein (1992, pp22{3), Szekeres (1955, p212), Fock (1959, p370, but see p xvi), Thirring (1979, p166). Einstein's 1918 response to Kretschmann also commands considerable assent. Einstein's response is encapsulated in the simple remark that general covariance is physically vacuous alone; however it achieves physical content and signi cant heuristic force when it is supplemented by the requirement that the laws of nature take simple forms. This viewpoint is advocated by: Painleve (1921, p877), Tolman (1934, pp33, 166{67)24, Bridgman (1949, pp339{40, 345), Whittaker (1951, vol II, p159), Weber (1961, p15{16), Skinner (1969, p 324), Adler, Bazin and Schi er (1977, p145). Ohanian (1976, pp253{4) states Kretschmann's objection and quotes Einstein's 1918 reply at length, but he proceeds to elucidate Einstein's response in terms of the requirement of general invariance of the absolute object tradition (see section 8 below). In his 1918 reply to Kretschmann, Einstein urged the heuristic power of general covariance and the basis of his brilliant success with general relativity. d'Ivorno (1992, p131) comes closest to this viewpoint when he suggests that we cannot ignore general covariance, even if it is vacuous, precisely because it was of such importance to Einstein, rather than because of some as yet unrealized heuristic power. But perhaps Misner et al (1973, section 12.5) capture Einstein's metaphysics most clearly when they recapitulate Kretschmann's objection and retort But another viewpoint is cogent. It constructs a powerful sieve in the form of a slightly altered and slightly more nebulous principle: `Nature likes theories that are simple when stated in coordinate free, geometric language' . . . According to this principle, Nature must love general relativity, and it must hate Newtonian theory. Of all theories ever conceived by physicists, general relativity has the simplest, most elegant geometric foundations. . . By contrast, what diabolically clever physicist would ever foist on man a theory with such a complicated geometric foundation as Newtonian theory? There are obvious problems with this view. To begin, it would seem that the view is plainly false. The very simplest laws, which nature ought to love the most, are just incompatible with experience. For example, it would be very simple of all of space, time and the distribution of matter were homogeneous; but they are not homogeneous. So Nature's preferences can only be exercised among the more complicated dregs that remain after experience has drained of the truly simple|Nature's preference here is a rather contrived one. Next, it is not clear by what rules we are to judge which of two theories is the simpler. It cannot just be a matter of intuitive impressions, since then we have no way of adjudicating disagreements. But even a basic count of the number of mathematical structures in a theory is hard to do unambiguously.25 Bondi (1959, p108), however, endorses the view that general covariance is physically vacuous and points out that conservation laws explicitly involving gravitational energy-momentum in general relativity are not tensorial, but pseudo-tensorial. Finally, it is not obvious why nature should be so kind as to prefer laws that we humans deem simple. Thus North (1965, p58) muses that the virtue of simplicity for covariant laws might merely be that they are more likely to be accepted by others. My own view is that one should not look on simplicity as resulting from the emotional attachments of Nature. Rather it arises from the labours of theorists who have constructed languages in which Nature's choices appear simple. Whether Nature's further choices will continue to appear simple in some language seems to me an entirely contingent matter
24Tolman gives Kretschmann's objections in its full form insofar as the possibility of generally covariant formulation is taken to follow necessarily from the point-coincidence argument. 25Is the stress-energy tensor of pressureless dust, T ab = U aU b, counted as one structure T ab or as two, the matter density  and the four-velocity eld U a?
General covariance and general relativity 827
and one takes a great risk elevating any language to the status of Nature's own. As we explore new domains of physical law, the one thing that is most clear is Nature's surprising versatility in frustrating our natural expectations. However this does not mean that there is no value in simplicity. Apart from its pragmatic value, it has an epistemic value. The more complicated a theory, the more likely we are to have introduced structures with no correlations in reality; and the more complicated a theory, the harder it will be to test for these physically irrelevant structures. We should prefer the simpler theory and seek languages that make our theories simple, but not because Nature is simple. Rather, if we restrict ourselves to simpler theories, we are more likely to know the truth when we nd it. There is a variation of Einstein's response to Kretschmann that avoids the dicult questions over simplicity. Its overall e ect is to direct us towards simpler theories by restricting the structures we can employ in our formulations. It focuses on the process of nding generally covariant formulations of arbitrary laws. If we restrict the number of additional mathematical structures that can be introduced in this process, it may no longer be possible to construct a generally covariant formulation for some laws, so that we once again have an interesting division between generally covariant and other theories. Fock (1959, p xvi) describes the idea in its most general form . . . the requirement of covariance of equations has great heuristic value because it limits the variety of possible forms of equations and thereby makes it easier to choose the correct ones. However, one should stress that the equations can so be limited only under the necessary condition that the number of functions introduced is also limited; if one permits the introduction of an arbitrary number of new auxiliary functions, practically any equation can be given covariant form. Trautman (1964, pp122{3) illustrates how unrestricted admission of new structures allows construction of a generally covariant formulation of equations that clearly are coordinate dependent. He considers the equation
A1 = 0
the vanishing of the rst component of a covector Aa in some coordinate system. If ua is
the coordinate basis vector eld associated with the x1 coordinate, then this law admits generally covariant formulation as
uaAa = 0
The villain is the vector eld ua, since (p123) one should not introduce such additional structures in addition to those already present in the axioms of the theory (e.g. the metric tensor, ane connection) and to those that are necessary to describe the physical system. If we now apply this thinking to general relativity, we arrive at a popular means of injecting content into the general covariance of general relativity. In a Lorentz covariant version of special relativity, the metrical properties of spacetime are not represented explicitly. In the transition to the generally covariant, general theory of relativity, these properties become explicit as a new structure, the metric tensor gab. It is required that this new structure represent some de nite physical element of reality and nut just be a mathematical contrivance introduced to force through general covariance. The metric tensor satis es this requirement in so far as it represents the gravitational eld as well as the metrical properties of spacetime. Pauli (1921, p150) describes this outcome
828 J D Norton
. . . Kretschmann . . . took the view that the postulate of general covariance does not make any assertions about the physical content of the physical laws, but only about their mathematical formulation, and Einstein : : : entirely concurred with this view. The generally covariant formulation of the physical laws acquires a physical content only through the principle of equivalence, in consequence of which gravitation is described solely by the gik and these latter are not given independently from matter, but are themselves determined by eld equations. We nd a similar view in Borel (1926, p172{3), Weyl (1921, pp226{7) Reichenbach (1924, p141), Anderson (1967, 1971|see section 8.1 below), Graves (1971, p138) and even as recently as Wald (1984, p57) who formulates the principle of general covariance as The principle of general covariance in this context [pre-relativistic and relativistic physics] states that the metric of space is the only quantity pertaining to space that can appear in the laws of physics. Speci cally there are no preferred vector elds or preferred bases of vector elds pertaining only to the structure of space which appear in any law of physics. (He cautions that the `the phrase \pertaining to space" does not have a precise meaning'.) Both Pauli and Weyl stress a special aspect of the physical character of the metric in their discussions: the metric is not given a priori but it is in uenced or determined by the matter distribution via invariant eld equations. This would, of course, rule out generally covariant formulations of special relativity. Weyl, in particular, sees this as the decisive property of general relativity. `Only this fact justi es us in assigning the name \general theory of relativity" to our reasoning . . . ' he wrote (p226). Further, he emphasized the result that `gravitation is a mode of expression of the metrical eld' and that `this assumption, rather than the postulate of general invariance, seems to the author to be the real pivot of the general theory of relativity' (pp226{7). We shall see that this theme will be incorporated into the absolute object approach (see section 8 below). A practical diculty still remains. At the most fundamental level, the general principle is clearly correct: we should deny admission to theories or structures that do not represent elements of reality. The hope is that this restriction will preserve a unique association between general covariance and the general theory of relativity. However the principle may well not be suciently precisely formulated to have any force in realistic examples. Consider the structures dta, hab and ra, introduced in constructing a generally covariant formulation of Newtonian theory. Are they admissible or not? Notice that Pauli and Weyl's emphasis on the dynamic character of the metric may not help us here. In versions of Newtonian gravitation theory, the gravitational eld is incorporated into the ane structure ra which then has similar dynamical properties to the metric of general relativity. The strategy so far has been to augment the requirement of general covariance with additional requirements that make it non-trivial. It turns out that there is an extremely simple way of augmenting the principle of general covariance so that we cannot render generally covariant such theories as special relativity and versions of Newtonian theory that do not incorporate the gravitational eld into ane structure. In both these cases, the associated generally covariant formulations have the property that they can be simpli ed by reintroducing restricted coordinate systems. This is not so in the case of general relativity, so we can pick between these cases by insisting that the generally covariant formulation not admit simpli cation. Bergmann (1942, p159) explicitly incorporates this requirement into the statement of the principle of general covariance: The hypothesis that the geometry of physical space is represented best by a formalism which is covariant with respect to general coordinate transformations, and that a restriction to a less general group of transformations would not simplify that formalism is called the principle of general covariance
General covariance and general relativity 829
At rst this seems like a purely ad hoc contrivance. However Bergmann's proposal connects directly with the view that relativity principles are geometric symmetry principles, as we shall see in section 6.2 below. Alternatively, Bondi (1959, p108) calls the proposal into question by recalling Fock's use of harmonic coordinates to reduce the covariance of general relativity (see section 9 below). There have been other studies of the relationship between a theory and its generally covariant reformulation and these studies arrive at conclusions uncomfortable for Kretschmann's objection. Scheibe (1991, 1981) has considered the relationship within a more precise formal setting. He concludes that it is simply not obvious that any geometry of restricted covariance can always be recast in a generally covariant formulation. Post (1967) concludes that the process of rendering theories generally covariant is far from automatic triviality and must be treated with some care. In the case of electromagnetic theory, he shows how di erent ways of rendering the theory generally covariant actually lead to distinct theories. Mashoon (1986) similarly emphasizes that, while any theory can be rendered generally covariant, the manner in which it is done can have physical consequences, in particular, in the measurements of accelerated observers. Many authors are prepared to accept Kretschmann's objection but feel that it has to be quali ed in signi cant ways if the true signi cance of general covariance is to be appreciated. While accepting Kretschmann's objections and that a requirement of general covariance is not a relativity principle like that of special relativity, Weinberg (1972, pp92, 111{3) characterizes general covariance as akin to the gauge invariance of electromagnetic elds. Accepting Kretschmann's objection, Bunge (1967, section 3.1.3) observes that if general covariance is understood as simply requiring form invariance of laws, then it does become a purely mathematical requirement. Therefore he concludes that general covariance is to be understood as a regulative rather than constitutive principle. Mavrides (1973, p66) also accepts Kretschmann's objection but sees the signi cance of the principle in absorption of acceleration into the non-Euclidean structure of spacetime. Zahar (1989, section 8.1) approaches the problem with a distinction introduced by logicians between an object language and its metalanguage. In this context, the object language contains the assertions about physics systems and the metalanguage contains assertions about the object language. Whether a body of object language assertions, such as Newtonian theory, is generally covariant is not itself an object language assertion. It belongs to the metalanguage. We may be able to nd a generally covariant formulation of Newtonian theory which is logically equivalent to the original Galilean covariant version. However the meta-level property of general covariance is not inherited by the original formulation, for meta-level properties are not transmitted by logical equivalence. Therefore we cannot say that Newtonian theory is itself generally covariant. Several other authors have approached general covariance as a principle of operating a meta-level of language. See Graves (1971, pp143{7). In particular, Tornebohm (1952, section 41) characterizes the principle of general covariance as a closure rule operating on a meta-level in which one quanti es over coordinate systems employed in statements of physical laws. Finally, see Kuchar (1988) for a reincarnations of the issues raised by the debate of Kretschmann's objection in Hamiltonian dynamics and canonical quantization of generally covariant systems.
6. Is the requirement of general covariance a relativity principle?
6.1. Disanalogies with the principle of relativity of special relativity
In addition to accusations that his principle of general covariance is physically vacuous, Einstein's treatment of general covariance has been besieged by continuing complaints
830 J D Norton
that the achievement of general covariance does not amount to a generalization of the principle of relativity to acceleration. These complaints have come in many di erent forms. Some of the earliest make the obvious point that such an extension of the principle of relativity to accelerated motion seems to be atly contradicted by the simplest observations. The principle of relativity of inertial motion ts the experiences of a traveller in a train moving uniformly on smooth tracks; nothing within the carriage reveals the train's motion. However, the same is not so if the train accelerates, as was pointed out acerbically by Lenard (1921, p15), whose involvement in the persecution of Einstein in Germany in the 1920s is
well known: Let the train in consideration undertake a distinct, non-uniform motion . . . If, as a result, everything in the train is wrecked through the e ects of inertia, while outside everything remains undamaged, then, I believe, no sound mind would want to draw any other conclusion than that the train had altered its motion with a jolt and not the surroundings. For Einstein's reply to this exact passage, see Einstein (1918a). It was only in the 1950s and 1960s that such long-standing worries took a prominent though still disputed place in the mainstream literature. This dissident view drew strength from such eminent relativists as Fock and Synge, who dared to proclaim what few would admit: they just could not see how Einstein's theory generalizes the principle of relativity| and they even suspected that Einstein could not see it either. So Synge (1966, p7) wrote: . . . the general theory of relativity. The name is repellent. Relativity? I have never been able to understand what that word means in this connection. I used to think that this was my fault, some aw in my intelligence, but it is now apparent that nobody ever understood it, probably not even Einstein himself. So let it go. What is before us is Einstein's theory of gravitation. See also Synge (1964, p3) and (1960, p ix) where he wrote . . . the geometric way of looking at space-time comes directly from Minkowski. He protested against the use of the word `relativity' to describe a theory based on an `absolute' (spacetime), and, had he lived to see the general theory of relativity, I believe he would have repeated his protest in even stronger terms. In similar vein, Fock (1959, pp xvi{xviii, 367{8, 375{6) treated a relativity principle as stating a uniformity of spacetime. Thus special relativity admits a relativity principle because of the uniformity of a Minkowski spacetime. The spacetimes of general relativity, however, manifest this uniformity only in the in nitesimal, so that the naming of the theory `general relativity' or `general theory of relativity' is simply incorrect, betraying Einstein's failure to understand his own theory. Fock continued (p368) The fact that the theory of gravitation, a theory of such amazing depth, beauty and cogency, was not correctly understood by its author, should not surprise us. We should also not be surprised at the gaps in logic, and even errors, which the author permitted himself when he derived the basic equations of the theory. In the history of physics we have many examples in which the underlying signi cance of a fundamentally new physical theory was realized not by its author but by somebody else an in which he derivation of the basic equations proposed by the author proved to be logically inconsistent. It is sucient, to point to Maxwell's theory of the electromagnetic eld ... Allowing in addition that the only admissible sense of `general relativity' is as purely formal property of general covariance, Fock (1974, p5) concluded Thus we can sum up: general relativity cannot be physical, and physical relativity cannot be general. These confessions were engagingly candid and their iconoclastic sentiments found receptive
General covariance and general relativity 831
audiences. The heresy of disbelief in Einstein became respectable. Fock and Synge are, of course, not alone in divorcing general covariance from a generalization of the principle of relativity and announcing the failure of Einstein's e ort in this regard. See for example Landau and Lifshitz (1951, p229), Davis (1970, p219) , Raine and Heller (1981, p135) and Bondi (1979, p129).
6.2 Relativity principles as symmetry principles
If covariance principles are not relativity principles, then what are relativity principles? New answers to this question have come repeatedly within the tradition that proposes the divorce of general covariance from a generalization of principle of relativity. We shall see that they eventually stabilize on the view that a relativity principle expresses a symmetry of the spacetime structure. One of the earliest proposals comes from Kretschmann. His famous objection to general covariance actually occupies a small part of his lengthy paper (1917). The bulk of it is devoted to developing an alternate interpretation of relativity principles. His proposals are embedded within extended calculations and circuitous verbiage. They appear to reduce to the following. The key idea in identifying the relativity principle of some given theory lies not in extending its covariance, but in reducing it to the minimum group possible. This reduction must be done in a way that identi es a group associated with the theory's physical content rather than some particular formulation of it. In the case of special relativity, his general proposal leads to the expected result: the Lorentz group expresses the theory's relativity principle. Consider the bundle of all lightlike worldlines in the theory. In the Lorentz covariant formulation, this bundle is described by the equation
(x1 x01)2 + : : : + (x4 x04)2 = 0 (8)
Where x = x1; : : : ; x4 = ict are the usual spacetime coordinates and x01; : : : ; x04 some arbitrary origin event. This bundle is mapped back into itself by any Lorentz transformation that preserves the origin. Kretschmann allowed that we could extend the usual Lorentz covariant formulation of the theory even as far as generally covariant formulation, using the methods of Ricci and Levi-Civita. However, in a formulation of extended covariance, an allowed transformation will, in general, not map this bundle back into itself. Rather, such a transformation will alter the coordinate image of the bundle. Again, one could consider a formulation whose covariance is restricted to a group smaller than the Lorentz group. However this formulation could only be constructed at the expense of altering the physical content of the theory26. The Lorentz transformation is the formulation of minimal covariance faithful to the theory's physical content. Therefore the Lorentz transformation is the group associated with the theory's relativity principle. A similar analysis in the case of general relativity leads to a quite di erent result. In e ect Kretschmann nds that the single membered identity group plays the same role in general relativity as does the Lorentz group in special relativity. As a result he can arrive at a conclusion that directly contradicts einstein's (p610)
26How Kretschmann arrived at this crucial conclusion is a little unclear to me. Such a formulation would need to replace (8) by another formula or formulae of more restricted covariance and presumably Kretschmann held that any such formulae would have to alter the physical content of (8). For example, to violate Lorentz covariance, the new formula might pick out one or other spatial direction as preferred, whereas equation (8) describing the bundle admits no such preferred directions.
832 J D Norton
Therefore Einstein's theory satis es no relativity principle at all in the sense developed [earlier in the paper]; on the basis of its content, it is a completely absolute theory. To arrive at this result, Kretschmann considered the bundle of light-like worldlines and of free material particles within the theory. He found the former xed the components of the metric tensor g up to a multiplicative factor  and the latter forced  to be a constant. (Notice that these are now familiar results. In modern language: conformal structure xes the metric up to a conformal factor and specifying ane structure forces the factor to be constant.) Finally consideration of spacetime curvature rules out any value of  other than unity. Thus the physical content of the theory xes the metrical components. But once these components are xed, the coordinate system is xed and no covariance transformation remains; in e ect the covariance group has become the identity group and one has no relativity principle. Kretschmann also showed that the same result could be arrived at in another way. As long as the spacetime metric is suciently non-uniform, it is possible to de ne a unique spacetime coordinate system for each metric by setting the four coordinates equal to unique curvature invariants. This once again reduces the covariance group to the identity. Finally Kretschmann could extract one nal blow from his calculations. In e ect he could conclude that the Lorentz group was the largest group possible for any relativity principle in a spacetime theory of the type of special and general relativity (p610): A physical theory, which accords an observationally accessible meaning to the external principle
 
Z
ds = 0 where ds2 = gdxdx

of a space-time manifold of Minkowski normal form of the line element or posits that the invariant metrical character of the manifold is in some other way in principle observable to the same extent, can satisfy no broader relativity postulate in the sense [developed earlier in the paper] than that of the original Einsteinian theory of relativity. Kretschmann's proposal has been criticized at length by Anderson (1966). He argues that the proposal fails since one can too readily reduce the covariance of a theory to the identity. His examples include electrodynamics and special relativity, provided that we add some other structure, such as a scalar eld, to the Minkowski spacetime. Cartan (1927) gave a less bellicose and mathematically more perspicacious characterization of the di erence between the general covariance of general relativity and the Lorentz covariance of special relativity. General relativity threw into physics and philosophy the antagonism that existed between the two principle directors of geometry, Riemann and Klein. The space-times of classical mechanics and or special relativity are of the type of Klein, those of general relativity are of the type of Riemann. Under Klein's Erlangen program a wide range of geometries were all characterized by their associated groups and the geometric entities they studied were the invariants of those groups. The key aspect of these Erlangen program geometries|the Euclidean, the projective, the ane, the conformal and others|was that all the spaces were homogeneous. In the Riemann tradition, one considered a space and a group of transformations. But the geometric entities investigated are no longer the invariants of the transformations, for in this case there are essentially none. Instead one is interested in the invariants of a quadratic di erential form, the fundamental or metrical form, that is adjoined to the space. As result, the groups associated with geometries in the two traditions have very di erent signi cance. The spacetime geometry of special relativity, as introduced by Minkowski, is in the tradition of Klein. As a result its characteristic group, the Lorentz group, is
General covariance and general relativity 833
associated with the homogeneity of the spacetime. General relativity lies in the Riemann tradition and, as a result, its general group of transformation is associated with no such homogeneity. Sesmat (1937, pp382{3) gave a more algebraic characterization of why the felt the general covariance of general relativity had failed to implement a generalization of the principle of relativity. What was needed was a theory whose laws would remain unchanged in form under transformations between all frames of reference including accelerated ones, in the same way that the laws of special relativity remained invariant under Lorentz transformation. The general covariance of general relativity just did not do this. Under the transformations of general covariance, such as transformation between Cartesian and polar coordinates, the expression for basic tensors do change. What general covariance does allow, however, is that a tensor, such as the Einstein tensor, can retain its zero value in empty space under these transformations, even though its expression changes. Sesmat's point seems to be precisely the point that Weinberg (1972, p92) is making when he explains the di erence between the Lorentz invariance of special relativity and general covariance. One could, he notes, expand the covariance of Newton's second law by transforming it under Lorentz transformation. However, a new quantity, the velocity of the coordinate frame would appear in the transformed equation. The requirement that this velocity does not appear in the transformed equation is what we call the Principle of Special Relativity, or `Lorentz invariance' for short, and this requirement places very powerful restrictions on the original equation. Similarly, when we make an equation generally covariant, new ingredients will enter, that is, the metric tensor g and the ane connection . The di erence is that we do not require that these quantities drop out at the end, and hence we do not obtain any restriction on the equations to start with; rather we exploit the presence of g and  to represent gravitational elds Fock (1957) (see also Fock 1959, p xiii{xiv, 166) gave a synthesis of all these ideas: the homogeneity of spaces in the Klein tradition, the mapping back into themselves of Kretschmann's bundle of light-like and inertial worldlines and he gave it in an algebraic form indicated by Sesmat and Weinberg. In considering the uniform or homogeneous spacetime of special relativity, he explained (p325): The property of spacetime being homogeneous means that (a) there are no privileged points in space and in time; (b) there are no privileged directions, and (c) there are no privileged inertial frames (that all frames are moving uniformly and in a straight line with respect to one another are on the same footing). The uniformity of space and time manifests itself in the existence of the Lorentz group. In particular, the equality of points in space and time corresponds to the possibility of a displacement, the equality of directions corresponds to that of spatial rotations, and the equality of inertial frames corresponds to a special Lorentz transformation. Fock then gave this condition mathematical expression. The Lorentz transformation leaves unchanged the Minkowski line element
ds2 = dx20 dx21 dx22 dx23 = g dxdx (9)
where the x0; : : : ; x3 are the usual spacetime coordinates of the Lorentz covariant formulation. This same condition can be stated in arbitrary coordinates in which the line element (9) becomes
834 J D Norton
ds2 = g dxdx
The mathematical expression of the homogeneity of the Minkowski spacetime is now stated as the preservation of the functional form of the components of the metric in some class of coordinate systems. That is, if the metric has components g in some arbitrary coordinate
system x, then it will be possible to transform to a new coordinate system x0 in which
the new components of the metric g0 are the same functions of x0 as the g are the x. That is,
g0 (x0) = g (x) (10)
where the equality must be read as holding for equal numerical values of the quadruples x and x0. This condition is considerably more restrictive than merely requiring that the
components g transform into g0 under the usual tensor transformation rule. And it
expresses a homogeneity of the spacetime since both coordinate systems x and x0 relate in indistinguishable fashion to the metric tensor. The set of coordinate systems with this property are related by a ten parameter group which corresponds to the Lorentz group. Notice that the algebraic expression for the transformations from x to x0 in the Lorentz group can no longer be the familiar formulae (1) of Einstein's original 1905 paper. For example, in generalizing the coordinates, the coordinate system of (9) may remain inertial but with the Cartesian spatial coordinates replaced by polar coordinates, in which case the expression for the Lorentz transformation would have to be altered correspondingly. However, whatever may be their altered form, the transformation equations must leave unchanged the fundamental form of the components of the metric tensor. Otherwise the spacetime would distinguish between two inertial coordinate systems, in violation of this uniformity. That is the condition expressed in (10). The distinction between simple covariance and transformation of form (1) seems to be distinction between Buchdahl's (1981, p29) `improper' and `proper form invariance'. In his example, the equation gijSiSj = 0 (where S is a scalar eld and commas denote di erentiation) is improperly form invariant if the transformed equation just retains this
form as, say, gi0j0Si0Sj0 = 0. It is properly form invariant if the gi0j0 of the transformed
equation also remain the same functions of the new coordinates as the untransformed gij were of the old. Fock's proposal now relates directly to Bergmann's (1942, p159) statement of the principle of general covariance as given in section 5.5. above. According to (10), a generally covariant formulation of special relativity will admit a ten parameter subgroup of transformation|the Lorentz transformation|that preserves the functional form of the components of the metric tensor g. It can do so in many di erent ways. One merely selects some arbitrary coordinate system in which the Minkowski metric has components g and allows condition (10) to generate the subgroup. If one begins with the usual diagonal form of the metric, , one arrives at the usual form of the Lorentz transformation (1). Each of these subgroups is associated with a formulation of special relativity of reduced covariance of the particular functional form of the metrical components that remain unaltered according to (10) will be built into its laws. Therefore Bergmann's statement of the principle of general covariance will judge the generally covariant formulation of special relativity to be inadmissible and thus preserves a distinction between the covariance of general relativity and of special relativity. Notice also that the formulations of special relativity of reduced covariance are now of a form compatible with Klein's Erlangen program, since the Riemannian quadratic di erential form are no longer transformed merely covariantly within the theory. Thus, in
General covariance and general relativity 835
accord with Cartan's observations, the transformation groups of the formulations are now associated with the homogeneity of the spacetime. Fock's condition (10) has an immediate expression in the geometric approach to spacetime theories. Let h be the dual manifold di eomorphism of the coordinate transformation de ned on a Minkowski hM; gabi. Then Fock's condition (10) becomes
h  gab = gab (11)
and the group of transformations satisfying this condition is the Lorentz group.27 That is, the Lorentz group is the group of di eomorphisms that are the symmetry transformations or isometries of the Minkowski metric. (Wald, 1984, pp 48, 60, 438). The existence of this group expresses the uniformity of the Minkowski spacetime. With this terminology, we can summarize why Fock and others believe that the transition from special to general relativity has failed to generalize the principle of relativity. Two groups are associated with the formulations of a theory: its covariance group characterizes purely formal aspects of its formulation; its symmetry group characterizes a physical fact, the degree of uniformity of the spacetime and this uniformity group allows the theory to satisfy a relativity principle. In the transition from a Lorentz covariant formulation of special relativity to a generally covariant formulation of general relativity, the covariance group is expanded. This is, however, merely an accident of formulation. The symmetry group is actually reduced from the Lorentz group to the identity group, for the general case. The identity group is associated with no relativity principle at all. Therefore the transition from special to general relativity does not generalize the relativity principle. It eradicates it.
6.3. Coordinate systems versus frames of reference
Fock took it as immediate that his condition (10) automatically realized the equivalence of inertial frames of reference whereas general relativity embodies no such equivalence. That this is correct may not be immediately clear given that such formulations of the principle of general covariance such as Bergmann's do preserve a sense in which the natural covariance. To give a precise statement of this result we require a clearer statement of what is a frame of reference. In traditional developments of special and general relativity it has been customary not to distinguish between two quite distinct ideas. The rst is the notion of a coordinate system, understood simply as the smooth, invertible assignment of four numbers to events
27To see the transition, let the metric gab have components g in some coordinate system and
let the transformation from coordinate systems x to x0 satisfy condition (10). To generate the
dual di eomorphism h, we now just consider the functional relation between x and x0 as a map
from quadruples of reals x to quadruples of reals x0(x). In one of the coordinate systems allowed under (10),the di eomorphism h maps an event p with the four coordinates x to an event hp with
coordinates x0(x) in the same coordinates system. Consider the metric h  gab carried along to hp from p under h. If the metric at p has components g, then the carried along metric at hp will have the same components g in the carried along coordinate system and the carried along coordinate system will assign coordinates x to hp. We now see that this carried along metric is the same as the original metric at hp, as (11) demands, by comparing their components in the original coordinate system. We transform the carried along metric back from the carried along coordinate system to the original by means of the coordinate transformation of (10) and nd that the carried along metric has components g0 at hp, which has coordinates x. Therefore the carried along
metric agrees with the original metric since the functional forms of g and g0 are the same. For further discussion of the duality of coordinate transformation and manifold di eomorphism, see Norton (1989, section 2.3)
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in spacetime neighbourhoods. The second, the frame of reference, refers to an idealized physical system used to assign such numbers. More precisely, since the physical systems tend to be space- lling, one is concerned with how such hypothetical system would behave were they to be constructed. Many such systems are possible. For example one can imagine space full of similarly constructed clocks and all of them attached to a rigid frame of small rods. The clock readings give us the time coordinates and the counting of rods gives us spatial coordinates. To avoid unnecessary restrictions, we can divorce this arrangement from metrical notions. Following Kopczynski and Trautman (1992, pp24{5), we could require only that the space- lling family of clocks bear three smoothly assigned indices (which could function as spatial coordinates), that the clocks tick smoothly, although not necessarily in proper time, and that time readings vary smoothly from clock to clock. Of special importance for our purposes is that each frame of reference has a de nite state of motion at each event of spacetime. Within the context of special relativity and as long as we restrict ourselves to frames of reference in inertial motion, then little of importance depends on the di erence between an inertial frame of reference and the inertial coordinate system it induces. This comfortable circumstance ceases immediately once we begin to consider frames of reference in nonuniform motion even within special relativity. This became a major problem for Einstein to negotiate as early as 1907, when he began to consider uniformly accelerated frames of reference in his new gravitation theory. He found (1907, section 18) the need to introduce coordinate times which could not be read directly from clock measurements. Similarly, due to the Lorentz contraction of rods oriented in the direction of motion, the geometry associated with a uniformly rotating frame of reference ceased to be Euclidean. As a result, spatial coordinates can no longer be assigned by the usual methods with measuring rods. The point of Einstein's rotating disk thought experiment ( rst published in Einstein (1912, section 1) and best known from Einstein (1916, section 3)) is that spacetime coordinates will lose this direct metrical signi cance once we stray from the familiar inertial coordinate systems of special relativity.28 With the advent of general relativity, Einstein wished to consider frames of reference with arbitrary states of motion. However he deemed it impractical to retain even a vestige of the idealized physical system of the frame of reference. In their place he simply used arbitrary coordinate systems. The association of an arbitrary coordinate system with an arbitrary frame of reference became standard in the literature for many decades. Thus, for example Bergmann (1962, p207) explains In all that follows we shall use the terms `curvilinear four-dimensional coordinate system' and `frame of reference' interchangeably. Thus, in Einstein's writings, whatever equivalence is established by general covariance of arbitrary coordinate systems is also conferred upon arbitrary frames of reference and, if we recall the connection between a frame of reference and a state of motion, the powerful suggestion is that this is all that is needed to extend the principle of relativity to arbitrary motions. The connection is complicated slightly by the fact that some coordinate
28The problem is even more complicated than Einstein indicated. An inertial frame of reference in a Minkowski spacetime is naturally associated with Euclidean spaces, with are the spatial hypersurfaces everywhere orthogonal to the worldlines of the frame's elements. The worldlines of the elements of a rotating disk admit no such orthogonal hypersurfaces. Since the spacetime of special relativity remains at, we may well ask in what space does the geometry become non-Euclidean. The most direct answer is that this geometry is induced onto the `relative space' formed by the worldlines of the elements of the disk. This space can be de ned precisely as in Norton (1985, section 3). For further discussion of the role of the rotating disk thought experiment in Einstein's thought, see Stachel (1980a).
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transformations clearly do not relate di erent states of motion, such as the transformation between spatial cartesian and polar coordinates. However some subgroup of the general group of coordinate transformations is the appropriate one, as Einstein (1916, section 3) makes clear when he writes: It is clear that a physical theory which satis es this postulate [of general covariance] will also be suitable of the general postulate of relativity. For the sum of all substitutions in any case includes those which correspond to all relative motions of three-dimensional systems of co-ordinates. More recently, to negotiate the obvious ambiguities of Einstein's treatment, the notion of frame of reference has reappeared as a structure distinct from a coordinate system. If one conceives of a frame of reference as a space lling system of hypothetical instruments moving with arbitrary velocities, then the minimum information needed to pick out the frame is the speci cation of an arbitrary frame of reference|and the one I shall use here| is that it is a congruence of curves, that is, a set of curves such that every event in the spacetime manifold lies on exactly one of its curves. (Torretti 1983, p28, Norton, 1985, section 3, Vladimirov et al 1987, p95). If the notion of timelike is de ned, we would also require the curves be timelike to ensure that they are the worldlines of physical elements. In the case of the semi-Riemannian spacetimes of relativity theory, whatever further information one might need is supplied by the theory's metrical structure. From it we can read the time elapsed as read by proper clocks moving with the frame, or changes in the directions and spatial distances of neighbouring elements of the frame. Various alternative de nitions of frame of reference are possible. Since a smooth congruence of curves can be speci ed as the unique set of integral curves of a smooth, nonvanishing time-like vector eld, one could take a frame of reference to be such a timelike vector eld (Earman 1974, p270, Jones, 1981, p163). Again, one can employ richer structures. The timelike vector eld could be supplemented by a triad of spacelike vectors pointing to the worldlines of neighbouring elements of vectors over the spacetime manifold. (Synge 1960, ch III.5, Vladimirov et al 1987, p95). Finally a coordinate system is adapted to a frame of reference if the curves of the frame coincide with the curves of constant spatial coordinates. Therefore we could take a frame to be the equivalence class of all coordinate systems adapted to some congruence (Earman 1974, 2270). This de nition has the advantage of bringing us closest to the traditional correspondence between frames of reference and coordinate systems. In special relativity, an inertial frame of reference is a congruence of timelike geodesics. An inertial coordinate system is a coordinate system adapted to an inertial frame of reference.
6.4. Relativity principles and the equivalence of frames
With the notion of frame of reference clari ed, it proves possible to give a more precise treatment of the principle of relativity in so far as it asserts an equivalence of various states of motion, that is, of various frames of reference. Einstein's original treatment of the principle of relativity in special relativity amounted to requiring that the laws of physics adopt the same form when expressed in any inertial coordinate system. This type of formulation of the principle was quite serviceable in the context of a Lorentz covariant special theory of relativity. As we have seen, however, there have been signi cant challenges to the idea that form invariance of laws can capture any physical principle when we are prepared to employ mathematical techniques powerful enough to render virtually any theory generally covariant. A precise formulation of the relevant notion of equivalence of frame has been developed
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within work that includes Earman (1974), Friedman (1983, especially ch IV.5) and Jones (1981). Their proposals explore many variant de nitions and do so within the context of a wide range of theories, including variants of Newtonian spacetime theory. The essential ideas they share can be illustrated by the following treatment of special and general relativity. The essence of the principle of relativity in the special theory is the indistinguishability of all the inertial states of motion. Thus Einstein's 1905 special relativity paper had been motivated by the realization that no experiment in mechanics, optics or electrodynamics could reveal the uniform motion of the earth through the aether. That is, space and time `look the same' experimentally to observers in any state of inertial motion. Einstein's task was to devise a theory in which they looked the same theoretically as well. This condition can be broken up into a kind of pseudo-experiment. We begin with an inertial observer, who performs a range of experiments in kinematics and other branches of physics. The observer is then boosted into uniform motion with respect to his original state of motion and carries along with him a complete record of all the experiments and their outcomes. These experiments are now repeated and the outcomes compared with those of the original set. The principle of relativity requires that both sets of outcomes must be the same and a theory satisfying the principle of relativity must predict that this will be so. (For a comparison of this sense of the principle and the one that requires form invariance of laws, see Anderson (1964, pp176{82).) This pseudo-experimental condition can be translated into a theoretical condition that amounts to the principle of relativity in special relativity. The theoretical dialog of the inertial observer is the inertial frame of reference. The analog of the setting of the observer into uniform motion is a Lorentz transformation of the frame of reference. The setting up and outcome of all experiments performed by the observer will be determined fully by the spacetime structures of the theory. Therefore the carrying along of the complete description of the observer's experiments and outcomes translates into the carrying along under Lorentz transformation of the spacetime structures of the theory.29 The principle of relativity now simply amounts to the requirement that the Lorentz transformation map spacetime structures allowed by the theory into spacetime structures allowed by the theory. Without further assumption it follows that special relativity satis es the principle of relativity as far as all kinematical experiments are concerned. These are idealized experiments in which the frame directly `sees' the metrical structure of the spacetime without assistance from further material systems. Their outcome is determined solely by that metrical structure. The satisfaction of the principle of relativity follows immediately from the fact that an arbitrary Lorentz transformation h is a symmetry of the Minkowski metric gab that is, it satis es Fock's condition (11). Therefore, if h transforms an inertial frame F1 into an inertial frame F2, then the metric seen by F1 and carried along to F2, h  gab, is the same as the metric gab seen by F2. In the more realistic case, the experiments will involve further spacetime structures, such as electromagnetic elds and charges. The principle of relativity will be satis ed only if these further spacetime structures satisfy the following condition, which is the geometric statement of the Lorentz covariance of the theories of these furthers structures. Let the theory have models
hM gab; (O1)ab:::; (O2)ab:::; : : :i (12)
29This treatments assumes that there are no spacetime structures that elude experimental test, such as the absolute spacetime rigging of a Newtonian spacetime, which introduces a state of rest that cannot be revealed in any experiment (see Friedman 1983, ch III).
General covariance and general relativity 839
where M is an R4 di erentiable manifold, gab a Minkowski metric, and (O1)ab:::; (O2)ab:::; : : : the extra spacetime structures. If h is any Lorentz transformation and (12) is a model of the theory, then
hM gab; h  (O1)ab:::; h  (O2)ab:::; : : :i
must also be a model of the theory. The satisfaction of the principle of relativity now follows. Let F1 be an inertial frame of reference in which are conducted experiments associated with structures (O1)ab:::; (O2)ab:::; : : :. If we transform via Lorentz transformation h to any other inertial frame F2, we require that the theory admit precisely the same experiments and outcomes. That is we require that the theory allow structures h(O1)ab:::; h(O2)ab:::; : : : This is precisely what the geometric version of Lorentz covariance allows. This analysis gives us a precise sense in which the equivalence of inertial frames of reference is realized within the special theory of relativity. The basic moral of the work of Earman, Friedman and Jones is that there is no natural sense in which this equivalence obtains in the spacetimes of general relativity and that there is certainly no extension of it to accelerated frames of reference. In this sense, there is no principle of relativity in the general theory of relativity. This moral follows immediately from the fact that special relativity admits a non-trivial symmetry group, the Lorentz group, which maps inertial frames of reference into one another. The spacetimes of general relativity in general admit no symmetries. In general relativity, the closest analog of an inertial frame of reference is a frame in free fall. It is represented by a congruence of timelike geodesics. In general, a transformation of that maps one freely falling frame of reference into another will not be a symmetry of the metrical structure. Therefore spacetime observers of the rst frame will see di erent metrical properties in spacetime than will those of the second. The indistinguishability required for the equivalence of frames does not obtain. Considering arbitrary frames of reference rather than those in free fall clearly does not change this result. That this sense of equivalence of frames fails to obtain in general relativity is not so surprising and it is dicult to imagine that Einstein ever expected that it would. The real puzzle, then, is to determine the sense in which Einstein believed the equivalence to be extended by general relativity. There is one reading in this geometric language that does allow a general equivalence of frames (Norton 1985, section 5). So far it has been assumed that the background spacetime is represented by the combination of manifold and metric. If instead one takes the manifold alone as the background spacetime, then one immediately has an equivalence of all frames of reference. For, considering just R4 manifolds for simplicity, an arbitrary automorphism is a symmetry of the manifold. Since any frame of reference can be mapped into any other by an automorphism, it follows that each frame `sees' the same spacetime background so that they are equivalent in at least that sense. If this equivalence is to be extended to the sort of equivalence of the principle of relativity of special relativity, then the metric tensor eld of general relativity must be treated in a similar fashion to the structures (O1)ab:::; (O2)ab::: of the above discussion of special relativity. Then a similar sense of equivalence of arbitrary frames follows directly from the active general covariance of general relativity. Let F1 be any frame of reference which sees a metrical eld gab and other elds (O1)ab:::; (O2)ab:::; : : :. That is, the theory has a model
hM gab; (O1)ab:::; (O2)ab:::; : : :i (12)
Then, if F2 is any other frame of reference, the theory must allow a model in which F2 sees an identically con gured set of elds. That is, if h is an automorphism that maps F1 into
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F2, then F2 must see the elds h  (O1)ab:::; h  (O2)ab::: so that the theory must also have a model
hM gab; h  (O1)ab:::; h  (O2)ab:::; : : :i
That it does follows directly from its active general covariance (section 5.4 above). The diculty with this proposal is that it allows an equivalence of arbitrary frames of reference in all theories that are generally covariant. Such theories include versions of special relativity and Newtonian spacetime theory. Thus, if this generalized equivalence of frames is to be distinctive to general relativity, there must be some principled way of relegating the metric tensor to the contents of spacetime in general relativity, whereas in other spacetime theories, such as special relativity, this metrical structure is to be part of the background spacetime. What makes such a division plausible is the fact that the metric tensor of general relativity incorporates the gravitational eld. Thus its state is a ected by the disposition of masses in the same way as a Maxwell eld is a ected by the disposition of charges. The analogy can be pressed further. In special relativity one can conduct an electrical experiment with some con guration of charges in an inertial frame of reference. The principle of relativity requires that, if we were to recreate that same con guration of charges in another inertial frame, then we would produce the identical elds and experimental outcomes. This is the sense in which all inertial frames of reference are equivalent. Similarly, one could consider some con guration of masses and the metric eld they produce in relation to an arbitrary frame of reference in general relativity as a kind of gravitational experiment in that frame. The active general covariance of general relativity then tells us that we could have laid out the same con guration of masses and elds in any other frame of reference, so that the gravitational experiment would have proceeded identically in any frame of reference. This gives us a sense in which arbitrary frames of reference are equivalent in general relativity. The success of this generalized equivalence depends fully on our being able to conceive of the metric eld as apart of the contents of spacetime in general relativity but not in other theories like special relativity. Einstein's 1918 version of Mach's principle allowed this conception since it required that the metric eld be fully determined by the matter distribution, so that this eld would have the same sort of status as the matter distribution. Since Mach's Principle in this form fails in many of the spacetimes of general relativity, it cannot be used to justify a generalized equivalence of frames in that theory. The only other well developed analysis that allows this conception of the metric eld concerns the distinction between absolute and dynamic objects, to be discussed in the section 8 below. As a dynamical object, the metric of general relativity is naturally classi ed as part of the content of spacetime. As an absolute object, the Minkowski metric of special relativity is naturally classi ed as part of the background spacetime.
General covariance and general relativity 841
7. General relativity without principles
7.1. General relativity without general relativity
Einstein's own developments and discussion of the general theory of relativity place so much importance on general covariance and the extension of the principle of relativity that most accounts of the theory seem compelled to take a position on their importance. Many essentially agree with Einstein as we have seen in section 4. Many others, as we have seen in sections 5 and 6, disagree with Einstein's views; they develop general relativity without claiming general covariance as a fundamental physical postulate and they explain why they do so. There is a third category of exposition of general relativity. These are the expositions that take no special notice of general covariance at all. Of course the develop general relativity in a generally covariant formalism, as is the standard practice. However the expositions are conspicuous for the absence of any statement of fundamental principle concerning covariance or relativity. There is no `principle of general covariance', no `general principle of relativity' and no pronouncement that the theory has extended the equivalence of frames of reference to accelerated frames. And there is no explanation of why these principles are not discussed. It is dicult to know what signi cance to read into such formulations of general relativity without general relativity. Many of these expositions are mathematically oriented. So we might suppose that their authors simply decided not to contend with the question of the physical foundations in favor of other more mathematical aspects of the theory. It is hard to imagine, however, that an author of writing on general relativity can be completely unaware of Einstein's views, if not also the disputes over them. Therefore when that author writes textbook length exposition of general relativity which fails to include such phrases as `general principle of relativity' or `principle of general covariance', one must suppose that the author is making a statement by omission. (The omissions are typically so complete that, if the text has an index, these terms will not be listed in it.) We have already seen that Synge and Fock object to `general relativity' as a misnomer. Thus it seems obvious that similar sentiments drive such authors as that of Time and space, Weight and Inertia: A Chronogeometrical Introduction to Einstein's Theory (Fokker 1965) who display remarkable ingenuity in avoiding the term `general relativity'. Finally, even if no statement is being made by omission, the very possibility and frequency of such accounts of general relativity do indicate that the place of these principles in the theory might not be so straightforward. If the principles are fundamental physical axioms, they would be hard to avoid, even as consequences in an alternate axiomatization. One is hard pressed to imagine a formulation of thermodynamics without the law of conservation of energy as a fundamental axiom or one of the earliest and most important theorems! The subtlety of the situation is captured by Trautman, who observed well into his exposition (1964, p122) of general relativity . . . we have managed to obtain general relativity by a (we hope) fairly convincing chain of reasoning without ever mentioning such a principle [of general covariance]. He did proceed, however, to list several senses of the principle and their non-trivial relationships to the theory. Thus one can nd general covariance relevant without mentioning it in development of the theory. With these interpretative cautions, we can proceed to note that the tradition of exposition of general relativity without general relativity extends back to the earliest of the theory. There are many exposition of relativity theory with this character from the 1920s. They include Bauer (1922), Birkho (1927), Darmois (1927), Chazy (1928) and De Donder
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(1925) (but De Donder (1921, pp10{15) had emphasized the arbitrariness of coordinates in general relativity and the invariance of its fundamental equations). Eddington (1924, ch I, section l ) labours in detail the notion that one can use arbitrary `space-time frames' for describing phenomena, but without ever mentioning a principle of covariance or a generalized principle of relativity. His earlier Eddington (1920, p20) had allowed that a generalization of the principle of relativity in the theory in so far as he conceded `it will be seen that this principle of equivalence is a natural generalization of the principle of relativity'. This remark was not repeated in Eddington (1924). The lean years after the 1920s saw several exposition of general relativity without general relativity: Rainich (1950) and the synopsis of general relativity by Zatskis (1955). The revival of interest in general relativity in the 1960s brought more such expositions and they have included some of the most important expositions of the theory: Fokker (1965), Schild (1967) (although he mentions (p20) that general relativity `shows there are no inertial frames at all'), Robertson and Noonan (1968), Ehlers (1971), Hawking and Ellis (1973), Dirac (1975), Falk and Ruppel (1975) (although the notion of a generalized principle of relativity is alluded to brie y, e.g., p323), Sachs and Wu (1977), Clarke (1979) (although section 3.1.3 does emphasize the loss of global inertial systems and the novelty of arbitrary coordinate systems in general relativity), Frankel (1979), Schutz (1985) (Although it is allowed (p 3) that general relativity is more general in allowing both inertial and accelerated observers), Martin (1988), Hughston and Tod (1990), Stewart (1990).
7.2. The principle of equivalence as the fundamental principle
While many of these accounts of general relativity, avoid mention of principles of general covariance an generalized relativity, many of them do nd a special place for just one of the three fundamental principles listed by Einstein in 1918, the principle of equivalence. Of course, the version used is typically not Einstein's but one or other variant of an in nitesimal principle of equivalence. The principle is not used in Einstein's manner as a stepping stone to a generalized principle of relativity. Rather it is used to establish a notion claimed as a fundamental principle of general relativity, that special relativity holds in nitesimally in the theory; or, less commonly, it is just taken to be as much of the generalized principle of relativity as general relativity will admit. Such treatments, which employ only the principle of equivalence as a fundamental principle, include: Silberstein (1922, p 12), Eddington (1924, section 17) (although emphasizing (p41) that the principle is to be derived rather than postulated in the exposition), Birkho (1927, pp 140{4), Landau and Lifshitz (1951, ch 10) Fokker (1965, section 6.9) (with the principle in Einstein's original form), Robertson and Noonan (1968, section 6.9), Schild (1967), Falk and Ruppel (1975, section 32), Clarke (1979, ch 3), Frankel (1979, ch 2), Raine and Heller (1981, ch 6.8) Schutz (1985, p 184), Martin (1988, section 1.6, 5.11), Stewart (1990, section 1.13). We have the exposition of Tonnelat (1959), who takes the principle of equivalence to be a `principle of generalized relativity' (p 327) and Wasserman (1992), who also remarks brie y (p342) that the principle of equivalence extends the principle of relativity to include accelerated frames of reference.
7.3 Challenges to the principle of equivalence
One might well wonder if we have not at last found the uncontroversial core of Einstein's accounts of the foundational principles of general relativity in these expositions. That core would now just be the principle of equivalence, even if it is in an altered form Einstein never endorsed. However not even the popular versions of the principle of equivalence have escaped telling attack. The best known challenge has been stated most clearly by Synge. His concern is that
General covariance and general relativity 843
the presence or absence of a gravitational eld must be characterized geometrically, that is, in invariant terms. He asserts that the presence of a gravitational eld corresponds just with non-vanishing curvature of spacetime. Such an invariant criterion is una ected by coordinate transformation, by change of frame of reference or by a change of the state of motion of the observer. Therefore none of these changes will be able to transform away a gravitational eld or bring one into existence, contrary to many versions of the principle of equivalence. He is unimpressed with the requirement that the spacetime metric become diag(1,1,1,-1) at some nominated event, thereby mimicking special relativity at least in some in nitesimal sense. Synge deems this trivial since it merely amounts to the requirement that the metric have Lorentz signature. Thus he wrote his famous lament (1960, p ix) about relativists who . . . speak of the Principle of Equivalence. If so, it is my turn to have a blank mind, for I have never been able to understand this principle. Does it mean that the signature of the spacetime metric is +2 (or -2 if you prefer the other convention)? If so, it is important, but hardly a principle. Does it mean that the e ects of a gravitational eld are indistinguishable from the e ects of an observer's acceleration? If so it is false. In Einstein's theory, either there is a gravitational eld or there is none, according as the Riemann tensor does not or does vanish. This is an absolute property, it has nothing to do with any observer's worldline. Spacetime is either at or curved, and in several places in the book I have been at considerable pains to separate truly gravitational e ects due to curvature of spacetime from those due to curvature of the observer's world-line (in most cases the latter predominate). The Principle of Equivalence performed the essential oce of midwife at the birth of general relativity. But, as Einstein remarked, the infant would never get beyond its long-clothes had it not been for Minkowski's concept. I suggest that the midwife be now buried with appropriate honors and the facts of absolute space-time faced. The idea that the presence of a gravitational eld is associated with the invariant property of curvature can be translated in to observational terms. The non-vanishing of the Riemann curvature tensor entails the existence of tidal forces acting on bodies in free fall. The goal of restricting versions of the principle of relativity to in nitesimal regions of spacetime is to eliminate these tidal forces. However they cannot be so eliminated; for example, the tidal bulges on a freely falling droplet remain as the droplet becomes arbitrarily small, ignoring such e ects as surface tension; see Ohanian (1976, ch 1, 1977) and Bondi (1979). See also Norton (1985, section 10) for an attempt to characterize the imprecise restriction to in nitesimal regions as a restriction on access to certain orders of quantities de ned at a point. Following a suggestion from Einstein, it turns out that an in nitesimal principle of equivalence can hold only at the expense of a restriction so severe that it trivializes the principle. See also Norton (1985, section 11) for Einstein's response to the idea that vanishing spacetime curvature is to be associated with the absence of a gravitational eld.
8. Eliminating the absolute
8.1. Anderson's absolute and dynamical objects
However else he may have changed his viewpoints, we have seen (section 3.9) that Einstein maintained throughout the lifetime of his writings on general relativity that it was distinguished from earlier theories by a single achievement, it had eliminated a causal absolute, the inertial system. If we are to have an account that truly captures Einstein's understanding of general covariance, then we should expect this rather imprecisely notion to play a prominent role. This notion surely lies behind Pauli and Weyl's emphasizing that the metric tensor is determined by the matter distribution through eld equations and that
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this justi es (Weyl) the name `general theory of relativity' (see section 5.5 above). Einstein's notion surfaces more clearly in Bergmann's (1957, pp11{12) conception of weak and strong covariance. Weak covariance is the type we see in when we use many di erent coordinate systems to describe the one phenomenon in Lagrangian mechanics. The fundamentally trivial nature of this `weak covariance' derives from the rigidity of the classical metric. This is quite distinct from the strong covariance of general relativity where30 it is one's task to calculate the metric . . . as a dynamic variable. We can take one coordinate system or another for this job, but all that we can know is the relation of one frame to the other: we do not know the relation of either to the world. `Strong covariance', therefore, contains not only a reference to the structural similarity of an equation and its transformation, it implies as well that one frame is as good a starting point as another|that we do not need prior knowledge of its physical meaning . . . which is generated at the end. Many important themes are touched on here, as has been indicated by Stachel (forthcoming, footnote 3). This distinction between weak and strong covariance amount to that between passive and active covariance. What concerns us here, however, is that contrasting of the `rigidity of the classical metric' with the metric of general relativity `as a dynamic variable'. The most precise context so far for the statement of Einstein's causal concerns has been provided by Anderson (1964, 1967, ch 4, 1971) (but see also Anderson (1962) for a de nition of absolute change within general relativity). In laying out his system, Anderson uses a somewhat idiosyncratic nomenclature. He labels the set of all possible values of the geometric objects of a theory the `kinematically possible trajectories'. Those sanctioned by the `dynamic laws' or `equations of motion' of the theory, he calls the `dynamically possible trajectories'. The principle novelty of Anderson's development is the distinction between `absolute' and `dynamical' objects. That distinction will be used to strengthen the principle of general covariance into a more restrictive `principle of general invariance'. Although allowing for a time that both special and general covariance principles are devoid of physical content (1964, p184), Anderson (1967, section 4.2, 1971, pp162{65) then came to urge that the requirement of general covariance is not physically vacuous. He allowed that one can take a physical theory and generate successive formulations of wider and wide covariance. However there is a point in the hierarchy at which we are forced to introduces elements which are unobservable or transcend measurement. Since we are prohibited from proceeding to this point in the hierarchy, covariance requirements have physical force. (This strategy for injecting physical content into covariance principles is essentially the one used by Pauli and others in section 5.5 above.) The absolute objects of a spacetime theory are distinguished by precisely the causal criterion that allowed Einstein to designate the inertial systems of special relativity as absolute. Anderson and Gautreau (1969, p1657) summarize: Roughly speaking, an absolute object a ects the behaviour of other objects but is not a ected by these objects in turn.
30The two ellipses `. . . ' and emphasis are Bergmann's.
General covariance and general relativity 845
The remaining objects are dynamical. Thus the Minkowski metric of special relativity is an absolute object. In special relativistic electrodynamics, the Minkowski metric a ects the Maxwell eld and charge ux in determining, for example, which are the inertial trajectories of charges. However neither Maxwell eld nor charge ux, the dynamical objects of the theory, a ect the Minkowski metric. Whatever their form, the Minkowski metric stays the same. This is the sense in which it a ects without being a ected. Since the Minkowski metric induces the inertial frames on spacetime, Anderson's identi cation of the Minkowski metric as an absolute object ts exactly with Einstein's identi cation of inertial frames as absolutes. This loose de nition must be made more precise and Anderson (1967, p83{4) (see also Anderson (1971, p166) gives a more precise de nition. Having eliminated irrelevant objects from the set of geometric objects yA allowed in the theory We now proceed to divide the components of yA into two sets,  and za where the  have the following two properties: (1) the  constitute the basis of a faithful realization of the covariance group of the theory. (2) Any  that satis es the equations of motion of the theory appears, together will all its transforms under the covariance group, in every equivalence class of dpt (dynamically possible trajectories) The  if they exist, are the components of the absolute objects of the theory. The remaining part of yA, the za are then the components of the dynamical objects of the theory. Condition (1) is an important but essentially technical condition that the transformation behaviour of the  respect the group structure of the theory's covariance group ( e. g. the  ought to transform back into themselves under an identity transformation of the covariance group.) Condition (2) essentially just says that the absolute objects  are the same in every dynamically possible trajectory (i.e. model) of the theory. The condition, however, must allow that an absolute object, such as a Minkowski metric, g can be manifested on many di erent forms as it transforms under the members of the covariance group. Therefore the second condition collects the dynamically possible trajectories into equivalence classes of intertransformable members. Since each class is closed under transformations of the covariance group, the one set of absolute objects and all their transforms will appear in each class. Thus condition (2) requires, in e ect, that the absolute objects that appear in all models are the same up to a transformation of the theory's covariance group. With this distinction in place, Anderson now de nes the symmetry group or `invariance group of a physical theory' (Anderson 1971, p166) as that subgroup of the covariance group of the theory which leaves invariant the absolute objects of the theory. In particular, if there are no absolute objects, the invariance group and the covariance groups are the same group. The `leaves invariant' is to be understood in the sense of a symmetry transformation such as given in (10) and (11) above. There is an analogous de nition for the `symmetry group of a physical system' (Anderson 1967, p87) Anderson's central claim (e.g. Anderson 1967, p338) is that this symmetry group is what Einstein really had in mind when he associated the Lorentz group with special relativity and the general group with general relativity. For a requirement on a symmetry group, not a covariance group, is the correct way to express a relativity principle. Even if we formulate our theories in generally covariance fashion, they continue to be characterized by the groups expected if we look to their symmetry groups. The symmetry group of a generally covariance special relativity is the Lorentz group. Again, consider a generally co
846 J D Norton
variant formulation of Newtonian spacetime theory with spacetime structures ta; habandra where the gravitational eld is not incorporated into ra. Then these three objects are the absolute objects of the theory and their symmetry group is the Galilean group. Finally, general relativity has no absolute objects. Its symmetry group is the general group. One can grasp the picture urged if one imagines that the background spacetime of a theory is the spacetime manifold together with the theory's absolute objects|although `background spacetime' is not a notion discussed by Anderson. In the cases of special relativity and the above version of Newtonian spacetime theory, both admit a family of preferred inertial frames of reference which remain unchanged under the Lorentz group or Galilean group respectively. In the case of general relativity, the background spacetime is just the manifold whose symmetry group is the group of arbitrary transformations. According to Anderson, what Einstein really intended with his principle of general covariance is what Anderson calls the `principle of general invariance'. This principle requires that the symmetry group of a theory be the general group of transformations or, as Anderson calls them, the `manifold mappings group'. This principle rules out the possibility of any non-trivial absolute objects in the theory, that is, those which have more than merely topological properties. In this sense, the principle of general invariance amounts to a no-absolute-object requirement and o ers a precise reading for Einstein's claim that general covariance has eliminated an absolute from spacetime.
8.2. Responses to Anderson's viewpoint
Anderson's ideas on absolute and dynamical objects have found a limited but favorable response in the literature. Misner et al (1973, section 17.6) present a requirement of no absolute objects in terms of the requirement of `no prior geometry' where: By `prior geometry' one means any aspect of the geometry of spacetime that is xed immutably, i.e. that cannot be changed by changing the distribution of gravitating sources. They describe Einstein as seeking both this requirement as well as a `geometric, coordinate independent formulation of physics' when he required general covariance|and that this has been responsible for half a century of confusion. Anderson's principle of general invariance appears in Trautman (1973), as does the distinction between absolute and dynamical objects in Kopczynski and Trautman (1992, ch 13). Ohanian (1976, pp252{4) uses Anderson's principle of general invariance to respond to Kretschmann's objection that general covariance is physically vacuous. He does insist, however, that the principle is not a relativity principle and that the general theory of relativity is no more relativistic than the special theory (p257). Anderson's ideas seem also to inform Buchdahl's (1981, lecture 6) notion of `absolute form invariance'. The distinction between absolute and dynamical objects has been received and developed most warmly by philosophers of space and time, so that in place of (6), the general model of spacetime theory is given as
hM; A1; A2; : : : ; D1; D2; : : :i
where A1; A2; : : : are the absolute objects and D1; D2; : : : the dynamical. However they do not generally allow that Anderson's reasoning has vindicated Einstein's claim that the general theory of relativity extends the principle of relativity of special relativity. See Earman (1974, 1989, ch 3), Friedman (1973, 1983), and Hiskes (1984). Earman (1989, section 3.4) investigates the possibilities of the symmetry group of the absolute objects of a theory di ering from the symmetry group of the dynamical objects.
8.3. No gravitational eld|no spacetime points
General covariance and general relativity 847
Stachel (1986, sections 5, 6) has provided an interesting extension of the viewpoint advanced by Anderson. Stachel's concern is that our formulations of general relativity are still not in a position to explicate Einstein's idea that spacetime cannot exist without the gravitational eld (see section 3.5 above). Stachel faults our representing of physical spacetime events by the mathematical points of the spacetime manifold. Read naively, this de nition tells us that a manifold without metrical eld represents a physical spacetime of events with topological properties but with no metrical relations. Stachel's proposal applies to spacetime theories without absolute objects, which he calls `generally covariant', and can be reviewed only informally here. To form the models of such theories one assigns various geometric objects|tensor elds, for example|to each point of the manifold in the usual way. In principle, many di erent such elds could be assigned. In the case of general relativity, we have a host of possible metrical elds of all sorts of di erent curvature. The loose notion of the space of all such possible elds is given precise formulation by Stachel as a bre bundle E over the manifold M . The particular elds that are chosen for inclusion in the theory's models are picked out though cross-sections of the bre bundle E. Loosely speaking, a cross section  amounts to an association of a point of the manifold M with the geometric objects assigned to it in some model of the theory. (More precisely, a cross-section  is a map that goes from a point p of the manifold M to a member (p) of the bre bundle E, where (p) must be associated with p by the bundle's projection map , so that (p) = p.) The core of Stachel's proposal is that the physical events of spacetime are represented by the inverse of this map . That is|loosely speaking|the physical events are not represented directly by the points of the spacetime manifold; rather, in their place, we use the association of the points of the manifold with the geometric structures de ned on them. We now automatically have the property of spacetime that Einstein announced. If we take away the gravitational eld, that is the metric eld, from a spacetime in general relativity, then we have taken away the bre bundle and with it the map that represents the physical spacetime events. In a theory with absolute objects, however, physical events are represented directly by points of the base manifold. Therefore their behaviour is quite di erent. See Stachel (1986) for further details of how theories with absolute objects are treated and of the machinery needed to allow that one physical situation is represented by an equivalence class of di eomorphic models.
8.4. What are absolute objects and why should we despise them?
There are two areas of diculty associated with the general theory of absolute and dynamical objects. The rst is that question of how we de ne absolute objects. Anderson's de nition was that an object was absolute if the same object (up to coordinate transformation) appeared in all the theory's models. In the coordinate free, geometric language how are we to understand the `same' ? The obvious candidate is that two objects are the same if they are isomorphic. Global isomorphism is the criterion used in Earman's (1974, p282) de nition of absolute objects to pick out when one has the same object in all models. Friedman (1973, p308{9, 1983, p58{60) uses only the requirement that the objects be locally di eomorphic.31 The rst diculty with this criterion of di eomorphic equivalence as sameness was pointed out by Geroch (Friedman 1983, p59). The criterion deems as the same all timelike
31More precisely, in the 1983 version of the de nition, what Friedman calls `d-equivalence' is this: If a theory has models hM; 1; : : : ; ni and hM; 1; : : : ; ni, then i and i are d-equivalent of, for every p 2 M there are neighbourhoods A and B of p and a di eomorphism h : A ! B such that i = h  i.
848 J D Norton
non-vanishing vector elds, so that however such a eld arises in a theory, it will be one of its absolute objects. Thus, in standard `dust' cosmologies, the velocity eld U a of the dust becomes an absolute object. To avoid the problem, Friedman suggests a rather contrived escape: formulate the theory of dust with the dust ux U a where  is the mass density, instead of  and U a separately. (Friedman is relying her on the possibility that  vanishes somewhere. A better choice would have been the stress-energy tensor for pressureless dust U aU b.) More seriously, modifying slightly an example of Torretti (1984, p285), we could imagine the following hybrid classical cosmology. The spacetime structure is given exactly by any of the Robertson-Walker spacetime metrics. The metrics are posited a priori and not governed by the presumed inhomogeneous matter distribution through gravitational eld equations, Therefore the curvature of the metric is unaltered in the vicinity of massive bodies. In this case, we would judge the metrical spacetime structure to act on the matter distribution without the matter distribution acting back on it. However, since models of the theory would allow metrics of di erent curvature, we cannot use existing de nitions to identify the spacetime metric as an absolute object. Torretti's counterexample shows us that the basic notion of `sameness' does not fully capture the notion of things that act but are not acted upon. The second area of diculty associated with the general theory of absolute and dynamical objects is a presumption of Anderson and Einstein (assuming that he is correctly interpreted by the theory). They presume that there is some compulsion to eliminate absolute objects. Of course they are right in the sense that our best theory of space and time happens not to employ absolute objects. Thus several of Anderson's arguments of the principle of general invariance can form a premise of arguments that lead to empirically con rmed results (Anderson 1967, section 10.3, 1971, p169). However absolutes are supposed to be defective in a deeper sense. It is not just that we happen not to see absolutes in nature; Nature is somehow supposed to abhor things that act but are not acted upon. The diculty is to clarify and justify this deeper sense. Anderson (1967, p339, 1971, p169) sees in nature a `generalized law [principle in 197] of action and reaction'. But the principle is so vague that it is unclear what the principle really says and where it can be applied. Does Planck's constant h or the gravitation constant G `act' on matter without su ering `reaction' ? With this vagueness how can we tell if the law is true or even whether we should hope for it to be true? Is it, perhaps, a dubious guilt by association with Aristotle's Unmoved Mover? Einstein comes closer to an explanation with his analogy (section 3.9 above) to pots of water, one boiling, one not. There has to be a sucient reason for the di erence. Analogously, the diculty with absolute objects is that there is no sucient reason for them to be one way rather than another. Now we might allow that such a principle of sucient reason applies to temporarily successive states of systems, although quantum theory calls even that into doubt. But why should we require this sort of principle to hold for aspects of the universe as a whole? In answer, we might take Born expansion of Einstein's (1916, section 2) denunciation of an absolute, inertial space as an ad hoc cause. Born (1924, p311) explains If, however, we ask what absolute space is and in what other way it expresses itself, no one can furnish an answer other than that absolute space is the cause of centrifugal forces but has no other properties. This consideration shows that space as the cause of physical occurrences must be eliminated from the world picture. It is hard to sympathize with Born's complaint. The absolute Minkowski metric of a special relativistic world has an extremely rich collection of properties all of which can be con rmed by possible experiences. It is dicult not to see the very objection of Born and Einstein as ad hoc. They seek to use vague and speculative metaphysics to convert
General covariance and general relativity 849
something that happens to be false into something that has to be false. These seem to be Schlick's 1920, p40) sentiments when he observes . . . we can . . . consider the expression `absolute space' to be a paraphrase of the mere fact that these [centrifugal] forces exist. They would then simply be immediate data; and the question why they arise in certain bodies and are wanting in others would be on the same level with the question why a body is present at one place in the world and not at another. . . . I believe Newton's dynamics is quite in order as regards the principle of causality. Special relativity has su ered too long form the crank myth that it not just happens to be true but it has to be true and that proper meditation on clocks and light signalling reveals it. Let us not create a similar myth for general relativity.
9. Boundaries and puzzles
9.1. Is general covariance too general? Or not general enough?
While most have been satis ed with general relativity as a general covariant theory, Fock (1957, 1959, pp xv{xvi, section 93) has proposed that the four coordinate degrees of freedom of the generally covariant theory be reduced by application of a coordinate condition. Fock's `harmonic coordinates' are picked out by the condition
 x
(p g g) = 0
Fock applies this condition to the case of spacetimes which are Minkowskian at spatial innity and nds that the resulting equations are the natural generalization of the standard Galilean coordinates of spatial relativity and are xed up to a Lorentzian transformation. Fock sees the physical importance of harmonic coordinates in such problems as the justifying of Copernican of the Ptolemaic cosmology. In harmonic coordinates, the earth orbits the sun and not vice versa. Fock's proposal proved controversial. Criticism of Fock's proposal was aired at a conference in Berne in July 1955 for the jubilee of relativity theory (Fock 1956). Infeld argued that a restriction to harmonic coordinates is acceptable as a convenience. `But to add it always (or almost always) to the gravitational equation and to claim that its virtue lies in the fact that the system is only Lorentz invariant, means to contradict the principle idea of relativity theory.' Trautman (1964, p123) and Kopczynski and Trautman (1992, p124) have also objected that Fock's proposal amount to the postulation of new spacetime structures for which no physical interpretation can be given.
850 J D Norton
In so far as Fock intended to reduce permanently the covariance of general relativity and introduce further structure, then these critical attacks are warranted. The harmonic coordinate condition is unacceptable as a new physical principle. But Fock (1959) seems to hold a milder position. He emphasized (pp350{1) that the introduction of harmonic coordinates is intended in a spirit no di erent from that which introduces preferred Galilean coordinates into a generally covariant formulation of special relativity. Thus `the existence of a preferred set of coordinates . . . is by no means trivial, but re ects intrinsic properties of space-time'. In the case of a spacetime Minkowskian at spatial in nity, harmonic coordinates simply reveal a structure already assumed as part of the boundary condition. Their use does not amount to an unwarranted postulation of new structure|unless one deems the boundary conditions themselves unwarranted. For further discussion see Gorelik (forthcoming) The issue surrounding Fock's proposal was whether a restriction of the covariance of general relativity could be justi ed. Arzelies (1961) has proposed a modi cation of general relativity which amounts to a kind of expansion of its covariance. He urges that Einstein's theory has still not satis ed the requirements of the generalized principle of relativity and that the transformations it allows should be extended in the following sense. If we start with a coordinate system Xi then, under coordinate transformation, the coordinate di erential dXi transform into new coordinate di erentials dxi. It is customarily assumed that the coordinate di erentials dxi are exact, so that they can be integrated into the new coordinate systems xi. Arzelies proposed that this restriction be dropped. This would certainly generalize the group of transformations since the functions ik of the equations dxi =
ikdXk need no longer be restricted by the requirement of exactness. The modi cation of extremely far reaching, however, in so far as it leads to the loss of many familiar theorems. For example, it will now be possible to transform the line elements of non- at metrics to the form
ds2 = (dx1)2 + (dx2)2 + (dx3)2 + (dx4)2
over a neighbourhood (not just a point), where this was formerly only possible if the metric was at.
9.2 The Einstein puzzle
There is a presumption in much modern interpretation of Einstein's pronouncements on the foundations of the general theory of relativity. It is that much of what he says cannot be taken at face value. (Why does Einstein make such a fuss about introducing arbitrary spacetime coordinates? We have always been able to label spacetime events any way we please!) Thus we are either to translate what he really meant into some more precise context, as does Anderson, or to dismiss it as confused. The proposal of Norton (1989, 1992) is that our modern diculty in reading Einstein literally actually stems from a change of context. (For related concerns see Norton (1993).) The relevant change lies in the mathematical tools used to represent physically possible spacetimes. In recent work in spacetime theories, we begin with a very re ned mathematical entity, an abstract di erentiable manifold, which usually contains the minimum structure to be attributed to the physical spacetimes. We then judiciously add further geometric objects only as the physical content of the theory warrants. Moreover, we have two levels of representation. We rst represent the physically possible spacetimes by the geometric models of form (6) and then these geometric models are represented by the coordinate based structures (7). General covariance is usually understood as passive general covariance and therefore arises as a mathematical de nition, as we have seen.
General covariance and general relativity 851
In the 1910s, mathematical practices in physics were quite di erent. The two levels of representation were not used. When one represented a general space or spacetime, one used number manifolds|Rn or Cn for example. Thus Minkowski's `world' was not a di erentiable manifold that was merely topologically R4. It was literally R4, that is it was the set of all quadruples of real numbers. Now anyone seeking to build a spacetime theory with these mathematical tools of the 1910s faces a very di erent problems from the ones we see now. Modern di erentiable manifolds have too little structure and we must add to them. Number manifolds have far too much structure. They are fully inhomogeneous and anisotropic. The origin h0; 0; 0; 0i is quite di erent from every other point, for examples. And all this structure had canonical physical interpretation. If one took the x4 axis as the time axis, then x4 coordinate di erences were physically interpreted as di erences of clock readings. Timelike straights would be the inertial trajectories of force free particles. The problem was not how to add structure to the manifolds, but how to deny physical signi cance to existing parts of the number manifolds. How do we rule out the idea that h0; 0; 0; 0i represents the preferred center of the universe and that the x4 coordinate axis a preferred state of rest? Felix Klein's Erlangen program provided precisely the tool that was needed. One assigns a characteristic group to the theory. In Minkowski's case, it is the Lorentz group. Only those aspects of the number manifold that remain invariant under this group are allowed physical signi cance. Thus there is no physical signi cance in the preferred origin h0; 0; 0; 0i of the number manifold since it is not invariant under the transformation. But the collection of timelike straights of the manifold are invariant; they represent the physically real collection of all inertial states of motion. As one increases the size of the group, one strips more and more physical signi cance out of the number manifold. We can put this in another way. A spacetime theory coordinates a physically possible spacetime with the number manifold. The characteristic group of the theory tells us that many di erent such coordinations are allowed and equally good. What is physically signi cant is read o as that part of each coordination common to all of them. This coordination of physical events with quadruples of numbers in is what was meant by `coordinate system' and the equivalence of two such systems was far from a mathematical triviality. It was the essence of the physical content of the theory. It is in this tradition that Einstein worked in the 1910s. His project was to expand the group of his theory as far as possible. But he had to proceed carefully since such expansions came with a stripping of physical signi cance from the number manifold. Thus Einstein (1916, section 3) needed to proceed very cautiously in explaining how the general covariance of his new theory had stripped the coordinates of their direct relationship to the results of measurements by rod and clock. The project is clearly also a project of relativization of motion. The imposition of the Lorentz groups stripped the x4 axis of the physical signi cance as a state of rest, implementing a principle of relativity for inertial motion. The transition to the general groups stripped the set of timelike straights of physical signi cance as inertial motion, extending the principle to accelerated motion. If this was all that Einstein had done, then his whole project would have remained within the Erlangen program tradition and there would be no debates today over whether Einstein succeeded in extending the principle of relativity. But, in the transition from the Lorentz tot the general group, Einstein added an element that carried him out of the tradition of the Erlangen program. He associated a Riemannian quadratic di erential form with the spacetime. (Thus Cartan (section 6.2 above) captures precisely the crucial point.) While Einstein could correctly say that he had generalized the principle of relativity insofar as he had stripped physical signi cance from the timelike straights of the number manifold, what remained to be seen was whether he had reintroduced essentially this same structure
852 J D Norton
by means of the quadratic di erential form. In e ect this question has become the focus of the debate over the generalized principle of relativity. Finally, it is helpful to bear in mind that what Einstein meant by `coordinate system' is not the same as the modern `coordinate charts' of a di erentiable manifold. The latter relate structures of (6) and (7) and the equivalence of each representation is a matter of mathematical de nition. Einstein's coordinate systems are actually akin the representation relation between physically possible spacetimes and the models of form (6). That two models represent the one physically possible spacetime is a physical assumption that amounts to assuming that their mathematical di erences have no physical signi cance. Correspondingly, within the context of Einstein's formulation of spacetime theories, that two coordinate system represent a physically possible spacetime is once again a physical assumption and for the same reason. That is, Einstein's covariance principles are most akin to modern active covariance principles. In sum, there is no real puzzle in much that of what Einstein said. Rather it now only seems puzzling since he is solving problems we longer have because of the greater sophistication of our mathematical tools. Indeed, in good measure we owe to Einstein's inspiration the development and widespread use of mathematical tools that automatically solve problems over which he laboured so hard.
10. Conclusion
The debate over the signi cance of general covariance in Einstein's general theory of relativity is far from settled. There are essentially three viewpoints now current. First is the viewpoint routinely attributed to Einstein. It holds that the achievement of general covariance automatically implements a generalized principle of relativity. In view of the considerable weight of criticism, this view is no longer tenable. Relativity principles are symmetry principles, the requirement of general covariance is not a symmetry principle. The requirement of general covariance, taken by itself, is even devoid of physical content. It can be salvaged as a physical principle by supplementing it with further requirements. The most popular are a restriction to simple law forms and a restriction on the additional structures that may be used to achieve general covariance. However neither supplementary condition has been developed systematically beyond the stage of fairly casual remarks. The second viewpoint has been developed by Anderson and is based on his distinction between absolute and dynamical objects. His `principle of general invariance' entails that a spacetime theory can have no non-trivial absolute objects. Anderson argues that the principle is a relativity principle, since it is a symmetry principle, and that it is what Einstein really intended with his principle of general covariance. In this approach, general relativity is able to extend the symmetry group of special relativity form the Lorentz group to the general group. This extension depends on the metric being a dynamical object, which is no longer required to be preserved by the symmetry transformations of the theory's relativity principle. The third viewpoint holds that the dynamical character of the metric is irrelevant in this context an that the metric must be preserved under the theory's symmetry group, if that group is to be associated with a relativity principle. Since the metrics of general relativistic spacetimes have, in general, no non-trivial symmetries, there is no non-trivial relativity principle in general relativity. Whatever may have been its role and place historically, general covariance is now automatically achieved by routine methods in the formulation of all seriously considered spacetime theories. The foundations of general relativity do not lie in one or other principle advanced by Einstein. Rather, they lie in the simple assertion
General covariance and general relativity 853
that spacetime is semi-Riemannian, with gravity represented by its curvature and its metric tensor governed by the Einstein eld equations.
Acknowledgements
The researching and writing of this review was supported by the National Science Foundation under Grant No. SBE-9121326. I thank the foundation for its support and also Jean Eisenstaedt, Don Howard, Al Janis, and Carlo Rovelli for helpful discussions. I am also very grateful to Don Howard for assistance with German translations.
References
Adler R. Bazin M and Schi er M 1977 Introduction to General Relativity 2nd ed (Tokyo: McGraw-Hill Kogakusha) Aguirre M and Krause J 1991 International Journal of Theoretical Physics 30 495{509
Anderson J L 1962 Recent Developments in General Relativity ed `Editorial Committee' (New York: MacMillan)
| 1964 Gravitation and Relativity eds H Y Chiu and W F Ho mann (New York: Benjamin) ch 9
| 1966 Perspectives in Geometry and Relativity ed B Ho mann (Bloomington IN: Indiana University Press) pp 16{27 | 1967 Principles of Relativity Physics (New York: Academic) | 1971 General Relativity and Gravitation 2 161{72 | and Gautreau R 1969 Phys. Rev. 185 1656{661 Arzelies H 1961 Relativite Generalisee Gravitation (Paris: Gauthier-Villars) Atwater H A 1974 Introduction to General Relativity (Oxford Pergamon) Bargmann V 1957 Reviews of Modern Physics 29 161{174
Bartels A 1993 Semantical Aspects of Spacetime Theories ed U Majer and H I Schmidt (Mannheim: BI)
Bauer H 1922 Mathematische Einfuhrung in die Gavitationstheorie Einsteins (Leipzig: Fmz Deuticke)
Becquerel J 1922 La Principe de la Relativite et la Theorie de la Gravitation (Paris: Gauthier-Villars) Bergmann P G 1942 Introduction to the Theory of Relativity (New York: Dover)
| 1957 Topics in the Theory of General Relativity, Lectures in Theoretical Physics Notes by N A Wheeler (Waltham, MA Brandeis University, Summer School, Institute of Physics) | 1961 Rev. Mod. Phys. 33 510{4
| 1962 The General Theory of Relativity Encyclopedia of Physics Vol IV ed S. Flugge (Berlin: Springer)
Birkho G D 1942 Relativity and Modern Physics (Cambridge, MA: Harvard University Press) Bishop R L and Goldberg S I 1968 Tensor Analysis on Manifolds (New York: Dover) Bondi H 1959 Rep. Prog. Phys. 22 97{120
| 1979 Einstein: A Centenary Volume ed A P French (Cambridge, MA: Harvard University Press) pp 113{29 Borel E 1926 Space and Time transl A S Rappaport and J Dougall (New York: Dover)
854 J D Norton
Born M 1924 Einstein's Theory of Relativity revised edn 1962, ed G. Leibfried and W Biem (New York:Dover)
Bose S K 1980 An Introduction to General Relativity (New York: Wiley)
Bowler M G 1976 Gravitation and Relativity (Oxford: Pergamon)
Bridgman P 1949 Albert Einstein: Philosopher Scientist 2nd edn, ed P A Schilpp (New York: Tudor) pp 315{54
Buchdahl HA 1981 Seventeen Simple Lectures on General Relativity (New York: Wiley)
Bunge M 1967 Foundations of physics (New York: Springer)
Butter eld J 1987 International Srudies in the Philosophy of Science 2 10{32
| 1988 Proceedings of the 1988 Biennial Meeting of the Philosophy of Science Association vol. 2 ed A Fine and J Leplin (East Lansing, MI: Philosophy of Science Association) pp 65{81
| 1989 British J. Phil. Sci. 40 1{28
Carmeli M 1982 Classical Fields: General Relativity and Gauge Theory (New York: Wiley)
Carmichael R 1920 The Theory of Relativity 2nd edn (New York: Wiley)
Cartan E 1923 Ann. Sci. ENS 40 325{412; 1924 Ann. Sci. ENS 41 1{25; transl 1982 A Magnon and A Ashtekhar in On Manifolds with an Ane Connection and the Theory of General Relativity (Naples: Bibliopolis)
| 1927 L'Ensignment Mathematique 26 200{225: 1952 Oevres Completes Part 1, voI II (Paris: Cauthier-Villars) pp 841{66
Cartwright N and Hoefer C (forthcoming) Philosophical Problems of the Internal and External Worlds: Essays on the Philosophy of Adolf Grunbaum ed J Earman, A Janis, G Massey, N Rescher (Pittsburgh PA: University of Pittsburgh University of Konstanz)
Charon J E 1963 15 Lecons sur la Relativite Generale avec une Introduction au Calcul
Tensoriel (Geneva: Editions Rene Kister)
Chazy J 1928 La Theorie de la Relativite et la Mecanique Celeste (Paris: Gauthier-Villars)
Clarke C 1979 Elementary General Relativity (London: Edward Arnold)
Cunningham E 1921 Relativity: The Electron Theory and Gravitation (London: Longmans Green & Co.)
d'Iverno R 1992 Introducing Einstein's Relativity (Oxford: Clarendon)
Darmois G 1927 Les Equations de la Gravitation Einsteinienne: Memorial des Sciences Mathematique, L'Academie des Sciences de Paris. Facs. XXV (Paris: Gauthier.Villars)
Davis W R 1970 Classical Fields, Particles and the Theory of Relativity (New York: Gordon and Breach)
De Donder T 1921 La Gravi que Einsteinienne (Paris Gaurhier-Villars)
| 1925 Introduction a la Gravi que Einsteinienne: Memorial des Sciences Mathematique, L'Academie des Sciences de Paris Facs. VIII (Paris: Gauthier-Villars)
De Felice F and Clarke C J S 1990 Relativity on Curved Manifolds (Cambridge: Cambridge University Press)
De Sitter (1916) Mon. Not. R. Astron. Soc. 76 699{728, 1916 77 155{184; 1917 78 3{28
Dirac P A M 1975 General Theory of Relativity (New York: Wiley)
Earman J 1974 Found. Phys. 4 267{89
| 1989 World Enough and Spacetime: Absolute versus Relational Theories of Space and Time (Cambridge, MA: Bradford/MIT Press)
Earman J and Friedman M 1973 Phil. Sci. 40 329{59
General covariance and general relativity 855
Earman J and Norton J D 1987 British J. Phil. Sci. 38 515{25
Eddington A S 1920 Report on the Relativity Theory of Gravitation 2nd ed (London: Fleetway)
| 1924 The Mathematical Theory of Relativity 2nd edn (1952) (Cambridge: Cambridge University Press)
Ehlers J 1971 Proc. Int. School of Physics 'Enrico Fermi' Course XLVII ed B K Sachs (New York: Academic) pp 1{70
Einstein A 1905 Ann. Phys. 17 891{921 (transl Lorentz 1923 pp 37{65)
| 1907 Jahrbuch der Radioaktivitat und Elektronik 4 411{462; 1908 5 98{99
| 1911 Ann. Phys. 35 898{908 (transl Lorentz 1923, pp 99{108)
| 1912a Ann. Phys. 38 355{69
| 1912b Ann. Phys. 38 443{58
| 1912c Vierteljahrsschrift fur gerichtliche Medizin und o enrliches Sanitatswesen 44 37{40
| 1912d Ann. Phys. 38 1059{64
| 1913 Physikalische Zeitschrift 14 1249{62
| 1914 Preussische Akademie der Wissenschaften (Berlin), Sitzungsberichte 1030{1085
| 1914a Scientia 15 337{48.
| 1915 Preussische Akademe der Wissenschaften (Berlin), Sitzungsberichte 778{86, 799{ 86, 831{9, 844{7
| 1916 Ann. Phys. 49 769{822 (translated 1923 Lorentz et al, pp 111{164 (without p 769))
| 1916 Ann. Phys. 51 639{642
| 1917 Preussische Akademie der Wissenschaften (Berlin), Sitzungsberichte 142{152 (transl 1923, Lorentz et al pp 175{88)
| 1917a Relativity: the Special and the General Theory (transl 1977 R W Lawson (London: Methuen))
| 1918 Ann. Phys. 55 240{44
| 1918a Naturwissenschaften 6 697{702
| 1919 Preussische Akademie der Wissenschaften, Sitzungsberichte 349{56 (transl 1923 Lorentz et al pp 191{8)
| 1922 Sidelights on Relativity transl G B Je rey and W Perrett (New York: Dutton) (Reprinted 1983 New York: Dover)
| 1922a The Meaning of Relativity 5th edn (Princeton NJ Princeton University Press)
| 1924 Schweizerische Naturforschende Gesellschaft, Verhandlungen 105 85{93
| 1927 `The Mechanics of Newton and Their In uence on he Development of Theoretical Physics' Ideas and Opinions (New York: Bonanza) pp 253{61
| 1933 `On the Methods af Theoretical Physics' Ideas and Opinions (New York: Bonanza) pp 270{7
| 1940 The Fundaments of Theoretical Physics Ideas and Opinions (New York: Bonanza) pp 33{35
| 1949 Autobiographical Notes (La Salle, IL: Open Court)
| 1950 `On the Generalized Theory of Gravitation' Ideas and Opinions (New York: Bonanza) pp 341{356
856 J D Norton
| 1952 Relalivity: the Special and the General Theory transl R W Lawson. (London: Methuen) Appendix V Einstein A and de Sitter W 1932 Proc. Nat. Acad. Sci. (Washington) 18 213{14
Einstein A and Grossmann M 1913 Entwurf einer verallgemeinerten Relativitatstheorie und einer Theorie der Gravitation (Leipzig: Teubner. separatum); addendum 1913 Einstein Zeitschrift fur Mathematik und Physik 63 225{61 Eisenstaedt J 1986 Archive for History of Exact Sciences 35 115{185
| 1989 Einstein and the Hislory of General Relativity: Einstein Studies, vol I eds D Howard and J Stachel (Boston: Birkhauser) pp 277v{92 Ellis G F R and Williams R M 1988 Flat and Curved Space-Times (Oxford: Clarendon)
Falk G and Ruppel W 1975 Mechanik RelaIivitat Gravitation: Ein Lehrbuch 2nd edn (Berlin: Springer) Fock V 1956 HeIv. Phys. Acta. Supplementum IV, pp 239{243 | 1957 Reviews of Modern Physics 29 325{333
| 1959 The Theory of Space Time and Gravitation transl N Kemmer (New York: Pergamon)
| 1974 Die Stellung des Copernicanischen Systems im Ideenkreis der Einsteinschen Gravitationstheorie (Leipzig: Karl Marx Universitat)
Fokker A D 1965 Time and Space, Weight and Inertia: A Chronogeometrical Introduction to Einstein's Theory transl D Bijl; transl and ed D Field (Oxford: Pergamon)
Foster J and Nightingale J D 1979 A Short Course in General Relativity (London: Longman)
Frankel T 1979 Gravitational Curvature: An Introduction to Einstein's Theory (San Francisco: Freeman)
Freundlich E 1919 The Foundations of Einstein's Theory of Gravitation transl H L Brose (London: Methuen) Friedman M 1973 Space, Time and Geometry ed P Suppes (Dordrecht: Reidel) pp 296{320
| 1983 Foundations of Space-Time Theories: Relativistic Physics and the Philosophy of Science (Princeton, NJ: Princeton University Press) Friedrichs K 1927 Mathhematische Annalen 98 566{75
Gorelik G (forthcoming) The Attraction of Gravitation: New Studies in History of General Relativity ed J Earman, M Janssen and JD Norton (Boston: Birkauser)
Graves J C 1971 The Conceptual Foundations of Contemporary Relativity Theory (Cambridge, MA: MIT Press) Havas P 1964 Rev. Mod. Phys. 36 938{65
Hawking S and Ellis G F R 1973 The Large Scale Structure of Space-time (Cambridge: Cambridge University Press)
Hilbert D 1915 Akademie der Wissenschaften, Gottingen, Nachrichten pp 395{407; 1917 Akademie der Wissenschaften, Gottingen, Nachrichten pp 53{76 Hiskes A L D 1984 Found. Phys. 14 307{32 Ho mann B 1932 Rev. Mod. Phys. 4 173{204
Howard D 1992 Studies in the Hislory of General Relativity ed J Eisenstaedt and A Kox (Boston: Birkhauser) pp 154{243
Howard D and Norton J D (forthcoming) The Attraction of Gravitation: New Studies in History of General Relativity ed J Earman, M Janssen and J D Norton (Boston: Birkhauser)
General covariance and general relativity 857
Hughston L P and Tod K P 1990 An Introduction to General Relativity (Cambridge: Cambridge University Press)
Jones R 1981 After Einstein ed P Barker and C G Shugart (Memphis, TN: Memphis State University Press)
Jordan P 1955 Schwerkraft und Weltall (Braunschweig: Vieweg)
Kenyon I R 1990 General Relativity (Oxford: Oxford University Press)
Kenzberg P 1989 Einstein and the History of General Relativity ed D Howard and J Stachel (Boston: Birkhauser) pp 325{56
Klein F 1872 Gesammelte Mathematische Abhnadlungen. vol 1, ed R Fricke and A Ostrowski (Berlin: Springer) pp 460{497
Kopczynski W und Trautman A 1992 Spacetime and Gravitation (Chichester: Wiley)
Kop A 1923 Grundzuge der Einsteinschen Relativitatstheorie (Leipzig: Hirzel)
Kottler F 1922 Encyklopadie der mathematischen wissenschaften mit Einschluss an ihrer Anwendung vol VI, part2, 22a Astronomie ed K Schwertzschild, S Oppenheim and W v Dyke (Leipzig: Teubner) pp 159{237
Kratzer A 1956 Relativitatstheorie (Munster: Aschendorfsche)
Kretschmann E 1915 Ann. Phys. 48 907{982
| 1917 Ann. Phys. 53 575{614
Kuchar K V 1988 Highlights in Gravitation and Cosmology (Cambridge: Cambridge University Press)
Landau L D and Lifshitz E M 1951 The Classical Theory of Fields transl M Hamermesh (Oxford:Pergamon)
Laue M 1911 Das Relativitatsprinzip (Braunschweig: Vieweg)
| 1921 Die Relativitatstheorie. Vol 2: Die Allgemeine Relativitatstheorie und Einsteins Lehre von der Schwerkraft (Braunschweig: Vieweg)
Lawden D F 1962 An Introduction to Tensor Calculus and Relativity (London: Methuen)
Lenard P 1921 Uber Relativitatsprinzip, Ather, Gravitation 3rd edn (Leipzig: Hirzel)
Levi-Civita T 1926 The Absolute Di erential Calculus transl M Long (New York: Dover)
Levinson H C and Zeisler E B 1929 The Law of Gravitation in Relativity (Chicago: University of Chicago Press) 2nd edn
Lorentz H A et al 1923 Principle of Relativity (London: Methuen); (1952 New York: Dover)
Mach E 1893 Science of Mechanics transl 1960 T J McCormack (La Salle, IL: Open Court)
Malament D 1986 From Quark to Quasars: Philosophical Problems of Modern Physics ed R G Colodny (Pinsburgh, PA: University of Pittsburgh Press) pp 181{201
Manin J L 1988 General Relativity: A Guide to its Consequences for Gravity and Cosmology (Chichester: Ellis Horwood)
Mashoon B 1986 Found. Phys. 16 619{35.
Maudlin T 1988 Proc. 1988 Biennial Meeting of the Philosophy of Science Association vol. 2, ed A Fine and J Leplin (East Lansing. MI: Philosophy of Science Association) pp 82{91
| 1990 Stud. Hist. Philos. Sci. 21 531{61
Mavrides S 1913 L'Univers Relativiste (Paris: Masson)
McVittie G C 1965 General Relativity and Cosmology (Urbana IL: University of Illinois Press)
Mehra J 1974 Einstein. Hilbert and The Theory of Gravitation (Dordrecht: Reidel)
858 J D Norton
Minkowski H 1908 Koniglichen Gesellschaft der Wissenschaften zu Gottingen, MathematischePhysikalische Klasse. Nachrichten, 53{111 | 1909 Physikalische Zeitschrift 10 104{111 (transl Lorentz 1923, pp 75{91) Misner C W, Thorne K S and Wheeler J A 1913 Gravitation (San Francisco: Freeman) Moller C 1952 The Theory of Relativity (Oxford: Clarendon)
Mundy B 1992 Proc. 1992 Biennial Meeting of the Philosophy of Science Association vol. 1 ed D Hull, M Forbes and K Okruhluk (East Lansing, MI: Philosophy of Science Association) pp 515{527
Newton I 1687 Mathematical Principle of Natural Philosophy transl 1934 F Cajori (Berkeley, CA: University of Los Angeles Press)
North J D 1965 The Measure of the Universe: A History of Modern Cosmology (Oxford:Clarendon)
Norton J D 1984 Historical Studies in the Physical Sciences 14 253{316: reprinted in Einstein and the History of General Relativity: Einstein Studies, Vol 1 eds D Howard and J Stachel (Boston: Birkhauser, 1989) pp 101{159
| 1985 Studies in History and Philosophy of Science 16 203{246: reprinted in Einstein and the History of General Relativity: Einstein Studies, Vol 1 eds DHoward and J Stachel (Boston: Birkhauser, 1989) pp 3{47. | 1987 Measurement, Realism and Objectivity ed I Forge (Dordrecht: Reidel) pp 153{188
| 1988 Proceedings of the 1988 Biennial Meeting of the Philosophy of Science Association Vol. 2 eds A Fine and J Leplin (East Lansing, MI: Philosophy of Science Assoc., 1989) pp 56{64 | 1989 Found Phys 19 1215{1263
| 1992 Studies in the History of General Relativity: Einstein Studies, Vol. 3 J Eisenstaedt and A Kox eds (Boston:Birkhauser) pp 281{315
| 1992a Introduction to the Philosophy of Science M H Salmon et al (Englewood Cli s, NJ: Prentice-Hall) pp 179{231
| 1993 Semantical aspects of Spacetime Theories ed U Majer and H I Schmidt (Mannheim: BI) Ohanian H C 1976 Gravitation and Spacetime (New York: Norton)
Page L 1920 The Principle of General Relativity and Einstein's Theory of Gravitation (New Haven. CT: Connecticut Academy of Arts and Sciences) Painleve P 1921 C. R. Acad. Sci. Paris 173 873{887 Papapetrou A 1974 Lectures on General Relativity (Dordrecht: Reidel) Pathria R K 1974 The Theory of Relativity 2nd edn (Oxford.Pergamon)
Pauli W 1921 Encyklopadie der mathematischen Wissenschaften, mit Einschluss an ihrer Anwendung. vol 5 Physik, Part 2 ed A Sommerfeld (Leipzig: Teubner) pp 539{775; 1958 Theory of Relativity transl G Field (London: Pergamon)
Post E J 1967 Delaware Seminar in the Foundations of Physics ed M Bunge (New York: Springer) pp 103{123
Prasanna A R 1971 Lectures on General Relativity and Cosmology, Matscience Report No 71 (Madras: Institute of Mathematical Sciences)
Raine D J and Heller M 1981 The Science of Space-Time (Tucson, AZ: Pachart Publishing House) Rainich G Y 1950 Mathematics of Relativity (New York: Wiley) Ray C 1987 The Evolution Of Relativity (Bristol and Philadelphia: Adam Hilger)
General covariance and general relativity 859
Reichenbach H 1924 Axiomatization of the Theory of Relativity transl 1969 M Reichenbach (Berkeley, CA: University of California Press, 1969)
Reinhardt M Z Naturf 28a 529{37
Ricci G and Levi-Civita T 1901 Math. Ann. 54 125{201: reprinted in Levi-Civita 1954 Opere Matematiche, vol. 1 (Bologna) pp 479{559
Rindler W 1969 Essential Relativity: Special, General, and Cosmological (New York: Van Nostrand-Reinhold)
Robertson H P and Noonan T W 1968 Relativity and Cosmology (Philadelphia, PA: Saunders)
Roll P G, Krotkov R and Dicke R H 1964 Ann. Phys. 26 442{517
Rosser W G V 1964 An Introduction to the Theory of Relativity (London: Butterworths)
Rovelli C 1991 Class. Quantum Grav. 8 297{316
Rynasiewicz R (forthcoming (a)) 'Rings, Holes and Substantivalism: On the Program of Leibniz Algebra' Phil. Sci.
Rynasiewicz R (forthcoming (b)) The Lessons of the Hole Argument
Ryckman T A 1992 Stud. History Phil. Sci. 23 471{497
Sachs R K and Wu H 1977 General Relativity for Mathematicians (New York: Springer)
Scheibe E 1981 Scienti c Philosophy Today eds J Agassi and R S Cohen (Dordrecht: Reidel) pp 311{31; reprinted 1983 Space, Time, and Mechanics ed D May and G Sussman (Dordrecht: Reidel) pp 125{47
| 1991 Causality, Method, and Modality ed G G Brittan Jr (Kluwer-Academic) pp 23{40
Schild A 1967 Relativity Theory and Astrophysics Vol. 1 Relativity and Cosmology ed J Ehlers (Providence, RI: American Mathematical Society) pp 1{t16
Schlick M 1920 Space and Time in Conremporary Physics transl H L Brose (New York: Oxford University Press)
Schrodinger E 1950 Space-Time Structure (Cambridge: Cambridge University Press)
Schutz B F 1985 A First Course in General Relativity (Cambridge: Cambridge University Press)
Sesmat A 1937 Systemes de Reference et Mouvements (Physique Relativiste) (Paris: Hermann)
Sexl R U and Urbantke H K 1983 Gravitation und Kosmologie: Eine Einfuhrung in die Allgemeine Relativitatstheorie (Mannheim: Bibliographisches Institut)
Silberstein L 1922 The Theory of General Relativity and Gravitation (University of Toronto Press)
Skinner R 1969 Relativity (Waltham, MA: Blaisdell Publishing CO)
Sommerfeld A 1910 Ann. Phys. 32 749{776; Ann. Phys. 33 649{89
Stachel J (forthcoming) Philosophical Problems of the Internal and External Worlds: Essays on the Philosophy of Adolf Grunbaum eds J Earman, A Janis, G Massey and N Rescher (Pittsburgh, PA: University of Pinsburg/University of Konstanz)
| 1980 'Einstein's Search for General Covariance' 9th Int. Conf. on General Relativity and Gravitation. Jena; reprinted in Einstein and the History of General Relativity; Einstein Studies, vol. 1 eds D Howard and J Stachel (Boston: Birkhauser, 1989) pp 63{100 | 1980a General Relativity and Gravitation: A Hundred Years After the Birth of Einstein ed A Held (New York: Plenum): reprinted in Einstein and the History of General Relativity: Einstein Studies. Vol. 1 D Howard and J Stachel eds (Boston: Birkhauser, 1989) pp 48{62
860 J D Norton
| 1986 Proc. 4th Marcel Grossmann Meeting on General Relativity ed R Runi (Amsterdam: Elsevier) pp 1857{1862
| 1992 Studies in the History of General Relativity: Einstein Studies, Vol. 3 eds J Eisenstaedt and A Kox (Boston: Birkhauser) pp 407{418
Stephani H 1977 General Relativity: An Introduction for the Theory of the Gravitational Field ed J Stewart, transl M Pollock and J Stewart. (Cambridge: Cambridge University Press) Stewart J 1990 Advanced General Relativity (Cambridge: Cambridge University Press) Straumann N 1984 Generai Relativity and Astrophysics (Berlin: Springer) Synge J L 1960 Relativity: The General Theory (Amsterdam: North-Holland)
| 1964 Relativity, Groups and Topology eds C De Witt and B De Witt (New York: Gordon and Breach) pp 4{90
| 1966 Perspectives in Geometry and Relativity ed B Ho mann (Bloomington, IN: Indiana University Press) pp 7{15 Szekeres G 1955 Phys. Rev. 97 212
Teller P (forthcoming) Substance, Relations and Arguments about the Nature of SpaceTime Phil. Rev. Thirring H 1922 Die Idee der Relativitatstheorie (Berlin: Springer)
Thirring W 1979 A Course in Mathematical Physics Vol. 2 transl EM Harrell (New York: Springer) Tolman R C 1934 Relativity, Thermodynamics and Cosmology (New York: Dover)
Tonnelat M 1959 The Principles of Electromagnetic Theory and of Relativity revised edn 1966, transl A J Knoedel (Dordrecht: Reidel)
Tornebohm H 1952 A logical Analysis of the Theory of Relativity (Stockholm: Almqvist & Wiksell) Torretti R 1983 Relativity and Geometry (Oxford: Pergamon) | 1984 British J. Phil. Sci. 35 280{292
Trautman A 1964 Lectures on General Relativity: Brandeis Summer Institute in Theoretical Physics Vol I 1964 (Englewood Cli s, NJ: Prentice Hall, 1965) pp 1{248
| 1966 Perspectives in Geometry and Relativity: Essays in Honor of Vaclav Hiavaty ed B Ho mann (Bloomington. IN: Indiana University Press pp 413{25 | 1973 The Physicist's Conception of Nature ed J Mehra (Dordrecht: Reidel) pp 178{98
Treder H-J, von Borzeszkowski H-H, van der Merwe A and Yourgrau W 1980 Fundamental Principles of General Relativity Theories: Local and Global Aspects of Gravitation and Cosmology (New York: Plenum, 1980)
Veblen O and Whitehead J H C 1932 The Foundations of Diferential Geometry (Cambridge: Cambridge University Press)
Vladimirov Yu, Mitskevisch N and Horski J 1987 Space, Time and Gravitation transl A G Zilberman, ed F I Fedorov (Moscow: Mir) Wald R 1984 General Relativity (Chicago, IL:University of Chicago Press)
Wasserman R H 1992 Tensors and Manifolds with Applications to Mechanics and Relativity (New York: Oxford University Press) Weber J 1961 General Relativity and Gravitational Waves (New York: Interscience)
Weinberg S 1972 Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity (New York: Wiley) Weyl H 1921 Space Time Matter transl 1952 H L Brose (New York: Dover)
General covariance and general relativity 861
Whitaker E T 1951 A History of Theories of Aether and Electricity. Vol. I The Classical Theories, Vol 2 the Modern Theories 1900-1926 (New York: Dover) Yilmaz H 1965 Introduction to the Theory of Relativity and Principles of Modern Physics (New York: Blaidsdell) Zahar E I989 Einstein's revolution: A study in Heuristic (La Salle, IL: Open Court) Zatzkis H 1955 in Fundamental Formulas of Physics ed D H Menzel (New York: Dover, 1960) Vol 2, ch 7

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Physics > History and Philosophy of Physics
arXiv:2408.02790 (physics)
[Submitted on 5 Aug 2024]
Einstein Against Singularities: Analysis versus Geometry
John D. Norton
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Einstein identified singularities in spacetimes, such as at the Schwarzschild radius, where later relativists only find a coordinate system assigning multiple values to a single spacetime event. These differing judgments derive from differences in mathematical methods. Later relativists employ geometrical structures to correct anomalies in the coordinate systems used in analytic expressions. Einstein took the analytic expressions to be primary and the geometrical structures as mere heuristics that could be overruled if physical assumptions required it. Einstein's non-geometric methods had a firm base in the history of mathematical methods. They continued the non-geometric orientation of Christoffel, Ricci and LeviCivita. Einstein's insistence that singularities must be eliminated marked a departure from earlier tolerance of singularities. It was founded upon his longterm project of eliminating arbitrariness from fundamental physical theories. However, Einstein was willing to theorize with singularities only temporarily if they were the least arbitrary approach then available.
Subjects: History and Philosophy of Physics (physics.hist-ph); General Relativity and Quantum Cosmology (gr-qc)
Cite as: arXiv:2408.02790 [physics.hist-ph]
  (or arXiv:2408.02790v1 [physics.hist-ph] for this version)
 
https://doi.org/10.48550/arXiv.2408.02790
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Journal reference: Philosophy of Physics 2(1) (2024) 13:1-73
Related DOI:
https://doi.org/10.31389/pop.91
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From: John D. Norton [view email]
[v1] Mon, 5 Aug 2024 19:13:41 UTC (4,871 KB)
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In this modern age of GPS and
precision long-range radar, it’s difficult to imagine the difficulty of navigating an aircraft at four miles a minute in darkness across blackedout enemy territory using only dead reckoning, star fixes and maps.
Thus it was hardly surprising that during WW2 the Luftwaffe adopted radio methods to guide night bombers to their targets in Britain. The story of the secret and silent ‘battle of the beams’ between the attackers who developed these specialised systems and the defenders who strove to disrupt them is one of the most fascinating in the history of short wave radio. It is a drama in which British radio amateurs played a pivotal role
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The Knickebein beams from Kleve and Stollberg could be directed to intersect over targets such as the Rolls-Royce aero-engine factory at Derby. (Image: Dahnielson/cc by-sa 3.0).
August 1941 photo of part of a 20m-high Knickebein transmitter antenna, possibly in Halinghen, Hauts-de-France. (Image: Bundesarchiv, Bild 101I-228-0322-04 / Friedrich Springorum / CC-BY-SA 3.0).
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80 Wing
,Q $XJXVW  D UDGLR FRXQWHUPHDVXUHV XQLW FDOOHG1R 6LJQDOV :LQJZDVIRUPHGE\ VLJQDOV VSHFLDOLVW (GZDUG $GGLVRQ WR SURYLGH
Dr Bruce Taylor, HB9ANY bgtaylor@ieee.org
Restoring an aircraft Knickebein system (foreground). Left: EBL2 signal processing unit; Middle: EBL3 superhet beam receiver; Right: U8 210V HT rotary converter. (CDV&T and Hans Goulooze).
Feature
82 May 2020
electronic intelligence and counter the German beams. Its motto was “Confusion to Our Enemies”. The Wing Headquarters was established in the Aldenham Lodge Hotel in Radlett, a village about 14 miles north west of London in convenient proximity to the London/ Birmingham GPO trunk cable. It was linked directly to the Fighter Command Operations Room at Bentley Priory in Stanmore. The old Lodge was infested with rats and cockroaches but it had a swimming pool, rather a rare asset for a WW2 RAF base! Because of their technical experience, resourcefulness and ability to improvise solutions rapidly, many British radio amateurs served in this unusual unit, with the General Secretary of the RSGB, John Clarricoats, G6CL, acting as a ‘Recruiting Sergeant’. Fifty BBC radio engineers also joined and within a year Addison had built up monitoring and jamming systems at over 120 outstations throughout the country. By September 1941, 80 Wing had a strength of 2000 men and
women of all ranks. A staff of 27 WAAFs was engaged to use 242 telephone lines to connect the Radlett HQ with the outstations. Before specialised systems to counter Knickebein could be built, Addison’s team improvised makeshift jammers by commandeering 150W 27.12MHz diathermy sets from local hospitals. These were converted WR 5) SRZHU DPSOLÀHUV DQG GULYHQ E\ VPDOO transmitters made at the Peto Scott factory to emit radio noise on the Knickebein frequencies. Two sets were installed in vehicles that could rapidly be despatched to any target area. Others were installed in dispersed police stations, which were alerted by telephone from Wing HQ when they were required. One village bobby put a set in his bedroom, where his wife could switch it on if he was out on his beat at the time of a call. The Rediffusion factory in south-west London produced a number of powerful jammers very UDSLGO\E\FRQYHUWLQJWKHN:DXGLRDPSOLÀHUV on their production line into radio transmitters.
:LQJDOVRPRGLÀHGHLJKW5$)/RUHQ]DLUÀHOG approach transmitters to radiate fake beams across the Knickebein ones to induce the attacking planes to stray off course, or to drop their bomb load in open country before reaching the target. The Air Arm of 80 Wing, which later became  6TXDGURQ FDUULHG RXW UHJXODU ÁLJKWV WR locate the radio beams. To narrow the search area for the Ansons, manned receiving stations were set up by lashing garden sheds to the tops of the towers of a few selected Chain Home radar stations. Braving the freezing cold in these high level shacks, the listening operators could indicate to Wing HQ the Knickebein frequencies that were being used on any night, and to which side of each station the beams lay. Knowing the antenna patterns of the Knickebein transmitters and their locations, the information from several such receiving stations could be combined to estimate the bearings of the main lobes. Since the beams were often turned on well before each night attack, this gave time to identify the probable target and set up the jammers. Meanwhile a more sophisticated antidote for Headache was being developed by Robert Cockburn and his team at the Telecommunications Research Establishment (TRE) in Worth Matravers, which included Martin Ryle, G3CY. This countermeasure was aptly named ‘Aspirin’. When a Knickebein raid started, the 500W Aspirins netted on to the frequency and transmitted dashes with the same modulation tone at exactly the same rate as the real transmitter. When the jamming signal was strong enough, pilots on the correct track continued to hear dashes, causing them to diverge from it. This even resulted in several ERPEHUV Á\LQJ LQ FLUFOHV QDYLJDWLRQ EHFDPH so unreliable that by mistake some German bombers landed in England instead of at their home bases. At least one inexperienced young bomber crew, who hadn’t been taught to navigate at night without the Knickebein beams, bailed out from their plane when they found they were jammed. When the start of systematic Aspirin jamming revealed that Knickebein had become well understood by the RAF, many German bomber pilots preferred to keep out of the beam VLQFHWKH\IHDUHG PLVWDNHQO\ WKDWQLJKWÀJKWHUV or aerial mines might be waiting for them all along the route to the target. This psychological effect may actually have caused more disruption than the jamming itself. By the autumn of 1940 raiders no longer considered Knickebein usable HQRXJK IRU WDUJHW LGHQWLÀFDWLRQ DOWKRXJK LW was several months before the young German pilots plucked up the courage to tell Göring that the system was useless. However, as we shall see in Part 2, the German Aviation Research Institute (DVL) had been developing another highly secret and much more accurate VHF radio beam system that would soon be used by the Luftwaffe with devastating effect.
Hallicrafters S-27 amateur radio receivers were used to search for the Luftwaffe beams.
After the occupation of the Netherlands and France, more compact second-generation 45m-wide FuSan721 Knickebein antennas could be used, as they could be sited nearer to Britain. (Model by Michael Kayser)
Radio amateurs played a
pivotal role in electronic countermeasures during WW2.
In Part 1 we saw how the RAF used amateur radio receivers to discover the Knickebein system of radio beams that the Luftwaffe employed to guide its night bombers to targets in Britain. ‘Aspirin’ jammers for this ‘Headache’ had been developed by TRE and deployed successfully by 80 Wing, and the system was considered no longer usable for accurate navigation. But the enemy had other tricks waiting in the wings.
X-Gerät
On 6 November 1940 a raiding Heinkel III bomber that had suffered compass failure over England tried to return to its base in occupied France by using a radio beacon at Saint-Malo. But the beacon was being jammed by 80 Wing, so the crew became disorientated and instead of landing in Brittany the plane ran out of fuel and crash landed just offshore from the beach at West Bay in Dorset. British Army soldiers waded into the shallows and secured a rope around the fuselage, but then the Royal Navy arrived and claimed that because the plane was in the sea it was theirs to salvage. When the sailors towed it into deeper water to secure it to a ship, the rope parted and the plane sank to the bottom! In spite of this incident the waterlogged radio equipment on board the aircraft was recovered and sent to RAE Farnborough, where it was found to include a new type of bombing radio navigation aid called X-Gerät. This system was considerably more sophisticated than Knickebein, having both coarse and Àne director beams and 20 operating frequencies in the higher frequency range of 65-77MHz. The X-Gerät system also laid three very narrow crossbeams across the director beam prior to the target, which allowed the aircraft’s ground speed to be determined and the bomb release point to be computed by a special ‘bombing-clock’
Feature Battling the
Radio Beams
82 June 2020
Part 2: Bromide, Domino and Benjamin
Locations of the radio beam transmitters in 1941. (Courtesy of Bill Rankin, www.afterthemap.info).
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June 2020 83
mechanism on board the plane. The 0.05q Àne director beam was so narrow that in calculating its bearing 5-Àgure log tables had to be used to take account of the fact that the earth isn’t a perfect sphere (it’s slightly Áattened near the poles). A result of the antenna conÀguration required to achieve this high directivity was that the radiation pattern had 14 lobes, several of which the bombers had to Áy across to Ànd the true guide beam. The crossbeams also had multiple sidelobes, and as the Áight progressed the aircrew had to resolve the ambiguity by counting them until they reached the genuine Àrst marker beam. These sidelobes also complicated 80 Wing’s task of determining the target. Since the X-Gerät system required special equipment and trained aircrew operators, it was Àtted only to the bombers of an elite group of pathÀnders called Kampf Gruppe 100 (KGr100), whose task was to mark the target with hundreds of 1kg thermite incendiaries, on which the main force would bomb visually. But the poor ballistics of these incendiaries resulted in considerable spread and they didn’t have a special Áare colour to distinguish them from Àres caused by misdirected bombs. Learning from experience with Knickebein, the 500W X-Gerät transmitters emitted spoof beams before each raid, while the real ones weren’t turned on until as late as possible, a tactic that sometimes confused the bombers as much as the defenders. Fortunately for the Allies, KGr100 was based at Vannes, far to the west of France and beyond the reach of secure German military landlines, so the unit had to use wireless for ground communications. This allowed the control messages to be intercepted by the Y Service and radio amateur VIs and decrypted at Bletchley Park. With these decrypts, Jones was able to deduce how the operating frequencies were related to the receiver settings that were transmitted to the pathÀnders before each raid. Using this information, Cockburn’s team at TRE rapidly introduced 100W X-Gerät jammers called ‘Bromides’ that were equivalent to the Aspirins for Headaches. Nevertheless, Bromide proved ineffective during the devastating 10-hour raid on Coventry, even though the jammers at Birdlip Hill, near Gloucester, Kenilworth and Hagley were well within range. This was because their modulation tone was set to 1500Hz, whereas the X-Gerät receivers had a sharp audio Àlter centred on 2000Hz. The mistake was corrected before the raids on Birmingham Àve days later, when the Luftwaffe bombers were partially disrupted and dispersed. By April 1941, 80 Wing had enough Bromides to disrupt all the X-Gerät director and crossbeam frequencies
and no other inland British city was to suffer such highly concentrated damage. In spite of at least eight attacks on the Rolls-Royce works at Derby during WW2, only a single bomb actually hit a factory building. Except on moonless or cloudy nights, no radio aids were required to Ànd the sprawling metropolis of London. But speciÀc industrial assets in the city couldn’t be targeted accurately without the help of reliable beams and the enemy bomb loads were scattered over almost 100 boroughs. Although no longer used by raiding bombers, the 6577MHz X-Gerät transmitters were kept functioning as decoys until they were Ànally dismantled in November 1942.
Y-Gerät
As early as mid-1940, when the existence of the Knickebein beams was conÀrmed, Enigma decrypts from Bletchley Park included mention of what appeared to be another system, code-named ‘Wotan’. Since this is the name of a Germanic God with only one eye, Jones guessed that it might refer to a new navigation aid that used only a single beam. It turned out that this reasoning was wrong but the conclusion was perfectly correct! Monitoring stations began to report beam signals between 42.1 and 47.9MHz that had different characteristics, with alternate right and left signals of equal duration transmitted at a high rate, for they were decoded in the aircraft electronically rather than aurally. The bearing analyser was coupled to the modiÀed He 111 autopilot by an automatic Áight control system that was much ahead of its time. This more advanced ‘Y-Gerät’ system reduced the number of confusing sidelobes by switching between a cardioid and a more directive antenna pattern. It achieved very accurate slant ranging by transmitting a 300Hz, 3kHz or 7.5kHz tonemodulated carrier to a transponder in the aircraft
on one frequency, and comparing the phase with the return signal carrying the same modulation sent back from the aircraft on a different one. The range measurement was made by the ground controller, who used a version of the X-Gerät stopclock to determine when to order the aircraft to release its bombs. Since the system was more complex and could only operate with Àve aircraft at a time, Y-Gerät equipped planes were formed into a specialised pathÀnder group (Group III of KG26) that led the main bomber stream. III/KG26 made the error of practising using Y-Gerät for many weeks before trying it on a major bombing raid. So Cockburn’s team had time to analyse the signals and devise a subtle countermeasure called ‘Domino’, which was ready for action on the very Àrst night that the system was used for a large-scale attack on Britain. They borrowed the powerful BBC TV transmitter at Alexandra Palace, which by chance operated in the same frequency band and had been shut down at the outbreak of war lest it be used by the Luftwaffe to home on London. An EMI TV receiver was set up at the former outside broadcast relay station at Swains Lane in Highgate, with its bandwidth enlarged to accept both the ground control transmission on 42.5MHz and the response from the pathÀnder bomber on 46.9MHz. From there, the modulation signal was sent by Post OfÀce landline to Alexandra Palace, together with a subdivision of the carrier frequency that allowed the TV transmitter to zero beat with the ground transmission. At Swains Lane Ewart Farvis sat listening to the German radio communications with his Ànger on a key that controlled Alexandra Palace remotely. At the critical moment, he sent the modulation back to the aircraft on 42.5MHz, using a power that was sufÀcient to give a false range indication but not enough to arouse suspicion of jamming. Thirty years after the event, when Farvis Ànally felt free to tell me about this secret war work, he described the result as hilarious. Being Áuent in German, he could follow the acrimonious radio dialogue between the bewildered young bomber aircrew and their ground controller as they argued about the cause of the perplexing behaviour of their instruments. The aircrew accused the ground station of sending bad signals, while the ground controller attributed the problems to airborne equipment failure, probably due to a loose wire. He even told the distraught operator to “thump the box”, which caused Farvis to remark that he was evidently a real radio man! The jamming was repeated successfully with more pathÀnders before the Luftwaffe abandoned the attack. At TRE, Farvis went on to analyse the signals of the German VHF IdentiÀcation, Friend or Foe
Dr Bruce Taylor, HB9ANY bgtaylor@ieee.org
The X-Gerät ‘bombing-clock’ measured the time WRÁ\EHWZHHQWZRFURVVEHDPVWRGHWHUPLQHWKH bomb release time. (Horst Beck Collection, photo Frank Dörenberg, N4SPP/F4WCN).
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(IFF) system, allowing the team to develop the ‘Perfectos’ radio device that RAF night Àghters used to trigger the transponders in enemy aircraft, to determine their positions without using radar. Following the deployment of Perfectos, many Luftwaffe crews Áew with their IFF switched off and were shot down by their own side’s Áak. After the capitulation of Germany, Farvis was given the temporary rank of Squadron Leader (and a revolver) when he was Áown to Munich to interrogate German engineers and scientists. He had a fruitful discussion with the designer of X-Gerät and Y-Gerät, Johannes Plendl.
Benjamin
Having established an effective countermeasure for the ranging system of Y-Gerät, Cockburn lost no time in manufacturing production versions of Domino, which could also deal with rapid frequency changes that were sometimes made in the middle of an operation. Although a Domino station on Beacon Hill near Salisbury was attacked by a small force of bombers it was soon back on the air and, during the Àrst two weeks of March 1941, only 18 aircraft of 89 Y-Gerät sorties received the bomb-release signal. Domino was an effective but complex countermeasure, requiring two-way communication between jammer and aircraft. But Cockburn soon found that Y-Gerät navigation could be disrupted by an even simpler form of jamming. When three Heinkel bombers were shot down during a raid over Liverpool in May 1941, the vulnerability of their Y-Gerät signal analyser was studied in detail at Farnborough. It was found that a short gap between the pair of direction signals was essential for the electronic bearing-analyser to lock to the beam. By Àlling in this gap by transmitting a continuous note on the beam frequency, the analyser unlocked and gave no useful indication. Within three weeks 80 Wing had a new jammer on the air that used this technique, and Àve more were operational before the end of the month. Cockburn called it ‘Benjamin’ (for ‘Ben jamming’, since Benito was the British codename for Y-Gerät). The Luftwaffe eventually realised that Y-Gerät had been compromised from the Àrst day that it was used. Bomber pilots no longer put any faith in wireless navigation aids, making the accurate night bombing of inland targets very difÀcult. In one raid the crews that thought they had bombed Nottingham dropped their weapons in open country 15 miles east of the city, killing two chickens with 230
Conclusion
In his memoirs on the Battle of Britain, Churchill wrote one sentence about the vitally important role of radar, but eight pages on the German radio beams. Were it not for Jones, Scott-Farnie, Cockburn, Farvis, TRE, 80 Wing and the efforts of numerous dedicated radio amateurs, there would undoubtedly have been many more instances like the destruction of Coventry. Without effective electronic countermeasures, concentrated pin-point bombing might well have destroyed the British aero-engine and SpitÀre factories, changing the course of the war. In a light-hearted tribute at the end of the conÁict, he wrote, “You certainly did pull the crooked leg”.
Correction
The Knickebein antenna shown on page 80 (May) is of the compact type and isn’t 60m high. The total distance from the bottom to the top of the stacked dipoles is less than 10m, which makes the total height of the structure less than 20m above ground. Even the giant antenna at Stollberg Hill was much less than 60m high, although it was 90m wide. The photo on page 82 isn’t a Knickebein antenna, although it does bear a resemblance. The one shown doesn’t have the ‘crooked leg’ angle characteristic of Knickebein. It is instead a photo of a ‘Bernhard’ radio navigational beacon, which had no connection with the bombing beams.
The Alexandra Palace TV transmitter was used to disrupt Y-Gerät on 42.5MHz. (Photo based on Duncan Harris/CC-BY-2.0).
7KH&RDOYLOOH2XWVWDWLRQRI:LQJRQWKHÁLJKWSDWKWR'HUE\KDG$VSLULQ to jam Knickebein, two Bromides for X-Gerät and Benjamin for Y-Gerät. ,Q/RXJKERURXJK$5&RSHUDWHG*%&+*IURPWKHVLWH &KDUOH\ +HULWDJH*URXS%OXHVN\*RRJOH(DUWK 
84 June 2020
high explosive bombs, one oil bomb and !ve sticks of 36 incendiaries. In some raids bombing was so scattered over the southern counties of England that it was impossible to deduce the intended target until it was revealed by the crews of downed bombers. Meanwhile, the tide of war began to turn. The experience of 80 Wing proved invaluable when the Allies began to take the !ght to the enemy and in the summer of 1942 the RAF used radio beams to guide the bombing of the Krupp arms factory in a precision night attack through ten-tenths cloud.
We apologise to Dr Taylor for the following errors that were introduced into Part 1 of this feature.
A downed Heinkel 111 pathfinder.

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1
July 20, 2001; rev. August 16, 2001
General Covariance, Gauge Theories and the Kretschmann
Objection.
Submitted to Symmetry in Physics: New Reflections,
Katherine Brading and Elena Castellani ( eds), in preparation.
John D. Norton 1
Department of History and Philosophy of Science
University of Pittsburgh, Pittsburgh PA USA 15260
jdnorton@pitt.edu
How can we reconcile two claims that are now both widely accepted:
Kretschmann's claim that a requirement of general covariance is physically
vacuous and the standard view that the general covariance of general relativity
expresses the physically important diffeomorphism gauge freedom of general
relativity? I urge that both claims can be held without contradiction if we attend
to the context in which each is made.
1 I thank Carlo Rovelli, John Earman, Elena Castellani and Chris Martin for their discussion
and for forcing me to think this through. I am also grateful for discussion by the participants
in the "International Workshop: General Covariance and Quantum?: Where Do We Stand,"
Department of Physics, University of Parma, June 21-23, 2001, organized by Massimo Pauri.
2
1. Introduction
Two views...
When Einstein formulated his general theory of relativity, he presented it as the
culmination of his search for a generally covariant theory. That this was the signal
achievement of the theory rapidly became the orthodox conception. A dissident view,
however, tracing back at least to objections raised by Erich Kretschmann in 1917, holds that
there is no physical content in Einstein's demand for general covariance. That dissident view
has grown into the mainstream. Many accounts of general relativity no longer even mention
a principle or requirement of general covariance.
What is unsettling for this shift in opinion is the newer characterization of general
relativity as a gauge theory of gravitation, with general covariance expressing a gauge
freedom. The recognition of this gauge freedom has proven central to the physical
interpretation of the theory. That freedom precludes certain otherwise natural sorts of
background spacetimes; it complicates identification of the theory's observables, since they
must be gauge invariant; and it is now recognized as presenting special problems for the
project of quantizing of gravitation.
...That We Need not Choose Between
It would seem unavoidable that we can choose at most one of these two views: the
vacuity of a requirement of general covariance or the central importance of general
covariance as a gauge freedom of general relativity. I will urge here that this is not so; we
may choose both, once we recognize the differing contexts in which they arise. Kretschmann's
claim of vacuity arises when we have some body of physical fact to represent and we are
given free reign in devising the formalism that will capture it. He urges, correctly I believe,
that we will always succeed in finding a generally covariant formulation. Now take a
different context. The theory—general relativity—is fixed both in its formalism and physical
3
interpretation. Each formal property of the theory will have some meaning. That holds for its
general covariance which turns out to express an important gauge freedom.
To Come
In Section 4 I will lay out this reconciliation in greater detail. As preparation, in
Sections 2 and 3, I will briefly review the two viewpoints. Finally in Section 5 I will relate the
reconciliation to the fertile "gauge principle" used in recent particle physics. An Appendix
discusses the difficulty of making good on Kretschmann's claim that generally covariant
reformulations are possible for any spacetime theory.
2. Einstein and Kretschmann's Objection
Einstein...
In November 1915 an exhausted and exhilarated Einstein presented the
gravitational field equations of his general theory of relativity to the Prussian Academy of
Science. These equations were generally covariant; they retained their form under arbitrary
transformation of the spacetime coordinate system. This event marked the end of a seven
year quest, with the final three years of greatest intensity, as Einstein struggled to see that a
generally covariant theory was physically admissible. 2
Einstein had several bases for general covariance. He believed that the general
covariance of his theory embodied an extension of the principle of relativity to acceleration.
This conclusion seemed automatic to Einstein, just as the Lorentz covariance of his 1905
formulation of special relativity expressed its satisfaction of the principle of relativity of
2 Over the last two decades there has been extensive historical work on this episode. Earlier
works include Stachel (1980) and Norton (1984); the definitive work will be Renn et al. (in
preparation).
4
inertial motion. 3 He also advanced what we now call the "point-coincidence" argument. The
physical content of a theory is exhausted by a catalog of coincidences, such as the coincidence
of a pointer with a scale, or, if the world consisted of nothing but particles in motion, the
meetings of their worldlines. These coincidences are preserved under arbitrary coordinate
transformations; all we do in the transformations is relabel the spacetime coordinates
assigned to each coincidence. Therefore a physical theory should be generally covariant. Any
less covariance restricts our freedom to relabel the spacetime coordinates of the coincidences
and that restriction can be based in no physical fact.
...and Kretschmann
Shortly after, Erich Kretschmann (1917) announced that Einstein had profoundly
mistaken the character of his achievement. In demanding general covariance, Kretschmann
asserted, Einstein had placed no constraint on the physical content of his theory. He had
merely challenged his mathematical ingenuity. For, Kretschmann urged, any spacetime
theory could be given a generally covariant formulation as long as we are prepared to put
sufficient energy into the task of reformulating it. In arriving at general relativity, Einstein
had used the "absolute differential calculus" of Ricci and Levi-Civita (now called "tensor
calculus.") Kretschmann pointed to this calculus as a tool that made the task of finding
generally covariant formulations of theories tractable. 4
Kretschmann's argument was slightly more subtle than the above remarks.
Kretschmann actually embraced Einstein's point-coincidence argument and turned it to his
own ends. In his objection, he agreed that the physical content of spacetime theories is
3 The analogy proved difficult to sustain and has been the subject of extensive debate. See
Norton (1993).
4 For further discussion of Kretschmann's objection, Einstein's response and of the still active
debate that follows, see Norton (1993) and Rynasiewicz (1999)
5
exhausted by the catalog of spacetime coincidences; this is no peculiarity of general
relativity. For this very reason all spacetime theories can be given generally covariant
formulations. 5
Kretschmann's objection doe s seem sustainable. For example, using Ricci and Levi
Civita's methods it is quite easy to give special relativity a generally covariant formulation.
In its standard Lorentz covariant formulation, using the standard spacetime coordinates (t,
x, y, z), special relativity is the theory of a Minkowski spacetime whose geometry is given by
the invariant line element
ds2 = c 2dt2 - dx2 -dy2 - dz2 (1)
Free fall trajectories (and other "straights" of the geometry) are given by
d2x/dt2 = d2y/dt2 = d2z/dt2 = 0 (2)
We introduce arbitrary spacetime coordinates x i, for i = 0,...,3 and the invariant line element
becomes
ds2 = gik dxi dxk (3a)
where the matrix of coefficients g ik is subject to a field equation
Riklm = 0 (3a)
with Riklm the Riemann-Christoffel curvature tensor. The free falls are now governed by
d2xi/ds2 + {kim} dxk/ds dxm/ds = 0 (4)
where {kim} are the Christoffel symbols of the second kind.
5 Rhetorically, Kretschmann's argument was brilliant. To deny it, Einstein may need to deny
his own point-coincidence argument. However a persistent ambiguity remains in Einstein's
original argument. Just what is a point-coincidence? Einstein gives no general definition. He
gives only a list of illustrations and many pitfalls await those who want to make the
argument more precise. For example, see Howard (1999).
6
Examples such as this suggest that Kretschmann was right to urge that generally
covariant reformulations are possible for all spacetime theories. While the suggestion is
plausible it is certainly not proven by the examples and any final decision must await
clarification of some ambiguities. See Appendix 1: Is a Generally Covariant Reformulation
Always Possible? for further discussion.
3. The Gauge Freedom of General Relativity
Active General Covariance
Einstein spoke of general covariance as the invariance of form of a theory's equations
when the spacetime coordinates are transformed. It is usually coupled with a so-called
"passive" reading of general covariance: if we have some system of fields, we can change our
spacetime coordinate system as we please and the new descriptions of the fields in the new
coordinate systems will still solve the theory's equations. Einstein's form invariance of the
theory's equations also licenses a second version, the so-called "active" general covariance. It
involves no transformation of the spacetime coordinate system. Rather active general
covariance licenses the generation of many new solutions of the equations of the theory in the
same coordinate system once one solution has been given.
For example, assume the equations of some generally covariant theory admit a scalar
field φ(xi) as a solution. Then general covariance allows us to generate arbitrarily many more
solutions by, metaphorically speaking, spreading the scalar field differently over the
spacetime manifold of events. We need a smooth mapping on the events—a
diffeomorphism—to effect the redistribution. For example, assume we have such a map that
sends the event at coordinate x i to the event at coordinate x' i in the same coordinate system.
Such a map might be a uniform doubling, so that x i is mapped to x' i = 2. xi. To define the
redistributed field φ', we assign to the event at x' i the value of the original field φ at the event
7
with coordinate x i.6 If the field is not a scalar field, the transformation rule is slightly more
complicated. For further details of the scalar case, see Appendix 2: From Passive to Active
Covariance.
Why it is a Gauge Freedom
The fields φ(xi) and φ'(xi) are mathematically distinct. But do they represent
physically distinct fields? The standard view is to assume that they do not, so that they are
related by a gauge transformation, that is, one that relates mathematically distinct
representations of the same physical reality. That this is so cannot be decided purely by the
mathematics. It is a matter of physics and must be settled by physical argumentation.
A vivid way to lay out the physical arguments is through Einstein's "hole
argument."7 The transformation on the manifold of events can be set up so that it is the
identity everywhere outside some nominated neighborhood of spacetime ("the hole") and
comes smoothly to differ within. We now use the transformation to duplicate
diffeomorphically all the fields of some generally covariant theory. Do the new fields
represent the same physical reality as the old? It would be very odd if they did not. Both
systems of fields agree completely in all invariants; they are just spread differently on the
manifold. Since observables are given by invariants, they agree in everything observable.
Moreover, the two systems of field will agree everywhere outside the hole, but they differ
only within. This means that, in a generally covariant theory, fixing all fields outside this
neighbor fails to fix the fields within. This is a violation of determinism. In short, if we
assume the two systems of fields differ in some physical way we must insist upon a difference
6 To visualize this redistribution in the two dimensional case, imagine that the original field
is represented by numbers written on a flat rubber membrane. If we now uniformly stretch
the rubber membrane so it doubles in size, we have the new field.
7 See Earman and Norton (1987), Norton (1999).
8
that transcends both observation and the determining power of the theory. The ready
solution is that these differences are purely ones of mathematical representation and that
the two systems of fields represent the same physical reality.
Its Physical Consequences
Accepting that this gauge freedom has important consequences for the physical
interpretation of a theory such as general relativity. 8 The theory is developed by positing a
manifold of spacetime events which is then endowed with metric properties by means of a
metric tensor field g ik. The natural default is to take the manifold of events as supplying
some kind of independent background spacetime in which physical processes can unfold. The
gauge freedom makes it very difficult to retain this view. For, when we apply a
diffeomorphism to the field and spread the metrical properties differently over events, the
transformation is purely gauge and we end up changing nothing physical. So now the same
events are endowed with different properties, yet nothing physical has changed. The simplest
and perhaps only way to make sense of this is to give up the idea of an independent existence
of the events of the manifold. In so far as we can associate an event of the manifold with real
events in the world, that association must change in concert with our redistribution of the
metrical field over the manifold.
Our notion of what is observable is affected by similar considerations. What is
observable is a subset of the physically real and that in turn is expressed by the invariants of
a theory. Might an observable result consist of the assertion that an invariant of some field
has such and such a value at some event of the manifold? No. The invariance must also
include invariance under the gauge transformation and the assertion would fail to be
invariant under the gauge transformation. In redistributing the fields, the transformation
8 For further discussion of these and related issues and their import for the quantization of
gravity see Rovelli (1997).
9
might relocate that invariant with that value at quite another event of the manifold. If some
result is eradicated by a gauge transformation, it cannot have been a result expressing
physical fact since the gauge transformation alters nothing physical. We must resort to more
refined ways of representing observables. For example, they may be expressed by an
assertion that two invariants are equal. The event at which the equality resided may vary
under gauge transformation; but the transformation will preserve the equality asserted.
4. Reconciliation
The Context in which Kretschmann's Objection Succeeds
Kretschmann's objection s ucceeds because he allows us every freedom in
reformulating and reinterpreting terms within a theory. Thus we easily transformed special
relativity from its Lorentz covariant formulation (1), (2) to a generally covariant formulation
(3a), (3b), (4). In doing so, we introduced new variables not originally present. The are the
coefficients of the metric tensor g ik and the Christoffel symbols { kim}.
With this amount of freedom, it is plausible that we can arrive at formulations of any
theory that have any designated formal property. 9 Imagine, for example, that we wanted a
9 I am distinguishing the formalism of the theory (and its formal properties) from its
interpretation. The formalism of a theory would be the actual words used, if the theory
consisted of an English language description, independently of their meanings. Formal
properties would include such things as the choice of English and the number of words. More
commonly physical theories use mathematical structures in place of words. These structures
can be considered quite independently of what we take them to represent in the world. The
properties we then consider are the purely formal properties. A real valued field on some
manifold is just a mathematical structure until we specify what it may represent in the
world. That specification is the job of the interpretation. See next footnote.
10
formulation of Newtonian particle mechanics in which the string of symbols " E=mc2"
appears. (This is a purely formal property since we place no conditions on what the string
might mean.) Here is one way we can generate it. We take the usual expression for the
kinetic energy K of a particle of mass m moving at velocity v, K=(1/2) mv2. We introduce a
new quantity E, defined by E = 2K, and also a new label "c" for velocity v, so that c=v. Once
we substitute these new variables into the expression for kinetic energy, our reformulated
theory contains the string " E=mc2".
The physical vacuity arises because we are demanding the formal property of general
covariance (or some other formal property) without placing further restrictions that would
preclude it always being achievable. The vacuity would persist even if we demanded a fixed
physical content; we must simply be careful not to alter our initial physical content as we
adjust its formal clothing. In the case of the discovery of general relativity, Einstein did not
keep the physical content fixed. It became fully fixed only after he found a generally
covariant formulation that satisfied a number of restrictive physical limitation.
The Context in Which the Diffeomorphism Gauge Freedom has Physical Content
Matters are quite different if we fix the formalism of the theory and its
interpretation. So we might be given general relativity in its standard interpretation. 10 If a
theory has any content at all, we must be able to ascribe some physical meaning to its
assertions. A fortiori there must some physical meaning in the general covariance of general
10 By "interpretation" I just mean the rules that tell us how to connect the various terms or
mathematical structures of the theory with things in the physical world. These rules can
vary from formulation to formulations and theory to theory. So, in ordinary formulations of
special relativity, "c" refers to the speed of light. In thermodynamics "c" would refer to
specific heat.
11
relativity. It may be trivial or it may not. 11 Consulting the theory, as we did in Section 2
above reveals that the content is not trivial.
Things are just the same in our toy example of forcing the string " E=mc2" into a
formulation of Newtonian particle mechanics. Let us fix the formulation to be the doctored
one above. We had forced the string " E=mc2" into it. But now that we have done it, the string
uses symbols that have a meaning and, when we decode what it says about them, we
discover that the string expresses something physical, the original statement that kinetic
energy is half mass x (velocity) 2. Mimicking Kretschmann, we would insist that, given
Newtonian particle mechanics or any other theory, some reformulation with the string is
assuredly possible; so the demand for it places no restriction on the physically possible. But,
once we have the reformulation, that string will express something.
The analogous circumstance arises in the generally covariant reformulation of special
relativity. The existence of the reformulation is assured. Once we have it, its general
covariance does express something. In this case, it is a gauge freedom of the geometric
structure just like that of general relativity. The Lorentz covariant formulation of (1) and (2)
admits preferred coordinate systems. In effect, some of the physical content of the theory is
encoded in them. They specify, for example, which are the inertial motions; a body moves
inertially only if there is a coordinate system in which its spatial coordinates do not change
with the time coordinate. In the transition to the generally covariant formulation, this
11 Indeed the assertion may prove to be a logical truth, that is, it would be true by the
definition of the terms it invokes or it may amount to the definition of term.While their truth
is assured, such assertions need not be trivial. For example in a formulation of special
relativity we may assert that that coefficients of the metric tensor are linear functions of the
coordinates. This turns out to place no physical restriction on the theory; it merely restricts
us to particular coordinate systems. It is what is known as a coordinate condition that
defines the restricted class of coordinate systems in which the formulation holds.
12
content is stripped out of the coordinate systems. We can no longer use constancy of spatial
coordinates to discern which points move inertially. This content is relocated in the
Christoffel symbols, which, via equation (4) determine whether a particular motion is
inertial. The general covariance of (3a), (3b) and (4) leave a gauge freedom in how the metric
gik and the Christoffel symbols { kim} may be spread over some coordinate system. In one
coordinate system, they may be spread in many mathematically distinct but physically
equivalent ways.
To summarize
There is no restriction on physical content in saying that there exists a formulation of the
theory that has some formal property (general covariance, the presence of the string of
symbols " E=mc2", etc.) But once we fix a particular formulation and interpretation, that very
same formal property will express something physical, although there is no assurance that it
will be something interesting.
5. Gauge Theories in Particle Physics
This summary generates a new puzzle. One of the most fertile strategies in recent
decades in particle physics has been to extend the gauge symmetries of non-interacting
particles and thereby infer to new gauge fields that mediate the interaction between the
particles. Most simply, the electromagnetic field can be generated as the gauge field that
mediates interactions of electrons. This power has earned the strategy the label of the "gauge
principle." How can this strategy succeed if Kretschmann is right and there is no physical
content in our being able to arrive at a reformulation of expanded covariance? In the particle
context, this corresponds to a reformulation of expanded gauge freedom. So why doesn't
Kretschmann's objection also tell us that the strategy of the gauge principle is physically
vacuous?
13
The solution lies in the essential antecedent condition of Kretschmann's objection.
The physical vacuity arises since there are no restrictions placed how we might reformulate a
theory in seeking generally covariance. It has long been recognized that the assured
achievement of general covariance can be blocked by some sort of additional restriction on
how the reformulation may be achieved. Many additional conditions have been suggested,
including demands for simplicity and restrictions on which extra variables may introduced.
(For a survey, see Norton, 1993, Section 5; Norton, 1995, Section 4.) The analogous solution
is what gives the gauge principle its content. In generating gauge fields, we are most
definitely not at liberty to expand the gauge freedom of some non-interacting particle field in
any way we please. There is a quite precise recipe that must be followed: we must promote a
global symmetry of the original particle field to a local symmetry, using the exemplar of the
electron and the Maxwell field, and the new field arises from the connection introduced to
preserve gauge equivalence. 12
There is considerably more that should be said about the details of the recipe and the
way in which new physical content arises. The recipe is standardly presented as merely
expanding the gauge freedom of the non-interacting particles, which should mean that the
realm of physical possibility is unaltered; we merely have more gauge equivalent
representations of the same physical situations. So how can physically new particle fields
12 The transition from special relativity in (1) and (2) to the generally covariant formulation
(3a), (3b) and (4) can be extended by one step. We replace the flatness condition (3a) by a
weaker condition, a natural relaxation, R ik = glmRilmk = 0. The result is general relativity in
the source free case. Arbitrary, source free gravitational fields now appear in the generalized
connection { kim}. We have what amounts to the earliest example of the use of the gauge
recipe to generate new fields. The analogy to more traditional examples in particle physics is
obvious.
14
emerge? This question is currently under detailed and profitable scrutiny. See Martin (2000),
(manuscript) and contributions to this volume.
Appendix 1: Is a Generally Covariant Reformulation Always
Possible?
As Earman (manuscript, Section 3) has pointed out, it is not entirely clear whether a
generally covariant reformation is always possible for any spacetime theory. The problem lies
in ambiguities in the question. Just what counts as "any" spacetime theory? Just what are
we expecting from a generally covariant reformulation? Let me rehearse some of the
difficulties and suggest that for most reasonable answers to these questions generally
covariant reformulation will be possible though not necessarily pretty.
The Substitution Trick...
Let us imagine that we are given a spacetime theory in a formulation of restricted
covariance. It is given in just one spacetime coordinate systems X i. Let us imagine that the
laws of the theory happen to be given by n equations in the 2n quantities A k, Bk
Ak(X i) = Bk(X i) (5)
where k = 1, ..., n and the A k and Bk are functions of the coordinates as indicated. Consider
an arbitrary coordinate system x i to which we transform by means of the transformation law
xi = xi(X m) (6)
We can replace the n equations (5) by equations that hold in the arbitrary coordinate system
by the simple expedient of inverting the transformation of (6) to recover the expression for
the X m as a function of the x i, that is X m = X m(xi). Substituting these expressions for X m into
(5), we recover a version of (5) that holds in the arbitrary coordinate system
Ak(X i(xm)) = Bk(X i(xm)) (5a)
15
We seemed to have achieved a generally covariant reformulation of (5) by the most direct
application of the intuition that coordinate systems are merely labels and we can relabel
spacetime events as we please.
...Yields Geometric Objects
While (5a) is generally covariant, we may not be happy with the form of the general
covariance achieved—one of the ambiguities mentioned above. We might, as Earman
(manuscript, Section 3) suggests, want to demand that (5a) be expressed in terms of
geometric object fields. The standard definition of a geometric object field is that it is an n
tuple valued field of components on the manifold, with one field for each coordinate system,
and that the transformation rule that associates the components of different coordinate
systems have the usual group properties.
While this definition may appear demanding, it turns out to be sufficiently
permissive to characterize each side of (5a) as a geometric object field. For example, in each
coordinate system x m, the geometric object field A has components A k(X i(xm)), which I now
write as Ak(xm). The transformation rule between the components is induced by the rule for
coordinate transformations. That is, under the transformation x m to yr(xm), Ak(xm)
transforms to A k(xm(yr)), where xm(yr) is the inverse of the coordinate transformation. With
this definition of the transformation law for A k, the components will inherit as much group
structure as the coordinate transformations themselves have; that is, it will be as much of a
geometric object field as we can demand. 13 For example, assume the transformations of
13 Why the hedged "as much group structure as the coordinate transformations themselves
have"? These general coordinate transformations may not have all the group properties if the
domains and ranges of the transformations do not match up well. Assume T 1 maps
coordinates x i on a neighborhood A to coordinates y i on a neighborhood B that is a proper
subset of A and T 2 maps coordinates y i on B to coordinates z i on A. Then the composition
16
coordinate systems z p to yr and yr to xm conform to transitivity. Then this same transitivity
will be inherited by A. We will have A k(xm(zp)) = A k(xm(yr(zp))) since the transitivity of the
coordinate transformation yields x m(zp) = xm(yr(zp)).
But areThey the Geometric Objects We Expect?
While the components A k turn out to be geometric object fields, they are probably not
the ones we expected. In brief, the reason is that the transformation rule induced by the
substitution trick does not allow any mixing of the components. That precludes it yielding
vectors or tensor or like structures; it turns everything into scalar fields. To see how odd this
is, take a very simple case. Imagine that we have special relativity restricted to just one
coordinate system X i. Our law might be the law governing the motion of a body of unit mass,
Fi = A i, where Fi is the four force and A i the four acceleration. Under a Lorentz
transformation
Y0 = γ(X 0 – vX 1) Y1 = γ(X 1 – vX 0) Y3 = X 3 Y4 = X 4
with velocity v in the X 1 direction, c=1 and γ = (1-v2)-1/2.The usual Lorentz transformation for
the components A i of the four acceleration would be
A' 0 = γ(A 0 – vA1) A' 1 = γ(A 1 – vA0) A' 3 = A 3 A' 4 = A 4 (6)
Note that the transformed A' 0 and A' 1 are linear sums of terms in A 0 and A1. For this same
transformation, the substitution trick merely gives us
A' i = A i(X m(Yr)) (6a)
That is, A' 0 is a function of A 0 only and A' 1 is a function of A 1 only.
This oddity becomes a disaste r if we apply the substitution rule in a natural way.
Instead of starting with Ai in one fixed coordinate system X i, we might start will the full set
T2T1 cannot coincide with the direct transformation of x i to zi since the composition has lost
that part of the transformation outside B.
17
of all components of A i in all coordinate systems related by a Lorentz transformation to X i. If
we now try and make this bigger object generally covariant by the substitution trick, we will
end up with two incompatible transformation laws for the transformation X i to Yi when we
try to transform the components A i—the law (6) and law (6a). We no longer have a geometric
object field since we no longer have a unique transformation law for the components.
The escape from this last problem is to separate the two transformation groups. We
consider A i in coordinate system X i and A' i in coordinate system Y i separately and convert
them into distinct geometric object fields by the substitution trick. As geometric object fields
they have become, in effect, scalar fields. The Lorentz transformation then reappears as a
transformation between these geometric objects.
The Coordinates as Scalars Trick
If this is our final goal, then another general trick for generating generally covariant
reformulations could have gotten us there much faster. We return to A k(X i) of (5). We can
conceive the X i as scalar fields on the manifold—that is really all they are. 14 Scalar fields are
geometric object fields already. The A i are functions of X i, that is, functions of scalar fields.
Therefore they are also geometric objects. So we can conceive of the entire structure A k(X i) as
a geometric object field. We have gotten general covariance on the cheap. We cannot avoid a
cost elsewhere in the theory however. Our reformulation is overloaded with structure, one
geometric object field for each of what was originally a component. There is clearly far more
mathematical structure present than has physical significance. So the theory will need a
careful system for discerning just which parts of all this structure has physical significance.
14 Ask, what is the X 0 coordinate in coordinate system X i of some event p? The answer will be
the same number if we ask it from any other coordinate system y i as long as we are careful to
ask it of the original coordinate system X i. That is, each coordinate can be treated as a scalar
field.
18
Temptations Resisted
These devices for inducing general covarianc e are clumsy but they do fall within the
few rules discussed. We might be tempted to demand that we only admit generally covariant
formulations if their various parts fall together into nice compact geometric objects. But what
basis do we have for demanding this? Are we to preclude the possibility that the theory we
started with is just a complicated mess that can only admit an even more complicated mess
when given generally covariant reformulations. (Newtonian theory has been accused of this!)
And if we are to demand only nice and elegant reformulations, just how do we define "nice
and elegant"?
My conclusion is that generally covariant reformulations are possible under the few
rules discussed and that efforts to impose further rules to block the more clumsy ones will
cause more trouble than they are worth elsewhere.
Appendix 2: From Passive to Active Covariance
As above, assume the equations of some generally covariant theory admit a scalar
field φ(xi) as a solution. We can transform to a new coordinate system by merely relabeling
the events of spacetime; x i is relabeled x' i, where the x'i are smooth functions of the x i. The
field φ(xi) transforms to field φ'(x'i) by the simple rule φ'(x'i) = φ(xi). Since the equations of the
theory hold in the new coordinate system, the new field φ'(x'i) will still be a solution. The two
fields φ(xi) and φ'(x'i) are just representations of the same physical field in different
spacetime coordinate systems.
This is the passive view of general covariance. It can be readily t ransmogrified into
an active view, a transition that Einstein had already undertaken with his 1914 statements
of the "hole argument". What makes φ'(x'i) a solution of the theory under discussion is
nothing special about the coordinate system x' i. It is merely the particular function that φ'
happens to be. It is a function that happens to satisfy the equations of the theory. We could
19
take that very same function and use it in the original coordinate system, x i. That is, we
could form a new field φ'(xi). Since this new field uses the very same function, it retains every
property except the mention of the primed coordinate system x' i. Thus it is also a solution of
the equations of the theory.
In short, the passive general covariance of the theory has delivered us two fields,
φ(xi) and φ'(xi). They are not merely two representations of the same field in different
coordinate systems. They are defined in the same coordinate system and are mathematically
distinct fields, in so far as their values at given events will (in general) be different. Active
general covariance allows the generation of the field φ'(xi) from φ(xi) by the transformation xi
to x'i.
References
Earman, John (manuscript) "Once More General Covariance."
Earman, John and Norton, John D. (1987): "What Price Spacetime Substantivalism? The
Hole Argument," British Journal for the Philosophy of Science. 38, pp. 515-25.
Howard, Don (1999) "Point Coincidences and Pointer Coincidences: Einstein on the Invariant
Content of Space-Time Theories," in H. Goenner, J. Renn, J. Ritter, T. Sauer (eds.)
The Expanding Worlds of General Relativity (Einstein Studies volume 7) pp. 463
500.
Kretschmann, Erich (1917): "Über den physikalischen Sinn der Relativitätspostulat, A
Einsteins neue und seine ursprünglische Relativitätstheorie," Annalen der Physik,
53, 575-614.
Martin, Christopher (2000) "The Gauge Argument," Talk at the Philosophy of Science
Association Biennial Meeting, Vancouver, 2-5, November, 2000.
Martin, Christopher (manuscript) Dissertation, Department of History and Philosophy of
Science, University of Pittsburgh.
20
Norton, John D. (1984) "How Einstein found his Field Equations: 1912-1915," Historical
Studies in the Physical Sciences, 14, 253-316; reprinted in Don Howard and John
Stachel (eds.) Einstein and the History of General Relativity: Einstein Studies, Vol.
1 Boston: Birkhäuser, 1989, pp.101-159.
Norton, John D. (1993), "General Covariance and the Foundations of General Relativity:
Eight Decades of Dispute," Reports on Progress in Physics, 56, pp. 791-858.
Norton, John D. (1995) "Did Einstein Stumble? the Debate Over General Covariance,"
Erkenntnis 42, pp. 223-45.
Norton, John D. (1999) "The Hole Argument," Stanford Encyclopedia of Philosophy
http://plato.stanford.edu/entries/spacetime-holearg/
Renn, Jürgen; Sauer, Tilman; Janssen, Michel; Norton, John D. and Stachel John (in
preparation) General Relativity in the Making; Einstein's Zurich Notebook.
Rovelli, Carlo (1997) "Halfway through the Woods: Contemporary Research on Space and
Time," pp. 180-223 in J. Earman and J. D. Norton (eds.) The Cosmos of Science:
Essays of Exploration. Pittsburgh: University of Pittsburgh Press.
Rynasiewicz, Robert (1999) "Kretschmann's Analysis of General Covariance and Relativity
Principles," in H. Goenner, J. Renn, J. Ritter, T. Sauer (eds.) The Expanding
Worlds of General Relativity (Einstein Studies volume 7) pp. 431-462.
Stachel, John (1980): "Einstein's Search for General Covariance," paper read at the Ninth
International Conference on General Relativity and Gravitation, Jena; printed in
Don Howard and John Stachel (eds.) Einstein and the History of General Relativity:
Einstein Studies, Vol. 1 (Boston: Birkhäuser, 1989) pp.63-100.

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Archaeological Discovery, 2023, 11, 189-202 https://www.scirp.org/journal/ad ISSN Online: 2331-1967 ISSN Print: 2331-1959
DOI: 10.4236/ad.2023.114009 Sep. 26, 2023 189 Archaeological Discovery
The German Radio Guidance Station K11, Stp
Mo 44c at Saint-Fiacre (Lanmeur-FR)
Giancarlo T. Tomezzoli
Faculté de Lettres et Sciences Humaines, Université de la Bretagne Occidentale, Brest, France
Abstract
It is common opinion that the Battle of Britain during the WWII was principally characterised by the role of the British radars and the RAF aircrafts in detecting and destroying incoming German bombers. This is partially true, because it ignores the role played by German installations of advanced technology for guiding German bombers during their missions over Great Britain and the British attempts to jam the German bomber guiding beacons. The German radio guidance station K11, StpMo44cat Saint-Fiacre (Lanmeur) is one of the best examples of German radio guidance station in France. The visits on the site, permitted to identify some K11,StpMo44c components and to determine their preservation state at about eighty years from the end of the WWII.
Keywords
Knickebein, K11, Mo44c, Lanmeur, Saint-Fiacre, Battle of England, Luftwaffe, Wassermann, See-Elefant
1. Introduction
It is common opinion that the Battle of Britain during the WWII was principally characterised by the role of the British radars and the RAF aircrafts in detecting and destroying incoming German bombers. This is partially true, because it ignores the role played by German installations of advanced technology, in particular the Knickebein systems, for guiding the German bombers during their mission over Great Britain and the British attempts to jam the German bombers guiding beacons.
2. History
The information about the Knickebein (Bent Leg) system came to the British
How to cite this paper: Tomezzoli, G. T. (2023). The German Radio Guidance Station K11, StpMo44c at Saint-Fiacre (Lanmeur-FR). Archaeological Discovery, 11, 189-202. https://doi.org/10.4236/ad.2023.114009
Received: August 13, 2023 Accepted: September 23, 2023 Published: September 26, 2023
Copyright © 2023 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access
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scientific, military intelligence through a note on a paper saved a day of March 1940 from the shot down German Heinkel aircraft 1H + AC belonging to the Kampfgeshwader26Löwen. Its translation was:” Navigational Aid: ... Radio Beacon Knickebein from 0600 hours on 315 ̊”. Radio beacons were normally used by navigators for figuring out the position of their aircrafts. The radio beacon 315 ̊ was unusual because it pointed north-west and appeared to have been pre-set before the beacon itself. Knickebein appeared as a beamed beacon set in that day for transmitting in a north-west direction. The interrogation of one of the prisoners allowed to establish that Knickebein was something similar to the German radio-guidance X-Apparatus, developed at the same time and, because of the short wave used, the British experts estimated that the beacon was not wider than a km in diameter over London. Further, a rumour arrived from France, according to which the Germans had set up a kind of radio beam station on their frontier (Kleve-Dutch border, Stollberg-Schleswig-Holstein, Lörrach-Baden, Trenkle, 1979) that the experts evaluated as having surprisingly narrow beacon. Such a narrow beam would have required very short wavelengths. The German attack exercises against Great Britain of March 1940 were followed by other exercises in June/July 1940. The beacons, surprisingly were directed against England although there was enough exercise space over France. Consequently, from early June, the British had the possibility to investigate such directional beams by means of one aircraft equipped with a radio landing system developed in Germany, and to prepare quickly countermeasures by means of diathermy transmitters (high frequency electric current devices) in the hope to jam the beacons by sending noise on the Knickebein frequencies (coded Headache), but with little effect (Jones, 2009). A secret weapon report update (Jones, 2009) for the new Prime Minister Churchill, who had taken over the same day as the German invasion of Holland and Belgium, warned: “It is possible that [the Germans] have developed a system of intersecting radio beams so that they can locate a target such as London sufficiently accurately for indiscriminate bombing. ..., but the accuracy expected by the Germans is something like a 1/2 mile over London from the western frontier of Germany. Efforts are still being made to determine the possible wavelengths so that counter measures can be employed”. The British Y Service intercepted German radio signals and a message from the Chief Signal Officer of the FliegerKorpsIVon 5th June at 1455, decoded at Bletchley which was successful in decoding some of the Enigmamessages, which informed: “Cleves Knickebein is confirmed (or established) at position 53 ̊24' north and 1 ̊ west”. It was now obvious that the Germans had an intersecting beam system for bombing England. The bombers of the FliegerKorpsIV were Heinkel111of KampfGeschwadern4 and 27, equipped with a receiver E.Bl.I (Empfanger Blind I—blind landing receiver type I), normally used for blind landing, improved for receiving Knickebein frequencies. Knowing the frequencies at which the receiver could be tuned allowed the identification of the Knick
G. T. Tomezzoli
DOI: 10.4236/ad.2023.114009 191 Archaeological Discovery
ebein emission frequencies. Another prisoner informed that Knickebein was a bomb-dropping device which involved two intersecting radio beams and which was developed in Germany at Rechling. He drew a sketch of what he thought to be a transmitting tower. In a ministry high-level meeting, it was taken the decision to jam these emission frequencies. Five British radar stations were equipped with signal receivers on radar towers, a RAF unit received the duty of detecting the beams in the air and new receivers and jamming systems were investigated (Jones, 2009). On 1940 a small Knickebein system version was developed by the German company Telefunken, comprising a rail ring of 45 m in diameter. Its antenna, on a turntable, was turned on the rail. In the middle, it comprised 2 × 4 half-wave dipoles each associated with a reflector. Because thick dipole tubes were used, a system, without changes to the antenna, was able to be tuned from 30.0 to 31.5 MHz and from 31.5 to 33.3 MHz. The systems were used against Great Britain from May to September 1940 but always disturbed and finally they could no longer be used. For recognizing the distance from the target each bomber was provided with a X-device. The system beacons served primarily to recognize the approach and return routes on the sea about 30 - 80 km parallel to the English coast outside the range of jammers. To indicate turning points, at the beginning, another Knickebein beacon was used and later other types of radio beacons. One system beacon was directed to the target indicating the pathway and it was crossed over the target by a second beacon used as signal for the bombing (Trenkle, 1979). The Knickebein beacon worked according to the Lorentz beam principle consisting in transmitting two fairly blunt beams, pointing in slightly different directions but overlapping one another in a relatively narrow region which was the beam along which the aircraft had to fly. The two overlapping beams were generated by two aerial systems pointing in slightly different directions and mounted together on a turntable. The radio transmitter was switched from one of these aerials to the other and back again in a repetitive sequence so that one aerial transmitted for a short time transmitting a dot beam, followed by a longer interval, while the other aerial transmitted for a longer time transmitting a dash beam followed by a short interval. On a receiver for the two aerial signals on an aircraft a dot signal was immediately followed by a dash signal giving rise to an equi-signal giving a continuous note. As the aircraft moved on one side toward the dot beam the dot signals became stronger above the continuous note and vice versa with the dash signals. This indicated to the pilots the direction to steer for bringing the aircraft back in the equi-signal beam. The turntable was turned so that the aerials were set in a direction such that the equi-signal beam crossed the target. In case of a bomber, a second system transmitted a beam crossing the equi-signal beam few kilometres before the target. On 1940 nine small Knickebein systems were installed along the coasts of Norway, Germany, Holland, and France. On 27th June 1940 another Knickebein information arrived through an Enig
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ma message “it is proposed to set up Knickebein and Wotan installations near Cherbourg and Brest” (Jones, 2009). Correspondingly, on the other side of the English Channel, a company working for the German Luftwaffe on the aviation camp of Morlaix was the first German unit to reach Lanmeur. The Luftwaffeinstalled one of the small Knickebein system at Saint-Fiacre, near Lanmeur (Figures 1-3). The system was defended by the 3rd battery of the group Flak752(Unit L32 999). The gunners were lodged at the ancient gendarmerie (Flock, 2012). From 13th August 1940 (AdlerTag) began large-scale operations of German bombers using Knickebein systems. So, Liverpool, among other, was attached from 28th to 30th August (Jones, 2009).
Figure 1. aerial oblique view of the radio guidance station K11, StpMo44cof Saint-Fiacre around 1947. Distinguishable are: the access road, the reinforced, buried bunker, concrete barracks or exhaust vents near the bunker, Flakemplacements, the Knickebein ring with two nearby constructions, a ditch for one shack or cistern; the Wasserman/SeeElefant antenna (Rapport Pinczon du Sel, 1947-1948a).
Figure 2. radio guidance station K11, StpMo44c of Saint-Fiacre (Rapport Pinczon du Sel, 1947-1948b)—a, tobruck; b, unburied concrete bunker; c, listening post; d, concrete cover for Flakgun—small model—20 mm; e unburied thick concrete bunker R622(11), flanked by a tobruck for machine gun; f barbed wire and mines; g farm.
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Figure 3. radio guidance station K11, StpMo44c of Saint-Fiacre—1, tobruck; 2, reinforced, buried bunker; 3, concrete barracks or ventilation towers; 4, three concrete barracks or ventilation towers; 5, possible light Flak emplacement or tobruck; 6, L409Flak emplacement; 7, Knickebein single rail ring; 8, possible light Flak emplacement or tobruck; 9, pit for shack or cistern; 10, possible Flak emplacement or tobruck; 11, R622. C0515-0021_1966_F0515-0915_0110, n ̊ 110, ech. 1/23364, Argentique, 16/05/1966.
The German site of Saint-Fiacre was fortified assuming the code name StpMo 44c and became an important Luftwaffe radio guidance station (Funk-SendeAnlage—FuSAn) coded Dora/Knickebein K11. It was built by the Organisation Todt(O.T.) dependent directly from the High Kommandanturand allowed the driving of the German bomber wings during night raids on Great Britain (Flock, 2012). It was equipped with: 1 × FuSAn721 Knickebein; 1 × FuMG402Wassermann; 1 × See-Elefantand 1 × FuSE(Funk-Sende-Empfänger—emitter) 62A (Lécuillier, 2003). Table 1 adds some more convergent information about the site. Ameliorated, more powerful jam senders (Aspirin) were successfully used from 7th September. These transmitted dash signals like those emitted by the Knickebein systems so that the German bomber navigators flying along the equi-signal beams, hearing the dash signal would be confused depriving them of navigation accuracy. In October the jammers were so powerful that the Knickebein beacons on England were almost worthless for insufficiently trained bomber crews and could only be used for marking approach routes across the sea including turning points (Trenkle, 1979). Apart from the accidental bombing night of 24th August, London was saved from attack up to the afternoon of 7th September, when London docks were touched and gone in fire visible from the British coast, facilitating the German night bombers. From 7th September to 13th November each night, except one, 160 bombers were sent against London (Jones, 2009).
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Table 1. Dora/Knickebein K11(Lippmann, 2021).
ID F3 Type Cover name Location Order/Duty Equipment
334 FuSAn Dora St. Fiacre/ 1 × FuSAn721Knickebein
Knickebein Nw Lanmeur (1944 dismantled)
K11 1 × FuMG402Wassermann
1 × See-Elefant
1 × FuSE62A
The Saint-Fiacre site was attached several times by allied bombers, but only
one bomb damaged the ring rail of the Knickebein system.
The FuMG402was formed by a square frame of ten meters length mounted
on a pivot at the extremities and a roll ring. On 1944, this emitter was replaced
by a device See-Elefant linked to a pylon forty-meter hight supporting the an
tennae. A reinforced, buried bunker (Figures 3-5) was built, comprising a three meters thick coverage, four garage cells for special tracking trucks, one electrical power plant, one data exploitation and transmission room to the wings in flight and rooms and depots for the troop.
Four bunkers two of which provided with a machine gun tobruck and two
other tobrucks (one nowadays destroyed) were located on the site. The anti-air
defence was composed by three emplacements each provided with a 20 mm Flak
30gun. The station was protected by a large net of barbed wires and mine fields
(Lécuillier, 2003).
Lanmeur was liberated on 9th August 1944 (Flock, 2012).
After the Liberation, the site, favourable for radar installations, was preserved
by the French Armée and Marine Nationale. The reinforced, buried bunker,
judged practically indestructible, was used as garage and agricultural depots by
the field proprietors.
Recently, the site has been transformed in a “stand de tir”—shooting range
and the large garages cells still preserve their original orange camouflage (Lécuil
lier, 2003).
3. The Visits
The visits took place on 20 July 2023 and 22 July 2023. The K11, StpMo44c (48 ̊39'58.31"N, 3 ̊43'48.7"W, height 120.69 m) identified structures (Figure 3) were the following. A tobruck(1) (48 ̊39'54.36"N, 3 ̊43'46.44"W, h. 115.58 m) (Figure 6) disposed as defence of the site entrance road, buried in the terrain. The exposed external concrete structure was well-preserved, without damages due to combats or bombardments. It presented green painted entrance walls due to a restauration attempt. The entrance gave access to a clean combat room preserving formwork board traces. The combat room aperture was obstructed by a blue metallic plate.
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(a)
(b) (c)
(d) (e) (f)
Figure 4. Reinforced, buried bunker—(a) Coverage three meters thick; (b) Entrances of the electrical power plant; (c) Entrance square and four garage cells for special vehicles with orange camouflage; (d) Entrance of the rooms and depots for the troop; (f) Internal telephone; (g) Watertight insulation.
A reinforced, buried bunker (2) (48 ̊39'54.62"N, 3 ̊43'47.6"W, h. 114.45 m), 14 × 9 m, Sonderkonstruktion, facing three sides of an entrance square (Figure 5). On its coverage were several meters of terrain and vegetation. The entrances of the electric generator room and the fuel depot faced the square left side. The four entrances of the garage cells faced the middle, larger square side. The entrance of the troop rooms and depots faced the square right side. All the entrances were obstructed by recent metallic, bleu painted doors, so that the interior remained inaccessible. The bunker external concrete structure appeared well-preserved without damages due to combats or bombardments. It preserved the traces of the formwork boards typical of the German masonry and the original orange camouflage on the garage cells entrances. A group of concrete barracks or ventilation towers (3) (48 ̊39'54.69"N,
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3 ̊43'48.24"W, h. 121.56 m) for the generator room and the garage cells, near the bunker coverage, disappeared or buried in the terrain. A three concrete barracks or ventilation towers (4) (48 ̊39'55.43"N, 3 ̊43'47.52"W, h. 121.26 m) for the garage cells and the troop rooms and depots, inaccessible (Figure 6). The visible coverages appear in good preservation state without damages due to combats or bombardments. A television antenna on the coverage of the larger one indicated a possible squat. A possible light Flakemplacement or tobruck(5) (48 ̊39'56.82"N, 3 ̊43'47.86"W, h. 117.31 m) disappeared or buried in the terrain. A FuMG402Wassermann(48 ̊40'54.49"N, 3 ̊43'51.52"W, h. 116.23 m) disappeared. Its basement was not identified because it was probably demolished or buried in the terrain. No concrete anchor blocks for the antenna on the terrain were identified.
Figure 5. reinforced, buried bunker plan—(a) Entrance square; (b) Electric generator room; (c) Fuel depot; (d) Workshop; (e) Garage cells; (f) Troop rooms and depots (Lécuillier, 2003; Peeters, 2003).
(a) (b) (c)
Figure 6. (a) Tobruck(1) entrance; (b) Aperture of the combat room; (c) Concrete barracks or ventilation towers (4).
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A See-Elefant (unknown position) disappeared. Its basement was not identified proba bly because it was demolished or buried in the terrain. No concrete anchor blocks for the antenna were identified on the terrain. A FuSE62A radar (unknown position) disappeared. Its possible concrete platform was not identified because it was probably dismantled or buried in the terrain. An L409 (6) (48 ̊39'57.25"N, 3 ̊43'50.08"W, h. 120.05 m), with one possible nearby other Flakemplacement, disappeared or buried in the terrain. A FuSAn721 Knickebein (7) (48 ̊39'58.39"N, 3 ̊43'49.4"W, h 120.76 m) disappeared. A possible light Flakemplacement or tobruck(8) (48 ̊39'58.98"N, 3 ̊43'50.13"W, h. 120 m) disappeared or buried in the terrain. A 7 × 10 m pit for shack or cistern (9) (48 ̊39'58.33"N, 3 ̊43'48.14"W, h. 120.45 m) disappeared. A possible Flak emplacement or tobruck (10) (48 ̊39'58.17"N, 3 ̊43'46.57"W, h. 117.6 m) disappeared or buried in the terrain. An R622(11) (48 ̊40'1.38"N, 3 ̊43'46.97"W, h. 117.22 m) buried in the terrain and covered by vegetation (Figure 7) (Appendix). The visible portion did not let possible to estimate its preservation state. Two elements of the electrified protection barrier (48 ̊39'57.05"N, 3 ̊43'48.11"W, h. 117.32 m) (Figure 8) each comprising an original, concrete support and five insulation glass elements some of them still in place.
Figure 7. R622(11) ruins.
(a) (b)
Figure 8. electrified protection barrier—(a) Remains of two concrete supports; (b) Glass insulation element, details.
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4. Discussion
K11 is sometime erroneously indicated in literature as located at Plestin-lesGrèves (N/O Morlaix) (Trenkle, 1979). The listening post (c) in Figure 2 might correspond to the Knickebein system. Two theories concern the vehicles parked in the reinforced, buried bunker cells. The first assumes that they were four trucks (Meßfahrzeugen) each provided with a shelter containing sensor devices for measuring the strength (Tomezzoli, 2019) of the Knickebein signals at different distances (Lécuillier, 2003). The second assumes that they were three trailers each provided with shelter containing radar instrumentation and a tractor. The tractor moved the trailers on the entrance square site to allow the cooling down of the instrumentation in the shelters. In case of attack the tractor would have pushed the trailers inside the garage cells. The same type of bunker, including the camouflage painting was constructed at K9(Beaumont-Hague-West Cherbourg). The Knickebein operators were probably lodged in the rooms and depots for the troop (f) of the bunker so as to have easy access to the data exploitation and transmission room. The location of this room inside the bunker is unknown. It is also possible that operators were lodged in the constructions near the Knickebein ring or in the nearby R622originally intended for two groups of soldiers.
The internal telephone (Figure 4(e)) bearing the inscription: ACHTUNG!
FEIND HORT MIT!—Danger! Enemy hears with!—has been indicated as a false
one.
The bombing missions managed by K11are unknown. The electric generator was similar to a Diesel motor of a ship. It supplied electricity not only to the Knickebein and the radar systems but also to the electrified protection barrier (Figure 7).
The K11rail ring was demolished on 1975 after some people had accidents on
it. The aerial systems were already dismantled on 1944.
The pit might have hosted and protected a shack for personnel lodgement as
those at Cap Fréhel (Tomezzoli, 2021), Qu500and Qu13at the Pointe du Raz
(Tomezzoli, 2021), on the Menez Hom (Tomezzoli, 2017) and at Flescou (To
mezzoli, 2022) or was a cistern/pool as those at Murs Érigné (Tomezzoli, 2016)
and the Domaine de Pignerolle (Tomezzoli, 2019) for providing relax to the per
sonnel in service and water in case of fire to the components on the site. The commissioning of FuMG402Wassermannstarted about on 1942, therefore that of K11 did not participate to the Battle of Britain as possible ranging system for detecting the German bombers positions on the equi-signal beam so as to allow the transmission of the second beam indicating the target. The FuMG 402 and the See-Elefant were long-range, early warning radars (range of about 300 km) intended for detecting incoming enemy aircrafts and alert the Flakemplacements not only those of the site but also those around Brest (Tomezzoli & Dupont, 2009). The FuSE62Awas a movable, short-range radar (range of about 30 km) able to detect azimuth and height of incoming enemy aircrafts so as to
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direct the fire of the gun batteries of the site and possible nearby other batteries. It is still recognizable here the coupling on the same site of long-range, early warning and short-range radars remarked also at the radar stations at Cap Fréhel (Tomezzoli & Moser, 2021), Pointe du Raz (Tomezzoli, 2021), Saint-Pabu (Tomezzoli & Colliou, 2017), Monterfil (Dupont et al., 2007) and Les Mées (Tomezzoli & Pottier, 2015).
The mast actually claimed as 40 m height of the See-Elefant radar-system
(Figure 2) was added on the site on 1944. The site included aFuSE62AWürzburg
with a circular antenna and a Wassermannradar at different times—though not
necessarily at the same time.
A photogrammetric analysis of Figure 1 revealed that the mast was actually 60
m height and was not pointed at the bottom. Based on this, it appears to be the
mast of a WassermannS (Schwehr—heavy) without the antenna elements. The
See-Elefant was not a complete radar system. It was only the half of a bi-static
radar system: the radar transmitter (See-Elefant, with a twin mast (!) antenna)
was not collocated with the associated radar receiver (“Russel”). They had large
antennas separated by about one km. No antenna system had a mast that looked
like the one in Figure 1.
A decoy-Knickebein (“Schein Knickebein” typically a wooden contraption)
was located 3.5 km North of K11, at Saint-Jean-du-Doit (Döremberg, 2004
2016). A search on satellite images for such a decoy actually permitted to identify
a circular structure of about 30 m in diameter at Guernevez (48 ̊42'14.02"N,
3 ̊46'19.22"W) in the municipality of Saint-Jean du Doigt, but the visit on the
site on 8th August 2023 and the information of the owner allowed to ascertain
that it was a waste water dump built on free terrain in the 1950s. The owner also
declared that no structure of the WWII was located at Guernevez.
The choice to place the Wassermann and after of the See-Elefant at the site
was rather obvious. In fact, the site already offered an elevated position (121 m),
a reinforced, buried bunker, an electric generator, a data exploitation room and
personnel lodgements.
The K11Site map, based on RAF Photographic Reconnaissance Unit (P.R.U.)
sorties in July 1940-Sept. 1941 (Döremberg, 2004-2016), identifies six more guns
light batteries around the site.
5. Conclusion
The development of the shooting range preserved the K11 reinforced, buried bunker, one cell of it is actually used as shooting training room and the troop rooms and depots (f) used as administration rooms. But it imposed also a deep alteration of the site by the erection, because of the neighbouring inhabitants protestations (Baudier, 2021), of terrain barriers to muffle the gunfire shots, which caused the covering or destruction of site structures like tobrucks(Figure 2) and concrete barracks or ventilation towers (3). The utilisation of the reinforced, buried bunker, at the moment, ensures its preservation and its survival in
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the near future. However, no classification as monument or architectural heritage of the site is foreseen. Moreover, no tourist board gives information about its existence, history and structures. In any case, the hope is that this article will attract the attention of archaeologists, scholars and a large public about the study and preservation of German installations of advanced technology operating in France during the WWII.
Acknowledgements
I am grateful Mr Döremberg for his explanations about the Knickebeinsystem, the first parked vehicle theory and his kind permission of using information about K11 coming from his internet site, to Mr. Denis for his explanations during a visit of the K11 site and about the second parked vehicle theory, to Mr. Peeters for his kind permission to insert in the article the reinforced, buried bunker plan and to Mr Fleuridas for his kind permission to insert in the Appendix the plans of the R622 bunker.
Conflicts of Interest
The author declares no conflicts of interest regarding the publication of this paper.
References
Baudier, L. (2021). ÀLanmeur,letorchonbrûleautourdustanddetir. Le Télégramme. https://www.letelegramme.fr/finistere/lanmeur-29620/a-lanmeur-le-torchon-brule-aut our-du-stand-de-tir-3765034.php
Döremberg, F. (2004-2016). “Knickebein”StationsKN-1-KN-13. https://www.nonstopsystems.com/radio/hellschreiber-modes-other-hell-RadNav-knick ebein.htm#Kn11
Dupont, P. H., Fresil, Y., & Tomezzoli, G. (2007). Deutsche Militärbauten bei Rennes. DAWANachrichten,49,56-66.
Flock, A. (2012). L’OccupationAllemandedansles162CommunesduNordFinistère19401944.
Jones, R. V. (2009). MostSecretWar.BritishScientificIntelligence1939-1945. Penguin Books.
Lécuillier, G. (2003) StationdeRadionavigation(Mo48c)puisstanddetir,Saint-Fiacre (Lanmeur). Association Pour l’Inventaire de Bretagne. http://patrimoine.bzh/gertrude-diffusion/dossier/station-de-radio-guidage-codee-k11-emet teur-knickebein-puis-see-elefant-en-1944-mo-48c/2d3c3f06-98a4-48d2-ab0e-531098d9b013
Lippmann, H. (2021).Funkmeß(ortungs)stellungeninFrankreich. Bretagne West mit Brest. http://www.atlantikwall.info/radar/france/rf_.htm#Bretagne_West
Peeters, D. (2003) Stationderadionavigation(Mo48c)puisstanddetir,Saint-Fiacre(Lanmeur). Association Pour l’Inventaire de Bretagne. http://patrimoine.bzh/gertrude-diffusion/dossier/station-de-radio-guidage-codee-k11-emett eur-knickebein-puis-see-elefant-en-1944-mo-48c/2d3c3f06-98a4-48d2-ab0e-531098d9b013
Rapport Pinczon du Sel (1947-1948a). Brest.CollectionGellat. Service Historique de la Marine.
Rapport Pinczon du Sel (1947-1948b). LeMurdel’AtlantiquelaCotedelaMancheetde
G. T. Tomezzoli
DOI: 10.4236/ad.2023.114009 201 Archaeological Discovery
l’AtlantiqueduMontSaint-MichelàLaita.Service Historique de la Marine. Brest, Livre IV. Plan n° 62_IV.
Tomezzoli, G. T. (2016). The German Base “the Bank” at Mûrs-Érigné (Anjou-FR). ArchaeologicalDiscovery,4,37-47. https://doi.org/10.4236/ad.2016.41004
Tomezzoli, G. T. (2017). The WW II German Stützpunkt on the Menez-Hom (FinistèreFR). ArchaeologicalDiscovery,5,224-237. https://doi.org/10.4236/ad.2017.54013
Tomezzoli, G. T. (2019). The Monitoring Mast of the WW II German W/T Station Be-2. ArchaeologicalDiscovery,7,224-237. https://doi.org/10.4236/ad.2019.72005
Tomezzoli, G. T. (2021). The German Radar Stations at the Pointe Du Raz (FR). ArchaeologicalDiscovery,9,198-222. https://doi.org/10.4236/ad.2021.93011
Tomezzoli, G. T. (2022). The Heer Küste Artillerie Abteilung 1161. ArchaeologicalDiscovery,10,193-214. https://doi.org/10.4236/ad.2022.104007
Tomezzoli, G. T., & Colliou, S. (2017). The WW II Saint-Pabu German Radar Camp and the Stützpunkte Re 03, Re 04. ArchaeologicalDiscovery,5,142-162. https://doi.org/10.4236/ad.2017.53009
Tomezzoli, G. T., & Moser, J.-L. (2021). The German Radar Station La 318 Frosch. ArchaeologicalDiscovery,9,113-134. https://doi.org/10.4236/ad.2021.92006
Tomezzoli, G., & Dupont, Ph. (2009). Die Flak Batterien der Festung Brest. DAWANachrichten,Ausgabe,54,4-43. (In German).
Tomezzoli, G., & Pottier, L. (2015). Die deutschen militärlogistischen Anlagen westlich von Mamers. DAWANachrichten,65,14-27.
Trenkle, F. (1979). DiedeutschenFunk-Navigations-undFunk-Fürungsverfahrenbis1945. Motorbuch Verlag.
G. T. Tomezzoli
DOI: 10.4236/ad.2023.114009 202 Archaeological Discovery
Appendix
Figure A1. R622twin group shelter—plan: 2 gas lock, 5 - 6 crew rooms (Courtesy Fleuridas P.).

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1
July 27, 2001; Revised August 15, 2001
Einstein's Triumph over the Spacetime Coordinate System:
A Paper presented in Honor of Roberto Torretti
John D. Norton1
Department of History and Philosophy of Science
University of Pittsburgh
Pittsburgh PA 15260
1. Introduction
Each student of Einstein must eventually make his or her their peace with Einstein's
pronouncements on relativity and spacetime coordinate systems. Einstein saw the
development of relativity as the ultimately successful struggle to overcome certain spacetime
coordinate systems and thereby to implement a generalized principle of relativity. This
signal achievement of relativity is embodied in its general covariance. We now hold
spacetime coordinate systems merely to be convenient devices for smoothly labeling events.
The selection of a coordinate system amounts to little more than a conventional choice of
1 Dr. Torretti has inspired my generation: in scholarship, by setting the standard in his
researches in history and philosophy of space and time; and in humanity with his generosity
and kindness. I take this opportunity to thank him personally for the stimulating model of
scholarship in his Relativity and Geometry and related writings and for his encouragement,
patience and instruction when I first worked in history and philosophy of space and time,
especially during a year we shared at the Center for Philosophy of Science, University of
Pittsburgh, in 1983-1984. He helped make it one the most exciting years intellectually of my
life.
2
numbers, much like the selection of definition. How can one proclaim victory over a
definition? If we are offended by a definition, the more appropriate attitude is just to decide
quietly not to use it.
Dr. Torretti's celebrated Relativity and Geometry and related writings represent a
landmark of scholarship. They provide our most detailed account of how Einstein's work in
relativity theory changed physical geometry. It is presented in a comprehensive historical
context with the uncompromised insistence that every geometric conception must be
explicated to the highest standards of mathematical rigor. So when Dr. Torretti makes his
peace with the problem of Einstein and spacetime coordinates in Section 5.5 "General
Covariance and the Einstein-Grossmann theory," this latter insistence ensures that the
peace will be uncomfortable—for Einstein. He takes Einstein's formulation of the postulate of
general covariance and rephrases in language that mimics Einstein's 1905 statement of the
principle of relativity of special relativity. Calling it the "principle of general relativity," Dr.
Torretti explains why the similarity of the two relativity principles is only superficial. Unlike
the case of the special principle, the general principle does not assert a physical equivalence
of states of motion. Dr. Torretti's analysis is careful, thorough and leaves no room to quibble.
So we are left with a puzzle. How could Einstein be so confused about the fundamentals of
his own theory?
My goal in this paper is small. I do not want to dispute Dr. Torretti's careful analysis.
Rather I offer an extended footnote to it. I want to try to explain what Einstein intended in
his remarks about coordinate systems. There is, I believe, a natural reading for Einstein's
claims that do make perfect sense. They require us to adopt a physical interpretation of
relativity theory that is now no longer popular, so the natural reading will no longer have
intrinsic interest. It will, however, allow us to make sense of Einstein's claims and his
program.
3
2. "The Vanquishing of the Inertial System"
A Letter to Besso
When we face claims that are unintelligible in the writing of an Einstein, we are
often tempted to dismiss them as remarks made in haste in the frenzied first moments of
great discovery. Might they not be retracted or qualified in some essential way as time brings
sober distance from those heady moments? While time mellowed Einstein, we can be sure
this was not the case with his proclamations over coordinate systems. He brought the general
theory of relativity to a generally covariant formulation in November 1915. Nearly 40 years
later, after his theory had been much celebrated and its foundations subject to minute
scrutiny, Einstein wrote to his lifelong friend and confidant, Michele Besso.
His letter of August 10, 1954, lays out a brief account of the essence of the general theory of
relativity, explicitly intended to be free of entanglement with the history of the theory.
(Speziali, 1972, p.525)2
Your characterization of the general theory of relat.[ivity] characterizes the
genetic side quite well. It is also valuable afterwards, however, to analyze the
whole matter logically-formally. For as long as one cannot determine the
physical content of the theory on account of temporarily insurmountable
mathematical difficulties, logical simplicity is the only criterion of the value of
the theory, even if it is naturally an insufficient one.
The special th.[eory] of r.[elativity] is really nothing other than an adaptation
of the idea of the inertial system to the empirically confirmed conviction of the
constancy of the velocity of light with respect to each inertial system. It does not
vanquish the epistemologically untenable concept of the inertial system. (The
2 I thank Karola Stotz for help in this translation.
4
untenability of this concept was brought to light especially clearly by Mach and
was, however, already recognized with lesser clarity by Huygens and Leibniz.)
The core of this objection against Newton's fundamentals is best explained
through the analogy with the "center point of the world" of Aristotelian physics:
there is a center point of the world, towards which heavy bodies strive. This
explains, f[or] e[xample], the spherical shape of the earth. The ugliness in it is
that this center point of the world acts on all others, but that all these others
(i.e. bodies) do not act back on the center point of the earth. (One-sided causal
nexus.)
It is just like this with inertial systems. They determine the inertial relations
of things everywhere, without being influenced by them. (Really one ought better
to speak of the aggregate of all inertial systems; however this is inessential.) The
essence of the gen.[eral] th.[eory] of rel.[ativity] (G. R.) lies in the vanquishing
[Ueberwindung] of inertial systems. (This was still not so clear at the time of the
setting up of G. R., but was subsequently recognized principally through Levi
Civita.) In the setting up of the theory I had chosen the symmetric tensor gik as
the starting concept. It provided the possibility of defining the "displacement
field" Γlik...
Einstein briefly explained the notion of the displacement field and its independence from the
metric gik. He continued:
But how is it that the displacement field really led to the vanquishing of
inertial systems? If one has vectors with the same components at two arbitrarily
distant points P and Q in an inertial system, then this is an objective (invariant)
relation: they are equal and parallel. On this rests the circumstance that one
obtains tensors again through differentiation of tensors with respect to the
coordinates in an inertial system and that e.g. the wave equation represents an
objective expression in inertial systems. The displacement field now allows such
5
tensor formation by differentiation in relation to an arbitrary coordinate system.
Therefore it is the invariant substitute of inertial systems and thereby--as it
appears--the foundation of every relativistic field theory.
Einstein then continued to explain how the metric and displacement field are used to
formulate general relativity and his unified field theory.
Its Unusual Treatment of Coordinate Systems
Einstein finds the essence of the general theory to lie in the vanquishing of inertial
systems, that is, inertial coordinate systems. Part of his account is that these systems have
the objectionable feature of acting without being acted upon. That aspect has been subject to
much discussion and analysis. It is usually explicated by the notion of "absolute object,"
geometric objects that act but are not acted upon. In special relativity, the pertinent absolute
object is the Minkowski metric.3 Here I pass over the problem of explicating the absoluteness
Einstein raises; I am interested in just one other aspect. Einstein's notion of the absolute
inertial [coordinate] system has been transmogrified into an absolute geometric object, the
Minkowski metric.
It is so tempting to say that this transformation is what Einstein really intended. But
then we must be amazed at his tenacity in avoiding the assertion. His remarks to Besso
mention the metric field and the displacement field, both geometric objects, but condemns
the inertial system for its absolute character—and this forty years after his achievement of
general covariance.4
3 For discussion see Norton (1993, Section 8).
4 Similar remarks on inertial systems span Einstein's life. They appear, for example, as early
as Einstein (1913, pp. 1260-61) and as late as a letter to George Jaffé of January 19, 1954
(Einstein Archive, document with duplicate archive control number 13 405).
6
2. Einstein's use of Coordinate Systems
Their Physical Content
There is a simple way to understand Einstein's remarks.5 He did not regard
coordinate systems as we now do, as essentially arbitrary systems of numerical labels of
events. In his theorizing, they initially carried significant physical content. The journey to
the completion of general relativity required the systematic elimination of this content.
That coordinate systems can be used to represent significant physical content is not
the modern view and it is tempting to think that no other view is possible. But that
narrowmindedness is quite incorrect. Our physical theories use mathematical structures to
represent aspects of interest of the physical world. We routinely use a manifold that is
topologically R4 to represent the set of physical events in special relativity. Nothing prevents
us using the structurally richer number manifold of quadruples of reals as this manifold. If
we do use a number manifold in this way, then we are assigning quadruples of reals to
events in spacetime. That is just what a coordinate system does.
A number manifold has considerably more structure than we use in standard
theories of spacetime. It has a preferred origin (0,0,0,0), for example. How are we to interpret
that? Does this preferred origin correspond to a real physical center point of the world?
Whether it does or not cannot be decided purely by the mathematics of the theory. The
mathematics can only affirm that (0,0,0,0) is indeed different from all other points in R4, but
not that the differences amount to nothing physically. This last judgment must be made by
the physical interpretation we supply for the mathematical structures. The modern view is to
discount it as physically insignificant. Einstein's default was the opposite. The various
5 I have developed the approach to Einstein's use of coordinate systems sketched below in
greater detail in Norton (1989, 1992).
7
features of coordinate systems represent physical features of the world. Most crudely, the
origin (0,0,0,0) is a physical center point. In Einstein's program, we must find a way of
depriving coordinate systems of this default physical content.
...and How it is Systematically Denied
Einstein used a single technique that was not his own invention. He used a strategy
codified by Felix Klein in the nineteenth century.6 Each geometric theory would be
associated with a class of admissible coordinate systems and a group of transformations that
would carry us between them. The cardinal rule was that physical significance can be
assigned just to those features that were invariants of this group. In special relativity, that
group is the Poincaré group. The origin (0,0,0,0) is not an invariant; under translations
within the group, the origin is not mapped back to itself. Thus it has no physical significance.
But the light cone structure –the complete catalog of the pairs of events that are lightlike
separated7—is invariant and thus has physical significance.
3. The Development of Relativity Theory
The Default Interpretation of Spacetime Coordinate Systems...
Einstein's natural starting point is to assign physical significance to the natural
features of a coordinate system. Using the familiar (t, x, y, z) as the spacetime coordinates,
we can list some of them:
6 For a more detailed account of the connection to nineteenth century geometry, see Norton
(1999).
7 In coordinate terms, the pair satisfies the condition ∆t2 - ∆x2 - ∆y2 - ∆z2 = 0, where (t, x, y, z)
are the usual spacetime coordinates, ∆ represents the coordinate differentials and the speed
of light is set to unity.
8
(a) The origin (0,0,0,0) corresponds to a central point; the distinction between the x, y and z
coordinates makes space anisotropic.
(b) The curves picked out by constant values of x, y and z are a state of rest.
(c) In a Lorentz or Galilean covariant theory, the set of all curves picked out by (b) for all
coordinate systems are the inertial states of motion.
(d) Coordinate differences have metrical significance; they represent the possible results of
clock and rod measurements by observers in the state of rest picked out by (b).
...and Their Loss of Physical Significance
The development of relativity theory brings the systematic elimination of these
default physical interpretations. As our starting point, we might imagine a one-coordinate
system theory. It would have all the physical structures of the list above (a)-(e). The first step
had already been taken in the nineteenth century. The spatial sections of the spacetime are
covered by coordinates x, y, z. The Euclidean character of space entails that we can use many
coordinate systems related by translations, rotations and reflections. None of the structures
of (a) are invariants of these transformations. They lose physical significance.
The Relativity of Motion
The theory would retain an absolute state of rest (b), however. That is eliminated by
the transition to a Newtonian spacetime, with the characteristic group the Galilean group, or
to special relativity with the characteristic group the Poincaré group. The states of rest (b)
are no longer invariant.
9
The next step marks the starting point of Einstein's 1907 quest for his general theory
of relativity.8 Einstein sought to expand the covariance of his theory further so as to deprive
the inertial states of motion (c) of physical significance. This, he believed, was achieved with
his postulation of the principle of equivalence which now allowed him to extend the Poincaré
group with transformations that represented uniform acceleration, although in only limited
circumstances. Einstein immediately interpreted the expansion as representing an extension
of the principle of relativity to acceleration. In this account, we see why: the inertial motions
of (c) are no longer invariants of the admissible transformations.
Metrical Significance
Presumably this much was all Einstein expected in 1907. In 1912, Einstein realized
that the development of his theory required him to take another step in depriving
coordinates of physical significance. He saw an analogy between the problem of gravitation
and relativity and the theory of curved surfaces of Gauss. The latter has led to a new
mathematics in which one could use arbitrary coordinate systems and in which coordinate
differences cease to have the direct metrical significance of (d).9
8 There has been very considerable investigation in recent decades of Einstein's passage to
the general theory of relativity. They span from early work including Torretti (1983), Norton
(1984) and Stachel (1980) to Renn (in preparation).
9 Here I will report Dr. Torretti's repeated lament that the group structure—or lack of it—of
Einstein's expanded coordinate systems brought many unintended problems apparently
ignored by Einstein. For example (Torretti, 1983, p. 153) observes that the ranges of two
coordinate charts may not overlap, so that the point transformation by induced the
corresponding coordinate transformation may have degenerate properties. Einstein largely
maintained a physicist's silence on these mathematical niceties.
10
Independent Existence
With this development, Einstein's quest for depriving coordinate systems of their
default physical significance has taken an unanticipated turn. It proved to be a trifle in
comparison to the final hurdle that Einstein needed to overcome in arriving at a generally
covariant formulation of his general theory of relativity. Having failed to find what he
thought were admissible generally covariant gravitational field equations in 1912 and 1913,
Einstein eventually found a way to discount the failure. He developed arguments that
purported to show that general covariance would be physically uninteresting, were it to be
achieved. The best known and most important of these was the "hole argument."
The error of Einstein's argumentation is now well known. He had generated two
intertransformable metric fields gik(xm) and g'ik(xm) in the same coordinate system, xm. He
had assumed that the two fields represented two distinct physical possibilities. That proved
to be the elusive error that took several years to find. Einstein presumed that it made sense
to say that the two fields were in the same coordinate system. That tacitly accorded an
existence to the coordinate system independent of the metric field defined on it. Figuratively,
it meant that it makes sense to say that we can remove the first field from the coordinate
system, leave a bare coordinate system behind and then deposit the second fieldin the very
same coordinate system.
One of the final stages of Einstein's development of a generally covariant theory was
to recognize that coordinate systems have no such independent existence. He described his
error to Besso in a letter of January 3, 1916:10
10 Schulmann et al. (1998) Papers, Vol. 8A, Doc. 178; Einstein's emphasis. I have argued
elsewhere that Einstein's according independent reality to coordinate systems may have had
catastrophic effects at an earlier stage of his quest for general covariance. See "What Was
Einstein's Fatal Prejudice?" in Renn et al. (in preparation).
11
There is no physical content in two different solutions G(x) [gik(xm)] and G'(x)
[g'ik(xm)] existing with respect to the same coordinate system K. To imagine two
solutions simultaneously in the same manifold has no meaning and the system
K has no physical reality.
4. Conclusion
These considerations, however, have little force with modern readers. We now
proceed from a quite different starting point. We do not accord default physical significance
to coordinate systems. If we wish to endow a spacetime with inertial structures, absolute or
otherwise, we start where Einstein ended. We start by endowing a manifold with an affine
connection (displacement field) whose natural straights are the inertial motions. In all this,
coordinate systems are little more than convenient labels for spacetime events.
For Einstein, however, matters looked quite different. His default was to load
physical content into the coordinate systems. The conceptual development through special to
general relativity is characterized by depriving coordinate systems of their default physical
significance in progressively greater measure. He had initially intended to end up just
depriving coordinate systems of absolute inertial motions. Once Einstein had started the
process, it could not be stopped. The natural development of the theory ended up forcing
much more. The coordinate systems lost their metrical significance and, after much
suffering, he finally recognized the need to dispense with a notion of independent existence
he had tacitly accorded them.
References
Einstein, Albert (1913a) "Zum gegenwärtigen Stande des Gravitationsproblems,"
Physikalische Zeitschrift, 14, pp.1249-1262.
Norton, John D. (1984) "How Einstein found his Field Equations: 1912-1915," Historical
Studies in the Physical Sciences, 14, 253-316; reprinted in Don Howard and John
12
Stachel (eds.) Einstein and the History of General Relativity: Einstein Studies, Vol. 1
Boston: Birkhäuser, 1989, pp.101-159.
Norton, John D. (1989) "Coordinates and Covariance: Einstein's view of spacetime and the
modern view," Foundations of Physics, 19, 1215-1263.
Norton, John D. (1992) "The Physical Content of General Covariance" in J. Eisenstaedt and
A. Kox eds., Studies in the History of General Relativity: Einstein Studies, Vol.3,
Boston: Birkhauser.
Norton, John D. (1993), "General Covariance and the Foundations of General Relativity:
Eight Decades of Dispute," Reports on Progress in Physics, 56, pp. 791-858.
Norton, John D. (1999) "Geometries in Collision: Einstein, Klein and Riemann." in J. Gray,
ed., The Symbolic Universe . Oxford University Press, pp.128-144.
Renn, Jürgen; Sauer, Tilman; Janssen, Michel; Norton, John D. and Stachel John (in
preparation) General Relativity in the Making; Einstein's Zurich Notebook.
Schulmann, Robert; Kox, A. J.; Janssen, Michel; and Illy, József (eds.) (1998) The Collected
Papers of Albert Einstein. Volume 8. The Berlin Years: Correspondence, 1914-1918.
Part A: 1914-1917. Part B: 1918. Princeton: Princeton University Press. (“Papers,
Vol. 8”)
Speziali, Pierre (ed., trans.) (1972) Albert Einstein Michele Besso: Correspondance 1903-1955.
Paris: Hermann.
Stachel, John (1980): "Einstein's Search for General Covariance," paper read at the Ninth
International Conference on General Relativity and Gravitation, Jena; printed in
Don Howard and John Stachel (eds.) Einstein and the History of General Relativity:
Einstein Studies, Vol. 1 (Boston: Birkhäuser, 1989) pp.63-100.
Torretti, Roberto (1983) Relativity and Geometry. Oxford: Pergamon.

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i
:
LIBRARY
OF THF.
UNIVERSITY OF CALIFORNIA,
GIFT OF"
Jl
Accession No. 836.9-U-.
>\0vta{/yvv<
Received ,190
J
TRAVERSE TABLES
WITH AN INTEODUCTOEY CHAPTEE ON
CO-ORDINATE SURVEYING
BY
HENEY LOUIS, M.A, A.E.S.M., F.I.C., F.G.S., ETC.
i\
PROFESSOR OF MIXING AND LECTURES ON SURVEYING, DURHAM COLLEGE OF SCIENCE, NEWCASTLE-ON-TYNE EXAMINER IN MINE SURVEYING TO THK CITY AND GUILDS OF LONDON INSTITUTE
AND
GEOKGE WILLIAM CAUNT, M.A.
LECTURER IN MATHEMATICS, DURHAM COLLEGE OF SCIENCE, NEWCASTLE-ON-TVNE
LONDON
EDWAED ARNOLD
37 BEDFORD STREET. STRAND
1901
a
PKEFACE.
THE publication of this little work is due to the writer's
conviction, gained in many years of miscellaneous surveying
practice, as well as in some spent in the teaching of surveying, that the co-ordinate method of plotting traverses is far preferable
to any other, on the score of both accuracy and expedition. There are, of course, several traverse tables already in existence ; but
whilst some of these are calculated with a degree of accuracy
greater than is required in ordinary surveying, and more
especially in ordinary mine surveying, others are not accurate enough, inasmuch as their calculations are not extended to
every minute of the degree. The price of the former works is,
moreover, somewhat prohibitive, at any rate as far as the
ordinary mine surveyor is concerned.
At the present day it is usual to employ, in ordinary underground and surface work, instruments divided into single
minutes, so that the tables must be calculated for this unit to be
of any real use. In ordinary chaining it may be taken that it
is rare for any traverse to exceed ten chains in length, whilst the
limit of accuracy for such lengths is about one link. The tables
are therefore calculated to five significant places (four places of
decimals), so that their accuracy is about ten times as great
as is attained in ordinary actual work. This limit is therefore
sufficiently near for all practical purposes, and, at the same time, does not involve any undue amount of arithmetical work.
iv PREFACE.
These tables are not intended for cadastral surveys, for which
seven decimal places are required, or at times even more. The
arrangement of the tables is one which the writer finds in
practice to be convenient for rapid work, all the figures needed
for any given angle being found at one opening of the pages and in one line. The tables have been entirely recalculated by
Mr. Gaunt, and checked in all possible ways, and every
precaution has been taken to ensure accuracy in printing, so as to warrant the hope that they may be found free from
error. The writer ventures to hope that their publication may
serve to popularize this most convenient method of working out
traverse surveys in this country, HENEY LOUIS.
NEWCASTLE-ON-TYNE, December, 1900,
TBAVEESE TABLES.
CO-ORDINATE SURVEYING.
CO-ORDINATE surveying, or, to speak more precisely, co-ordinate plotting, is the name given to a method of recording the results
of traverse surveys in which the draughtsman represents each draft of the survey by means of its rectangular co-ordinates. It cannot well be applied to any other than traverse surveying, hence its utility is mainly restricted to such forms of survey work
as depend upon traverses, that is to say, mine surveys, surveys of roads, rivers, or railways, and surveys of areas. In a traverse survey the lengths and directions of the various traverses or drafts are determined in the field by methods with which all
surveyors are familiar; it need only be here observed that, however determined, the direction of any traverse is the angle which it makes with any determinate direction ; the latter may
either be an absolutely fixed direction, such as the terrestrial
meridian, or it may be comparatively fixed, as the magnetic meridian, or it may be purely arbitrary, such as the direction of the first draft of the survey, or of any other traverse, or of one of
the main directions in which the survey extends, e.g. the main
road of a large colliery, the principal street of a town, etc. In mining surveys it is customary in this country to refer all directions to the magnetic meridian, in spite of several obvious
inconveniences to which this practice is subject; although it is certainly better to use the terrestrial meridian, yet the
method of plotting by co-ordinates is exactly the same whatever a2
vi TRAVERSE TABLES.
be the line of reference that is used. For the sake of sim
plicity it will here be supposed that a method of surveying
has been adopted by which the angle which each traverse makes with the terrestrial meridian can be accurately determined.
Thus, in Fig. 1, let the traverse line of length OA (= I)
make an angle a with the meridian line YY' through 0, and
let XX' be drawn at right
angles to TOY'. Draw Aa
and Aa' perpendicular respec
tively to the lines XX' and
YY' ; then Aa = Oa' = I cos a,
and Aa' = Oa = I sin a, are
**f
"" the co-ordinates of the point A referred to its origin 0, or the co-ordinates of the traverse OA.
Oa', the meridian co-ordinate,
*' is usually spoken of as the difference of latitude (generally abbreviated into latitude), and Oa, the equatorial co-ordinate, is generally called the departure of the traverse OA, and these words, latitude and departure, are adhered to even when the
reference lines, YY' and XX' , do not correspond with either the terrestrial or the magnetic meridian and equator respectively. It is obvious that the co-ordinates of any traverse can
be calculated by the aid of a table of sines and cosines, but this is a laborious and slow operation. Traverse tables are merely tables in which the results of these calculations are recorded so as to save time; in the present traverse tables the latitude and departure are given for every minute of angle and for all lengths from 1 to 10, so that the co-ordinates for any desired length can be taken out by simple addition, at the same
time moving the decimal point as may be required. Thus, required the co-ordinates of a traverse 1638 links long, making an angle of 27 49' with the meridian line. Entering the table headed 27, the minutes are found in the column at the left
hand (headed Min.), and looking horizontally along the line corresponding to 49', the several figures are taken out under the unit distances (Dist.) which head each double column of lati
tude (Lat.) and departure (Dep.), thus
TRAVERSE TABLES. vii
27 ,49' Dist. Lat. Dep. 1000 884-5 466-6 600 530-7 280-0 30 26-5 14-0 8 7-1 3-7
1638 1448-8 764'3
So that the required latitude is 1449 links, and the required departure 764 links. It will be noticed that the figures are
only taken out to the first decimal place ; in ordinary surveying fractions of links are not recognized, so that the co-ordinates are merely required to be correct to the nearest unit ; there is
therefore no object in using more than one decimal place. Whenever the angle given exceeds 45, the angle must be sought for at the bottom right-hand corner, and the minutes
read upwards in the last right-hand column; care must be taken also to read the latitudes and departures upwards in accordance with the respective designations at the bottom of the page. In this connection it is worth remembering that
when the angle is less than 45, latitudes are greater than departures, and when the angle exceeds 45, latitudes are less
than departures, A useful check is also obtained by noting
that
(Distance)2 = (Latitude)2 + (Departure)2
When one traverse only has to be plotted, but little is gained by the use of co-ordinates ; but when a number of successive traverses have to be laid down, as is the case in an ordinary
traverse survey, the advantage is evident, as the various latitudes
and departures can be added together arithmetically, and thus the exact position of the end point determined before the survey
is plotted. Thus, let OA, AB, and BC (Fig. 2) be three traverses, of which the lengths and the angles which they make with the meridian are known. Then Oa' and Oa are, as before, the
co-ordinates of the traverse OA or of the point A referred to
its origin ; similarly, J93/ and AM are the co-ordinates of B
referred to its origin A. But Ob = Oa + ab = Oa -J- AM, and
Ob' = Oa' -f- a'V = Oa' -f MB; therefore the co-ordinates of
the point B referred to the origin are the sums of the re
spective latitudes and departures of the two traverses OA and AB. In the same way Oc and Oc', the co-ordinates of the point
Vlll TRAVERSE TABLES.
C referred to the origin 0, are the sums of the co-ordinates OA,
AB, and BC, it being noted that BG runs in the opposite
direction to OA and AB} and its latitude is therefore negative.
In other words, the meridian and equatorial co-ordinates of any
point that is reached by a series of traverses, are the algebraical sums of the respective latitudes and departures of each one of the component traverses. It is usual to treat the directions
OJC and OY as positive, and OX' and OY' as negative; in other
words, northerly latitudes and easterly departures are treated
as + quantities, and southerly latitudes and westerly departures as quantities. In loose-needle surveys either meridian or quadrant angles
may be read at the will of the surveyor. In ordinary theodolite
surveys and in " racking " or " fixed-needle " surveys with the Vernier dial, the angles are determined that any given traverse makes with the meridian (or other arbitrary direction), so that
any angle may be registered from to 360. The fii'st step is therefore to reduce these meridian angles (or azimuths, as they
are often called) to quadrant angles by the following rules : If the meridian angle is letween and 90, the quadrant is
N.E., and the quadrant angle = meridian angle.
J. V J^JTVOJ.
TRAVERSE TABLES. ix
If the, meridian angle is between 90 and 180, the quadrant
is S.K, and the quadrant angle = 180 meridian angle.
If the meridian angle is between 180 and 270, the quadrant
angle is S. W., and the quadrant angle = meridian angle 180.
If the meridian angle is between 270 and 360, the quadrant
is N. W., and the quadrant angle = 360 meridian angle.
For example, to find the quadrant angles corresponding to
the following meridian angles : (a) 17 23' ; (6) 141 44' ; (c) 250
21'; (d) 339, 08'.
Meridian angle. Quadrant angle. (a) 17 23' N. 1723'E.
(6) 141 44' S. (180 - 141 44') E. = S. 38 16' E.
(c) 250 21' S. (250 21' - 180) W. = S. 70 21' W. ,
(d) 339 08' N. (360 - 339 08') W. = N. 20 52' W.
Sometimes these angles are simply written +17 23' + , -38 16'+, -70 21'-, +20 52'-, this method being specially convenient when any arbitrary line is selected as the direction of reference in preference to a meridian ; it is under
FIG. 3.
stood that the first sign always refers to the latitude and the
last to the departure. The successive stages in working out a traverse survey by
co-ordinates, preparatory to plotting, are best illustrated by an
example. Let Fig. 3 represent a traverse survey of an area
x TRAVERSE TABLES.
bounded by straight lines, executed by the " double fore-sight
"
method with an ordinary theodolite, the area forming a seven
sided polygon. The first two columns (see p. xii), namely the measured lengths of the sides and the observed theodolite readings, are obtained in the field and taken from the field-book in which they were entered.1 At the beginning of the survey
the theodolite is supposed to be pointed due north; the first reading gives therefore the meridian bearing of the first traverse
OA; the meridian bearings, or azimuths, of the subsequent traverses are obtained by the well-known rule : Add the observed theodolite reading to the last meridian bearing and subtract 180 from, or add 180 to, the sum, according as that sum is greater or less than 180. The result in this ca.se is as
follows :
Meridian bearing of OA 295 12'
Theodolite reading of AB 72 13'
367 25' 180
Meridian bearing of AB 187 25'
Theodolite reading of B C 135 37'
323 02' 180
Meridian bearing of B C 143 02'
Theodolite reading of CD 87 20'
230 28' 180
Meridian bearing of CD 50 28'
Theodolite reading of DE 240 05'
290 33' 180
Meridian bearing of DE 110 33'
Theodolite reading of EF 41 26'
151 59' 180
Meridian bearing of EF 331 59'
Theodolite reading of FO 79 10'
411 09' 180 Meridian bearing of FO 231 09'
The meridian bearings thus obtained are entered in their
1 It goes without saying that the closing angle at 0, which in this case
should be equal to 244 03', is observed and noted in the field-book as a check, though it is not required for these calculations.
TRAVERSE TABLES. xi
proper column, and then the column of quadrant bearings is at once filled in (see p. xii), in accordance with the rules already given. By reference to the tables, the latitudes and departures are then determined by simple addition ; the first two may be
given in full by way of example :
64 48' DUt. Lat. Dep. 1000 425-78 904-83 400 170-31 361-93 8 3-41 7-24
1408 599-5 1274-0
7 25' 800 793-31 103-27 40 39-67 5-16 7 6-94 0-90
847 839-9 109-3
The latitudes and departures are entered in their re
spective columns. As this is a closed survey, returning to the starting point 0, the total north and south latitudes and the
total east and west departures ought to be respectively equal to each other, and it will be seen that such is practically the
case, fractions of a link being disregarded. The last two columns, headed total latitudes and departures, are really the successive co-ordinates of each of the survey stations ; they are obtained by the successive algebraical additions of the latitudes and departures respectively, the sum or difference taking the same sign as the larger of the two
figures. Thus, to take the latitudes, the latitude of the point
A
is evidently 599*5 links N; then we have :
Latitude of point B = 599'5 N. + 839-9 S. = (839-9 - 599-5) S. = 240-4 S.
Latitude of point C = 240'4 S. + 1428*6 S. = 1669*0 S.
Latitude of point D = 1669-0 S.+ 1059-2 N. = (1669-0 - 1059-2) S. = 609'8 S.
Latitude of point E = 609-8 S + 347-9 S. = 957-7 S.
Latitude of point F = 957-7 S. + 1743-6 N. = (1743-6 - 957-7) N.= 785-9 N.
Latitude of point = 785'9 N. + 786-0 S. = (786-0 - 785-9) S. = 0-1 S.
The total departures are calculated in precisely the same way. The clerical work of the addition is checked by adding up the two columns of latitude and the two of departure ; the differences between these respective pairs should be equal to the final total latitudes and departures.
Xll TRAVERSE TABLES.
3s
FABCDEOODCABEF
TRAVERSE TABLES. xiii
the irregular expansion and contraction of even the best drawing paper 1 is more than enough to introduce grave inaccuracies into the best drawn plan. As an example of the method of calculation, let it be
required to determine the distance and bearing of station E
from station B. From the column of total latitudes and departures we have
Station B. Lat. S. 240-4. Dep. W. 1383-3 Station E. Lat. S. 957-7. Dep. E. 1903-2
Therefore E is 717-3 links S. and 3286'5 links E. of B.
Bearing of line BE = S. tan -1 -~j E. = S. 77 41' 15" E.
Distance EB = . = .
*ep'. = */tep* + lat.* = '
.* . ,
cos bearing sin bearing cos 77 41 15
sn + 3286-5* = 3364 links
These calculations are best made in the usual way by the aid of tables of logarithms. In case of need, the traverse tables
can be used for them, as the departure column for distance
=
1, is practically a table of natural sines, whilst the corresponding latitude column is practically a table of natural
cosines, and these evidently give all the elements required for the calculation. In ordinary practice it is, however, far better to use any good table of logarithms for this portion of the work. The above survey is an imaginary one, and there is therefore no closing error. In actual closed traverse surveys there is
of course usually some error. By working out the co-ordinates,
and by adding up the observed angles (including the closing angle), it is at once obvious whether the error is in the linear
or in the angular measurements ; in the latter case, if it is only
the closing angle that has been read wrong, the co-ordinates will close, though the angles do not. If the error falls within the required limits of accuracy, it is easily distributed between the co-ordinates, and the plotting is done from the co-ordinates thus rectified.
The following is an example from actual practice, of a survey
in a coal mine. A survey was started from a peg in the " flat,"
1 Those interested in this matter should consult an important paper by
Mr. C. C. Leach. Transactions of the North of England Institute of Mining
Engineers, Vol. xxxiv., 1884-85, p. 175.
I
XIV TRAVERSE TABLES.
and was extended to a point in a " back place
" to which it was desired to drive a road from the peg in the flat. The theodolite was set up in the flat, using the centre line of the flat as the axis
of direction to which the survey was to be referred. A copy of the field-book is given below, many of the minor details
being, however, omitted.
=
TRAVERSE TABLES. xv
The co-ordinates are worked out as previously explained, and the total latitudes and departures obtained as follows :
XVI TRAVERSE TABLES.
becomes one of quite secondary importance. All that is required to be known is already determined before the plotting is commenced. It may also be remarked that all the opera
tions up to and including the taking out of the total latitudes
and departures are of the utmost simplicity, involving no higher
S cede % inch - 1 Chcdrv
FIG. 4.
arithmetical knowledge than the addition and subtraction of decimals, and may hence be entrusted to any moderately intelligent lad, instead of occupying the time of the surveyor himself. The advantages of the use of co-ordinates are, however,
TRAVERSE TABLES. xvn
most evident when it is necessary to determine the area included in a closed traverse. Unless co-ordinates are used the
only method of determining such areas accurately is by an involved trigonometrical method, consisting of cutting the area up into triangles the apices of which meet in any assumed point.
The angles of each triangle have then to be calculated, the triangles solved, and the sum of their areas thus determined. This method is so laborious that it is never used in practice. Unless this or the method of co-ordinates is used, however, the determination of the area can only be made by first plotting the survey, by which a number of errors of more or less importance are necessarily introduced.
By the use of co-ordinates, all these difficulties are avoided,
and the area of any closed traverse can be calculated directly
and easily from its latitudes and departures, without any
plotting at all. The principle of the calculation is best seen from a simple example :
Let the five sided figure OABCD (Fig. 5) be the plan of
a traverse survey situated wholly on one side of the meridian
through the point 0, and let it be required to determine the area of the figure. The total latitudes and departures are calcu
lated in the usual manner, and we have for the respective survey stations :
xviii TRAVERSE TABLES.
Total latitude. Total departure.
00
A Oa'( = -y) Oa( = 'x)
B Ob'( = - yi) Ob( = *:)
C Oc'( = ya) Oc( = x,}
D Od'( = #3) Od( = a?8)
Then the area of the figure
OABCD = d'DCSAa' - d'DO - OAa'
d'DCBAa' = d'DCc' + c'CBV + VBAu'
d'DCc' = UDd' + Cc'}d'c'
= H+0)(-y-0) Hence
= J[(0 + 3 )(0 - 2/ 3 ) + (aJ 3 + a; a)
/(dep. of + dep. of D)(lat. of - lat. of D)
(dep. of D 4- dep. of (7)(lat. of 7) - lat. of (7)
/. the area OABCD = J ( (dep. of (7 + dep. of 5) (lat. of C' - lat. of 5)
(dep. of 5 + dep. of -4)(lat. of B - lat. of A)
((dep. of A + dep. of 0)(lat. of A - lat. of 0)
The rule for the calculation of the area contained by a closed traverse is therefore as follows :
The algebraic sum of the total departures of each pair of adjacent angular stations is multiplied by the algebraic difference of their total latitudes ; the products thus obtained are added
together, and the sum divided by two gives the area required. In applying this rule it must be borne in mind that the station points must always be taken in strict order.1 To each
total latitude or departure the correct algebraic sign must be prefixed, and regard must be had to it in the arithmetical
1 It makes no difference whether the points be taken in the order in which they have been surveyed, or in the opposite order; the essential point
is that one regular order shall be adhered to. If the points are taken in the
opposite order the only difference will be that the area will have a instead
of a 4- sign. This is easily seen; for in the above calculation if the points
be taken in the opposite order, the signs of the sums of the departures will be
unaltered, and the signs of the differences of latitudes will be changed (e.g.
(y2 ?/3 ) instead of (y3 y2 )> etc.), so that the sign of the area will be
changed, its numerical value being unaffected. The sign obtained for the area of any closed traverse depends upon the direction of the first traverse,
and upon that in which the points are taken ; it is always considered as positive.
TRAVERSE TABLES. xix
operations involved. The result will be expressed in squares of the unit of measurement employed, square links if the survey was made in links, square feet or square metres if the distances were measured in feet or metres, etc. The above rule is occasionally stated in a different way, which is sometimes more convenient for calculation. The total latitude of each station is multiplied by the
algebraic sum of the departure of that traverse, and of the one next
following ; 1 the sum of the products thus obtained, divided by 2,
gives the area required. The departure here referred to is not the total departure
referred to the origin of the survey, but the departure of the traverse referred to its own starting station. It can easily be shown that these two rules are practically the same. For in Fig. 5, taking the values given above, we shall have for the departures of each traverse
Departure of point D referred to O
C
1 *7')
> ^" ^^
Then according to the second rule
Twice area OABCD =
x
l - x.2
X -Xxl
Again, according to the first rule, we have seen that
Twice area OABCD =
*s - s/3 - + 0*3 + s2)(ys - 2/2) + (a?2 + i)(y
- XIJ\ + Xl*J the same result as that given by the second rule. All that has been said of the first rule holds equally good of the second. In both of them the words latitude and
departure may also be interchanged without altering the result, so that there are really four different arithmetical operations
that can be employed indifferently. Yet another method is sometimes employed, known as that of
the " double meridian distance." In this the successive latitudes
are multiplied by multipliers obtained from the departures ; a
1 It is evident that the suras of the departures of any two traverses is
equal to difference between the total departures of the point before and the
point after the one being worked.
XX TRAVERSE TABLES.
column of " double departures " is formed by adding each
departure to the preceding one ; from these double departures the multipliers are obtained by adding each double departure to the last multiplier, the first multiplier being always zero.
By way of example, the area of the figure OABCD may be
calculated, the values of the departures and latitudes being as follows :
TRAVERSE TABLES. xxi
In both cases the results are of course identical, namely 49,910 square links or 0*4991 acre. It will be seen that the second method of calculation here produces a negative sign ; this would have been positive had the points been taken in the opposite order.
The following is an example of the application of the second rule to the same area :
Total latitudes.
XX11 TRAVERSE TABLES.
Latitude.
TRAVERSE TABLES. xxin
Stations.
XXIV TRAVERSE TABLES.
to select the traverse lines so as to equalize as nearly as possible the offset areas on either side ; this has to be done by inspection,
on the ground, and of course requires a good deal of practice. It occasionally happens that some of the points in a survey are determined by methods of triangulation instead of by
traversing. Broadly speaking, the term triangulation may be applied to the determination of any point by angular measure
ments from, the two ends of a base-line of known length ; the triangle is then solved, and the lengths of the two unknown sides calculated. This calculation is simply and easily performed by means of co-ordinates.
The problem in its most general form is shown in Fig. 7.
Suppose the points A,B have been already determined, their
CL'
Y' FIG. 7.
departures Oa and 01 being x and ^ and their latitudes Oa'
and Ob' being y and ^ respectively. The angles AC(= a)
and ABC( = &) are determined by observation ; from these data the latitude and departure of have to be calculated. Let
the quadrant bearing of the line BA be N". a E. ; then the
quadrant bearing (]3) of the line EC = 1ST. (a + 6) E., and the
quadrant bearing (y) of the line A C = S. (a a) E. Care must be taken in every case that the signs are correct according to
the particular quadrant.
Then tan 7=-^-=
a'c' y
tan * ~
b'c Oc' yl
Whence Oc' = * tan ? + x
tan 7 + tan y8
TRAVERSE TABLES. xxv
The departure Oc may be calculated from the corresponding formula : QC _ *i cot & + V + x cot 7 yt
cot /3 + cot 7
The above is the method generally employed, and is perhaps the most convenient when the ordinary mathematical tables are
available. It is, however, possible to use a method to which the traverse tables can be applied, and the work thus consider
ably simplified. For in Fig. 7 Oc = Oa + ac = x + OK
... Qc = x sin (a + b)
which may be written
n AB sin b . 10 sin y
10 sin (a + b)
All these values can now be taken from the traverse tables
because
AB sin b is the departure of distance AB for the angle b
10 sin 7 is the departure of distance 10 for the angle 7
10 sin (a 4- &) is the departure of distance 10 for the angle a -f Z>; if
a + b is greater than 90, the angle 180 (a + b) should be used instead.
Another form for the above expression is
n
, AB sin a . sin
:a?1+ *in(a + b)
For the latitude Oc', either of the two following expressions may be used:
^
, , AB sin a . cos fl
1
sin (a + i) s^n ^ C08
sin (a + b)
Any of these may be used with the traverse table as above
indicated, by multiplying numerator and denominator by 10, or by any other convenient number so that in the last case the second term of the formula for Oc would read
(dep of AB for angle &) x (lat. of 10 for angle 7)
dep. of 10 for angle (a + 6)
As an example of these calculations let the co-ordinates of the two points A,B of a traverse survey be as follows :
XXVI TRAVERSE TABLES.
Lat. ofJ. ... N. 87 links Dep. of^L ... W. 204 links
Lat. of ... S. 85 Dep. of B ... E. 89
Quadrant bearing of AB = S. 59 35' E. Length of AB - 340 links.
From A and B, Fig. 8, the angles between the direction AB
and the lines joining these points with the two points C and D,
Scale inch,<-1 Chain.
which it is desired to fix, have been observed, and found to be as follows :
Angle CAB = 40 28'
= 69 13'
Angle ABC = 68 59'
Angle A BD = 38 05'
Then, to determine the point C, we have by the first method
Meridian bearing of AC = 180 00' - 59 35' - 40 28' = 79 57'
Quadrant bearing of AC = N. 79 57' E.
Meridian bearing of BC = 360 00' - 59 35' + G8 59' = 369 24'
Quadrant bearing of BC = N. 9 24' E.
T} , (87 x tan 79 57') + (85 x tan 9 24') + 89 + 204
tan 79 57' - tan 9 24' = N. 146 And Oc = ( 2Q4 x cot 7 9 57') + (89 x cot 9 24') + 87 + 85
= E. 127
cot 9 24'^- cot 79 57'
As a check upon the arithmetical work of the calculations
we have
Tan 9 24' = I27
n
"" 89 = 0-1 G5
14G + 85
To determine the point D, we have
TRAVERSE TABLES. xxvii
Meridian bearing of AD = 180 - 59 35' + 69 13' = 189 38'
Quadrant bearing of AD = S. 9 38' W.
Meridian bearing of BD = 360 - 59 35' - 38 05' = 262 20'
Quadrant bearing of BD = S. 82 20' W.
T
, n r _ (87 x tan 9 38') + (85 x tan 82 20') + 204 + 89
tan 82 20' - tan 9 38' = S. 129 . d , = (204 x cot 9 38') + (89 cot 82 20?
) + 87 + 85 cot 9 38' cot 82 20' = W. 240
In applying these formulas special attention must be paid to the signs of the departures and latitudes. Using now the second method given above
O -201 + (34 ' sin 68 59/ )( 10 sin 79 57/)
10 sin (68 59' + 40 28')
From the tables
Departure of 300 = 280-04 for angle G8 59'
Departure of _40 = 37-34
Departure of 340 = 317-38
Departure of 10 for angle 79 57' = 9'8466
Departure of 10 for angle 109 27' = departure for angle 70 33' = 9-4293
= -204 + 331-4 = +127-4
, = 87 , (340 . sin 68 59') x (10 cos 79 57')
10 sin (68 59' + 40 28')
From the tables
Latitude of 10 for angle 79 57' = 1-7451 , . 7 317-38 x 1-7451 9-4293 = 87 + 58-7 = +145-7
Od = -904 - (34 sin 38 05') x (10 . sin 9 38')
10. sin (69 13' + 38 05') 9fu _ 209-71 x 1-6734 9-5476 = -(204 + 36-7) = -240-7
Od' = 87 (340 . sin 38 05') x (10 . cos 9 38')
10 . sin (69 13' + 38 O5'j~~ 209-71 x 9-859 9-5476 = 87-216-5 = -129-5
UNIVERSITY
CALIF01
xxviii TRAVERSE TABLES.
The results obtained are of course practically the same if the calculations are made with a sufficient degree of accuracy, but the use of the traverse tables even in such triangulation
problems is seen to very much shorten the calculations.
TRAVERSE TABLES.
Degrees.
Dist.
e
1 Degree.
Dist.
6
2 Degrees.
Dist.
8
3 Degrees.
Dist.
6
4 Degrees.
Dis
t
5 Degrees.
Dist.
6
6 Degrees.
Dist
7 Degrees,
Dist
6
8 Degrees.
Dist
6
9 Degrees.
Dist.
e
10 Degrees.
Dist
e
11 Degrees.
Dist.
e
12 Degrees.
Dist.
13 Degrees.
Dist.
6
14 Degrees.
Dist.
e
15 Degrees.
Dist.
e
16 Degrees.
Dist
(
17 Degrees.
Dist.
6
18 Degrees.
Dist.
6
19 Degrees.
Dist.
6
20 Degrees.
Dist.
6
21 Degrees.
Dist.
6
22 Degrees.
Dist.
23 Degrees.
Dist.
6
24 Degrees.
Dist
6
25 Degrees.
Dist
6
26 Degrees.
Diet.
I UNIVERSITY I
Vog . -*\*-S
27 Degrees.
Dist
6
28 Degrees.
Dist.
6
29 Degrees
Dist.
6
30 Degrees.
Dist,
(
31 Degrees.
Dist.
6
32 Degrees.
Dist.
6
33 Degrees.
Dist.

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The AWA Review
Volume 30 • 2017
Published by
THE ANTIQUE WIRELESS ASSOCIATION PO Box 421, Bloomfield, NY 14469-0421
http://www.antiquewireless.org
Devoted to research and documentation of the history of wireless communications.
THE ANTIQUE WIRELESS ASSOCIATION PO Box 421, Bloomfield, NY 14469-0421 http://www.antiquewireless.org
Founded 1952. Chartered as a non-profit corporation by the State of New York.
The AWA Review
EDITOR
Eric P. Wenaas, Ph.D.
ASSOCIATE EDITORS
William (Bill) V. Burns, B.Sc. Joe A. Knight
FORMER EDITORS
Robert M. Morris W2LV, (silent key) William B. Fizette, Ph.D., W2GDB Ludwell A. Sibley, KB2EVN Thomas B. Perera, Ph.D., W1TP
Brian C. Belanger, Ph.D. Robert P. Murray, Ph.D. Eric P. Wenaas, Ph.D. David P. Bart, BA, MBA, KB9YPD
OFFICERS OF THE ANTIQUE WIRELESS ASSOCIATION DIRECTOR: Tom Peterson, Jr. DEPUTY DIRECTOR: Robert Hobday, N2EVG SECRETARY: William Hopkins, Ph.D., AA2YV TREASURER: Stan Avery, WM3D AWA MUSEUM CURATOR: Bruce Roloson, W2BDR
©2017 by the Antique Wireless Association, ISBN 978-0-9890350-4-0
Cover Images: The cover page of Marconi’s Ocean Radio News distributed circa 1914 appears on the front cover of this issue (courtesy of Joe Knight), and the back page of an edition of the Wireless News distributed on the RMS Makura appears on the back cover of this issue. Both images are taken from “The Wireless News” by Bart Lee.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the copyright owner.
Book design and layout by Fiona Raven, Vancouver, BC, Canada Printed in Canada by Friesens, Altona, MB
Contents
■ Volume 30, 2017
FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
PARADIGM LOST: NIKOLA TESLA’S TRUE WIRELESS
David Wunsch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
ZEH BOUCK, RADIO ADVENTURER PART 1: THE PILOT RADIO FLIGHT TO BERMUDA
Robert Rydzewski. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
A SOVIET ERA BROADCAST RECEIVER SYSTEM OF THE 1950s FOR REMOTE LOCATIONS
Robert Lozier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
WESTINGHOUSE RADIO AND TELEVISION PRODUCTION
Mike Molnar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
THE WIRELESS NEWS
Bart Lee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
HENRY K. HUPPERT AND HIS VACUUM TUBES
Eric Wenaas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
THE NAVAL RADIO SCHOOL AT HARVARD: A NEW ERA IN MILITARY TRAINING
David and Julia Bart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
THE CRADLE OF COLLEGE RADIO: WJD AND THE PRESCIENT PROFESSORS
Mike Adams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
LETTERS TO THE EDITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
iv The AWA Review
Foreword
This year we celebrate the 30th issue of the AWA Review marking thirty years of publishing the most respected journal chronicling the history of electronic communication with a focus on antique wireless. It should be noted that the thirty issues were not published in consecutive years because there were no issues published in the years 1994 and 1997. Robert M. Morris, W2LV, was the editor for the first issue published in 1986, and he was supported by managing editor William B. Fizette, K3ZJW. This issue contained eight articles in 123 pages, and the introductory article by Charles M. Brelsford, K2WW, covered the founding and development of the Antique Wireless Association and the development of the AWA Museum. This issue must have been very popular because it was reprinted in January 1991. From inception, there have been a total of eight editors and coeditors, all of whom are listed on the masthead of this issue. Robert Murray had the longest run as editor with ten issues (Vols. 19–28), while William Fizette was second with six issues as editor (Vols. 9–13) plus three issues as managing editor (Vols. 1–3). William Fizette’s most memorable issue is undoubtedly Vol. 12, published in 1999, with a single article entitled “The Atwater Kent Radios” written by Ralph O. Williams, NV3T. This issue is the only one that was devoted to a single feature article. The format of the AWA Review and the cover created for the first volume endured for the first sixteen issues. The first three issues had a photograph of antique wireless equipment on the front cover that had nothing do with the articles inside. When William Fizette became editor, he started the tradition of placing a photograph on the cover that was associated with one of the articles within. Brian Belanger gave the cover a new look when he became editor of Vol. 17 in 2004 by placing a table of contents on the cover, which was accompanied by a photograph from each of the five papers in the issue. He repeated this cover format on the 2005 issue. When Robert Murray became editor of Vol. 19 in 2006, he instituted many changes over his ten-year tenure that improved the articles and modernized the format. He is credited with expanding the range of content, requiring peer review of all articles, adding full color to selected papers and the cover, and engaging Fiona Raven Book Design to develop creative layouts and unique covers. Bob Murray’s wrap-around design on the cover of the 2012 issue depicting the Silent room of the Titanic on the front and the Marconi wireless room on the back will long be remembered. That issue, marking the centennial of the sinking of the Titanic, quickly sold out and was reprinted the next year. This year continues the traditions set by Bob Murray with eight high-quality, peer-reviewed articles and another creative cover layout using images appearing in Bart Lee’s article, “The Wireless News.” All but one of these articles were
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written by returning authors that have published in the AWA Review before. We welcome our new author this year, and hope to have many more new authors in the future. A brief summary of each paper follows in the order they appear.
■ David Wunsch examines an article written by Nikola Tesla entitled “The True Wireless,” which appeared in the Electrical Experimenter magazine in May of 1919. He finds that Tesla was unable to assimilate a paradigm shift in the scientific discipline that explained the existence and generation of electromagnetic waves—the basis for wireless telegraphy and eventually radio. He quotes Tesla’s classic statement from the article: “The Hertz wave theory of wireless transmission may be kept up for a while, but I do not hesitate to say that in a short time it will be recognized as one of the most remarkable and inexplicable aberrations of the scientific mind which has ever been recorded in history.”
■ Robert Rydzewski writes about Zeh Bouck, born John W. Schmidt (1901–1946), who was an early radio pioneer, engineer, writer, and adventurer. He helped design the Pilot Super Wasp and flew it on the first ever flight to Bermuda, penned stories and radio plays, was an associate editor for Radio Broadcast and CQ, and was also an IRE Fellow and a member of the Radio Club of America. Despite an array of achievements worthy of a real-life Indiana Jones, today Zeh Bouck is an obscure footnote to radio history. Robert revives him and gives him new life with his article.
■ Robert Lozier continues his tradition of writing about interesting and unusual broadcast receivers manufactured outside the United States. Robert does not disappoint us this year with his description of a unique broadcasting system operated in the former USSR known variously as “radio-diffusion exchanges,” “cable radio,” or “wired radio.” They were centralized receivers with wire lines going to subscriber apartment buildings, factories, public halls, or schools and were operated much like telephone exchanges. Even more unusual were the thermoelectric generators that powered these radios, one of which is chronicled in the article.
■ Mike Molnar explores the history of consumer radio and television manufacturing at Westinghouse from the late 1910s to the end of the twentieth century. He raises many questions about Westinghouse sets and answers most of them. When was it made? Where was it made? Why are the ID tags on two radios so different? Surprisingly, the collector may have to ask, who really manufactured it? Read on and puzzle through some of these mysteries with the author.
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■ Bart Lee informs us that for well over a century, wireless radio provided ships at sea and their well-off passengers with current news of the world, market data, and sports. The wireless news has been indispensible to voyagers of many sorts, especially on transoceanic routes. We learn about the general content of wireless news publications, the companies who provided the wireless news, and how the news was received, printed and distributed to passengers on the ships. Bart also provides many examples of publications carrying wireless news—many in full color.
■ Eric Wenaas discovered the previously unknown papers of Henry K. Huppert, which he recently found in the possession of his granddaughter, Claudia M. Benish, who inherited them from her father, Ralph M. Huppert. These papers chronicled in his article contain technical notes, photographs, and other memorabilia of Henry Huppert, who designed the Solenoid tube, the Two-in-One tube, the Quadrotron tube, a unique thermionic X-ray tube with a control grid but with no trade name, and a diathermy machine with the trade name “American Radio-Thermy.”
■ David and Julia Bart tell us about the contributions of the U.S. Naval Radio School that was established at Harvard University in 1917 to train naval personnel to operate and repair radio equipment used in WWI. They explain how, in only eighteen months, the Navy came to train nine of every ten naval radio operators who served in the war. The article is filled with historic photographs taken at Harvard as well as photographs of associated memorabilia from the authors’ collection.
■ Mike Adams recently discovered the unchronicled story of early radio broadcasting at Denison University while researching at the Denison University Library. This library holds papers of Richard Howe, the prescient professor that instituted radio broadcasting at Denison in the early 1920s. The Denison story is so compelling because Howe kept detailed records and memorabilia of his radio broadcasting activities, which included correspondence with the Department of Commerce, early broadcast and experimental licenses, listener verification cards, photos of equipment, and much more.
We extend our sincere thanks to the authors for their excellent articles and to the reviewers for their able assistance in reviewing the articles and making suggestions that improved the manuscripts. I also thank the two associate editors, Bill Burns and Joe Knight, who assisted me this year. Their contributions were considerable. The AWA Review used the services of book designer Fiona Raven once again to prepare the AWA Review. Her help this year was invaluable,
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as it has been in the past. We thank Fiona again this year for her contributions and creative spirit. The word-searchable cumulative Table of Contents has been updated this year and is now current though Vol. 30. This index can be accessed on the AWA website at http://www.antiquewireless.org/awa-review.html. I have enjoyed serving as editor of the AWA Review this year and working closely with each and every author. I will continue to serve as editor of the AWA Review for at least one more year. I look forward to receiving manuscripts for your articles next year. Tips for authors who intend to submit articles follow.
Eric Wenaas, Ph.D. Editor San Diego, California
Tips for Authors
The AWA Review invites previously unpublished papers on electronic communication history and associated artifacts with a focus on antique wireless. Papers will be peer reviewed to verify factual content by reviewers whose identity will remain anonymous. This process gives the AWA Review credibility as a source of correct historical information. The papers will be edited to provide uniformity in style and layout among the articles. In general, shorter articles of six to eight pages (3,000 to 4,000 words) or less should be submitted to the AWA Journal, which is published quarterly. The AWA Review is intended for longer articles on the order of 6,000–8,000 words. Longer articles may be accepted with preapproval by the editor. The AWA Review will also publish Letters to the Editor as deemed appropriate. The letters should comment on articles published in the previous issue of the AWA Review or make brief comments on wireless history as it relates to one of the articles. Letters will not be peer reviewed, but they may be edited. Text is limited to 400 words and no more than 10 references. The editor reserves the right to publish responses to letters. It is strongly recommended that authors planning to prepare an article for the AWA Review send an abstract of approximately 200 words to the editor describing the subject and scope of the paper before writing the article, including an estimate of the number of words. It is never too early to submit an abstract. Space in the AWA Review is not unlimited, so it is important for both editors and authors alike to have an estimate of the expected number of articles and number of pages for each article as soon as possible. The deadline for submissions of manuscripts in 2018 is January 1. Papers will be accepted after January 1, but papers submitted
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and accepted for publication before January 1 will have priority in the event that there is not space for all papers submitted. Authors with an interesting story to tell should not be discouraged by a lack of writing experience or lack of knowledge about writing styles. The AWA Review will accept manuscripts in any clearly prepared writing style. Editors will help inexperienced authors with paper organization, writing style, reference citations and improving image quality. Edited manuscripts will be returned to the author along with comments from the editor and anonymous reviewers for the author’s review and comment. The manuscript will then be set in its final form and sent back for one final review by the author. Normally, only one review of the layout will be accommodated. To summarize, please submit completed manuscripts by January 1, 2018 (or earlier if possible) in three separate files:
1) A manuscript file without embedded figures or figure captions using Microsoft Word or other software that is compatible with Word. The manuscript should have a 200-word abstract, a main body with endnote citations and endnotes, acknowledgements, and several paragraphs summarizing the author’s background.
2) A figure file with numbered figures that match the figure call-outs that must appear in a sentence of the manuscript text.
3) A figure caption file with a short description of each figure and an attribution for each figure identifying its source.
You may use the articles in this issue as a template for the style and format of your paper. For more information, consult the AWA website at http://www .antiquewireless.org/awa-review-submissions.html. Please feel free to contact me for any questions:
Eric Wenaas, Ph.D. Editor eric@chezwenaas.com
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Paradigm Lost: Nikola Tesla’s True Wireless
© 2017 A. David Wunsch
We examine an article written by Nikola Tesla entitled “The True Wireless,” which appeared in the Electrical Experimenter magazine in May of 1919. His essay is analyzed as an example of the inability of a scientist or inventor to assimilate a paradigm shift in his discipline, and we use the language and thought of Thomas Kuhn in this discussion. The paradigm shift in question was created by Maxwell and Hertz in the latter third of the 19th century, a shift that explained the existence and generation of electromagnetic waves—the basis for wireless telegraphy and eventually radio. We also focus on the magazine in which Tesla’s piece appeared and consider why the article might have been written and accepted for publication.
“The Hertz wave theory of wireless transmission may be kept up for a while, but I do not hesitate to say that in a short time it will be recognized as one of the most remarkable and inexplicable aberrations of the scientific mind which has ever been recorded in history.” —Nikola Tesla, “The True Wireless” 1919
“... the man who continues to resist after his whole profession has been converted has ipso facto ceased to be a scientist.” —Thomas Kuhn, The Structure of Scientific Revolutions 1962
The Paradigm
For historians of radio and the wireless telegraph, one of the strangest documents they are apt to encounter is an article entitled “The True Wireless” that was published in the May 1919 issue of the popular magazine, the Electrical Experimenter. The author was the renowned Serbian-born inventor, Nikola Tesla (1856–1943). Tesla spent most of his professional life in the United States, and by 1919 he was just past the peak of his fame—a man as nearly well known to the general public as Edison. He was a contributor to the
Sunday supplements of newspapers, where he described his latest proposed inventions such as a weapon that would make war obsolete by creating an enormous tidal wave.1 Although his reputation as an inventor may have faded, he persists today as a cult figure. A web search will lead to sites proclaiming that he invented radio, radar, x-rays, alternating current, the laser, the transistor, and limitless free energy. His name also endures as the brand of a pioneering high-priced electrical automobile.
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There is some irony in this—the car is powered by batteries that supply direct current (DC), while Tesla’s great accomplishment resides in his contribution to the generation and distribution of polyphase alternating current (AC). He developed an ingenious device, the induction motor, that is ideally suited to polyphase AC because of the ease with which such current creates the rotating magnetic field required by many motors. Readers of this paper should have at their disposal a copy of “The True Wireless,” which can be found on the Internet.2 Note that the insert appearing in the article was written by the magazine’s editor, Hugo Gernsback, who asserted, “Dr. Tesla shows us that he is indeed the ‘Father of wireless.’” Tesla is referred to variously as an engineer, physicist, scientist, and inventor on many websites, including the Wikipedia, which contain his biography. Historically, this blurring of occupations has a distinguished lineage: Galileo, for example, invented telescopes and other instruments and was also an astronomer, and the transistor was invented by men trained as scientists, not engineers.
A Paradigm Missed
Had Tesla’s paper appeared fifteen years before—circa 1904—its content would be unremarkable. Coming as it does in 1919, just before the era of broadcast radio, it becomes useful as a notable example, in the field of science and technology, of an inventor’s failure to grasp what the distinguished historian
of science Thomas Kuhn has described as a “paradigm shift.” This term first appears in Kuhn’s book The Structure of Scientific Revolutions published in 1962. The work is among the most cited scholarly books produced in the last half of the 20th century and has been in print in various editions for over 50 years. We refer here to the 3rd edition of 1996.3 The expression paradigm shift has entered everyday language, and its use has steadily increased since Kuhn coined the phrase. The concept will be employed here in the discussion of Tesla’s paper. What does Kuhn mean by this term? In the sciences, he asserts that a paradigm derives from “universally recognized scientific achievements that for a time provide model problems and solutions to a community of practitioners.” The word “model” is key here. The Greek-Egyptian astronomer Ptolemy (100–170 AD) had a model of what we now call our solar system: his earth was at its center, and the sun revolved around the earth. The concept has a limited use—it does explain sunrise and sunset, but as mankind’s knowledge of the planets and stars increased, it became unworkable. Copernicus, Galileo, Kepler, and Newton killed the old model—their work, which began circa 1540 and occupied nearly two centuries, led to a classic paradigm shift. The shift describes the discarding of an old model whose use is unfruitful and untenable in favor of a new paradigm that more gracefully and convincingly describes recent experimental evidence.
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For our present discussion, the important paradigm shift began with the Scotsman James Clerk Maxwell (1831–1879). Consider what Nobel Laureate Richard Feynman said about Maxwell’s work of the period 1860–1873: “From a long view of the history of mankind—seen from, say, ten thousand years from now—there can be little doubt that the most significant event of the 19th century will be judged as Maxwell’s discovery of the laws of electrodynamics.”4 Maxwell produced a paradigm, or a model, for light: it was an electromagnetic wave having transverse electric and magnetic fields. The theory described a wave moving at the speed of light that could be generated by electrical means, and it did not specify a wavelength—it could be, for example, 700 nanometers (like visible light, whose wavelengths were known in Maxwell’s era), or around 300 meters (like broadcast AM radio of our time). In the late 17th century, Newton had maintained that light consisted of streams of particles, which he named corpuscles; his prestige was such that his model still had some adherents as late as Maxwell’s era, although there was much evidence favoring a wave theory. To further complicate matters, others analyzed light as a ray that describes the path of the light energy.5 We now come to a narrative familiar to many readers. In the period 1886–1889, the German physicist Heinrich Hertz carried out a series of experiments in which he generated a wave that exhibited wavelengths on the
order of meters, possessed a measurable electromagnetic field, and to a fair approximation moved at the known speed of light.6 These waves could be reflected, polarized, and diffractedjust as visible light, whose properties had been studied for several centuries. Had the Nobel Prize been awarded in the lifetimes of Maxwell and Hertz, they would surely have been winners. Hertz’s work was published in the period 1887–1891 and served as a stimulus to such people as Guglielmo Marconi, Oliver Lodge, and Karl F. Braun, who sought to employ Hertz’s discovery in the field of wireless telegraphy. The story is well told in the book by Aitken.7 Tesla recounts a meeting with Hertz in the document we are studying: he traveled to Hertz’s laboratory in Bonn, Germany, in 1892 and describes in “The True Wireless” an unfruitful encounter where he informs Hertz that he had been unable to reproduce his results. If we believe Tesla, the two parted “sorrowfully” with our narrator subsequently regretting his trip.8 He also informs us that later, even having developed a “wireless transmitter which enabled me to obtain electromagnetic activities of many millions [sic] of horse-power,” he was unable to “prove that the disturbances emanating from the oscillator were ether vibrations akin to those of light...” Unable to generate what soon became known as Hertzian waves, and having read articles describing such waves over the eighteen-year period preceding this article, he remarks, “The Hertz-wave
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theory, by its fascinating hold on the imagination, has stifled creative effort in the wireless art and retarded it for twenty-five years.” By the time Tesla wrote his article, wireless telegraphy had been a business for nearly 20 years—and had grown into a very big one at that. When the United States entered World War I in 1917, the Marconi Wireless Telegraphy Company of America (American Marconi) had outfitted 582 wireless stations on ships and possessed 45 coastal stations for ship-to-shore and international communication.9 The Navy took these over at the beginning of the war. At the cessation of the war, British Marconi was eager to buy exclusive rights to the Alexanderson alternators from General Electric; these were powerful and efficient successors to the spark gap and arc transmitters used earlier in wireless telegraphy. Initially, they planned to spend over $3M on 24 alternators and employ them both in their own corporation and in American Marconi.10 If, as Tesla alleges, the big business of wireless telegraphy did not employ Hertzian waves, how did it operate? He specifically denies that the “disturbances” (a name he uses in lieu of Hertz’s waves) emanating from an oscillator “were ether vibrations akin to that of light.” It is interesting to examine the language of his paper. He speaks of “some kind of space waves” and “transversal vibrations in the ether,” and except to disparage them, he does not refer to Hertz’s (or Hertzian) waves. By 1919, his words and thinking were archaic.
The terminology in the discourse of radio and wireless telegraphy engineering had evolved since Hertz’s work and the growth of international wireless telegraphy. We now employ the Google Book’s Ngram Viewer, a piece of free Internet software that quantifies how frequently a word turns up in a large number of books during a specified time period. The output of this software is a graph showing the number of mentions in books versus time (in years) for a word or phrase supplied. The frequency of use of the term Hertzian waves over more than a century is shown in Fig. 1. We see the term gaining currency beginning with Hertz’s famous experiments and reaching a peak at about the time of Tesla’s paper. It is not hard to understand that it subsequently lost popularity. A search of the term electromagnetic waves, which ultimately replaced Hertzian waves, is shown in Fig. 2. As it became clear to the engineering community that the waves generated by Hertz were merely a part of the electromagnetic spectrum—one which was to become increasingly exploited by broadcast AM radio, television, and FM broadcasting—the locution Hertzian waves would have seemed anachronistic. It is evident that at the time of Tesla’s writing, the term “Hertzian waves” had already been eclipsed by “electromagnetic waves.” Incidentally, an Ngram of the term “radio waves” displays a curve much like that for electromagnetic waves. Both gained favor at the same time.
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Tesla “Disproves” Hertzian Theory
Electricity and Hydraulic Analogies
How did Tesla explain wireless communication without Hertzian waves or its synonyms? The answer is fascinating. He used a fishy version of alternating circuit theory. A close reading of “The True Wireless” reveals that he promoted a form of circuit theory employing but a single wire—in other words, there is no real circuit such as those who understood the subject are accustomed to. He also maintains that the earth itself can
function—must function—as this lone wire. He seeks to explain this with a labored hydraulic (fluid) analogy that is illustrated in Fig. 4 of his paper, which is reproduced here as Fig. 3. Of course, you can send a disturbance down a water filled pipe without employing a return circuit—just strike one end with a hammer. His analogy proves nothing, but its use is understandable. When Tesla was in college in the late 1870’s and early 1880’s, alternating current theory was a new and difficult subject.11 If he learned
Fig. 1. Frequency of use of the term “Hertzian waves.” (Google Ngram)
Fig. 2. Frequency of use of the term “electromagnetic waves.” (Google Ngram)
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it there, or, as seems likely, on his own after college, he would have encountered textbooks that sought to treat this discipline using analogies drawn from hydraulics—a much older and better-understood subject.12 It was not uncommon then to use the word “pressure,” taken from fluid mechanics, where we now use “voltage” or “electrical potential.” Such analogies, which might employ water wheels to represent inductors and elastic diaphragms as proxies for capacitors, convey only an intuitive feeling for AC circuits and are of no use for communication systems employing electromagnetic waves.13 Thus, Tesla attempted to apply a dubious electric circuit approach where
it had no validity. In fact, one wonders why no one asked him if the return wire in the circuit could be eliminated, then why not also the wire that carries the current that is outgoing from the generator. Had he taken that radical step, he might have been on his way to understanding communication between two antennas in the absence of any earth.14 In criticizing Tesla for his wrongheaded model, are we in fact guilty of what has become known as Whig history? The term Whig history was introduced by the distinguished English historian Sir Herbert Butterfield in 1931. It can refer to an unfair judgment of historical figures and their actions that are based on our present
Fig. 3. Tesla’s fluid “circuit.” (True Wireless, Fig. 4)
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knowledge of what is humane and progressive and acceptable. For example, to condemn Thomas Jefferson for writing in the Declaration of Independence “All men are created equal” (where are the women?) would be to engage in Whig history. In the sciences, Whig history has a similar meaning: it would be to criticize a scientist or inventor of the past for failing to use concepts that we now take for granted.15 From our present perspective, Tesla’s not using a wave model to explain radio seems bizarre, but given what was known in 1919, are we being unfair and leaving ourselves open to the accusation of Whiggishness? An example of Whig history of science would be to condemn Ptolemy for his earth centered view of astronomy. Given the tools at his disposal, his mistake is understandable.
And to disparage Maxwell for his frequent use of the term ether—when we know that the concept is not validwould be Whig history. I will seek to explain in what follows that I have not fallen into the trap of Whig history in discussing Tesla.
Influence of Mountains or Obstacles
Tesla seeks to disprove Hertzian wave theory as a means of communication with several examples. Consider his Fig. 17, reproduced here as Fig. 4. Tesla claims that “unless the receiver is within the electrostatic influence of the mountain range”—in what we would now call “the near field of the antenna”—the signals at the receiver “are not appreciably weakened by the presence of the latter because the signal passes under it [italics added]
Fig. 4. Tesla analyzes the effect of an obstacle. (True Wireless, Fig. 17)
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and excites the [receiving] circuit in the same way as if it is attached to an energized wire.” No radio propagation engineer would have accepted such an argument in 1919. Indeed, the receiver might well detect the transmitted signal, but not for the reasons stated by Tesla. No model of wave propagation asserts that the signal goes under the mountain.16 Following the work of Hertz, it was apparent that laws of optics could be applied to electrically generated waves. There would have been no problem in explaining the reception of waves by a detector lying on the shaded side of the mountain—it would be described as Fresnel diffraction, a theory put forth by the eponymous French physicist in the period 1815–1818.17 The theory asserts, in part, that the greater the wavelength used, the stronger the signal that makes its way into the optical “dark side,” provided the distance from the diffracting edge (here, the mountain top) is small measured in wavelengths.18 Given the long wavelengths employed by Tesla (10 kHz => 30 km. => 18 miles), a number taken from Fig. 1 in his article, there is no trouble in explaining wireless reception on the far side of the mountain. By the time Tesla published this piece, the subject of diffraction of electromagnetic waves had become sophisticated and had engaged the attention of a number of distinguished mathematicians. If the mountain is modeled as a hemispherical impediment to the wave, and if the earth is a good conductor, then the problem of scattering
by the mountain can be attacked using the method of images. The problem becomes that of a plane wave incident upon a sphere. This problem had been solved in the period 1908–9 by Debye and Mie and would also show a signal in the optical shadow cast by the hemispherical mountain.19 In the period beginning in 1889 and ending in the era of Tesla’s writing, the Scottish mathematician H. M. Macdonald had treated waves from a Hertzian dipole diffracted from the earth, which he modeled as a perfectly conducting sphere.20 His work was improved by the great French scientist and philosopher, Henri Poincaré, who in the period 1909–1912 converted Macdonald’s series of Bessel functions into a definite integral that could be better evaluated. The German mathematical physicist Arnold Sommerfeld, unlike his predecessors, treated the earth as an imperfectly conducting surface, although he simplified matters by making the earth flat. He placed a vertical, electrically short dipole above the earth and derived an expression for the resulting electric and magnetic fields. His results of 1909 were expressed in terms of an integral that he evaluated asymptotically for an observer far from the antenna. He found that a surface wave had been generated, and his theory nicely supported that of another German, Jonathan Zenneck, whose less rigorous work had led to what became known as the Zenneck wave, which existed on the ground at some distance from the antenna. The latter turned out to be the asymptotic solution
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of Sommerfeld’s theory. In 1919, the German mathematician Herman Weyl solved Sommerfeld’s configuration and ended up with a different approach that did not contain Zenneck’s wave. This result caused Sommerfeld to rework his solution, and his new findings did not agree with Zenneck. In short, the first two decades of the 20th century was a lively and sometimes contentious period in the theory of radio wave propagation, but there is no hint of this in Tesla’s paper. Nor is there any indication in anything he wrote that he had the sophisticated mathematical skills to comprehend what was being written by the people cited above. There were, of course, great inventors with minimal knowledge of higher mathematics (think of Edison, Morse, Bell) but these largely belonged to the 19th century, and one does see Tesla as part of that tradition. His clinging to a sketchy circuit theory explanation seems pathetic. Incidentally, as early as 1904, a textbook of Henri Poincaré had addressed the primacy given to currents flowing through the earth in Tesla’s model of wireless telegraphy. He points out that if a coherer is placed in a hole in the ground “it will operate [as a detector of wireless telegraphy] when uncovered; if the hole be filled with earth, the oscillations produce no effect. We must look for something more than earth currents to explain the phenomena.”21 Recall that the most common detector in use at that time was the Branly coherer. Putting aside theoretical considerations, Tesla’s paper is notable for the
omission of major empirical findings contained in the famous and practical Austin-Cohen formula, a concise expression that describes the strength of the electric field experienced by a receiving antenna when both receiver and transmitter are over the ocean. Louis Winslow Austin and Louis Cohen had worked for the U.S. Navy in the early 1910’s, making shipboard electrical measurements of the field radiated from various transmitters manufactured by Reginald Fessenden’s company, the National Electric Signaling Company, or NESCO. By 1911, the two men had devised a successful empirical formula that gives the received field.22
Ir = 4.25 Ish1h2 e-ad/√λ.
dλ
Here Ir is the current received by an antenna driving an impedance of 25 ohms, Is is the transmitting antenna’s current, h1 and h2 are the lengths of the two vertical antennas, l is the wavelength, d is the distance separating the antennas, and a = .0015. Lengths are in kilometers and currents in amperes. The formula was effective only during the day and was so useful that it became the basis for testing new theoretical predictions of received fields. The presence of the square root of the wavelength in the exponent was later derived theoretically by the English mathematician G. N. Watson and published in 1919, only a few months after Tesla’s paper.23 Interestingly, Tesla, speaking of the formula, states unequivocally “... the actions at a distance cannot be proportionate to the
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height [length] of the antenna and the current in the same,” which is in direct contradiction to what the much-used equation asserts. Tesla’s statement “the current in the same” is especially puzzling, not only because it had been established experimentally but also because he has essentially been using alternating circuit theory, in a strange form, and the device he is employingan antenna, and a conducting earthare mathematically linear and should, according to linear circuit analysis, create a response in linear proportion to the current exciting the antenna. Strange to say, Tesla then uses Austin-Cohen to reject Hertzian waves, saying that, “...I cannot agree with him [Austin] on this subject. I do not think that if his receiver was affected by Hertz waves he could ever establish such relations as he has found.” So, on
the one hand, he rejects the famous formula but then embraces it as a means to argue against Hertzian wave theory. Let us now study Fig. 18, in Tesla’s paper, reproduced here in Fig. 5. He has now introduced a second mountain that is further from the transmitter than the one in the previous figure. He argues that if Hertzian wave theory were true, then the second mountain “could only strengthen the Hertz wave [at the receiver] by reflection, but as a matter of fact it detracts greatly from the received impulses because the electrical niveau between the mountains is raised...” [niveau is a French word for level surface]. What Tesla fails to understand here is that without knowing the wavelength of the radiation, the separation of the two mountains, and the position of the antenna between them, we can make
Fig. 5. Tesla considers the effect of two hills. (True Wireless, Fig. 18)
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no statement about the enhancement or reduction of the signal at the receiver caused by the presence of the second mountain. In fact, using elementary wave theory or a transmission line analog, we can argue that if the two mountains are separated by half a wavelength and if the receiver is midway between them, and if the soil is of reasonably high conductivity, then we have what is called a standing wave between the mountains. In this case, the effect of the more distant mountain is to enhance the signal at the receiver. There are waves moving from right to left and vice-versa between the mountains. Such an arrangement, when set up in a room, as Hertz did in his famous experiment published in 1888, is known as an interferometer.24
Kuhn tells us that if we want to see what constitutes “normal science” and the paradigms it embraces, we should look at the textbooks of that era.25 By 1904, we can say confidently that the paradigm shift created by Maxwell and Hertz had taken hold and was part of normal science. This was the date of publication of Poincaré’s book, whose chapters 7, 8 and 9 are devoted to the propagation of waves along wires, dielectrics, and air. It seems evident that Tesla was not reading the textbooks of his epoch.
Tesla and Antenna Theory
Another puzzling segment of Tesla’s anti-Hertz diatribe is his Fig. 16, shown below as Fig. 6. Tesla would have us believe that the antenna on the right
Fig. 6. Tesla considers a straight and bent antenna. (True Wireless, Fig. 16)
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(which nowadays is called “an inverted L”) is just as effective as a receiver or transmitter as the straight antenna on the left. He claims that he has performed an experiment that supports this conclusion. He also asserts that the experiment proves that “currents propagated through the ground, and not ... space waves” is the reason for true wireless telegraphy. In 1919, an understanding of the theory of receiving antennas was still fairly primitive.26 And it was only in 1924, with the work on reciprocity of John R. Carson at Bell Labs, that the tools that had been developed to analyze transmitting antennas could be brought to bear on receiving antennas.27 So, we must not be harsh in condemning Tesla for his wrongful assertion. However, it was known as early as 1898 that if antennas are placed above a flat highly conducting earth, one can invoke the method of images for analyzing them.28 It was well known before 1919 that if the earth is a good conductor, the electric field of a propagating radio wave would be primarily perpendicular to the earth, and the field strength would be proportional to an integral of the current along the vertical portion of the antenna. It should have been apparent to Tesla that if a transmitting vertical wire antenna is small, measured in wavelengths, and has the shape of the antenna on the left of Fig. 6, and if it is now bent into the shape shown on the right, then the electric field normal to a flat highly conducting earth is reduced.29 However, the situation here
is potentially quite complicated. The difficulty occurs with an imperfectly conducting earth. Marconi, in 1906, described to the Royal Society an array he built consisting of inverted L antennas and observed that the array broadcasts most effectively in the direction of the arrow shown below, i.e., away from the horizontal element.30 Fig. 7 is taken from Principles of Wireless Telegraphy by G. W. Pierce, published in 1910.31 Jonathan Zenneck, in the same era as Pierce, describes the work of H. von Hoerschelmann, a student of Arnold Sommerfeld, who apparently was the first to explain the directive properties of Marconi’s antenna. His earth is assumed to be imperfectly conducting. He includes the vertical portions of the current induced in the earth directly under the horizontal wires of the array.32 The upshot is that whether one assumes a highly conducting earth or one of imperfect conductivity (as is required for Marconi’s antenna), Tesla’s assertion “that the antennas can be put out of parallelism without noticeable change in action on the receiver” is utterly wrong. Marconi’s inverted L was constructed in the year 1905, and the explanation by Hoerschelmann was
Fig. 7. Marconi’s directional inverted L antenna. (G. W. Pierce, Principles of Wireless Telegraphy, 1910, p. 298)
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published in Zenneck’s book, which came out in German in 1912, both well before Tesla’s paper.33
Skin Effect
Tesla repeatedly speaks of his system of wireless telegraphy implemented by sending messages through the earth. Here he displays his ignorance of what is now referred to as “skin effect”: that alternating currents have a marked tendency to cling to the outside (skin) of conductors. Knowledge of this goes back to the work of the Englishman, Sir Horace Lamb, in 1883 and was advanced further by his countryman, Oliver Heaviside, in 1885.34 The results showed that the higher the frequency in use, the greater the tendency for the current to adhere to the outside of the conductor. It is especially puzzling that Tesla does not mention this phenomenon as he took advantage of it in arranging for photographs of himself enveloped by sparks.35 The frequency of the generator he was using was such that the energy would not penetrate deeply into his body, which meant that although he might have been burnt, he would not have been electrocuted. In an 1893 lecture before the Franklin Institute in Philadelphia, he sought to explain his not being shocked with a confused discussion.36 By 1919, skin effect and the concept of skin depth (the depth of penetration of the current) would have been in the better electrical engineering textbooks.37 We can calculate how far a wave might penetrate into a mountain
in the United States where typical soil conductivity, s = .005 mhos/meter and the relative permittivity, er = 10.38 We will assume a frequency f = 100 kHz. Using the standard formula for skin depth that applies when conduction current greatly exceeds displacement current,39 we have
δ=√ 1
π f μσ
Here d is the skin depth and m is the permeability of the soil, assumed here to be nonmagnetic. The skin depth for the numbers chosen here is about 22 meters. It is virtually impossible for the signal that Tesla imagines to penetrate a mountain having these typical parameters.
Dismissal of Gliding Waves
Let us now focus on Tesla’s Fig. 13 (shown here as Fig. 8) and his accompanying discussion. At the very top of his figure Tesla has the caption, “Hertz’s waves passing off into space through the earth’s atmosphere.” To someone acquainted with even elementary antenna theory, the picture is a puzzle. It depicts what appears to be a vertical antenna fed by a generator connected between the base of the antenna and the earth. In 1919, such an antenna would likely be of small height when measured in the wavelengths in use. Using the method of images and antenna analysis dating from the turn of that century, it should have been apparent that no radiation propagates along the axis of the antenna; instead, the radiation
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tends to be focused along the ground. In fact, if the current in amperes along the antenna is I0, then elementary antenna theory establishes that the strength of the electric field is at a distance r from the antenna, above the earth, is given by
Eθ = I0120πh sinθ for 0 ≤ θ ≤ π / 2 ,
λr
where h is the length of the antenna, l is the wavelength in use and r is the distance of the observer from the antenna.40 All the distances are in meters. The meanings θ and Eθ should be evident from Fig. 9. Observe that directly above the antenna corresponds to q =0, so that sinq = 0, which indicates there is no radiation normal to the earth, while along the earth q = 90 degrees, and the radiation is maximum, which might
suggest a wave gliding along the surface of the earth, provided we are close enough to the antenna to neglect the earth’s curvature. This result would have certainly been known well before 1919. The book Robison’s Manual of Radio Telegraphy and Telephony for
Fig. 8. Tesla condemns the “Gliding Wave.” (True Wireless, Fig. 13)
Fig. 9. Electric field and spherical coordinates.
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the use of Naval Electricians, published in 1918, contains the following diagram showing the direction of electric lines (see Fig. 10).41 It illustrates that a monopole antenna radiating above a flat perfectly conducting ground tends to radiate in a direction parallel to the ground and not in a direction along the axis of the antenna. This is not a polar plot of the field strength vs. angle but a picture showing the direction of the electric field at various locations. Incidentally, one can argue that there is no radiation along the axis of the antenna even if the ground has imperfect conductivity.42 Tesla specifically condemns any theory that claims “[space waves] pass along the earth’s surface and thus affect the receivers. I can’t think of anything more improbable than this ‘gliding wave’ theory which... [is] contrary to all laws of action and reaction.” Of course, this gliding wave concept that we would now call a “surface wave” did describe daytime radio propagation and was central to the work of such theorists as Sommerfeld, Zenneck, and Watson.43
Tesla Debunks the Ionosphere
Warming to the task of diminishing other theorists, Tesla then damns what was then only a conjecture: the belief in what was then known as the KennellyHeaviside layer. We now call this the ionosphere—a set of layers of three or more ionized gases in the earth’s upper atmosphere. It was first postulated, as a single layer, in 1902 by Arthur Kennelly and Oliver Heaviside, working independently, as a way of explaining how radio waves propagate beyond the horizon.44 Although its existence and height were not verified experimentally until 1924 by the Englishman Edward Appleton, for which he was later awarded the Nobel Prize, its presence was generally accepted in 1919, especially as a means to explain the long distances that radio waves would propagate at night.45 Tesla tells us, “I have noted conclusively that there is no Heaviside layer, or if it exists it is of no effect.” One wonders if he recanted this statement after Appleton’s experiment.
Communication with Airplanes
Among the more perplexing aspects of Tesla’s article is his discussion tied to his Fig. 15. He is showing here in Fig. 11 a “Hertz oscillator” suspended in the air, and uses this arrangement to explicate something that became well known during World War I: an airplane could communicate with a wireless receiver on the ground. Also known, but not discussed by Tesla, was that two airplanes in the air might experience radio contact with each other.
Fig. 10. Electric field lines of a short monopole antenna. (Manual for U.S. Navy Electricians, 1918)
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What Tesla must explain is how his transmitter in the air might communicate with the receiver on the ground in spite of its not having a direct connection to the earth that would be capable of effectively launching his crucial earth currents. His explanation is that “we are merely working through a condenser.” Stating incorrectly there is a capacity that “is a function of a logarithmic ratio between the length of the conductor and the distance from the ground,” he says the receiver is affected in the same manner as with an ordinary transmitter. Evidently, we are to believe that the capacitance between earth and ground makes possible the earth currents crucial to his argument. The formula for the capacity of a wire that he is most likely referring to would have been well known by the 1910s when it already had appeared in textbooks and handbooks:46
C = 1.111 L picofarads.
2h
2 ln ( r )
This expression is the capacity of a wire of length L above, and parallel to, the earth’s surface, which is assumed to be highly conducting. An airplane in flight dragging a wire antenna behind itself would create this situation. The wire is at height h above the earth, and its radius is r. All dimensions are in centimeters, and the logarithm is base e. Note that the capacity is proportional to the wire length L, not to the logarithm of L as Tesla asserted.47 Using the well-known formula for capacitive reactance X = 1/(2p f C), where f is the operating frequency, we could in principle obtain the impedance between the wire and earth. Dividing the voltage of the antenna, with respect to the earth,
Fig. 11. Tesla denies there is “Space Wave” transmission in wireless telegraphy. (True Wireless, Fig. 15)
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by this impedance, we might think we have obtained the current on the earth. But what voltage are we to use? Because the antenna illuminates the earth with an electromagnetic wave, the concept of voltage difference or potential difference cannot be applied. It was known in the late 19th century that electric potential difference between two points is calculated by the line integral of the electric field along a path between those points. When there is a time varying electromagnetic field between these points the result will depend on the path taken and so the concept of voltage difference ceases to be of use.48 Note that Tesla skirts entirely the phenomenon of airplane-to-airplane wireless communication, which had been observed during the war.49 Such communication could not possibly involve earth currents if the transmission took place over a desert or dry sandy soil.
The Hertzian Wave Discourse
The publication of Maxwell’s Treatise on Electricity and Magnetism in 1873, which described his work of the previous decade, together with Hertz’s experiments of 1886–9, created the paradigm shift which Tesla was unable to accept. We might be a little indulgent here—the new paradigm was slow to be accepted—consider Marconi for example. By the late 19th century Marconi was being lionized in the British press because of his demonstrations of wireless telegraphy, but an interview in McClure’s magazine from 1899 has him
declining to say what sort of waves he was using: “What kind of waves they were Marconi did not pretend to say; it was enough for him that they did their business well.”50 When asked about the difference between his waves and those used by Hertz he replied “I don’t know. I am not a scientist, but I doubt if any scientist can tell you...”51 What seemed to impede the connection of Marconi’s waves to those of Hertz’s was that it was known by 1897 that the former’s radiation could pass through the walls of a building while Hertz’s, which was based on a model of radiation as visible light, would apparently not perform such a feat.52 Marconi’s first British patent, number 12039, which was filed in 1896, speaks of an arrangement that he calls “a Hertz radiator” producing effects “which propagate through space [as] Hertzian rays.” But he also talks of electrical actions or manifestations “...transmitted through the air, earth, or water by means of electrical oscillations of high frequency.” For a while, Marconi’s manifestations in the ether were known in some circles as Marconi waves, but the term soon died. Some further indication of the confusion, circa 1900, is a question raised by the historian of early wireless, J. J. Fahie, in his publication of 1901, “... is the Marconi effect under all circumstances truly Hertzian...?”53 After 1899, we find that Marconi began to refer more frequently in his work to “Hertzian waves.” In a speech given before the Institution of Electrical Engineers (now the IET) in
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England on March 2, 1899, he says, “I think it desirable to bring before you some observations and results I have obtained with a system of Hertzian wave telegraphy, which was the first with which I worked....”54 His U.S. patent 676,332 of 1901 refers to “a transmitter producing Hertz oscillations.” And, following Kuhn, we can say that Hertzian waves entered the discourse of “normal science” because we find extensive references to them in a textbook, e.g., Poincaré, cited above. In fact, studying the index of Poincaré, we find that he uses Hertzian waves and electromagnetic waves as synonyms. John Ambrose Fleming, who was the first Professor of Electrical Engineering at University College, London, and who did major work for Marconi beginning in 1899, published a textbook titled Hertzian Wave Wireless Telegraphy in 1903, in which there is not the slightest doubt that wireless telegraphy relies on the waves of the title. Interestingly, Tesla, in certain of his turn-of-the-century U.S. wireless patents, refers to Hertzian waves, or “radiations,” being “brought into prominence” by Heinrich Hertz.55 In all of these instances, such waves are disparaged as being of an outmoded or less desirable way of transmitting signals, or energy, which should be discarded in favor of one that either uses extremely strong electric fields and high antennas to ionize a layer of the earth’s atmosphere which is to then act as a conductor of a transmission system (which includes the earth’s crust)—or of another that uses
wavelengths so long as to make the earth into a conducting sphere that has been brought to a resonant condition. In the later case, he recommends using frequencies lower than 20,000 cycles per second (cps) and asserts one might go as low as 6 cps (patent 787,412, lines 260–270).
Maxwell and Einstein: Difficulties for Tesla
When Tesla wrote his True Wireless paper he was not a young man—he was 63. Male life expectancy in the United States was then 54. His formal education in science and engineering had taken place many years before. He had studied for somewhat less than three years at the Austrian Polytech in Graz Austria in the late 1870’s. In 1880 he audited courses at Charles Ferdinand University in Prague but was not enrolled. His course work should have given him a solid grounding in electric circuit theory, and it was in school that he developed a great interest in alternating currents, especially for motors.56 It is highly unlikely that Tesla would have studied Maxwell’s theory while at school. As first presented in 1873, it was so difficult that few could understand it; nowhere will you find in Maxwell’s treatise the four succinct equations studied today by all electrical engineering and physics students. His analysis is based entirely on potentials, not the electric and magnetic fields used now. He used 20 equations and 20 variables, and it was only through the efforts of such people as Hertz, Heaviside, and Willard Gibbs
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in the late nineteenth century that the equations were to assume the form we find them in today.57 Even with their simplifications, we know that Maxwell’s theory was not systematically taught at Cambridge University until after around 1900.58 Because Hertz’s famous experiment was inspired by Maxwell’s work, which Tesla most likely did not understand, it seems plausible that Tesla might cling to an electric circuit theory paradigm in explaining what was called wireless communication. Note however, this was not canonical circuit theory—Tesla had added some bizarre features of his own to force it to explain wireless telegraphy. Maxwell’s theory and its experimental verification by Hertz is not the only paradigm shift in Tesla’s era that he was unwilling to accept and understand. Throughout his life, he spoke often of particles that moved faster than light—a direct contradiction of Einstein’s theory of relativity.59 In an interview with Time magazine on the occasion of his 75th birthday in 1931, he claimed to have “split atoms” with no release of energy—again a contradiction of relativity. He also asserted that he had, using “pure mathematics,” come up with a theory that “tend[s] to disprove the Einstein theory.” There is no indication that Tesla ever had the knowledge to derive a competing theory. Circa 1930, Tesla wrote a poem for his friend George Sylvester Viereck in which he muses about science.60 One stanza addresses Newton and contains these lines:
“Too bad, Sir Isaac, they dimmed your renown And turned your great science upside down. Now a long haired crank, Einstein by name, Puts on your high teaching all the blame. Says: matter and force are transmutable And wrong the laws you thought immutable.”
Note the “long haired crank”—Tesla’s name for the man who overthrew the Newtonian paradigm of mechanics. Much has been written about opposition to Einstein’s theory of relativity; this hostility reached its peak in the two decades following the confirmation of the general theory of relativity via the measurement of the bending of starlight by the sun’s gravitational field in 1919.61 Some of this opposition was rooted in anti-Semitism, as the preceding reference shows, and we do know that Tesla had anti-Jewish tendencies.62 In addition, Hertz, whom he diminishes, was, like Einstein, of Jewish origin,—only partly in Hertz’s case—but it seems more likely that the statement to Time magazine derives more from an almost pathological narcissism that compelled him to be in the public eye. Tesla has been called a scientist, engineer, and inventor. While the confusion and angst that can befall a scientific community having difficulty in adapting to a paradigm shift has been much written about, especially after Kuhn’s seminal publication, the effect of a scientific paradigm shift on
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inventors, as opposed to scientists, has been less explored.63 When we study the lives of individual inventors or engineers we can find failure to adapt to a paradigm change.
Shifting Paradigms in Invention
Besides Tesla, whose inability to absorb a new paradigm should be evident, we have the example of yet another great inventor, Thomas A. Edison. Edison had little formal teaching in schools and was largely educated by his mother and by his own readings. His first important work experiences and inventions were in the field of the [wired] telegraph, which operates using direct currents, and it is clear that he obtained a strong intuitive grasp of DC theory. It is understandable that his subsequent system of generating and distributing electric power was all based on DC. Paul Israel, the esteemed biographer of Edison and editor of the Thomas Edison papers, remarks, “While experimenting with generators, Edison again relied on his experience with telegraph technology to provide a useful analogy that guided laboratory research.” Israel points out how Edison and his workers sometimes envisioned direct current generators as “carbon battery elements.”64 Historians have written about Edison’s unwillingness to adapt to the newly introduced system of AC electric power, which posed a direct economic threat to his own DC system.65 We will probably never know for sure if his objection to AC was truly based on his concern that it was more lethal
than DC, or whether he was acting out of pride, inertia, economic self-interest, or an inability to grasp a phenomenon requiring some mathematical sophistication that eluded him. His statement in 1891 to Henry Villard, President of Edison GE, “The use of alternating current instead of direct current is unworthy of practical men,” has proved to be as fatuous as Tesla’s notion that Hertzian wave theory is “an aberration of the scientific mind.”66
Age and Vanity
We are left to wonder why Tesla wrote this long paper displaying a wealth of ignorance. One clue might come from an article about him that appeared in the New York Times of January 9, 1943, a few days after the inventor’s death. The generally admiring piece observes, “His practical achievements were limited to the short period that began in 1886 and ended in 1903. And what achievements they were.” By 1919, Tesla’s last important work had taken place more than half a generation before. Studying a list of Tesla’s patents, we find that about 90% of them were filed on or before 1903, and all of his important ones were granted before this date.67
Resurrecting Tesla’s Reputation
His Electrical Experimenter piece can be read as a rather sad effort to resurrect his reputation. Moreover, his denigration of Hertzian waves and promotion of the primacy of earth currents may be seen as an attempt to preserve respect for his construction of a 187-foot tower (capped with a sphere) in 1901–1903 on
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Shoreham, Long Island, whose purpose was to produce a “World Wireless System” that would radiate “several thousands of horsepower” and permit the connectedness of all the telephone and telegraph exchanges in the world by wireless means. The system was to use currents in the earth but was never demonstrated.68 Consider his allusion in “The True Wireless” to a speech he gave in 1893 at the Franklin Institute where there is a portion entitled “Electrical Resonance.” He remarks in 1919, “This little salvage from the wreck has earned me the title of ‘Father of Wireless’ from many well-disposed workers ...” Perusing the speech, we wonder who these well-disposed workers are. In his Institute lecture he asserted, “I do firmly believe that it is practicable to disturb by means of powerful machines the electrostatic condition of the earth and thus transmit intelligible signals and perhaps power... We know now that electrical vibration may be transmitted through a single conductor. Why then not try to avail ourselves of the earth for this purpose [italics added]?”69 Notice the use of the word electrostatic. His proposal is not based on any use or understanding of electromagnetic waves. As further proof of this, he goes on to wonder what the electrical capacitance of the earth might be and “the quantity of electricity the earth contains.” None of this thinking proved germane to communication by wireless telegraphy nor is his obsession in the article with determining the period of oscillation
of currents that might be induced in a resonant earth.
Strengthening Tesla’s Claims
In a further attempt to strengthen his claims to invention in wireless, Tesla lays claim to discovering the forerunner of the Audion in the caption to his Fig. 9 (reproduced here as Fig. 12). The captions reads, “The Forerunner of the Audion—the Most Sensitive Wireless Detector Known, as described by Tesla in His Lectures Before the Institution of Electrical Engineers, London, February, 1892.” It is instructive to read the text of the talk where he discusses his “forerunner.”70 He begins by paying homage to Professor Crookes and his invention, the Crookes tube. Like Crookes, Tesla is not using thermionic emission. He employs a cold evacuated glass bulb, like a lamp bulb, but with no filament. The bulb, which has a “high vacuum,” contains some conducting powder, which in turn is connected by a wire to one terminal of a high frequency, high voltage induction coil. The bulb has a sheet of metal foil on its surface that is also connected to the coil for some experiments, but not others. The
Fig. 12. Tesla’s “Forerunner of the Audion.” (True Wireless, Fig. 9)
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straight lines that you see in the figure he calls a “brush”; it gives off a glow that he calls luminosity—whose shape and form he reports is very sensitive to the presence of objects or nearby electric or magnetic fields. However fascinating his demonstration, Tesla still has not produced the forerunner of the Audion. The latter, we recall, was invented by Lee de Forest, and was the first working three-element vacuum tube. His patent application is dated January 29, 1907, and it issued on February 18, 1908. Despite de Forest’s confused understanding of his invention, within the next half dozen years it was proving its worth as both an amplifier and an oscillator. If we want to see the forerunner of the Audion we must look to the work of Fleming and Edison, whose devices, like de Forest’s, relied on thermionic emission. The distinguished historian of the vacuum tube, Gerald Tyne, makes no mention of Tesla in his well-regarded opus.71 This is not surprising—Tesla’s bulbs responded by glowing only in the presence of strong, quasi-electrostatic fields produced by his machines. It is regrettable that Tesla’s narcissism caused him to write this paper—it can only provide difficulty for his acolytes and apologists. The ignorance he displays of classical electromagnetic theory, which by 1919 was a mature subject, can only diminish his reputation.
Gernsback and His Magazine
If Tesla’s True Wireless is so utterly wrong, and if it conflicts with the paradigms used by engineers and scientists
of 1919, how did he get his article published? To answer this, we must focus on the magazine where it appeared and its editor/publisher Hugo Gernsback (1884–1967).72 Almost a generation younger than Tesla, Gernsback had certain things in common with him: they were both inventors with substantial lists of patents—Gernsback had 22, Tesla 112; both came from groups that placed them in small minorities in the United States (Gernsback was a Jew from Luxemburg); both studied science and engineering on the European continent; and both occupied a kind of nether world bridging science and fantasy.73 They apparently had a lasting friendship that would tend to counter suspicions that Tesla was an anti-Semite. Gernsback pressured the Westinghouse Company, which had benefited greatly from Tesla’s work in three phase power and induction motors, to give the near destitute inventor a pension in 1934.74
Gernsback’s Electrical Experimenter
The Electrical Experimenter, started by Gernsback in 1913, is where we find Tesla’s article six years later.75 Although the term “science fiction” did not exist until coined by Gernsback in 1929, his magazine Modern Electrics carried a serialized story of that genre in 1911–12, written by Gernsback—something to keep in mind when we look at the Electrical Experimenter, where Tesla was to publish abundantly in the 7-year life of that magazine.76 What sort of magazine was the Electrical Experimenter? It was dense
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with ads for radio hardware, e.g., Murdock headphones and audio interstage transformers as well as Grebe and De Forest radios. Mainly, it carried stories of new inventions, especially those with an electrical basis, such as a new radio compass, a method of abolishing smoke electrically, new electric stoves, and quack medicine—anesthesia via electricity and an electrical cure for tuberculosis using the Tesla coil.77 Much of the magazine was given over to what we would now call “techno-euphoria”—a belief that technology would bring us wonderful things in the not-too-distant future. One example was the Thought Recorder, shown in Fig. 13. The author of the article is none other than Gernsback himself. He imagines a man in an office who is connected to a halo on his forehead. The halo is supporting an Audion amplifier tube that detects and amplifies the
man’s thoughts. They are then sent to an instrument on his desk that converts his thoughts to an inscription on a moving tape. The latter is supplied to the man’s secretary who is capable of reading the information on the tape and who can now write letters or memos based on what the boss has been thinking. The article appears in the same issue as Tesla’s, and Tesla, in an introduction, gives some measured support to the idea. Interestingly, Greenleaf Whittier Pickard, a distinguished electrical engineer who helped develop what we would now call the crystal radio, circa 1904, also comments and employs the term “Hertzian waves,” illustrating how commonly the phrase was used.
The Electrical Experimenter does seek to explain legitimate recent advances in the sciences. For example, Einstein’s special and general theory of relativity and the general theory’s
Fig. 13. The “Thought Recorder.” (Electrical Experimenter, May 1919)
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confirmation by the observed bending of light are carefully described in the January 1920 issue by an unusual person for the era: a female astronomer, Isabel M. Lewis, M.A, who was a regular contributor and the first woman astronomer to be hired at the U.S. Naval Observatory.78 The magazine also published pure science fiction stories, such as “At War with the Invisible” appearing in the March and April 1918 issues, which described a war between the planets Mars and Earth in the 21st century.79
Science Fiction, Nostalgia for the Future Unfortunately, a magazine mixing techno-euphoria, future studies, science fiction and real science is playing dangerous games: the boundaries became diffuse. The March 1918 Electrical Experimenter has an article by Gernsback starting on page 743 entitled “Can Electricity Destroy Gravitation?” The author asserts it can, and describes the work of a Prof. Francis E. Nipher of the Saint Louis Academy of Science. The professor’s experiment is described thusly: He suspends a small lead ball from a string. It is placed in proximity to a very heavy lead ball that rests on a bench. The small ball and string are seen to be deflected toward the heavy ball because of the force of gravitational attraction—a straightforward replication of the famed Cavendish experiment of 1797–8.80 The professor then passes a direct current through the large ball. Nothing has changed. But then he applies an AC current, et voilà, the small ball moves away from the
large one, thereby proving that gravity has been weakened by electricity. Anyone with a modicum of knowledge of electromagnetic theory would see what was happening here. The AC creates a time varying magnetic field that induces eddy currents in the small ball. These currents interact with the magnetic field to push the small ball away from the large one. The clue that Faraday’s law of induction and the induced current serve as the explanation should have been the failure of the experiment to work with a direct current. The gravitational field, like DC and its resulting fields, is static. A direct current cannot induce a voltage or current in a neighboring circuit, while alternating currents have that ability. Eddy currents were well understood by 1919. One wonders how much real science Gernsback knew; it is no surprise that he permitted another paper based on dubious physics to be published the next year: Tesla’s “The True Wireless.” The Electrical Experimenter morphed into another Gernsback magazine: Science and Invention, in 1920.81 This publication, although it did in some ways live up to its title, increasingly carried science fiction and proved so successful that Gernsback was able to introduce more magazines (e.g., Amazing Stories, Wonder Stories) that were wholly devoted to the science fiction genre, and he is best known as a publisher of science fiction. At least one historian has suggested that many of the ideas in Gernsback’s science-fiction stories promoted Tesla’s “still unrealized ideas” for inventions.82
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Endnotes
1. Nicholson Baker and Margaret Brentano, “The World on Sunday: Graphic Art and Joseph Pulitzer’s Newspaper (1898–1911),” (Bullfinch Press, Boston, 2005) pp. 102–103. 2. Nikola Tesla, “The True Wireless,” Electrical Experimenter, vol. 7, no. 3, May 1919, pp.22–23, 61–63, 87. The following website has images of the original pages: http://w w w.free-energ y-nfo.com/Tesla TrueWireless.pdf. Other sources of the paper can be found by Googling the search term “Tesla True Wireless.” Vendors of CD’s having a complete run of the issues of the Electrical Experimenter can be found on eBay.
3. Thomas Kuhn, The Structure of Scientific Revolutions, 3rd ed., (University of Chicago Press, Chicago, 1996). 4. R.P. Feynman, R. B. Leighton, and M. Sands, “The Feynman Lectures on Physics, vol. 2,” (Addison-Wesley, Reading, MA, 1964) pp. 1–6. 5. Jed Buchwald, The Rise of the Wave Theory of Light, (University of Chicago Press, Chicago, 1989); With the birth of quantum theory circa 1900–26, a particle theory of light based on photons was to reemerge, but it did not undermine Maxwell’s work thanks to the concept of the wave-particle duality. See for example Ian Walmsley, Light: A Very Short Introduction, (Oxford University Press, Oxford, 2015).
6. Hugh Aitken, Syntony and Spark: The Origins of Radio, (Princeton University Press, Princeton, 1985), Chapter 3.
7. Hugh Aitken, Syntony and Spark.
8. Interestingly, we have only Tesla’s word that this meeting took place. There is no supporting entry in Heinrich Hertz: Memoirs, Letters, Diaries by Mathilde Hertz and Charles Süsskind, 2nd edition (San Francisco Press, San Francisco, 1977). As Tesla was a famous inventor by the time of the meeting, it is puzzling that he was not mentioned by Hertz. Also, no meeting is described by Bernard W. Carlson in his definitive biography of Tesla: Tesla: Inventor of the Electrical Age, (Princeton University Press, Princeton, 2013).
9. Tom Lewis, Empire of the Air: The Men Who Made Radio, (Harper-Collins, New York, 1991), p 136.
10. Paul Schubert, The Electric Word: The Rise of Radio, (Macmillan, London, 1928) pp. 166–168.
11. It was not until 1893, well after Tesla had completed his education, that the great simplification in AC circuit analysis made possible by the use of complex quantities began to be adopted, thanks to the work of C. P. Steinmetz. See, for example, Charles Proteus Steinmetz, “Complex Quantities and their Use in Electrical Engineering,” AIEE Proceedings of International Electrical Congress, July 1893, pp. 33–74. 12. Alfred Hay, The Principles of Alternate Current Working, (Biggs and Co, Boston, 1897) pp. 137–148. Available at Google Books; for other 19th century engineers who used fluid analogies—or rejected them—see Paul J. Nahin. Oliver Heaviside: Sage in Solitude, (IEEE Press, Hoboken, NJ) 1988, p. 59 (note his footnote 3 and the derisive comment “drainpipe theory”). 13. There is a stern critique of using mechanical explanations for explaining electrical phenomena in Henri Poincaré, Maxwell’s Theory and Electrical Oscillations, (McGraw-Hill, NY, 1904) Chapter 1, pp. 1–2. This book is available at Google Books. Tesla was so committed to hydraulic analogies that he supplied one for his high voltage, high frequency invention, the Tesla coil. See N. Tesla, My Inventions. This series of articles originally appeared in the Electrical Experimenter in 1919. They have been republished in his book My Inventions (Barnes and Noble, NY, 1995). See especially pp. 76–77. The analogy is so complicated that one is better served by studying the original electrical device and applying the laws of AC circuit theory and resonance. 14. Interestingly, in U.S. patent 645,576, Tesla has not yet discarded the return wire in a communication/power distribution system he is proposing. Part of his circuit consists of a path through an atmospheric layer that his powerful transmitter will, he asserts, succeed in ionizing. The earth is also employed in the circuit. The patent was granted in 1900, but by 1919 he has dispensed with the return part of the circuit. 15. For an explanation of the concept of Whig history, as it applies to the history of science, see Steven Weinberg, “Eye on the Present, The Whig History of Science,” New York Review of Books, vol. 62, no. 20, Dec. 17, 2015. 16. J. Zenneck and A. E. Seelig (translation), Wireless Telegraphy, (McGraw-Hill, NY 1915)
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Paradigm Lost: Nikola Tesla’s True Wireless
pp. 258–259. This book provides an idea of how textbooks, circa 1910–1920, explained waves received on the far side of the mountain. 17. See the article on diffraction in the 11th edition of the Encyclopedia-Britannica, vol. 8, 1911. https://en.wikisource.org/wiki/1911_Encyclop %C3%A6dia_Britannica/Diffraction_of_Light /11. Also, for a modern treatment see Y. T. Lo, Y. T and S. W. Lee, Antenna Handbook, (Van Nostrand-Reinhold, NY, 1988) sec. 29. 18. R. W. P King and S. Prasad, Fundamental Electromagnetic Theory and Applications, (Prentice Hall, Upper Saddle River, New Jersey 1986) chapter 7.
19. Jules Stratton, Electromagnetic Theory, (McGraw-Hill, New York. 1941), secs. 9.22–9.24.
20. Chen-Pang Yeang, Probing the Sky with Radio Waves (University of Chicago Press, Chicago. 2013). I am greatly indebted to this source. 21. Henri Poincaré and F. King Vreeland (translation), Maxwell’s Theory and Wireless Telegraphy, (McGraw-Hill, New York, 1904) p. 161. Tesla might have countered by asserting that the Branly coherer responds to the electric field—not the magnetic field—and the earth weakens the former. 22. L. W. Austin, “Some Quantitative Experiments in Long Distance Radio Telegraph,” Reprint No. 159, Bulletin of Bureau of Standards, vol. 7, no. 3, Feb. 1, 1911; see also Robison, 1918, p. 228. 23. Watson, G. N. “The Transmission of Electric Waves Around the Earth,” Proc Royal Society (London) Series A, vol. 95, July 15, 1919, pp. 546–553. 24. Heinrich Hertz, Electric Waves, (Dover Books, Mineola NY, reprint of Macmillan book 1893) chapter 8 (dating from 1888, especially Fig. 26). 25. Kuhn, page 43.
26. Samuel Robison, Robison’s Manual of Radio Telegraphy and Telephony for Naval Electricians (U.S. Naval Institute, Annapolis, MD, 1918) p.131. He asserts that the directivity behavior of the “flat top antenna” attributed to Marconi, which involves a long piece of wire or wires parallel to the ground, is still not understood. 27. L. J. Chu, “Growth of the Antennas and Propagation Field Between World War 1 and World War 2. Part 1, Antennas,” Proceedings of the IRE, vol. 50, no. 5, May 1962, pp. 685–7.
28. Charles Burrows, “The History of Radio Propagation up to the End of World War I,” Proceedings of the IRE, vol. 50, no. 5, May 1962, pp. 682–684. 29. Note that Marconi had described arrays formed from inverted L antennas as early as 1906, as noted in G. W. Pierce below. The horizontal elements were much longer than the vertical ones, a configuration not suggested in Tesla’s Fig. 16. G. W. Pierce, Principles of Wireless Telegraphy, (McGraw-Hill, New York, 1910) Chapter 25. See also Practical Wireless Telegraphy, Elmer Bucher, Wireless Press, 1917, sec. 233. Here, the horizontal portion of the antenna is nearly a mile long. 30. See G. Marconi, “On Methods Whereby the Radiation of Electric Waves May Be Mainly Confined to Certain Directions, and Whereby the Receptivity of a Receiver May Be Restricted to Electric Waves Emanating from Certain Directions,” Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character 77.518 (1906): 413–21; Electrician, vol. 60, 1908, p. 883. 31. Pierce, p. 298. 32. Zenneck and Seelig, Sec. 202–204. The book contains the reference to Von Hoerschelmann, which was published in German as a dissertation in 1911. 33. Aitken, p. 267. 34. Nahin, pp. 142–143.
35. Bernard Carlson, Tesla: Inventor of the Electrical Age, (Princeton U. Press, Princeton NJ, 2013) p. 200–202; note that some images were the result of multiple exposures where Tesla was not present when the sparks were being generated, see pp. 297–299.
36. T. C. Martin, editor, The Inventions, Researches and Writings of Nikola Tesla, 1893; republished by (Barnes and Noble, NY, 1992) Chapter 6. From the lecture: “The reason why no pain in the body is felt, and no injurious effect noted, is that everywhere, if a current be imagined to flow through the body, the direction of its flow would be at right angles to the surface; hence the body of the experimenter offers an enormous section to the current, and the density is very small, with the exception of the arm, perhaps, where the density may be considerable...The expression of these views, which are the result of long continued experiment and observation, both with steady and
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varying currents, is elicited by the interest which is at present taken in this subject, and by the manifestly erroneous ideas which are daily propounded in journals on this subject.” Tesla misses the essential point here—the very shallow depth of penetration of the energy. The arm plays no special role. Notice that he takes a swipe at other workers’ “erroneous ideas.” 37. Indeed, it was in Poincaré’s book of 1904 (see above). 38. E. C. Jordan and K. Balmain, Electromagnetic Waves and Radiating Systems, 2nd ed., (Prentice-Hall. NJ, 1968) p. 655. 39. Note that this is a simplification of a formula derived by Heaviside in 1888. See Nahin, who also gives the formula we are using here, p. 176 40. King and Prasad, section 5.9. The sinθ variation was derived by Hertz in the 19th century (see Hertz, Electric Waves, p. 143 above) and was popularized by Louis Cohen in a paper written for engineers in 1914. See his “Electromagnetic Radiation,” Journal of the Franklin Institute, April 1914, vol. 177, no. 4, pp. 409–418. 41. Robison, 1918, p. 62. Notice that the same picture appears in an even earlier edition of Robison, dating from 1911, on page 76. This book is available from Google Books. 42. R.W.P King, Theory of Linear Antennas, (Harvard University Press, Cambridge, MA, 1956) chapter 7. Note that this work is based in part on Sommerfeld’s work of 1909. 43. Burrows. 44. Ibid. 45. The ionosphere, although not called by that name, could be found in electrical engineering handbooks as early as 1915; see for example W. H. Eccles, Wireless Telegraphy and Telephony: A Handbook of Formulae, Data and Information. (Electrician, London, 1915), pp. 162–3. 46. Eccles, p. 120. 47. In the unlikely event that the wire hangs straight down from the aircraft, the preceding formula does not apply. However, it would still be incorrect to say that the capacitance varies with the logarithm of the length of wire. The required formula shows a more complicated behavior. See Eccles p. 120. 48. James Clerk Maxwell, A Treatise on Electricity and Magnetism, vol. 1.(Clarendon Press, Oxford 1891) p. 76. This has been reprinted by Dover Books, NY, 1954. For a modern treatment that emphasizes the limitations of the
concept of voltage difference see Edward.C. Jordan and Kenneth. Balmain, Electromagnetic Waves and Radiating Systems, second ed., (Prentice-Hall, New Jersey 1968) p. 36. 49. ht t p:// blogs.m hs.ox .ac.u k /i n novat i ng incombat/ See also R. W. Burns, Communications: An International History of the Formative Years, (IEE Press, UK, 2004) p. 407. 50. http://earlyradiohistory.us/1899marc.htm, McClure’s Magazine, (London), June 1899, pp. 99–112.
51. Sungook Hong, Wireless: From Marconi’s Black Box to the Audion, (MIT Press, Cambridge, MA, 2001) p. 205. See Aitken, his footnote 12 page 195. Note (same page) that even Fleming, Marconi’s well-regarded consulting engineer, was at first misled by the misuse of analogies drawn from the theory of light. 52. Aitken, pp. 285–286 and Hong p. 42, footnote 48.
53. J. J Fahie, A History of Wireless Telegraphy, (Blackwood, Edinburgh, 1901) p. 216. 54. Guglielmo Marconi, “Wireless Telegraphy,” Journal of the Institution of Electrical Engineers, vol. 28, 1899, pp. 273–291. 55. U.S. Patent 685,955 of 1901, 685,954 of 1901, 685,956 of 1901, 787,412 of 1905. 56. Carlson, chapter 2. 57. Nahin, chapters 7 and 9. 58. Bruce Hunt, The Maxwellians, (Cornell U. Press, Ithaca, NY, 1991) p. 202.
59. Marc Seifer, Wizard: The Life and Times of Nikola Tesla, (Citadel Press. New York, 1998) p. 423. 60. Margaret Cheney & Robert Uth, Tesla: Master of Lightning, (Barnes and Noble/Metro Books, NY, 2001) pp. 138–139.
61. Milena Wazeck , Einstein’s Opponents, The Public Controversy about the Theory of Relativity in the 1920’s. (Cambridge University Press, Cambridge, UK, 2014). 62. Seifer, p. 212. 63. For an example of writing on the subject of paradigm shifts in physics after Kuhn, see Jaume Navarro, “Electron Diffraction Chez Thomson: Early Responses to Quantum Physics in Britain.” The British Journal for the History of Science, vol. 43, 2010, pp. 245–275. 64. Paul Israel, Edison: A Life of Invention, (John Wiley & Sons, New York, 1998) p. 176. 65. Thomas Parke Hughes, Networks of Power: Electrification in Western Society, (Johns Hopkins University Press, Baltimore, 1983).
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66. Matthew Josephson, Edison: A Biography, (Wiley, New York, 1992) p. 359. 67. The web site https://en.wikipedia.org/wiki/ List_of_Nikola_Tesla_patents lists 111 or 112 U.S. Tesla patents (depending on how they are counted). 68. Nikola Tesla, “My Inventions,” Electrical Experimenter, 1919, see chapter 5, available on the Internet http://www.teslasautobiography .com/ See also Carlson, chapter 15. 69. T. C. Martin, pp. 346–7. In the late 19th century, Tesla spoke repeatedly of disturbing the electrostatic condition of the earth as a means of sending intelligence. See also Martin p. 292 for an example used in a speech before the British IEE in 1892. 70. This tube appears in a speech he gave in 1892 to the Institution of Electrical Engineers (London). See T. C. Martin ed. pp. 225–229.
71. Gerald Tyne, Saga of the Vacuum Tube, (Antique Electronic Supply, Tempe AZ. 1977). 72. Mike Adams, “Hugo Gernsback: Predicting Radio Broadcasting, 1919–1924,” Antique Wireless Association Review, vol. 27, August 2014, pp. 165–192. 73. For a listing of the Tesla U.S. patents see http:// web.mit.edu/most/Public/Tesla1/alpha_tesla. html. The number for Gernsback was obtained from a search of Google Patents using his name as the inventor. Footnote 64 above also gives a source of Tesla’s patents. 74. Carlson, p. 379. 75. K. Massie, and Stephen Perry, “Hugo Gernsback and Radio Magazines: An Influential Intersection in Broadcast History,” Journal of Radio Studies, vol. 9, no. 2, 2002. Note that the magazine was originally titled The Electrical Experimenter. The title was shortened during 1917. 76. The term was apparently first used in Gernsback’s magazine Wonder Stories in the issue of June 1929; Gernsback had earlier coined the term “scientifiction.” See Leon Stover, Science Fiction from Wells to Heinlein, (McFarland Publishers, Jefferson, NC, 2002) p. 9. 77. Frederick Strong, “The Home Treatment of Tuberculosis by High Frequency Currents,” The Electrical Experimenter, vol. 5, no. 10, Feb. 1918. 78. http://maia.usno.navy.mil/women_history/ lewis.html. 79. M Ashley and R. Lowndes, The Gernsback
Days, (Wildside Press, Rockville, MD, 2004) p. 51–2. 80. https://en.wikipedia.org/wiki/Cavendish_ experiment. 81. Ashley, above, p. 53. 82. Stover, p. 175. In 1923 Gernsback produced a book, Radio for All, published by Lippincott. The work was designed to introduce people to what was still in many ways a hobby. Thus, there were instructions for building simple radios—crystal and one-or two-tube sets, as well as transmitters. It is puzzling that the book makes no mention of the work of Tesla, given his friendship with Gernsback, although there are numerous allusions to Marconi as well as single references to such inventors as Poulsen, Pickard, Fessenden, and Dunwoody.
Acknowledgements
I would like to thank Dr. Elizabeth Bruton of the University of Manchester, Jodrell Bank Discovery Centre, for reading this paper and offering useful advice. And I would also like to thank Prof. Karl Stephan of Texas State University, San Marcos, for giving me a valuable library of early textbooks on wireless telegraphy. I would like to thank Prof. Chen-Pang Yeang of the University of Toronto, a distinguished historian of early 20th-century wave propagation theory, for his comments. I am indebted to this journal’s editor Dr. Eric Wenaas for many useful suggestions that resulted in my paring down this paper and making it clearer.
About the Author
A. David Wunsch was born in Brooklyn, NY, on December 15, 1939. He grew up in the same Flatbush neighborhood of red diaper babies as Bernie Sanders. David studied electrical engineering at Cornell and later earned his Ph.D. at
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Harvard where he was a student in the Antenna Group directed by Professor R.W.P. King. David has spent most of his professional life at the University of Massachusetts, Lowell which is located in Lowell, Massachusetts. He is now Professor of Electrical Engineering Emeritus. In 1995 he started the course for liberal arts majors at Lowell, Principles and History of Radio. It is described in the article “Electrical engineering for the liberal arts: radio and its history,” IEEE Transactions on Education, vol.41, no.4, pp.320–324, Nov 1998. David is the book review editor of the IEEE Magazine Technology and Society. He is the author of two textbooks: Complex Variables with Applications (Pearson), currently in its third edition, and the recently published A MATLAB Companion to Complex Variables (Taylor and Francis).
David recently rebuilt the Heathkit oscilloscope that he constructed in 1957. He thought it would make him 17 again but his beard remains white.
David Wunsch
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Zeh Bouck, Radio Adventurer
Part 1: The Pilot Radio Flight to Bermuda
© 2017 Robert M. Rydzewski, KJ6SBR
Zeh Bouck (2PI, W4FCP, W8QMR), born John W. Schmidt (1901–1946), was an early radio pioneer, engineer, writer, and adventurer who represented amateurs in Washington, D.C. and met with President Hoover. He helped design the Pilot Super Wasp, was one of the first newspaper radio columnists, penned stories and radio plays, and was an associate editor for journals such as Radio Broadcast and CQ: The Radio Amateur’s Journal. An IRE Fellow and member of the Radio Club of America, he was most famous in his day for his role aboard the airplane Pilot Radio, a “flying laboratory.” In 1930 the plane made two historic journeys: the first flight from the United States to Bermuda and the first flight of any land plane around the South American continent. This article provides a brief biography of Bouck to 1930 and summarizes the history of the Pilot Radio Company of Brooklyn and its interest in aircraft radio. Along the way, other figures such as Reginald Fessenden, Hugo Gernsback, and Milton Sleeper are encountered. A detailed account of Bouck’s famous and hazardous Bermuda flight with pilot William Alexander and navigator Lewis Yancey follows, focusing on the role of radio communications. Remarkably, Bouck, who remains largely forgotten today, accomplished all this in spite of a serious disability caused by childhood polio.
Zeh Bouck
Accomplishments
Zeh Bouck visited the White House in 1930 and met with President Hoover, and at one point he represented the Hoover administration, acting as an unofficial U.S. ambassador to foreign nations.1 Alongside Hiram Percy Maxim and Edwin Howard Armstrong, he advocated for radio amateurs at the Third National Radio Conference in Washington in 1924. He was one of the first radio columnists, writing for the New York Sun by 1922, and a
newsmaker himself. He wrote hundreds of articles for magazines ranging from Boys’ Life to Radio News to Cosmopolitan, plays for the radio, technical pamphlets, and books. Largely selfeducated in radio engineering from a childhood spent chasing DX (longdistance communication) in the days of spark, he became a Fellow of and served on committees for the Institute of Radio Engineers and was a Member of the Radio Club of America. He contributed to the design of the Pilot Super Wasp and early receivers made by the National Radio Company. He helped
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Zeh Bouck, Radio Adventurer
edit several journals, including Radio Broadcast, Aero News & Mechanics, and the radio amateur’s journal CQ. He was an aircraft radio pioneer, spending more than a thousand hours in the air and many more in the lab trying to solve the many problems involved in aircraft communications. He served as radioman aboard the Pilot Radio, a “flying laboratory,” on the very first flight from the U.S. mainland to the speck in the ocean known as Bermuda. Soon after, he served on the first flight of any land plane around the South American continent, surviving a plethora of emergency landings, mishaps, and one hellacious crash landing that took the Pilot Radio to its watery grave.
Despite an array of achievements worthy of a real-life Indiana Jones, today Zeh Bouck is an obscure footnote to radio history. One might have read his fate in the tealeaves of his later years. He was no Horatio Alger; if anything he went from riches to rags—not uncommon in those years of the Great Depression. By World War Two, he had seen his fame and fortune rise and fall. Time would not allow him to reach those heights again. Most people who have seen a picture of Bouck have come across it in the pages of old Radio News accounts of his aeronautical adventures. There he is, standing next to that vintage Stinson airplane in some exotic locale, a short,
Fig. 1. From left to right: Emile Burgin, Zeh Bouck, and Lewis Yancey. Photo taken at Roosevelt Field, New York, May 14, 1930. (Author’s collection)
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pipe-smoking, broad-shouldered man with a boyish face, Harry Potter-like glasses, and upswept dark hair, looking a bit old-fashioned even then with his signature cravat, and perched conspicuously on a pair of crutches (see Fig. 1). Most readers probably assumed he had just been injured in his adventures. Not so. Like a more famous American of the time, Franklin D. Roosevelt, day in and day out Zeh Bouck stared down a major disability that would have left most people satisfied to just be able to get around the house, much less the cockpit of a plane or the jungles of the Amazon. But Bouck was different. His was a spirit and determination that few possess. He didn’t try to conceal his handicap, nor did he curse the rotten card that fate had dealt him in the form of childhood polio. In what may have been his greatest achievement of all, he simply ignored it and did what he set out to do, struggling along step by step.
A Short Biography
The story of Zeh Bouck has many chapters, the aerial adventure recounted here being just one of them. He was born John W. Schmidt in New York in 1901, the son of John A. Schmidt, a German dry goods merchant, and Alice White, whose maternal grandparents had the Dutch surnames Zeh and Bouck.2 The Boucks had produced a governor of New York. His mother’s brother had changed his name from Charles White to Bouck White and was famous (or infamous) as a firebrand revolutionary and writer who was, at various times, jailed, tarred and feathered, and driven
out of town.3 The Zeh and Bouck clans hailed from rural Schoharie County in upstate New York, where Zeh Bouck would later live and where Zehs and Boucks still live to this day. By the mid1920s, his parents had divorced, and he lived with his mother in New York City. John “Jack” Schmidt wrote under the pen name Zeh Bouck and later legally changed his name to that as well. Possible reasons for the name change could include the anti-German sentiments prevailing in the years around World War One, a preference to be associated with his mother’s side of the family, or just the more distinctive sound of the name. Unfortunately, his reasoning on this is unknown. Despite the thousands of available documents by and about Zeh Bouck, many blank spots on the map of his life remain. Writing about himself in the third person, he said that he had “blossomed forth as an operator in the heyday of the E.I. Co. to the crackling tune of the one-inch spark coil and the rat-tattat of the decoherer. His first call was issued by Gernsback in his Wireless League of America, and his first code was Morse.”4 All of this was before he had reached the ripe old age of 11. He attended Townsend Harris High School in New York City and took classes at the City College of New York, although he never received a degree.5 In 1928 Zeh Bouck married Charlotte Bosse, with whom he would have a daughter who, sadly, lived for only a few weeks, and a son, Paul. A natural born writer as well as a superb radio operator and experimenter, his works began appearing in
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Zeh Bouck, Radio Adventurer
newspapers and magazines shortly after World War One. His earliest known article is a short story he wrote around the time he graduated high school, which was called “A Ham on the Telephone.” This appeared under the pen name of “Tewpieye” (a play on his callsign, 2PI) in the August 1920 issue of QST.6 By early 1922, he was penning a regular radio feature for the Saturday New York Globe (which later was merged into the New York Sun), thereby becoming one of the world’s—not just the Globe’s—very first newspaper radio columnists. His column reflected radio enthusiast interests of the day, the earlier ones being more technical (like how to build your own resistance-coupled amplifier), while later ones in the 1930s included critiques of popular radio shows, guides to listening in on shortwave bands, and observations on European shortwave propaganda broadcasts.7 In all, Bouck probably wrote several thousand articles in his short life, many of which can still be found. He also worked in various capacities for a number of radio parts manufacturers at times including Daven, Amsco, Arcturus, and later, Pilot Radio & Tube Corporation of Brooklyn (see Fig. 2). Ever busier, he wrote some fiction for national magazines including Cosmopolitan and Argosy, a few radio plays, books (one of them with a chapter on how to write radio plays),8 and he was a contributor, editor, or associate editor for a number of magazines, including Radio News, All-Wave Radio, Boys’ Life (which had some remarkably technical
articles for youths), Radio Broadcast, and Aero News & Mechanics. At one point he even helped organize a radio department for an advertising agency.9 Looking at his circumstances in those decades, like many another, it is likely that his jobs in the 1920s represented burgeoning opportunities, while those in the 1930s had more to do with keeping the wolves at bay. Back in the early 1920s, when more radio receivers were “homebrewed” than commercially manufactured, more money could be made selling radio parts than factory-assembled sets. Close ties existed between parts manufacturers, their engineers, salesmen, copywriters, publicity agents (who might all be the same guy), and magazine and newspaper publishers. “Every Saturday, The New York Sun published a 32-page supplement on how to build various circuits. Everyone followed the writings of Stuart Blyden, the radio editor at The Sun,” explained Harry Kalker, an M.I.T. educated engineer. “I was a salesman for Amperite... If I wanted to live well the following week, I regularly called on Thursday to see if Blyden of The Sun and Casson of The Telegram had specified my Amperite parts by name in the ‘Circuit of the Week’ for that issue.”10 It wasn’t unusual, then, for Bouck to “kill two birds with one stone” and write articles on circuits featuring Daven or Amsco resistors or Arcturus tubes in those years. But from the time he joined Pilot Radio in 1928, his job was different—and considerably more interesting.
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Fig. 2. Advertisement for the Pilot Radio & Tube Corporation. (Radio Design, Vol. 2, No 4, Winter, 1929, inside back cover)
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Zeh Bouck, Radio Adventurer
Pilot Radio of Brooklyn
Management
The Pilot Electric Manufacturing Company made and sold parts as well as complete kits, the latter being something like the Heathkits of their day, if not as easy to assemble. Pilot ran the full gamut of activities, including manufacturing primary parts, designing circuits, publishing schematics, advertising in their house organ, Radio Design, and selling by mail order through their distributor, “the fastest radio mail order service in the world,” Speed, Inc.11 “Pilot was one of the very few real fabricators of the radio industry,” wrote former Pilot employee Robert Hertzberg. “In a crowded factory in Brooklyn, NY, it made its own tools and dies and manufactured all the bits and pieces of its components and assemblies. It did all its own turning, stamping, winding, plating, forming, etc.”12 Pilot’s pilot, so to speak, was Isidor Goldberg, who was raised in an orphanage on New York’s Lower East Side. Goldberg had been exposed to the possibilities of wireless by the age of 16 when he worked at Hugo Gernsback’s Electro Importing Company (E.I. Co.) factory.13 Later, he managed to construct a radio parts empire out of nothing but hard work, savvy, and determination. Goldberg had big ideas and knew how to take chances. His company, Pilot Electric Manufacturing Company, morphed into the Pilot Radio and Television Corporation, and then the Pilot Radio and Tube Corporation
in 1929; all will be referred to as “Pilot Radio.” Pilot Radio didn’t confine itself to just manufacturing parts for homebrew or manufactured radios; the company also explored promising new areas like television and aeronautical radio communication. Much later, it would be a pioneer in the new “high fidelity” audio field.
Pilot Radio and Early TV
Pilot Radio’s foray into television, back in those spinning disk days, may have contributed to the forced bankruptcy of former boss Hugo Gernsback’s publishing empire early in 1929.14 The year before, in a U.S. first, Gernsback had collaborated with Pilot Radio and its brilliant young chief engineer, John Geloso, to broadcast televised images for five minutes at the top of each hour (after a much more ambitious schedule had been abandoned) over his New York City radio stations, WRNY (920 kHz) and W2XAL (9700 kHz). One could watch “faces of living people, the WRNY placard... a moving toy monkey, and a moving ‘roly poly man.’”15 The Pilot television receiver used in the first public demonstration of wireless television in the United States is shown in Fig. 3. What could one see on the television that Pilot developed? According to Bouck, “One gazed hopefully through the window in the upper center and saw all sorts of things with zig-zags of dull red light predominating... Occasionally an image could be seen—the fringy call letters of the broadcasting station, or an equally fringy head and shoulders.
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This would float with varying degrees of rapidity across the field of vision and disappear in parts or wholly like the Cheshire cat.” There was a control for synchronization, but “this was usually accomplished far more satisfactorily by the rule of thumb—i.e., by placing the thumb against the periphery of the scanning disk as a light brake. You could always tell a television engineer... by the callous on his right thumb.”16 The images, of course, were unaccompanied by sound, except for the drone of the motor. The equipment and broadcasting costs involved probably helped push Gernsback’s own empire into the red at the time. Gernsback wrote in his
autobiography, “Indeed, the experiment, the first of its kind, cost a small fortune, with no income whatsoever even contemplated.”17 But mere bankruptcy couldn’t keep the futuristic Gernsback down, and a new series of magazines like Radio-Craft quickly rose from the ashes to compete with his old ones like Radio News. But the television venture hadn’t done much good for Pilot either. “I betcha I must have paid to have the darn things [Pilot television sets] thrown away in ’29,” Goldberg said decades later. “If I’d kept up all those programs, I’d have gone broke.”18 Television back then was definitely not ready for prime time. “After a few rounds,” concluded Bouck a while
Fig. 3. Rear and front view of the Pilot television receiver used at New York University in the fall of 1928 in a successful demonstration of images broadcast from Hugo Gernsback’s radio station, WRNY. Note the motor and large disk. The screen measured 1.5 inches. (Radio Design, Vol. 4, No. 1, Fall, 1931, p. 23)
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later, “television never even came out of the corner.”19 When it finally did, after decades had passed and cathode ray tubes had supplanted spinning disks, Pilot Radio would have better luck, if more competition.
Wasps and Super Wasps
In late 1920s, it was in a different arena that Pilot Radio proved to be a quite a contender—that of shortwave receivers. Its introduction of the 3-tube, regenerative Pilot Wasp shortwave receiver in 1928 tapped into the burgeoning shortwave and amateur long-distance reception (DX) markets in a big way. With a $21.75 price in kit form including plug-in coils (around $300 today!),
it represented a good balance of economy and performance, and it became a popular choice for young amateurs and DXers. According to QST, by 1930 more amateurs were using Pilots than any other receiver. Adding a fourth tube, a screen-grid 224, in a front-end-tuned RF section was expected to improve its performance considerably. To this end, Goldberg assembled an all-star team including Robert Hertzberg, chief engineer John Geloso, Alfred Ghirardi, Zeh Bouck, and Robert S. Kruse. According to Hertzberg, the circuit was designed largely by Kruse (see Fig. 4), and the packaging was done by Geloso, while he himself did the field testing and manual writing. The roles of the others are less
Fig. 4. Pilot Super Wasp original schematic hand drawn by Robert Hertzberg in 1929. (Courtesy of son Paul Hertzberg, K2DUX)
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clear, but Bouck is credited with having an input into the design of the final product, the Pilot Super Wasp (see Fig. 5), which, gratifyingly, ended up living up to everyone’s expectations. It was an instant success, which Hertzberg attributed to its bulletproof design, favorable sunspot conditions, and the growing popularity of programs from the BBC in Chelmsford and PCJ in Eindhoven, Holland, with its star Edward Startz. The set was popular both in America, where one could either order the kit from Pilot Radio or buy it at Kresge’s, and abroad, where Pilot did a surprisingly large amount
of its business. Hertzberg himself personally installed a set in New York for the King of Siam (and he was).20 The success of the Super Wasp ensured that the AC Super Wasp, Universal Super Wasp, and eventually a very strange superhet cathedral set called the Super Wasp Allwave would follow. As for Bouck, he had previously designed circuits published in Radio Broadcast, and later he would have a hand in the design of some National shortwave receivers, along with Robert Kruse (again) and David Grimes.21 Based on his own choice of receivers in later years, Bouck would remain partial
Fig. 5. Robert Hertzberg at the controls of the Pilot AC Super Wasp in 1929. (Courtesy of son Paul Hertzberg)
40 The AWA Review
Zeh Bouck, Radio Adventurer
to National sets for life. But in 1928, it was Pilot Radio that offered young Zeh Bouck truly soaring career opportunities as it entered a field where “the sky’s the limit” and let its Super Wasp fly.
Aircraft Radio
Utility
There were many reasons for airplanes to carry radios. Air-to-ground communications could greatly increase aviation safety. Bad weather might be avoided, flights tracked, emergency messages sent, aerial navigation improved, lives saved. As runways became crowded, hop-offs and landings could be coordinated to avoid accidents. Flight safety was not then what it is now; accidents were appallingly common, especially among small planes with fearless (or clueless) pilots. Improving flight safety was mostly a concern of commercial airlines that conducted regular flights, such as Pan American Airways and United Airlines. They preferred to keep their expensive planes and pilots intact and had to convince potential passengers that buying an airline ticket was not a form of assisted suicide. Manufacturers of small planes were more laissez-faire about it, as they were essentially selling the thrill—not the safety—of flying: “A half hour in flight on a bright sunny day will dispel all those memories of the difficulties of flying in a storm or fog.”22 But only if you made it through the storm or fog. Improving aerial navigation was another important use of aircraft radio. Early flight navigation relied mostly on
visual landmarks. In some states, towns over a certain size (e.g., a population of 4,000 in Maryland) were required to paint their names prominently on a roof or large tank for the benefit of flyers. Amelia Earhart herself wrote, “An arrow pointing the direction to the nearest landing field is also desirable.”23 According to Bouck, “Piloting a plane across country... is a tiresome undertaking, requiring constant vigilance of the man at the controls. Winds move much more rapidly than sluggish ocean currents, and the plane travels so fast that it requires only small errors in compass or judgment to throw the flyer off his course.”24 Worst of all, visual landmarks could not help at night, with low clouds or fog, or at sea. Navigation by radio waves would have no such limits. A. K. Ross noted, “No longer will it be necessary for the long-distance flyer, crossing the trackless ocean or fog-hidden land, to be isolated from those on land and sea as effectively as though he were on a different planet.”25 Radio beacons would point the way—literally. Using a system developed by the National Bureau of Standards in the mid-to-late 1920s, a central radio tower would support the tops of two large, side-by-side triangular loops, each of which would broadcast an aero band signal (315–350 kHz). Both would use the same frequency, but one would be modulated with a 65-cycle tone and the other at 85 cycles. The setup would allow these signals to propagate in figure-eight patterns at right angles to each other. Using a goniometer (an “overgrown variometer”),
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the orientations of the two figure eights could be rotated to any desired compass bearing without physically moving the antenna. The 65-cycle and 85-cycle signals would be of equal strength only at the centerlines of the four areas of overlap (see Fig. 6). A plane using a nondirectional antenna (often a 5- or 10-foot vertical rod) would receive the signals, which would be amplified and detected; the signals would ultimately cause two mechanically resonant reeds (one resonating at 65 cycles, the other at 85 cycles) to vibrate up and down rapidly, tracing out apparent white lines side-by-side on a black background. The lines would be of equal length when the signals were of equal strength, indicating an approach (or departure—beacons could be used for both) along the desired course (see Fig. 7). A shorter line on one side meant that the plane
was off course in that direction and the pilot would turn in the direction of the longer line until the two were equal.26 This visual indication enjoyed some advantage over a competing system that had used audio signals sending letters in code (A and N—with the di dah and dah dit starting at the same time so that it came out as a long dah or T, along the centerline). The pilot or navigator would have a hard time hearing these above engine noise (which he would rather listen to for signs of malfunction) and interference, even with the best headphone-equipped helmet.27 All of which points out just a few of the many problems that needed to be overcome in developing aircraft radio systems.
Aircraft Radio Challenges
Bouck describes various problems that had to be addressed in the design of radios for aircraft in an article entitled “The Problems of Aircraft Radio”
Fig. 6. Field characteristics of radiating loop antenna system for radio beacon. The two signals are of equal strength only along the crosshatched area. (Radio Design, Vol. 1, No. 4, Fall 1931, p. 127)
Fig. 7. Radio beacon indicator for panel mounting in plane. The instrument was “about the size of a pack of cigarettes.” (Radio Design, Vol. 1, No. 4, Fall 1931, p. 125)
42 The AWA Review
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published in Radio News. He writes, “A plane is capable of lifting a certain gross weight.”28 After subtracting out the machine itself, pilot, fuel and oil, “what is left is payload, and comprises passengers and express or mail.” Every pound added in radio equipment, antenna, and radio operator, including the effective poundage added by wind resistance of externally placed radio accessories like a generator, was one pound less that the plane could carry for profit. Aerial radiotelephony (voice) had an advantage over telegraphy (code) in that the radio operator’s weight would be eliminated and the pilot didn’t need to transmit and receive code, which required the use of hand and brain. Most pilots were not proficient in code and didn’t want to deal with it.29 But even after adding in the weight of an operator, telegraphy was still more efficient than telephony. As Table 1 shows, after including the operator’s weight for telegraphy (assumed to be 150 pounds here), pound-for-pound a readable code signal would still reach further than voice. With either method,
making the apparatus as lightweight as possible helped maximize payload, and aircraft radio found extensive use for aluminum in place of iron and steel wherever possible. Perhaps the biggest problem to confront aircraft radio designers in those days was noise caused by the ignition system with its multitude of spark generators and the audible noise of the engines themselves. Both were much worse than for autos and far harder to deal with. The U.S. Navy as well as many radio companies had found that the entire ignition system including plugs, high-tension wires, magnetos, and even the magneto switches needed to be shielded. This was best done at the time the plane was built, but unfortunately aircraft manufacturers didn’t seem too concerned with this. The audio noise generated by aircraft engine was another problem, and vibration of the plane could wreak havoc on vacuum tubes and create loud microphonics. Shock mounting the sets to the rack with just the right degree of rigidity and the use of special tubes helped with the
Table 1. Airplane Radio Ranges at 300 kc. (Z. Bouck, Radio News, July 1929, p. 20)
Power (W) Telephone Telegraph
(Antenna) Weight
(lbs)
Distance (mi)
Weight* (lbs)
Distance (mi)
50 100 50 250 200
100 175 100 300 300
150 200 120 325 350
200 250 135 350 400
250 275 150 375 450
*Including 150 pound weight of operator
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latter. According to Bouck, who had worked for Arcturus, the heavy-cathode AC Arcturus tubes were the best. The vibrations also affected variable condenser plates, causing rapid fluctuations in capacitance and therefore wavelength. Larger or more numerous, thicker (0.0025 inch) plates with wider spacing were called for. For ground-based applications, raising the antenna up high enough is never easy, but getting a good ground usually is. Aloft, the problem is strangely reversed. The metal fuselage (or frame with canvas-covered planes such as the Pilot Radio) could be used as a counterpoise surrogate for ground, but that required special preparation. All metallic parts not rigidly fastened together had to be bonded into a single electrical structure to provide a good counterpoise and reduce noise caused by rubbing together and sparking at imperfect contacts.30 Again, this was something best done during aircraft manufacture, but that often didn’t happen. Bouck tells of his own experience where a radio serviceman bonding structural elements accidentally bonded a rudder cable to a flipper control tube putting both rudder and elevator out of commission, which resulted in a narrow escape from what could have been a fatal crash caused by a radio serviceman improperly installing the ignition shielding.31 For airborne antennas of the late 1920s, the trailing wire type then in use came with a host of problems. The advantages were that the length of antenna reeled out could be adjusted to resonate at the desired frequency,
aerodynamic drag was modest, space and weight allocations were small, and there was no drag when not in use. But there were many disadvantages aside from a flyer forgetting to reel them out (or reel them in before landing). The line was typically terminated with a one or two pound lead “fish” to keep it from flapping around and tearing itself to bits or wrapping itself around the wings. If it were let out too quickly, the wind could take it, causing the whole antenna to snap off. A drag mechanism similar to that used on a fishing reel was called for, and more sophisticated antennas came with a centrifugal clutch to keep the release rate even. Still, things went wrong—farmers complained that their houses or barns were “beaned” by lead weights falling from the sky. Trailing wire antennas weren’t much use for planes on the ground. Another problem was the directionality of a relatively long wire antenna. This made it unsuitable for use with directional beacons mentioned previously. Loop antennas could be used and could even provide radio direction finding (RDF) for transmitters like broadcast radio stations, but they had to be mounted externally (that drag factor again), were low gain, and couldn’t be used to transmit. Bouck noted that a loop used with a superheterodyne broadcast band receiver was much less perturbed by ignition noise than other arrangements. Various configurations of dipoles strung from wingtips, fuselage, and tail were sometimes used, but were too short to have much gain on a small plane, particularly at the long
44 The AWA Review
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aero band wavelengths then in use. The best antenna to use seemed to be “up in the air.”
The Flying Laboratory
At the time Pilot Radio entered the field, the idea of airborne radio was not new. As noted by Arthur Lynch, radio and aviation grew up at about the same time and even in the same neighborhood. He observed that Professor Fessenden “conducted much of his preliminary work on radio on Roanoke Island, just about three miles from where the Wright brothers were doing their first work with gliders at Kitty Hawk, at the same time.”32 Aircraft wireless telegraphy from the plane to ground by spark transmission predated World War One, primarily due to its “eye in the sky” military potential for aerial reconnaissance and artillery spotting.33 Airborne wireless equipment had played an important role in the first transatlantic crossing by the U.S. Navy flying boat NC-4 in 1919,34 and a lesser one in Admiral Richard Byrd’s 1926 flight to the North Pole.35 Although the market for aircraft radio among explorers would always be miniscule, the markets for military aviation, airmail and airfreight, and the expanding passenger air service were huge. The fact that radio in those days had been tied to exploration and adventure in the public’s mind offered a way of increasing sales of whatever the company happened to manufacture. After all, Eugene McDonald hadn’t outfitted the MacMillan expedition with his company’s equipment with the goal
of marketing it to the Inuit peoplesalthough if anyone could do that he could. Instead, he provided a way for ordinary Americans to make a vicarious connection to the thrill of Arctic exploration without risking frostbite or having to eat their dogs—simply by buying a radio marked “Zenith.”36 Others in the radio business had tapped into the romance and adventure of flying for promotional purposes as well, including Powel Crosley, who sometimes supplied his radios to selected dealers in well-publicized flights of his personal plane.37 His company even manufactured a plane for a while, the Crosley Moonbeam.38 In short, an association with airplanes or exploration could sell radios—or anything else. Whether Pilot Radio ever seriously aimed to build and sell receivers and transmitters for the small plane market (where most pilots didn’t want to be bothered with what they’d initially see as another complication), or the commercial flight or military aircraft markets (which corporate giants like RCA, GE, and Western Electric had already sunk their talons into) is debatable.39 More likely, the impetus behind Pilot Radio’s efforts had to do with Goldberg’s aerial enthusiasm. He had previously sold aeronautical parts and even model planes. In 1909 and 1910 he had worked with Glenn Curtiss at Curtiss Field. As Pilot’s president, Goldberg had a landing strip built near his home in Westchester County, and his use of the Pilot Radio for business travel no doubt allowed for tax advantages to help defray its expense.40
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A second and more practical reason for Pilot’s involvement in aero communications was to use Pilot Radio flights, which involved constant air-to-ground HF contact, to generate publicity and boost sales of their popular shortwave Super Wasp receivers, a Bouck-modified version of which their plane carried. Whatever the reasons, between 1928 and 1930 Pilot Radio acquired, maintained, equipped, and flew a “flying laboratory,” a Stinson Detroiter monoplane aptly christened the Pilot Radio. Other companies had their own flying laboratories as well, including RCA, which also used a Stinson Detroiter and flew it cross-country, awarding prizes to the amateurs who communicated with it at the greatest distances.41 Pilot Radio’s interest in airborne radio likely began in 1927, the year of the Lindbergh transatlantic flight. An article in the Brooklyn Standard Union on May 15 states that Milton B. Sleeper, a “well known radio engineer and originator of the transatlantic receiving tests in 1919,” had joined Pilot as Chief Research Director.42 Sleeper, who was four years older than Bouck, had also started out in amateur radio before World War One. Soon he was writing about the latest radio circuits and kit building for magazines such as Everyday Engineering. He later founded his own magazines, including Radio and Model Engineering, and, much later, High Fidelity. Like Bouck, he was a prolific writer and a colorful figure in radio history. Although Alan Douglas refers to him as “primarily a writer” in Radio Manufacturers of the 1920’s,43
Sleeper’s technical abilities must have been considerable as well since he not only had his own radio company in the early 1920s, but he also had been a radio engineer for Western Electric.44 He would later go on to serve as editor of the Proceedings of the Radio Club of America.45 His plunge into aviation may have begun with his decision to volunteer for the Royal Flying Corps (RFC) during World War One. He had ground training in Toronto and the fascinating accounts he published about it in Everyday Engineering may be the only known documentation of that process.46 Sleeper was discharged from the RFC, which had an overabundance of volunteers, after only five months, and he apparently never flew in combat.47 A Popular Aviation article in early 1929 identified Sleeper as overseeing the f lying laboratory.48 Curiously, although the Pilot Radio name and logo can be seen painted on the plane behind him in an accompanying photo, the article never once mentions Pilot Radio, which could not have pleased Goldberg. It would not be the last time Pilot’s pricey sponsorship would be unreported, its public relations and promotional value lost. How long Sleeper stayed at Pilot Radio is unclear; a month after that article appeared, his primary affiliation was with his own Sleeper Research Laboratories, from which he penned an article deriding the type of spinning disc television that Pilot had worked on.49 Although correct about the limits of that technology, it seems he chose to rub salt in Goldberg’s wound.
46 The AWA Review
Zeh Bouck, Radio Adventurer
Bouck and Sleeper must have known each other, since both were early amateurs, engineers, writers, and members of New York’s Radio Club of America, and Bouck had taken over as editor of Radio Engineering magazine following Sleeper’s departure in 1927. Bouck began his affiliation with Pilot Radio the following year, overlapping with Sleeper for a time. Their hierarchical relationship at that point is not known. Aviation Week reported that both Bouck and Sleeper oversaw Pilot’s radio engineering.50 But then again, they also reported that they were working on aero television. After Sleeper’s departure from Pilot, however, there is no doubt that Bouck, with the title of Engineer in Charge of Aeronautics, led its aerial efforts.51
Aerial Feats
By 1930, many dazzling aerial feats had already been accomplished by deathdefying (if they were lucky), leatherhelmeted, flying idols—the rock stars of their day. Charles Lindbergh had successfully soloed the 3,500 miles across the Atlantic from New York to Paris three years earlier, becoming a national hero and the most famous man in America overnight. About three months later, pilot Roger Q. Williams and able navigator Lewis “Lon” Yancey attempted the 4,000+ mile transatlantic flight from Maine to Rome.52 Their first attempt ended in a plane wreck, but some people never learn. They set out again in the Bellanca monoplane The Pathfinder, and by flying blind part of the way, they were able to reach that
destination after an emergency landing in Spain. Arriving in Rome, they were greeted by Air Marshal Italo Balbo, cheered by admiring throngs, and decorated by Il Duce (Mussolini) himself.53 New York Times headlines and a parade down Broadway followed upon their return. Two weeks earlier, on the opposite side of the United States, two Army Air Corps flyers, Lieutenants Albert Hegenberger and Lester Maitland (in whose honor two streets near the Oakland, California, airport are still named), accomplished the first nonstop “hop” from the U.S. mainland across the Pacific to the Hawaiian Islands. Starting from Oakland, they set down their Fokker C-2 trimotor, Bird of Paradise, some 2,400 miles away at Wheeler Field on Oahu the next morning (see Fig. 8).54 Interestingly, although radio beacons had been installed at both fields, because of spotty reception and limited range at both ends,55 the oldfashioned, visible beacon of the Kilauea lighthouse proved more useful in guiding the flyers to their destination.56 By April of 1930, many of the biggest feats in long distance aviation had already been accomplished. But one peculiar challenge remained: no one had ever flown a plane from the U.S. mainland to the tiny islands of Bermuda, just over 700 miles away. Bermuda had neither runways nor radio beacons, and unlike the European continent (almost 4 million square miles) or the Hawaiian Island chain (4000 square miles), at 20.5 square miles it was truly “a dot in the ocean.” In those
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days before LORAN, GPS, or Google Maps, when aerial navigation (or “avigation” as it was sometimes called) was via compass, sextant, and other dated methods, a deviation of just a few degrees could mean never seeing land and being stranded at sea, far from help, or worse, as befell Amelia Earhart in the Pacific seven years later. So the challenge remained. Bermuda was a British dependency, and therefore not subject to U.S. Prohibition, making it a very popular destination for wealthy American tourists in those years. A two-day trip by steamer was the only way to get there. The island’s merchants, however, realized the economic opportunities that tourists arriving by air could present, and just getting a plane to reach the islands was the obvious first step.
Armstrong’s Seadromes
Interestingly, Armstrong had an idea that would convert that step into two
shorter ones—that is, Edward R. Armstrong, an engineer and former aviator. He proposed that a giant (1,100 foot long, 28,000 ton) floating mid-ocean platform be constructed about halfway between Bermuda and the United States.57 This would ride 80 feet above the surface, anchored to the sea floor with steel cables, and it would come complete with a landing strip, radio and visible light beacons, a weather station, service and refueling facilities, and a hotel equipped with a Prohibition-free bar for nervous passengers and thirsty aviators.58Armstrong had met with, and received encouragement from, Bermudian officials. The first seadrome, the Langley, was to be anchored 395 miles southeast of New York. Although a concept endorsed by many, including Igor Sikorsky,59 the Armstrong seadrome fell victim to the unpredictable (poor financial timing) as well as the totally predictable (planes with extended ranges). Armstrong attempted for years to revive
Fig. 8. Arrival of the Bird of Paradise, the first flight from the United States to Hawaii, at Wheeler Field, Oahu, June 29, 1927. (Photo on display at the Kilauea lighthouse in Hawaii, credited to U.S. Air Force Museum)
48 The AWA Review
Zeh Bouck, Radio Adventurer
the seadrome idea in the interest of patriotism (boosting jobs during the Depression, bringing bits of America closer to Europe whether they wanted them there or not), or in a seedier form, as a tourist destination “beyond the reach of the 18th Amendment,”60 which would only have to be “free from practices that would shock the conscience of mankind.”61 But the Langley and its kin would be at sea only in the figurative sense. The technology Armstrong pioneered, though, would later enable the development of offshore oil rigs.
Bermuda Safety Prize
To encourage efforts to reach it by air, with or without seadromes, the Bermuda Trade Development Board had offered a prize of £2,000 (about $140,000 today) to be awarded to the first flyer to reach it from the United States.62 Although it was termed the Bermuda Safety Prize (see Fig. 9) and would supposedly be awarded based on the safety measures employed rather
than speed, doubts were raised that it might instead only serve to lure reckless flyers to their doom. Lost at sea or crash-and-burn would be bad for business, not to mention the airmen. At the behest of the Director of the National Aeronautical Society in the United States, the prize offer was withdrawn before anyone tried for it.63 But the lure of being the first remained. Prize or no prize, there was the glory that went along with the risk, and to many flyers that was enough. On October 28, 1928, the Ireland N-2B Neptune amphibian Flying Fish, with pilot W. N. “Bill” Lancaster, navigator Henry W. “Harry” Lyon, and passenger George Palmer Putnam, publisher and future husband of Amelia Earhart, attempted the nonstop flight from Long Island Sound, with Amelia herself waving goodbye from shore. Other than Putnam, this was an experienced crew. Lancaster was a pioneering aviator and Lyon a legendary character who had recently been the navigator on
Fig. 9. Bermuda Safety Prize announcement and map. (Aero Digest, September 1927, p. 276)
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the first flight from the United States (Oakland) to Australia (via Hawaii and Fiji).64 But great expectations couldn’t lift the ship. Placid waters made for too much surface tension, making it impossible for the heavily laden flying boat to take flight. The ship was later able to hop off from Hampton Roads, Virginia, but various problems including water in the gas were blamed for it ultimately setting down off Atlantic City, New Jersey, rather than Hamilton, Bermuda.65 The flight of the Flying Fish to Bermuda was postponed and later rescheduled, but it never took place.66 Among those who thought they could do better was Captain Lewis Yancey (see Fig. 10), the navigator on
the much-publicized Williams flight to Rome. A native Chicagoan, he had enlisted in the U.S. Navy at 16, had been a lieutenant in World War One, received master mariner certification in civilian life, then joined the U.S. Coast Guard, becoming interested in aviation and especially the application of the science of navigation to flying. A true navigator’s navigator, Yancey went on to write a book on aerial navigation.67 He found the challenge of locating that dot in the ocean irresistible, and publicly announced that given just 48 hours’ notice he could guide any good plane and pilot to Bermuda.68 William H. Alexander was one good pilot. A World War One flyer and flight instructor who had trained at the Wright brothers’ aviation school, he held the Fédération Aéronautique
Internationale, or FAI (an international organization based in Paris), flying license No. 1.69 But unlike Yancey, Alexander had recently experienced more ignominy than adulation. On Saturday, September 7th of the fateful year 1929, after dropping off six passengers from his Coastal Airways plane at North Beach he took off again but soon ran out of fuel. Taking his seaplane down off Coney Island in the fog, he landed among the shocked bathers at Seventh Street, killing two children and wounding ten other people. Alexander, “haggard and grief-stricken,” held that his water landing would have injured no one had not a wing accidentally struck a warning sign, deflecting the plane into the bathers. Nevertheless, his pilot’s license was revoked and he was charged
Fig. 10. Captain Lewis Alonzo “Lon” Yancey, navigator on the historic flight of the Pilot Radio to Bermuda. (Aero News and Mechanics, Vol. 2, No. 1, Feb. 1930, p. 9)
50 The AWA Review
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with homicide.70 In what now seems too far-fetched for even a Perry Mason courtroom drama, the judge agreed to fly with Alexander in a reenactment, after which he suggested further safety regulations for aviators and not only cleared him of all charges but noted that it was “a marvelous experience.”71 Alexander’s license was soon reinstated. How navigator Yancey, pilot Alexander, and radioman Bouck came together on the Pilot Radio for the historic first flight to Bermuda and exactly what their hierarchical relationship was are not exactly clear. Bouck was no stranger to Bermuda; he had already visited the islands ten times,72 including at least once with his wife Charlotte,73 and he had friends there. A document providing important clues to the origin of the Bermuda flight can be found in the Bermuda Archives.74 On January 9, 1930, Zeh Bouck wrote to J. P. Hand, the chairman of the Bermuda Trade Development Board, that a friend, Allan Thompson, suggested that he contact Hand about flying to Bermuda. Bouck said he was “seriously contemplating” flying to Bermuda from New York within the next month “if it is worth while.” “Can you,” he asked, “get the Board of Trade to put up a cash price [sic] for the first flight to the Islands?” He must have been aware of the previously withdrawn prize, and was hoping to get it reinstated. “I should like to know what the Board of Trade can offer me and my co-pilot for the first and necessarily historic flight to your beautiful islands.” This, and a later reference (“I am flying my ship to
Miami. . .”) would seem to indicate that Bouck, who needed crutches to walk due to what one newspaper account said was “infantile paralysis” (childhood polio),75 could still fly a plane. A number of other accounts over the years suggest this as well,76 and reports of Bouck driving a car can also be found. A recent search was not able to uncover a pilot’s license for Bouck, but these can be hard to find, and in those days some flyers (including Lewis Yancey) apparently considered them optional.77 So for now, this remains yet another unknown in the story of his life.78 Another surprising thing about Bouck’s letter is his affiliation. His letterhead was from Mackinnon Fly Publications, Inc., the publisher of Aero News & Mechanics, of which he was the Managing Editor. Neither his employer, the plane’s owner (Pilot Radio), nor radio in general is mentioned at all. In the letter, Bouck noted that his secondary purpose was to arrange for a series of annual air races to Bermuda, to be sponsored “more or less” by Aero News & Mechanics (see Fig. 11). Bouck mentioned that manufacturers (aircraft, instrument, or radio?) and pilots were enthusiastic about this, and informed Hand that he was tentatively scheduling the races for May! This letter and a few other available documents on Bouck’s private business dealings give the impression that, rather than being meek and mild as one might expect from his photos, Bouck’s was a hardnosed, “take-charge” personality that would put Alexander Haig to shame. Being crammed into a confined space
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Fig. 11. Cover of Aero News and Mechanics, Volume 2, Number 1, Feb. 1930. Zeh Bouck was Managing Editor for this magazine, published by Experimenter Publications, and originally envisioned it sponsoring a first flight to Bermuda followed by annual races to the island.
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(the Pilot Radio) on stressful missions with two other gentlemen similarly not lacking in ego or self-proclaimed authority surely had interesting consequences, but unfortunately little about this remains in the historical record. In writing to Hand, Bouck didn’t fail to note that “we all appreciate the publicity and trade that would accrue to Bermuda as a result of my primary flight and the subsequent annual races.” Bouck did receive a reply to his letter—a negative one. He was advised to “abandon any such idea until proper navigational and meteorological facilities exist.”79 Bermuda had already voted funds for the construction of a meteorological station and planned to eventually install a radio beacon, but the government was slow to act, which may, in fact, have prompted the flyers to hurry up and reach the islands while doing so was still a challenge. Replying to the Bermudian objections, the ever-resourceful Bouck wrote back, suggesting that Bermuda station BZB could be used as a navigational aid (RDF). Permission to land, required by international convention, was never granted,80 the prize was not reinstated, and the proposed races would never take place, but the proposed first flight to Bermuda did... “more or less.”
The Flight to Bermuda
Preparations
Financial support for the flight came from a variety of companies. Isidor Goldberg, provided the lion’s share by providing the Pilot Radio, the radio
equipment, and payments for the crew. Goldberg no doubt anticipated his company’s name being featured nationwide in news accounts of the flight. Richfield Oil provided the fuel and oil. The Pioneer Instrument Company was a sponsor. The Edo Corporation, named from the initials of founder Earl Dodd Osborn, fitted the “ship” with the pontoons that would allow for water takeoff and landing. This was carried out in secret lest someone else beat them to the punch. Aero News & Mechanics was apparently not involved,81 but other publications, notably the New York Times, were. In fact, Bouck would be pounding out exclusive in-flight dispatches to the Times radio station WHD on 43rd Street in Manhattan and its chief engineer and crack operator, R. J. Iverson, thus reducing to practice the idea of constant two-way air-toground HF communication. WHD already had an impressive record of DX communications with explorers and flyers (although not necessarily continuous contact) and would build on this in coming years.82 The Pilot Radio itself was a recently manufactured, modified 6-seat Stinson SM-1FS “Detroiter” high-wing monoplane (NR 487H) powered by a 9-cylinder, 300 horsepower Wright “Whirlwind” (J-6) engine, with brakes by Harley Davidson (see Fig. 12). The ship, acquired in mid-to-late 1929 to replace an earlier Pilot Radio flying lab (a Stinson SM-1B, NC 4876),83 was specially equipped with extra gas tanks in the wings, for a total fuel capacity of 200 gallons, enough to cruise at 100
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mph for 12 hours. Oil could be added from inside the plane. It had a maximum speed of 135 mph and a service ceiling of 17,000 feet.84 Its rated carrying capacity was 4,700 pounds, but the fully laden plane at takeoff would weigh 5,200 pounds.85 The plane would carry two transmitters, one longwave (600–1100 meters) for the old aero beacon/emergency band and the other a shortwave transmitter (35–50 meters) for anticipated in-flight communications. Both were housed in a single unit, and both employed a Hartley oscillator. Communications would be entirely radiotelegraph. All of the radio equipment had been built by Pilot Radio under Bouck’s direction. The receiver was a modified AC Super Wasp that used Arcturus AC tubes, which, with heavy cathodes, were less prone to microphonics than DC tubes. Special coils allowed it to be tuned between 14 and 1200 meters. Receiver and transmitters were combined in a single unit suspended from the top of the plane’s frame. An Exide “non-spillable,” 12-volt, lead-acid aircraft battery supplied filament voltage
to both receiver and transmitters and powered an Esco dynamotor that fed 1000 volts at 100 milliamps to the plate of the De Forest 510A transmitting tube. The Exide, in turn, was continuously charged (except when receiving) by a wind-driven generator mounted on the plane. Receiver B and C voltage was supplied by Eveready batteries. A trailing antenna of variable length was used. Communications would be carried out with the antenna spooled out to 90 feet to work the third harmonic on 41 meters. When not in the air, an emergency antenna could be strung up between the wingtips or flown via kite,
Fig. 12. The Pilot Radio, Pilot’s “flying laboratory,” a Stinson SM-1FS Detroiter that made the historic first trip from the U.S. mainland to Bermuda. (Aero News and Mechanics, Vol. 2, No. 1, Feb. 1930, p. 52)
Fig. 13. Zeh Bouck at his station aboard the Pilot Radio. (Radio News, July 1930, p. 12)
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and Bouck estimated there would be enough power to communicate for ten hours without charging.86 The entire radio setup weighed 140 pounds, and the plane’s callsign was W2XBQ (see Fig. 13).
The Bermuda Short Hop
It was April Fool’s Day, 1930, but the mission that day was dead serious. The flyers were eager to hop off as soon as possible to forestall possible competition for the title of first to fly from the United States to Bermuda, but weather was a major factor. For advice on weather, they turned to Dr. James H. Kimball, chief meteorologist at the New York Weather Bureau, whom Bouck referred to as “that Palladium of oceanic flyers”87 (i.e., their protector). He had prognosticated weather conditions for Lindbergh for his famous transatlantic flight and for Byrd on his flight to the North Pole.88 At 11 p.m. on March 31, Kimball’s report had come in: calm weather was predicted the next
day for the entire area between New York and Bermuda. The hop was on (see Fig. 14). In the wee small hours of the morning at Bouck’s New York apartment “provisions had to be packed and other domestic arrangements completed, much to the annoyance of the folks living below. They rapped viciously and repeatedly on their ceiling with some variety of battering ram. After eighteen hours of a hard day’s work, this was an amusing interlude, and I responded, in my kindly way, by dropping encyclopedias on the floor at judicious intervals.”89 After just a couple of hours of sleep, Bouck went to pick up the battery that he had left at a battery station for charging after specifically warning the attendant not to top them off. Batteries meant for airplane use were constructed differently from car batteries to compensate for in-flight sloshing; the cells were not meant to be filled completely. Of course, after a
Fig. 14. The Pilot Radio being towed from its hangar into the water at College Point, Queens, the morning of April 1, 1930, for its historic first flight from the U.S. to Bermuda. (Author’s collection)
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shift change the new attendant took a look, saw the low level, and proceeded to top them off. “I discovered this at 6 a.m. with our takeoff scheduled for a half an hour later,” wrote Bouck. “There was only one thing to do: empty out most of the electrolyte and add sulfuric acid. Unfortunately, there was no sulfuric acid to be found. I tried frantically for a half hour to locate an open drug store without success.” He finally located some at 7:30, dumped the old electrolyte and filled each cell with 24 hydrometers full, one by one. “We blew through the gates at North Beach a quarter hour later, held up for a moment by an importunate member of the press who was clamoring for a story. We explained that we were somewhat busy at the moment, whereupon he sweetly expressed himself with the following sentiment: ‘I hope — — plane sinks!’ This didn’t bother me at the time, though I did recall this touching farewell that night.”90 Because of the battery, Bouck was nearly two hours late for the “hop off” and out of contact with Alexander, Yancey, and others who were probably searching for him the whole time. Usable daylight hours, important for this long flight, had burned away. The greeting he received from his fellow crewmembers can only be imagined; about it he wrote nothing. The plane was afloat on Long Island Sound at Clason Point where the takeoff was attempted. Inauspiciously, the takeoff failed four times in a row because the fair weather had left the waters too calm, which made for high surface
tension, which produced significant drag on the pontoons of the heavily laden plane. This was the same problem that had beset the earlier Bermuda attempt by Lancaster and Lyon. Even the big 300-horsepower Wright Whirlwind engine struggled with this. Takeoffs in choppy water were easier. To lighten the load, the weight needed to be reduced, and it wouldn’t be surprising if the idea of jettisoning Bouck and his batteries came up. Instead, a sea anchor, spare pontoon plates, and some extra fuel were discarded. The fifth attempt again failed, but the sixth was a charm. This time they took advantage of the wakes created by two ferryboats and some helpful waves created by an assisting Edo seaplane. “Bill Alexander gave her the gun,” chronicled Bouck. “In another second the Pilot Radio was on the step, the bumps becoming sharper and sharper as the air speed indicator rose from fifty to fifty-five, sixty, sixtyfive miles an hour. One more sharp rap on the pontoons and we were off. We gained altitude rapidly and cleared the bridges in good style.” Yancey remembered it differently. “I saw the Hells Gate Bridge straight ahead. I pointed it out to Bill. He nodded and said he saw it. Meanwhile, when destruction seemed certain and it appeared we were going to crash into it, Zeh Bouck, calmly oblivious, proceeded to reel out his fishing line antenna . . .”91 The oblivious Bouck then began his radiotelegraph dialog with the New York Times station WHD. “What provisions were they carrying?” asked the
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Times. “Rations on board consist of two broiled chickens, four boxes wholewheat crackers, five pounds of chocolate, twelve oranges, five gallons water, one quart Scotch,” he radioed back. In those Prohibition days, the last item seemed to create some excitement, but Bouck noted that it was for medicinal use only—later observing that they were probably the only ones ever bringing whiskey to Bermuda. Yancey took sightings by sextant after sliding back a plastic (pyralin) window at the top of the cabin, letting in 100 mph winds. Sightings taken through the pyralin would have been more comfortable, but they would have been in error because of its refraction.92 Yancey carried three Longines chronographs so that if one got out of whack the other two would give a consensus on which one was in error. The plane sped on its way at an altitude of 2,000 feet. Bouck communicated with WHD regularly the whole way, and the station relayed his messages.93 At 1:55 p.m. Bouck sent a message, “Greetings from mid-Atlantic to you, mother....JACK.” WHD was asked to relay hotel reservations to BZB in Bermuda. Yancey asked Bouck to tap out, “The sky is partly cloudy and we hope it will get no worse, as it might prove hard to find the islands.” At 5:20 p.m. the message from the Pilot Radio was, “If we don’t see the islands pretty soon, we will set her down for the night. If we have to set her down for the night, don’t let anyone worry about us. The sea is like a lake.” Fifteen minutes later the update was, “we may make it and
we may not.” It was getting dark and they had been fighting headwinds. The morning’s delay loomed larger and larger. Had Yancey really steered them on the correct course? At 5:50 PM a decision was reached: “Setting her down right now. Position sixty miles north of Bermuda. Tell everyone not to worry... Will continue to Bermuda in the morning.” GN (good night) followed. The New York Times would tell its readers the next morning: “TwoHour Delay in Taking Off Is Blamed for Failure to Reach Objective.” Bouck decided that after landing on the water, he would let his notorious batteries rest until morning rather than string up an emergency antenna and run them down overnight. Fully charged batteries would be most useful in case of problems taking off in the morning. While the Pilot Radio had been fitted out with pontoons for water takeoff and landing, actually being able to land on the open, rolling sea and then take off again the next morning after the engine had potentially been sprayed with brine all night was not assured. And with the sea anchor left behind, there was the possibility of drifting into a coral reef overnight that could sink the plane (after all, there was that reporter’s curse). In fact, to that date no plane forced down in the middle of the ocean had ever successfully taken off again. For one thing, as Bouck was to note, “water is a hard thing to hit at 60 miles per hour.” But Alexander, an experienced seaplane pilot, managed to set her down and the Edo pontoons held. Seen up close, the
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sea turned out to be rather unlike a lake. The sea anchor having been jettisoned, a couple of 10-quart pails were strung together to provide some stability, but these proved useless for much of the time. Afloat, the flyers endured swells and pitches. “‘Gentlemen, I’m going to be sick,’ Alexander said. And he was.” The plane was too far away from Bermuda for it to have been spotted, and the flyers rather conspicuously made no attempt to contact the Bermudian authorities, who had pointedly denied them permission to land there in the first place.94 Bermudians were therefore unaware of the plane’s presence off their shores until a cable from New York reached them after 8 p.m. The sound reasons behind denying landing permission then became apparent. With incomplete information from New York and nothing from the plane, Bermudian authorities had to assume that it was in distress and mobilize their resources for assistance. Much to their credit, this they did, fully and immediately. Bermudian authorities tried to communicate with W2XBQ (the Pilot Radio) at the 600 meter (500 kHz) international emergency frequency from their St. George’s wireless station, which was kept open all night, but received only silence in return. A little-publicized consequence of the Pilot Radio’s silence was that U.S. East Coast radio stations briefly shut down at about 5:52 p.m. Eastern time per protocol to “clear the airwaves” for a possible 500 kHz SOS transmission.95 Upon learning that the plane had been working 41 meters, the Bermu
dians attempted to reach the flyers on that band as well, but the De Forest 510A tube remained unlit, perhaps unlike the flyers with their bottle of Scotch. Searchlights were switched on. A lookout was kept at the Gibb’s Hill lighthouse. All ships anywhere in the vicinity were asked to be on the lookout. Arrangements (which included insurance issues and financial considerations) were made to have a steam tender, the Mid-Ocean, leave Hamilton at dawn to search for them.96 In short, the Bermudian authorities went to great lengths to aid the aviators perceived to be in distress, who had given them no notice, intentionally remained silent, had been warned not to attempt it, and were pointedly informed that no assistance would be offered if they did. Three times during the night the flyers spotted the lights of a ship in the distance. After considering the possibility that it might be out looking for them, at 3:15 a.m. they fired off the “Very pistol” (a flare gun). The ship, which turned out to be the Canadian steamer Lady Sommers, hove to and headed towards them. They could have communicated with her at some distance by code using a flashlight, but Yancey had lost the plane’s only flashlight while inspecting the pontoons. Fortunately, this was a problem that even the dullest of the Radio Boys—much less Zeh Bouck himself—could easily solve. Gathering together a spare bulb, a couple of wires, and an extra flashlight battery he tapped out Morse messages, touching wire to battery terminal. The Lady Sommers had in fact been sent out to
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look for them and offered to take them aboard. Its captain was surprised at the flyers’ reply; they did not wish to be rescued. They would weather the swells for the rest of the night and proceed to Hamilton in the morning, asking Captain Armit to kindly relay the message.
Land Ho!
At daybreak, around 5:40 a.m., despite the swells and seasickness, “Bill [pilot William Alexander] showed his mastery of a ticklish job, and for the first time in the history of flying, a plane forced down in the middle of the ocean took off again.” Five minutes later the antenna was out again, the 50-watt transmitter and modified Pilot Super Wasp receiver fired up, and there on 41 meters was the radio operator at WHD New York, “as loud and clear as when we were over the East River,” happy to find the adventurers alive and well and approaching Bermuda. He informed them that some
other New York papers had already written them off as dead, “which news amused the lads up forward [Alexander and Yancey].” A copy of the message they sent to Edo 10 minutes after taking off praising the quality of their pontoons is shown in Fig. 15. At 6:15 a.m., an island was spotted dead ahead—Yancey had made good on his boast, guiding them on a beeline to Bermuda. Bouck would go on to chronicle this flight in at least four publications: Radio News, Radio Design, The New York Sun, and Yachting.97 These accounts differ slightly in length and a few minor details, but for the most part are quite consistent, even using the same text—recycling copy having always been popular among writers. The first three of these, however, end with the sighting of Bermuda in the distance that April morning and Bouck calling Yancey “the finest aerial navigator in the world.” The reader is left
Fig. 15. Part of an advertisement for EDO pontoons. Note that the telegram’s letterhead refers to the South American Good Will flight, which would not take place until later, but had apparently been in preparation for some time. Also note that Bouck is listed as navigator and Yancey’s name is absent from the letterhead. (Aero Digest, June, 1930, p. 101)
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with the impression that from there it was just a matter of setting her down in Hamilton Harbor—presumably to loud huzzahs—to complete their historic flight. In fact, the end of the journey was quite a bit more complicated, as Bouck related only in his article in Yachting. Since then, many secondary accounts of the journey either contain differing accounts of this stage or leave it out entirely. But of all the reports at the time or since, Bouck’s eyewitness account most has the “ring of truth” to it and consequently is presented here. With the islands in sight, Bouck asked Alexander how much fuel was left. “About one hour,” he replied. But a few minutes later, “‘Putt . . . putt . . . putt,’ says the motor, and conked . . . Once having heard that sound, it is as easily forgotten as the shake of a rattlesnake’s tail. We were definitely out of gas.” An overly optimistic fuel gauge had deceived them. They had been spotted from shore by Commander Landman, the pilot warden, but they wouldn’t know this until later. Alexander again set Pilot Radio down at sea, this time in an emergency landing about five miles short of the islands “just inside of the reefs.” In fact, their improvised sea anchor actually caught on the rocks just a few feet below the pontoons, temporarily anchoring the plane in place. Bouck began stringing up an emergency antenna, but before they could call for help, the frayed anchor line snapped and the current caused the plane to drift west, “toward New York City,” as Bouck said, but by way of the pontoon-piercing reef.
The story continues at that point: “Bill’s genius rose to the situation. He figured that rocking around out there, as we had been doing for the past half hour, we might have sloshed a quart of gasoline down into the equalization tank. Lon [navigator Lewis Yancey] cranked the engine. She took instantly and Bill gave her the gun with Lon climbing through the door, and ten fathoms of rope and radio antenna streaming out behind. We had two minutes of gas—enough to set down definitely in the steamer channel just off Shelley’s Bay.” Here they were met by Messrs. Tucker and Meyer in a speedboat, the first two from Bermuda to contact the new arrivals. Informed of their dry tanks, they soon went back to get the flyers some gas. In the meantime, along came a more official delegation from Bermuda aboard the Golden Wedding (see Fig. 16). The flyers’ arrival was commemorated on a Bermuda postage stamp many years later (Fig. 17). Mr. J. P. Hand, who had personally been involved in refusing Bouck permission to land in Bermuda, various newsmen, photographers, and others gathered around to gawk at and document the historic spectacle.
Arrests and Celebrations
Amid smiles, handshakes, and slaps on the back, Hand welcomed the crew (see Figs. 18 and 19), and then he proceeded to put them under arrest “for flying over Bermuda without a permit and similar diplomatic necessities.” It wouldn’t be the last time Bouck would be arrested in the course of his adventures. When
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Fig. 16. The Pilot Radio arrives in Bermuda on April 2, 1930. Bouck is sitting atop the plane with “Pilot Radio” showing on his back. (Roddy Williams Collection, Bermuda Archives)
Fig. 18. Another view of the Pilot Radio’s arrival in Bermuda. On the plane: Lewis Yancey, William Alexander, Zeh Bouck, and J. P. Hand. (Roddy Williams Collection, Bermuda Archives)
Fig. 17. Commemorative postage stamp issued by Bermuda in 1983 based on the figure above. (Author’s collection)
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the other boat arrived with the gas, Hand and a Mr. Richardson joined the crew on board the plane as it again went aloft, this time for a quick aerial tour of the islands, after which at last on April 2 at 8 a.m., the plane alighted in Hamilton Harbor (see Fig. 20) in a landing “so smooth that one could not have told that the plane was hitting water.98 When asked if they wanted anything, Yancey replied, “Anything, as long as it’s alcoholic.” Obligingly, a boatload of cocktails and ale from the famous Inverurie Hotel, a favorite of Bouck’s, was brought out to “liven up our brief period of incarceration.” Soon “pratique” was granted, diplomatic rough
Fig. 19. Front: William Alexander, Zeh Bouck (sitting on wing strut), and J. P. Hand. Person on the rear pontoon wearing spats is probably a Mr. Richardson. (Roddy Williams Collection, Bermuda Archives)
Fig. 20. The Pilot Radio arrives in Hamilton and is greeted by officials and spectators. Yancey, Alexander, and Bouck can be seen on the plane near the wing struts. (Roddy Williams Collection, Bermuda Archives)
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spots smoothed over, and the silly arrest forgotten “through a mist of Martini drys.” Later the crew was presented with flowers at the Inverurie Hotel in Hamilton (see Fig. 21). The Bermuda Governor would eventually go on to grant them post hoc landing permission.
Thus began the next phase of their trip, a grueling series of dinners, celebrations, toasts, and speeches. Bouck celebrated his 29th birthday in cocktailladen Bermudian glory. At a dinner in honor of the flyers he was introduced as “outstanding among radio experts
Fig. 21. The flyers are presented with a bouquet of fresh lilies at the Inverurie Hotel in Hamilton on April 2, 1930. Left to right: Miss Kathleen Jones, Lewis Yancey, Zeh Bouck, and William Alexander. (Roddy Williams Collection, Bermuda Archives)
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in the United States, and regarded as the young Fessenden.”99 In fact, Bouck took the occasion to make a pilgrimage to see the real Professor Fessenden and his wife, who were living in Bermuda. She wrote: “We counted it a fine tribute that Mr. Bouck devoted the better part of an afternoon of his short stay on the island to a call at ‘Wistowe’ to pay his respects to the man who had done so much to advance radio. When this call revealed to us the fact of his great physical handicap, it revealed too that the courage which led him to choose his profession must be of a very high order.”100 While the receptions continued in Bermuda, back home the sponsors’ PR machines had sprung to life. Yancey had made a promotional deal with Richfield Oil, which proceeded to praise the aviators for conserving fuel by landing at night rather than trying for the island in the dark. “And the famous Partners in Power, Richfield—California’s famous gasoline and Richlube—100% pure Pennsylvania Motor Oil had scored another triumph.”101 Isidor Goldberg of Pilot Radio, of course, expressed his admiration of the consistency with which the flyers were able to keep in touch at all times using his company’s equipment. Osborn of pontoon-maker Edo was especially pleased with the ocean landings. Pioneer Instruments, manufacturers of the plane’s navigation equipment, noted that the water landing (only one or two were mentioned in American news reports) “served to dispel popular beliefs that sea landings
are always disastrous unless saved by an unusual stroke of luck.”102 The Times in its inimitable way pontificated on lessons learned from the flight, finding the radio signals “remarkable for their clarity all along the 759-mile stretch” and concluding that there should certainly be radio beacons and radio direction finders installed in Bermuda to make flights routine rather than dependent on extraordinary navigation. It found that “what aviation needs is compact, light equipment in the form of receivers, transmitters and radio direction finders.”103 But it said nothing about Pilot Radio equipment—the publicity value of the flight for Pilot was minimal. Most accounts referred to it as “Yancey’s flight” and not “Pilot Radio’s flight”; almost none of them mentioned the Super Wasp. Again, the spotlight had been directed elsewhere. In Bermuda, the flyers met with local U.S. and British officials, which must have been anticlimactic for Yancey after his audiences with Mussolini and the Pope in Rome. Now that the airmen had actually made the journey and lived, the Bermuda Board of Trade, the organization that had earlier offered and then withdrawn the £2,000 Bermuda Safety Prize, voted $1,000 to each of the crewmen to express their gratitude, which must have seemed something like the Bermuda Consolation Prize, but was no doubt still welcomed. Alexander applied for permits to fly local officials around and then fly back home.104 As to how Bermudians viewed the flight, editorials suggest excitement over what it augured for
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eventual connection with North America and Europe by air, but also plenty of caution. “The fact remains that a forced landing happened under favourable conditions and converted what might have been a disaster into a mere unfortunate incident.”105 The extraordinary nature of their flight underscored the need for a radio beacon. “I hope no one else will try this flight until we put in radio beam facilities here, and I believe Captain Yancey would say the same,” Hand concluded.106 Those facilities were a long time in coming, but were in place seven years later when Pan American Airways and Imperial Airways began regular service to Bermuda, employing constant radiotelegraph communications just as Bouck had proposed.
The Heroes Return
The Pilot Radio was inspected by British Navy mechanics, who found a serious problem: the landings at sea had damaged one of the pontoon struts. Lacking the special equipment needed to weld the duralumin alloy they could try fixing it, but couldn’t guarantee that the weld would hold when the again heavilyladen plane took off. There were also other potential problems. No aviationgrade fuel was available in Bermuda, and it would take three weeks to ship some in. The regular gasoline that the plane used for the last few miles would do in a pinch but not for a long flight. And after everything that the Bermudians had already gone through, they were none too keen on the prospect of potentially mounting another search-and-rescue mission, especially for the same flyers.
So the plane was partly dismantled and hauled up onto the deck of the SS Araguaya (see Fig. 22), which sailed for New York with plane and crew. They arrived to a festive reception featuring flyovers by fellow aviators including Emile Burgin, a friend of Yancey’s who had flown the Pilot Radio before and would soon do so again. They shook hands with officials, were photographed, were met by their wives, and feted at the Majestic Theatre that night. Guests of Isidor Goldberg and 200 others at the Biltmore the following evening, they spoke of their overnight ocean experience, which they all agreed was “not bad,” over the NBC radio network via station WJZ. As far as their having made a stop en route (actually, from one to three stops, depending on how you defined the destination), they were satisfied that they had still met their primary but unstated objective, proving conclusively that an air service between New York and Bermuda would be feasible with the proper equipment. When a newspaperman (perhaps the one who laid the unsuccessful curse on Bouck?) tried to spoil the party by telling Alexander of a bootlegger who claimed to have already made regular flights to Bermuda, he dismissed the claim. “I don’t think anyone ever flew there before,” he said.107 A few weeks later Bouck, speaking over WGBS in New York, summarized what their flight had proven: 1) that it was possible to “come down in the middle of the ocean, spend a night, and then take off again,” 2) that it was the first time any plane was able to find
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Bermuda, and 3) that a two-way wireless conversation (in code) could be carried out over the whole route by HF.108 In fact, he was pleasantly surprised that there was no sign of a “skip distance effect,” which at some point (they had estimated 500 miles) would cause the signal to be lost. Quite to the contrary, Bouck had needed to attenuate the overly strong signal at times. In light
of these successful communications, it made little sense to add the weight of a longwave set. He again emphasized that planes making the journey should be in constant contact with a land station.109 When asked whether shortwave communications could be carried out from a plane by “phone” (voice) he said that it could, but would require heavier equipment.110
Fig. 22. Crew and plane returning to the United States aboard the steamer Araguaya. Left to right: Lewis Yancey, William Alexander, and Zeh Bouck. (Collection of Tom Singfield)
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While the dinners and speeches, toasts, interviews, and photos continued, the Pilot Radio was quietly being overhauled. Workers removed her pontoons and gave the plane back her land legs (wheels). She would soon depart on a marathon journey that would make her last adventure seem like a short stroll in the park. To be continued. . . .
Endnotes
1. The South American flight of the Pilot Radio (to be addressed in Part 2) was sponsored by the Hoover administration, and as a member of that party, Bouck was something of an unofficial U.S. ambassador.
2. Thirteenth Census of the United States (1910), Essex County, NJ; Fourteenth Census of the United States (1920), New York, NY; Fifteenth Census of the United States (1930), New York, NY; Enumeration of Inhabitants, New York State (1925), New York City. 3. For general overview, see Bouck White entry in Wikipedia. For writing, see B. White, The Mixing: What the Hillport Neighbors Did (Doubleday, Garden City, NY, 1913). For scandals, see New York Times archives. 4. Z. Bouck, “Hamfest,” All-Wave Radio, Mar. 1937, p. 139.
5. Who Was Who Among North American Authors 1921–1939, Volume I (Gale Research Co., Los Angeles, 1976), p. 185. 6. Tewpieye (Zeh Bouck), “A Ham on the Telephone”, QST, Aug. 1920, p. 6. 7. Hundreds of articles by and about Zeh Bouck including many of his regular New York Sun columns are available online at the website Fultonhistory.com/Fulton.html, a valuable resource for this and many other topics.
8. Z. Bouck, Making a Living in Radio (McGrawHill, New York, 1935). 9. “Among Our Authors,” Radio Broadcast, Jun. 1924, p. 188. 10. N. B. Kim, “The Early Radio Days of Harry Kalker,” Antique Radio Classifed, Jul. 1994, p. 8. 11. Radio Design, Vol. 1, No. 4, Winter 1928, p. 132.
12. R. Hertzberg, “Super-Wasp Shortwave Set,” Old Timers Bulletin, Dec. 1970, p. 16.
13. H. Gernsback, “The Old E.I. Co. Days,” Radio News, Mar. 1938, p. 632. 14. “Radio News Publisher in Hands of Receiver,” New York Times, Feb. 21, 1929.
15. R. Hertzberg, “Successful Television Programs Broadcast by Radio News Station WRNY,” Radio News, Nov. 1928, p. 415. 16. Z. Bouck, “Channel Echoes,” All-Wave Radio, May 1937, p. 237.
17. L. Steckler, ed. Hugo Gernsback: A Man Well Ahead of His Time (Poptronix, Inc., Marana, AZ, 2007) p. 327. 18. “Once He Paid to Throw Them Away, Now He Seeks 1928 Vintage Television Sets,” San Bernardino Sun, Apr. 14, 1950.
19. Z. Bouck, “Channel Echoes,” All-Wave Radio, Jan. 1937, p. 19. 20. Robert Hertzberg, “Super-Wasp Short-Wave Set,” Old Timers Bulletin, Vol. 11, No. 3, Dec. 1970, p. 17. 21. D. F. Plant, “Designed for Application: The Story of James Millen, W1HRX,” CQ, Jul. 1967. 22. Quotation from aviation magazine provided by Ed Lyon. My thanks to Ed for this and other valuable insights into early flying and radio communications. 23. A. Earhart, The Fun of It (Harcourt Brace, New York, 1932) p. 91. 24. Z. Bouck, “Making the Air Safe for Traffic,” Radio News, Jun. 1929, p. 1068. 25. A. K. Ross, “Making Radio Easier for Aviators,” Radio News, Sep. 1928, p. 202. 26. S. R. Winters, “Radio Progress,” Popular Aviation, Jul. 1928, p. 36; Z. Bouck, “The Airplane Radio Beacon,” Radio Design, Vol. 1, No. 4, Winter 1928, p. 125; “And NowRadio Guides Airplanes,” Radio News, Feb. 1930, p. 748. 27. S. R. Winters, “Radio Beacons to Guide Planes Across Continent,” Radio Age, Sep. 1926, p. 15. Adopted by the military, the A-N system came to dominate. https://en.wikipedia. org/wiki/Low-frequency_radio_range. 28. Z. Bouck, “The Problems of Aircraft Radio,” Radio News, Jul. 1929, p. 18. 29. Milton Sleeper, who had trained as a cadet in the Royal Flying Corps, noted that cadets would sometimes break the training transmitter to get out of code practice, which they detested. See A. Perry, “The Flying
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Laboratory,” Popular Aviation & Aeronautics, Feb. 1929, p. 26. 30. See M. F. Eddy, Aircraft Radio (Ronald Press, New York, 1931), Chapter 8.
31. Bouck, Making a Living in Radio, p. 37.
32. A. Lynch, “Radio and Aviation,” Radio News, May 1929, p. 985. 33. See, for example I. M. Philpott, The Birth of the Royal Air Force (Pen and Sword Military, South Yorkshire, UK, 2013), pp. 304–306. For early radio experiments on U.S. Navy planes, see L. S. Howeth, History of CommunicationsElectronics in the United States Navy, chapter XIV, available at http://earlyradiohistory .us/1963hw14.htm. 34. D. Crocker, “Radio and the Historic Flight of the NC-4,” Antique Radio Classified, Jan. 2008, p. 14.
35. S. Bart, Race to the Top of the World: Richard Byrd and the First Flight to the North Pole (Regnery History, Washington, D.C., 2013). 36. For one account of the Commander, a true marketing genius, and the 1925 MacMillan expedition, see J.H. Bryant and H.N. Cones, Dangerous Crossings (Naval Institute Press, Annapolis, MD, 2000). 37. D. Crocker, “The Dolphin: Crosley’s Personal Plane,” Antique Radio Classified, Nov. 2005, p. 22. 38. D. Crocker, “Crosley Takes to the Air: The Moonbeam,” Antique Radio Classified, Aug. 2004, p. 9. 39. For a perspective on the state of aircraft radio and the companies involved at the time, see M.F. Eddy, Aircraft Radio, and “Aircraft Radio Communications,” Aero Digest, March 1929, p. 66. 40. Letter from E. Meyer, Secretary to Mr. Goldberg, to Mr. W. L. Hamberger, publisher of the International Cyclopedia of Aviation Biography dated July 28, 1931. Available through Wright State University Special Collections. 41. Ross, Radio News, p. 202; “Flying Radio,” Popular Aviation, Jun. 1928, p. 23. 42. Brooklyn Standard Union, May 15, 1927, p. 12.
43. A. Douglas, Radio Manufacturers of the 1920’s (Sonoran Publishing LLC, Chandler, AZ, 1991), Vol. 3, p. 99. 44. World War One draft registration card for Milton Blake Sleeper, Serial No. 705, Order No. 803, Sep. 12, 1918. 45. Previous editors included Austin Lescarboura
and Carl Dreher. See D. Bart, Comprehensive Index to the Proceedings of the Radio Club of America For 1913-2013, p. xv, available at http://radioclubofamerica.org/wp-content/ uploads/2015/07/proceedings-index-opening-pages.pdf. 46. “Sleeper to Be Birdman With the Allies,” Everyday Engineering, Dec. 1917, p. 131; M.B. Sleeper, “Experiences of an R.F.C. Cadet,” Everyday Engineering, Jul. 1918, p. 162; Aug. 1918, p. 201; Oct. 1918, p. 27; and Dec. 1918, p. 125. 47. Neither did Sleeper ever acquire a pilot’s license, as far as a search at the Smithsonian’s National Air and Space Museum could determine.
48. Perry, Popular Aviation, p. 26.
49. M. B. Sleeper, “What Price Television?,” QST, Mar. 1929, p. 48. 50. “Stinson Detroiter for Radio Research,” Aviation Week, Jul. 9, 1928. 51. Z. Bouck, “W2XBQ Flies to Bermuda,” Radio News, Jul. 1930, p. 12. 52. H.A . Bruno; W. S. Dutton, “The OceanHopping Bug,” Liberty, May 6, 1933, p. 32. 53. A. Cortesi, “Italians ‘Rush’ Pathfinder,” New York Times, Jul. 11, 1929.
54. M. Maurer, Aviation in the U.S. Army, 19191939 (U.S. Government Printing Office, Washington, D.C.). Available at http://media. defense.gov/2010/Sep/23/2001330114/-1/1/0/AFD-100923-007.pdf. 55. “Pacific Fliers Led by Radio Beacon,” Science and Invention, Nov. 1927, p. 623. 56. Check out the display inside the Kilauea lighthouse on Kauai, if you can take your eyes off the incredible surrounding landscape and seascape. 57. “The Armstrong Seadrome,” Aero Digest, December 1929, p. 152; Sherwin L., “Seadrome for Atlantic Flyers Will Be Completed in a Year,” New York Evening Post, April 6, 1931. 58. W. Raleigh, “Seadromes,” Flying, February 1930, p. 22. 59. I. I. Sikorsky, “Airplanes of the Future,” Aero Digest, Dec. 1929, p. 54. 60. Unidentified newspaper, “Building of 1st Seadrome Starts Within 90 Days,” Mar. 26, 1931. Available through Wright State University Special Collections. 61. Unidentified newspaper, “Airport at Sea Legal, Inventor Asserts,” Mar. 27, 1931.
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Available through Wright State University Special Collections. 62. “Bermuda Safety Flight Contest,” Aero Digest, Sep. 1927, p. 276.
63. C. A. Pomeroy, The Flying Boats of Bermuda (Colin A. Pomeroy, 2000) p. 10. 64. Lyon was a U.S. Admiral’s son and mariner, and was alleged to also be a bootlegger, gun runner, and many other things besides. See, for example, http://www.mainememory.net/ sitebuilder/site/272/page/531/display?use_ mmn=1. Accessed Jan. 8, 2017. 65. “Putnam and Fliers Hop for Bermuda,” New York Times, Oct. 29, 1928; “Putnam Airplane Arrives at Norfolk,” New York Times, Oct. 30, 1929; “Postpones Flight,” Daily Independent (Murphysboro, Illinois), Nov. 7, 1928. 66. See E. Partridge, T. Singfield, Wings Over Bermuda: 100 Years of Aviation in the West Atlantic (National Museum of Bermuda Press, Old Royal Naval Dockyard, Bermuda, 2014). This meticulously researched, lavishly illustrated volume is the definitive book on Bermudian aviation history, must have been a true labor of love for its authors, and is highly recommended reading. 67. Anyone who thinks that aerial navigation must have been simple in those simpler times is invited to try working out the problems in that book. See L.A. Yancey, Aerial Navigation and Meteorology (Norman H. Henley Publishing, New York, 1929). 68. C. V. Glines, “First Flight to Bermuda,” Aviation History, Jul. 2001. Available at http:// www.historynet.com/aviation-history-firstflight-to-bermuda.htm. Accessed Jan. 8, 2017. 69. See his account of WWI combat, W. Alexander, “Dawn Patrol—A True Story of the R.F.C.,” Aero News and Mechanics, Vol. 2, No. 3, June–July 1930, p. 17. 70. B. Gould, “Yancey Nearing Bermuda on Hop,” New York Evening Post, April 1, 1930. 71. “Pilot of Coney Disaster Hero of Bermuda Flight,” Standard Union (Brooklyn, New York), Apr. 2, 1930, p. 1. 72. “Dinner in Honour of the Fliers,” Royal Gazette and Colonial Daily (Hamilton, Bermuda), Apr. 9, 1930. 73. List of United States Citizens, S.S. Bermuda, sailing from Hamilton to New York, arriving May 3, 1928. 74. Z. Bouck, letter to J.P. Hand, Jan. 9, 1930. Bermuda Archives document CS 3056/8:10.
My thanks to Thomas Singfield who originally unearthed this document. 75. “Zeh Bouck at Summer Home,” The Enterprise (Altamont, New York), May 27, 1932, p. 3. 76. See Z. Bouck, “The First Airplane Reaches Bermuda,” Yachting, Jun. 1930, p. 53, where Bouck says that he could take over for navigator or pilot in an emergency. Also see “Plane Carries Stowaway Back to Maine Home,” Scranton Republican (Scranton, Pennsylvania), Jun. 27, 1929, p. 24, and “Dinner in Honour of Fliers,” Royal Gazette and Colonial Daily. 77. Yancey, who piloted The Pathfinder for most of the flight from Maine to Rome, later admitted to not having a pilot’s license at the time, and later still, in 1931, received his first license. See “Lawyer’s Queries Incense Yancey,” New York Times, May 13, 1930; “Yancey, Rome Flier, Wins Pilot’s License,” unidentified newspaper, Jun. 5, 1931, available from Wright State Special Collections. 78. Attempts to confirm the reason for Bouck’s disability through his own accounts or medical records, or to find descendants or living friends and neighbors who could provide these kinds of details were, sadly, unsuccessful. 79. Quoted in Partridge & Singfield, Wings Over Bermuda, pp. 32–33. 80. Bouck was warned that “no sanction could be given nor assistance offered.” See “The New York-Bermuda Flight,” Royal Gazette and Colonial Daily (Hamilton, Bermuda), Apr. 4, 1930, p. 2. See also Yancey’s statement in “Out of Fuel, Yancey Landed Off St. Georges to Get Gas,” New York Times, Apr. 3, 1930. 81. The only reference to the flight in that journal that this author could find was an editorial by Arthur Lynch crediting Bouck with conceiving of and directing the flight and praising the flyers for their accomplishment. See “The Bermuda Hop,” Aero News and Mechanics, Vol. 2, No. 3, Jun.–Jul. 1930, p. 5. 82. E. Matlack; R. Matlack, “The Paper, the Station, and the Man—A Brief History of the New York Times Radio Stations,” 73, Feb. 1980, p.54. 83. Z. Bouck, “How High is Up?,” Radio Design, Vol. 2, No. 4, Winter 1929, p. 31; “Pilot Radio Firm Acquires Flying Laboratory,” Aero Digest, Sep. 1929, p. 120.
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84. Bouck, Yachting, p. 53. See also Jane’s All the World’s Aircraft, 1930, p. 317c.
85. “Yancey Starts Bermuda Flight,” New York Times, Apr. 1, 1930. 86. Bouck, “W2BXQ Flies to Bermuda,” p. 12; Z Bouck, “How the ‘Pilot Radio’ Made the First Bermuda Flight,” Radio Design, Vol. 3, No. 2, Summer 1930, p. 42. 87. Z. Bouck, “The Story of Three Men in a TubOn Wings,” New York Sun, Apr. 10, 1930. 88. J.H. Kimball, “Telling Ocean Flyers When to Hop,” Popular Science, Jul. 1928, p. 16. 89. Bouck, “The Story of Three Men in a Tub—On Wings.” 90. Ibid. 91. “Yancey and His Aides Honored at Dinner,” New York Times, Apr. 12, 1930. 92. Bouck, Yachting, p. 53. 93. Z. Bouck, “The Log of the Seaplane, the Pilot,” New York Times, Apr. 2, 1930.
94. “The New York–Bermuda Flight,” Royal Gazette and Colonial Daily (Hamilton, Bermuda), p. 2. See also “Out of Fuel, Yancey Landed Off St. Georges to Get Gas,” New York Times, Apr. 3, 1930. 95. “Zeh Bouck, Well Known Here, in Plane that Flies to Bermuda,” Schoharie Republican (New York), Apr. 3, 1930 says that WGY programs were interrupted. “Plane Flying New York–Bermuda Comes Down in Calm Sea Sixty Miles North of Here,” Royal Gazette and Colonial Daily (Hamilton, Bermuda), Apr. 2, 1930 lists WEAF among the stations maintaining radio silence. 96. “Plane Flying New York-Bermuda Comes Down in Calm Sea Sixty Miles North of Here,” Royal Gazette and Colonial Daily (Hamilton, Bermuda), Apr. 2, 1930. 97. Zeh Bouck, “W2XBQ Flies to Bermuda;” Bouck, “How the Pilot Radio Made the First Bermuda Flight;” Bouck, “The Story of Three Men in a Tub—On Wings;” and Bouck, “The First Airplane Reaches Bermuda,” all cited above. 98. “Three Aviators Arrive in Nick of Time,” Royal Gazette and Colonial Daily (Hamilton, Bermuda), Apr. 3, 1930. 99. “Dinner in Honour of Fliers,” Royal Gazette and Colonial Daily (Hamilton, Bermuda). 100. H. M. Fessenden, Fessenden—Builder of Tomorrows (Coward-McCann, New York, 1940), p. 337. 101. Richfield Gasoline advertisement, Reading
Times (Reading, Pennsylvania), Apr. 9, 1930, p. 8. 102. “Wives Unworried During Long Vigil,” New York Times, Apr. 3, 1930. 103. “On the Way to Bermuda,” New York Times, Apr. 6, 1930. 104. “Delay Repairs by Yancey,” New York Times, Apr. 5, 1930. 105. “The New York—Bermuda Flight,” Royal Gazette and Colonial Daily.
106. “Dinner in Honour of the Fliers,” Royal Gazette and Colonial Daily.
107. “Bermuda Fliers Return on Liner,” New York Times, Apr. 11, 1930. 108. “Bouck Lauds Yancey,” New York Times, Apr. 19, 1930. 109. “Radio Devices Aid Safety in Flying,” New York Times, May 4, 1930; Bouck, “How the ‘Pilot Radio’ Made the First Bermuda Flight,” Radio Design.
110. “Bouck Lauds Yancey,” New York Times.
Acknowledgments
This paper would not have been possible without the gracious help of the following people: Mike Adams and Bart Lee (California Historical Radio Society); Colleen Ayers (Radio Club of America); Carl Bobrow, Dr. Peter Jakab, Roger Connor, and Elizabeth Borja (National Air and Space Museum); John Guttman and Karl Vonwodtke (Aviation History Magazine); Kieron E. Hall (Bermuda National Library); Karla Ingemann (Bermuda National Archives); Ellen Keith (Chicago History Museum Research Center); Steve and Anne Lamont (Middleburgh Library); Rick Leisenring (Curtiss Museum); Mrs. John McCabe; David Miller (FlightLine Designs, Inc.); Patrizia Nava (U. Texas at Dallas Eugene McDermott Library); Bernd Neumann; Ludwell Sibley; and Bill Stolz (Wright State University Special Collections).
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Special thanks go to Phillip Krejci for incredible photographic restorations involving many hours of work; to Paul Hertzberg, K2DUX, for much useful information on Pilot Radio along with the photo of and schematic hand-drawn by his father, the late Robert Hertzberg; to Ed Lyon (Mid-Atlantic Antique Radio Club) for informative discussions about the challenges of early aircraft radio; to Andrew Pentland for guidance on finding and interpreting Milton Sleeper’s RFC records; to Thomas Singfield, co-author with Ewan Partridge of the outstanding book Wings Over Bermuda, for access to details on the Pilot Radio’s flight that would otherwise be unfindable; and to Bob Winn for help with Zeh Bouck genealogy.
About the Author
Bob Rydzewski, KJ6SBR, is a native of Chicago, Illinois, where his parents had worked at various times for Teletype Corporation, Belmont Radio, and Zenith. One of his earliest memories is of looking up to the eerie green magic eye of a 1930s Zenith console. His interest in electronics as a hobby began about the time he assembled an Eico 460 oscilloscope in a high school physics lab. Around 2000 he developed an interest in collecting and restoring old radios. Inspired by Alan Douglas’s
Radio Manufacturers of the 1920’s, he began searching out the fascinating and often forgotten stories behind the early days of wireless. Bob received an MS in chemistry from DePaul University and went on to a 25-year career in pharmaceutical and biotech R&D, eventually penning a textbook on drug discovery. His writing abilities came to the fore in his current career as a professionally accredited medical writer, helping doctors present clinical trial results through journal articles and congress presentations. Bob and his better half live in the San Francisco Bay Area where he is a proud member of the California Historical Radio Society.
Bob Rydzewski
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A Soviet Era Broadcast Receiver System of
the 1950s for Remote Locations
© 2017 Robert Lozier
For nearly 20 years I have taken a special interest in studying how the various national broadcast systems of the world have developed. These variations have often resulted in the development of very different hardware to serve these systems. I was recently given a Russian made thermoelectric generator of the 1950s in very poor condition prompting me to research its significance before investing time in restoration. I was already aware of their existence for powering small broadcast receivers in remote locations of the former USSR and English language Google searches produced links to basic information. Examination of serial numbers found in Google Images searches lead me to believe that these generators were at least made in the tens of thousands and not just a novelty. With little to lose in trying to make my unit presentable, I started preservation and restoration activities. After about 15 to 20 hours work, I concluded that it could be made presentable for exhibition; this prompted me to locate an appropriate radio that would have been powered by these generators. A fellow collector provided me with a fine example that turned out to have one surprising construction method, perhaps making a virtue of necessity, and several other very interesting features that prompted a new round of research. This paper describes my research into this broadcast receiving system, and provides a narrative of how these artifacts were prepared for conservation and exhibition. Many aspects of this receiving system and these artifacts will be largely unfamiliar to American readers.
Introduction
Based on 20 years of study, it became obvious that very different types of hardware were developed to support the various national broadcast systems of the world. I wrote two papers on this subject for the AWA Review describing various aspects of broadcast receiver development outside of the United States, the first treating Italian systems and the second treating radios from a number of other western European countries.1 This paper addresses several
unique broadcast radio systems in the Soviet Union. Beginning in the early 1920s and into the early 1930s, the Soviet Union recognized the value of establishing a broadcast radio system to unite, indoctrinate, and educate the populace. At that time, the primary means of providing radio reception to the populace was accomplished by placing radios in administrative buildings with loudspeakers distributed along city and
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town streets or by centralized receivers with wire lines going to subscriber apartment buildings, factories, public halls, schools, etc., which were operated much like telephone exchanges. The same type of receiver could be placed in an apartment block, dormitory, factory, or school to drive 50 to 250 small speakers. This distribution from a single receiver to multiple loudspeakers in an area was referred to as “radio-diffusion exchanges,” “cable radio,” or “wired radio.” People paid a small subscription fee for the service. At least from the late 1940s, these wired networks distributed program content from 6 a.m. to midnight. The number of receivers in the Soviet Union reported in census figures during the 1930s are considered to be highly suspect by Western historians. The official claim of 170.6 million people in the 1939 census is believed to be inflated by 10 to 20 million. Reports of Soviet statistics in 1940 claim 1.1 million radios at that time, but that is actually the tally of radios manufactured since 1932.2 According to the research of Alex Inkeles, the whole of the Soviet Union possessed 650,000 receiving sets in 1936; of these, 270,000 were crystal receivers, and about 200,000 were considered outmoded types in need of replacement.3 The Radio Committee was able to claim only 500,000 sets as being “ready” to broadcast Stalin’s address before the Supreme Soviet on November 25, 1936. The number of broadcast receivers in operation as of 1940 was reported to be 760,000, with more than five million wired speakers
of the cable radio systems. After the ravages of World War II, less than 18% of listeners in 1947 were said to be receiving their programming via individual receivers. It should be noted that in the rural areas, only a small percentage of the population heard any radio programming on a regular basis. In any case, the penetration of broadcast radio reception via individual receivers lagged far behind most modern industrialized countries that the Soviets were trying to surpass. The government realized that postwar efforts to manufacture broadcast receivers would have to be dramatically increased, and so design bureaus within ministries, universities, and a few radio factories were tasked to develop new designs for low-cost, mass-produced radios. These designs were reported in detail to the public in the pages of the Soviet magazine Радио (Radio) beginning in the very late 1940s.4 Actual volume production was low and did not begin to increase significantly until after 1953, due in large part to the deemed higher priority of rebuilding the electrical, electronic, and communications resources of the Red Army. It was not until the latter half of 1956 that all radio assembly plants were reportedly operating on a continuous assembly-line basis.5 Rural electrification in the Soviet Union lagged behind that in the United States by some 25 or 30 years, such that there was still a significant need for battery-powered broadcast receivers into the 1970s. Adequate distribution of expensive dry batteries to remote
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locations was at times unreliable and, of course, a continuing expense. Many people remember magazine, newsreel, and television coverage of long lines of Soviet citizens in seeming endless queues for basic goods. Consequently, the Soviet Union began to develop thermoelectric generators as an optional power source. I recently obtained a Russian-made thermoelectric generator of the 1950s in very poor condition, which prompted additional research to determine its significance before investing in a restoration project. English language Google searches for thermoelectric generators that powered small broadcast receivers in remote locations of the former USSR produced links to basic information. Examination of serial numbers found in Google Images searches determined that these generators were made at least in the tens of thousands—not just as a novelty. After 15 to 20 hours
of preservation and restoration work, it became apparent that it could be restored to a condition suitable for presentation. It was obvious that a presentation of the generator would be much enhanced by connecting an appropriate Soviet radio to the generator. A fellow collector provided a fine example of a Soviet radio that turned out to have one surprising feature and several other very interesting features that prompted a new round of research. These features will be described in Part II herein addressing Soviet receivers powered by thermoelectric generators. This paper combines my research into thermoelectric generators in particular and Soviet broadcast receiving systems in general. A description of how these artifacts were prepared for conservation and exhibition is also included. A great deal of this information will be new to most American readers.
PART I. THERMOELECTRIC GENERATORS
Early Thermoelectric Generators
The fact that heated junctions of dissimilar metals can create a magnetic field was discovered by Seebeck in 1821. Seebeck thought that the phenomenon he observed was that of conversion of heat into magnetism. It was left to Ørsted to correct this misperception and properly describe it as creation of an electric current, and in doing so he coined the term “thermoelectricity.” The electrical output of individual dissimilar metallic junctions is very
small, generally seldom more than 3 to 15 millivolts. The first patent for the use of thermoelectricity instead of batteries for useful work in electroplating was by Moses Poole in 1843.6 By the middle 1860s, thermopiles (assemblages of multiple thermocouple junctions to provide useful voltages and currents) were being noted in journals of scientific societies. The junctions were of metals and metallic alloys with junction potentials well under 20 millivolts.
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These early thermopiles were said to have been unsuccessful for continuous work because of oxidation of the metals and junctions as well as stress fracturing of constituent metals during cooling or heating. By 1874, a gas fired commercial version of the Clamond Thermopile was reported to be in operation at the printing works of the Banque de France, presumably for electroplating copper in the electrotyping print process.7 In 1876 the (British) Government Telegraph Service under the direction of Sir W. H. Preece issued a contract to the Thermo Generator Company to supply thermopiles as a replacement for the usual system of electrochemical batteries, but the project was in short order declared a failure. Preece indicated it was his opinion that the faults could be corrected, but the company collapsed before they were able to complete the contract.8 There were a number of investigators in the last quarter of the 19th Century that attempted to overcome the deterioration of junctions and improve efficiency, but the development of practical small dynamos for electroplating virtually eliminated the primary market for thermopiles. In 1909, engineer Edmund Altenkirch is credited with expressing a mathematic relationship between physical properties of thermoelectric materials and the efficiency of a simplified thermopile.9
Thermoelectric Generator Applications to Wireless Sets
The Science Museum in London has exhibited a Thermattaix gas-fired ther
mopile designed circa 1925 for charging “wireless set accumulators” (vacuum tube radio receiver filament supply batteries) over the range of 2 to 10 volts (see Fig. 1). The magazine Amateur Wireless for April 1929 carried an ad for a Thermattaix, claiming that it could work your wireless set by gas, petrol, steam, or electricity. . . . Electricity? On the surface, this claim to operate a radio by electricity seems to be an oxymoron, but it is one way to convert high-voltage alternating mains to the low-voltage direct current required for charging accumulators. Or, if the high voltage mains came from a jittery onecylinder motor/generator outfit, it could act as a voltage stabilizer. The ad goes on to claim that amongst their customers were gas companies, the Italian Air Force, architects of note, and guides for big game expeditions in Africa and India. It is not known how many units were manufactured, but very few, if any, are in the hands of collectors.
Fig. 1. Thermattaix gas powered generator for charging filament batteries. (Science Museum, London)
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In the mid-1930s, the Cardiff Gas Light & Coke Company (South Wales, UK) placed the ad shown in Fig. 2 that advertised “THE THERMO-ELECTRIC GENERATOR which makes your Battery Set Independent of Batteries of any kind.” There were mentions of this outfit in Wireless World, and the son of a dealer reports his father having sold a number of these. The advertisement shows a radio of a style that would leave us to presume the thermopiles must have produced 2 volts at 0.5 amps for the valve filaments and 90 to 120 volts at 10 milliamperes for the plate circuits. But again, neither the actual number placed in service nor the cost is known, and there appear to be no surviving examples. Four articles on thermoelectric generators to power radio receivers and radiotelephones have been found in the Russian language magazine Radio (Радио), which began publication in 1946. The February 1952 issue states that under the direction of the prominent Soviet physicist and academician Abram F. Ioffe, investigations in the 1930s turned towards a search for semiconductor materials such as a zinc–antimony alloy (SbZn) bonded to a copper–nickel alloy (constantan) that could produce significantly greater potentials (55 mV in production devices) at higher thermal efficiencies (still, well under 4%). It was stated that the first claimed Soviet use of thermocouples using semiconductors was in “The Great Patriotic War” (WW II) to power small—presumably headphone-only—radio receivers used by partisan forces. One very small line
drawing shows a hanging cast metal pot with a flat bottom. The thermocouples are bonded to the bottom of the pot, and the pot is suspended over an open campfire. Water boiling in the pot becomes the “cold” side for this primitive thermopile.
TGK Series of Soviet Thermoelectric Generators
Later, in 1949–1956, Ioffe derived a “ZT” value parameter as a figure of merit to indicate how efficiently a material converts heat into electricity. He
Fig. 2. Dating from circa 1934, this thermo-electric generator may have been the first product to supply all the power needs of a conventional battery powered broadcast receiver. It was built only in very small quantities. (http://www .douglas-self.com/MUSEUM/POWER/thermo electric/thermoelectric.htm#ca)
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used the new parameter to calculate the practical efficiency of thermoelectric generators.10 A team of engineers then developed a thermoelectric generator powered by a kerosene lamp burner that was capable of delivering 3 watts—enough to power a low-power vacuum tube radio with loudspeaker (see Fig. 3). These generators were made at the Metallamp factory in Moscow. A TGK-3 version of the generator described in the February 1954 issue had two thermopile circuits; one circuit supplied 2 volts at 2 amperes to a synchronous, mechanical, vibrator-type of DC-to-DC converter. It provided 90 VDC for the plate circuits of the radio and -9 VDC for grid bias. The other
thermopile circuit provided 1.2 VDC at a nominal load of 300 mA for lighting the vacuum tube filaments. No storage battery was used in this power system. The February 1956 issue of Radio announced an improved generator, TZGK-2-2, that eliminated the need for a vibrator power supply with its inherent RFI emissions.11 This was a matter of considerable importance because many of these generator-powered radios were in weak signal areas at considerable distances from broadcast transmitter sites. This new generator provided the 90 VDC for plate circuits and -9 VDC for grid bias directly from a series string of approximately 2600 pairs of hot and cold junctions. In the same year, another low-voltage version of the generator, designated TGK-10, was announced in the September issue of Radio (see Fig. 4). This unit did not serve the double purpose of providing room lighting in addition to radio power. This somewhat higher power version, 10–12 watts, was only for battery charging service. A vibrator type power supply sourced by a storage battery was still needed to deliver the peak power requirements of the KRU-2 “cooperative radio center,” which used a multi-band broadcast receiver designed to drive up to 50 low-power loudspeakers in apartment buildings, dormitories, etc. This was for the “cable radio” scheme of distributing broadcast programming in “off-the-grid” communities or collectives. This generator was also employed to power the “Vintage U-2” and “Harvest-1” low-power, 2–3 MHz, AM radio
Fig. 3. The TGK-3 generator powered a DC-toDC mechanical converter to provide +90 and -9 volts for a vacuum tube receiver. (TGK-3 Instruction Manual)
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telephones used on large agricultural collectives, etc. An article published on the www.radionic.ru web site states that 20,000 of the Harvest radio telephones would be manufactured in 1956, with another 25,000 scheduled to be built in following years. The article states that 70,000 radiotelephone stations will be in service.12 It is unknown if those production goals were ever achieved, and there are no comments on how many were powered from the thermoelectric generators.
Small Thermoelectric Generators to Power Broadcast Receivers
The thermoelectric generator in my possession is stamped ТЭГК-2-2 (1958), which translates to TZGK-2-2 in English (see Fig. 5). The “2-2” of the part number is the guaranteed minimum power output of the generator (i.e., 2.2 watts). This generator seems to have the same outward appearance as the one described in the February 1956 issue of Radio. Web searches of images indicate that the 1958 in parenthesis
Fig. 4. This TGK-10 generator was used to charge batteries in “Harvest-1” low-power HF radio telephones. (Radio, No. 8, 1956, p. 7)
Fig. 5. A TZGK-2-2 (1958) Thermoelectric Generator. (Author’s collection)
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does not represent the year of manufacture; instead, it is an indication of a new model. I have not been able to determine what changes were made internally that would have caused the model number to change. The operating instructions give specific requirements for placement of the generator in a room. It must be near a window and hang from its supplied chains at a minimum distance of 10 cm from the ceiling and at least 1.5 m from any wall. The generator provides 1.2 volts to light the filaments of 7-pin miniature tubes, which are in many ways electrically and dimensionally interchangeable with the miniature tubes introduced by RCA in 1939 and first used in the RCA Victor BP-10 pocket portable radio of 1940 (see sidebar). Another bank of thermocouples provides a nominal 9 volts for grid bias, and a third bank produces 90 volts at a maximum of 10 mA for the plate circuits. These thermopiles are built around a cast aluminum core with six prismaticcross-section channels at the center for the hot gasses to pass through. A sheet metal flue at the top improves draft.
The thermopile is heated by a kerosene lamp burner of the Argand type to raise the temperature of the hot junctions to about 400°C.13 In the case of the TGK-3 and TZGK-2-2, the clear glass globe allows it to serve double duty as room lighting that should produce something approaching 200 lumens. The font holds enough kerosene for about eight hours of operation. Russian language publications provide extensive analyses of various thermocouple materials and thermocouple theory but provide no information on how the thermocouples are actually fabricated for these generators. English language Google Images searches produced no internal construction photographs of these generators. Eventually, I was able to use Google Translate to craft Russian language queries that produced links to a number of dissected generator photographs made by a former Soviet region vintage radio enthusiast in 2009. Even these photographs shed little light on how these junction slabs were fabricated. It is apparent from inspection that the thermocouples were fabricated in many multi-layer monolithic slabs,
How Did the Soviets Develop Their “Finger Lamp” Technology?
How the Soviets acquired the vacuum tube technology described here is an interesting question. Was it acquired directly from RCA or via Lend-Lease agreements with the Soviets during World War II. RCA had indeed entered
into contracts with the Soviets during the 1930s but they were completed by 1938. Most notable was the contract providing a complete electronic TV broadcast system in Moscow. There were attempts to renew agreements
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during the war and shortly thereafter, but deteriorating government relations ended cooperation by 1949. The LendLease policy enacted in March 1941 did not have in its scope the transfer of technology—only goods. Alex Magoun of the IEEE History Center commented to me in a 2016 e-mail: “American officials were puzzled and frustrated by Soviet refusal to let them observe the use of equipment on the Eastern Front so that they could ensure the Soviets were getting the right goods or using them effectively. I suspect that you’ll know better than me if these tubes were in standard military radios and other electronic combat devices. If the U.S. didn’t ship tubes separately and the glass-based tube was not part of the RCA contract, it certainly would not have been hard for the Soviets to remove tubes from the radio equipment shipped under Lend-Lease and reverse engineer it.” In 2009, the RKK Radio Museum of Veleriy Gromov in Moscow exhibited radios identified as having been provided to the Soviets via various Lend-Lease agreements. One showcase holds a BC-611-B handy-talkie containing the 7-pin miniature tubes developed by RCA. Close examination of Soviet made miniature tubes do show different internal construction details, although by the 1950s, a number of the tubes were carrying dual part numbers that include 1R5, 1T4, 1S5, etc. However, some tubes they made do not have electrically identical specifications to U.S. tubes. Therefore, it seems likely that their “finger lamps” are indeed the
product of reverse engineering. The same could be said for the immediate post-war agreements between RCA and the Soviets, as outlined in a speech by Alex Magoun in 2004: “This [agreement] was apparently signed, and new Russian engineers appeared at RCA’s factories. They gained access to the licensing bulletins and craft knowledge behind RCA’s electron microscope, a device championed by Zworykin as another, more beneficial means of “distant vision;” the latest in cathode-ray tube technologies for radar and television displays; radio-frequency heating for various industrial processes; the beginnings of electronic computer memory; and RCA’s image orthicon, developed for guided missiles during the war and converted to commercial cameras 100 to 1,000 times more sensitive than the pre-war iconoscope. The sale of information and technology came to a halt when the U.S. Commerce Department established an export control system in 1949 to go into effect by midnight, Monday. Between the announcement Saturday and the deadline, an American Amtorg official located a cargo ship and arranged for the loading of $5 million of machinery. This included RCA cameras and electron microscopes, useful in the processing of materials for nuclear weapons. By the time the FBI arrived to impound the goods, the ship was already in international waters.” (Alex Magoun, “Adding Sight to Sound in Stalin’s Russia,” speech presented at the Society for the History of Technology (SHOT), Amsterdam, October 8, 2004).
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but without having slabs to dissect, the method of fabrication could not be determined. A small line drawing appearing in several contemporary articles purports to show a side face of an assembly, but it does not look anything like the photographed assemblies (see Fig. 6). The outside of the cast aluminum core has 14 flats. Each surface is covered by a mica insulating sheet, and one edge of the junction strip is in contact with the mica. This becomes the HOT side of the junctions. Another mica sheet covers the outer face of the junction strip and is in contact with a dual-fin soft aluminum radiator, thus becoming the COLD junctions. A heavy gauge steel U-channel bar clamps the dual-wing radiator fin to the core end caps. There is no evidence of any type of “thermal grease”; that
type of material did not enter the market until the early 1960s. The bottom junction strip pictured in Fig. 6 is part of the 1.2-volt, 300-mA circuit to light the tube filaments. Each junction strip has 18 pairs of hot and cold junctions, and these are mounted to 5 of the 14 flats of the thermopile core. The top junction strip pictured is actually four smaller scale 50-pair junction strips bonded together and connected in series to form the 9-volt bias supply circuit (see Fig. 7). The 90-volt plate circuit supply is made of the same small-scale, 50-junction pairs as the 9-volt bias supply but they are bonded in groups of six and mounted to the eight remaining faces of the thermopile core in the same fashion. There are wedges of corrugated asbestos between each bank of thermocouple slabs. The area between each bank of junctions is
Fig. 6. The two configurations of thermocouples for low- and high-voltage circuits. (Author’s collection)
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topped off with an asbestos-filled caulk. By the nature of this construction, the asbestos is well protected from any possible abrasion. Note the void highlighted by the arrow in Fig. 6. There is a space of about 4 mm between the aluminum central core casting and the bottom heavygauge steel end plate of the thermopile, which forms a necessary thermal break. There was evidence of random gaps in the caulking of the thermal break that would allow flue gasses to condense onto the end connections of the junction slabs. Heavy corrosion is evident at these gaps. It would be interesting to know if this was a common defect such that few or none of these generators actually put into general service are still operational. An article in Radio for September 1956 describing the TGK-10 version of these generators designed to charge the batteries of the KRU-2 “cooperative radio center” states that the thermocouples last for about 4,000 hours
before the internal resistance of the thermopile becomes too high to service the load.14 This referenced 4000 hours would suggest that the generators may have had a practical lifetime of 3 years or less if in continuous service, but that is not necessarily the case. The KRU-2 was initially designed to accept power from a wind generator to charge the batteries, in which case the thermoelectric generator would have been a backup device. An article found on the Internet states that the TZGK-2-2 generator was rated for 5,000-hour service life.15 The article also describes a lower-power generator designated TZGK-9 (9-volt output at 300 mA) with a service life of 10,000 hours, which was developed to power transistor radios. It may not have been produced in significant quantities since rural electrification had grown considerably by the time Soviet transistor radios reached significant production levels. No other references to the TZGK-9 have been found.
Fig. 7. Bundles of TC slabs in groups of 4 and 6. (www.mobipower.ru)
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New old-stock (NOS) TZGK-2-2 generators have been found in South America, Africa and Eastern Europe. These were most likely used at Industrial Trade Shows, available for retail sale and maybe also for distribution as aid to Communist Party affiliated activities. They rarely show up for sale on eBay, but when they do, asking prices are well above $800 and shipping to the United States can add another $250. However, they don’t seem to attract many bids. The TZGK-2-2 and TGK-3 generators are stamped with serial numbers. Images found on the Internet have shown numbers ranging from 43,000 to 84,000. There were also three examples that use a letter plus a 5-digit number. Therefore, something around 50,000 may have been manufactured over a ten-year period. (This does not include other models.)
Conservation and Restoration of the Generator
The TZGK-2-2 generator was in very poor condition when it was acquired, and there was little expectation of being able to make it presentable for exhibition. Resistance measurements revealed that the 9-volt bias-circuit thermocouples were almost open circuited. The 90-volt circuit measured an erratic 20kΩ to 50kΩ and the 1.2-volt circuit measured a few hundred ohms. In order to determine if it was possible to generate an electric current, the 1.2-volt and 90-volt circuits were connected in series, and heat was applied to the core with a 1,100-watt heat gun. After 5 or
10 minutes of blowing heat through the core, the open circuit voltage climbed to about 15 volts. At that point a single white LED was connected to the circuit and the LED did light! But not very brightly. The series resistance of the circuit was simply too high, perhaps due to the heavy corrosion at the ends of the thermocouple slabs. It was clear that restoring the electrical connections would require the total disassembly of a thermopile filled with asbestos sheeting and asbestos filled caulking. The generator certainly appeared to have been in service for a considerable period of time, so that the thermocouples were probably nearing their end of life anyway. Since there was no point in trying to make it service as a practical source of current, the goal changed to preserving the unit as a historical artifact. At the time of acquisition, the lamp burner was heavily rusted with the nickel plating almost completely gone from some parts (see Fig. 8). The rusted kerosene font had a 2mm pin hole rusted in the bottom. The original flue had been replaced by a scrap length of aluminum pipe. The original nickelplated “sash chain” from which the generator hangs was missing and replaced with incorrect welded-link chain. The lamp burner is made of four stampings that are swaged together. Some of the rust could be scraped off to the point that it could be re-plated with nickel, but other parts of the same swaged assembly were so heavily rusted that virtually no good metal existed on which to plate. Consequently, the assembly was scraped and wire brushed,
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cleaned with a solvent in an ultrasonic cleaner, sprayed with a zinc-rich cold galvanize paint, and finished off with a coat of decorative nickel lacquer. The metal around the pin-hole in the bottom of the font was sound enough to scrape down to bare steel, insert a fragment of copper braid into the hole, and flare the braid on the inside by fashioning a steel-rod tool that could be worked from the kerosene filler opening. The braid was then flooded with low-temperature silver solder and the bump was filed down to an almost flush surface. There was no point in filling the lamp since electrical tests indicate that the generator thermocouple connections have corroded to the point it surely cannot deliver the minimum of approximately 1.6 watts to operate the 4 to 6 tube radios intended to be powered by the generator. One can find two versions of the kerosene font on the Internet. One is
silver colored and the other is green. Fortunately there were traces of the original paint visible on perhaps 5% of the font and a few small spots where the remaining paint was thick enough to scrape with a razor knife to reveal the true color. It is a spruce-green enamel that is easy to match with commonly available spray lacquers. There was very heavy rusting on both the nickel-plated steel thermopile end caps and most of the U-channel steel clamp bars holding the radiator fins in place. After soaking the clamp bar screws overnight with Liquid Wrench penetrating oil and using light hammer blows, the screws came loose. Two of the clamp bars still had more than 95% of the original nickel plate, so after cleaning, they were given a coating of high-temperature clear lacquer to attest to the fact that these were indeed originally nickel plated. The other clamp bars were so heavily rusted that they were simply cleaned in an ultrasonic cleaner, sanded level, sprayed with a coat of the cold galvanized paint, and finished with a coat of the decorative nickel colored lacquer. Because of their placement at the bottom of the radiator fins, the difference between the original nickel plate and the nickel colored lacquer is only noticeable under critical inspection. The screws and lock washers were cleaned in the ultrasonic cleaner as well, but as an added step, the parts were then soaked in a Sunbelt Chemicals Corp. SMART #3000 “Rust Converter & Metal Treatment.” This was necessary because the very fine metric threads could not
Fig. 8. Burner made of four swaged stampings, some too rusted to be re-plated. (Author’s collection)
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be cleaned effectively with a wire brush. This phosphate conversion solution produces an excellent bonding surface for primers and paints. The fasteners were coated with a high-temperature clear lacquer before installing the screws, and the screws were then painted with a clear lacquer as they were screwed into the tapped holes of the thermopile end caps. Afterwards, the threads were painted again with the clear lacquer to maximize delay in new rusting. The top of the glass globe was sealed and cushioned by a thick but soft asbestos gasket that was missing. A replacement was fabricated of ceramic fiber matting engineered to replace asbestos in just such applications. Fortunately small sheets are available on e-Bay at low cost. Had the original asbestos gasket remained, it would have to be removed for safety reasons because it is positioned so as to be subject to considerable abrasion every time the generator is disassembled for transport or cleaning—unlike the protected asbestos on the generator radiator fins. The pure aluminum radiator fins were first cleaned in solvent to remove cooking grease and then sprayed with a full strength caustic cleaner named SuperClean “Cleaner-Degreaser.” After a rinse, it was washed down with a cloth saturated in a weak acid solution of sodium bisulphate in water, followed immediately with a hot rinse in tap water and a quick force-dry with a hot air gun. This produces a clear matte finish that must be protected by spraying with high-temperature clear lacquer. Sodium bisulfate in granular form is
added to spas and swimming pools to increase the acidity (lower ph); therefore, it is widely available in retail stores and very inexpensive. While the correct 60-cm top suspension chains were missing, the lower chains, springs, spiral wire rings, and flat rings were present, and although very grimy with cooking grease and rust, they cleaned up well enough. Exact duplicate rings were made for the top suspension chains using a scrap piece of steel salvaged from the cabinet of an old microwave oven and then nickel plated to match the originals. I searched for chain that I eventually learned is called “sash chain.” It comes in three different metal gauge thicknesses. This lamp requires the lightest gauge but is apparently only available in 160 foot long bulk reels at about $95. I opted to spend $24 for a 10-foot length of much heavier gauge chain but of the same pattern and scale. The original sheet metal flue was missing. Photos on the Internet indicate that there were two variations of the flue. One is a rolled sheet of steel riveted closed at one end only, and the other is brass, or possibly steel, thin-wall tubing that is nickel plated. Both styles of flue have rolled beads at each end. Finding the correct metric specification tubing would be difficult here in the United States. Fortunately, a local sheet metal shop had an old bead-rolling tool small enough to do the job with rolled sheet steel. The precise length of the flue is only a guess. There appears to be a variation in length from picture to picture in photos found on the Internet.
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The more than four-meter-long power cord and the termination box are original, but they were in a sorry state requiring radical cleaning, filling of rusted metal with glazing putty, and spray painting (see Fig. 9). The original vinyl insulated wires were filthy, but the vinyl insulation was able to withstand cleaning with the SuperClean brand caustic cleaner. The cable was completely unwrapped to gain access for cleaning. The careful cleaning and application of paints and clear coatings will preserve the appearance for a very long time if exhibited in controlled environments.
More Recent Thermoelectric Generators From time to time in the age of transistor-equipped radios, and in other parts of the world, there have been attempts to make kerosene lantern-powered thermoelectric generators. The argument for this power source is the continuing expense of batteries for radios receiving educational instruction in
areas of extreme poverty. With transistor radios, the generator need only deliver a half a watt of power. From the 1960s onward, developers attempted to use semiconductor base junctions because of their higher efficiencies, but in practice they were apparently not able to develop a cost-effective means of limiting the maximum temperature to which the junctions could be subjected in such lanterns. In bringing these generators to market, there has been little indication that the developers received significant government-sponsored engineering support, subsidized manufacturing, or assistance in distribution, all of which occurred in the former USSR. The net result is that none of the products to date have proved reliable enough or cheap enough to sell into the marketplace. One can search for consumer-grade thermoelectric generators today on the Internet and find a number of products designed to charge cell phones, but in
Fig. 9. The generator termination box duplicates receptacles of standard dry batteries. (Author’s collection)
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evaluating the literature it appears that all these products have the same high vulnerability to excess heat damage. Also, the price of these devices can easily exceed that of a cheap cell phone. Thus, the generators remain more of a novelty for “gadgeteers” with disposable income than a practical solution
for the needy and isolated of the world. However, there are still viable applications for thermoelectric generators. Generators using radioisotopes as a heat source power all deep-space satellites, and there are highly specialized applications for powering remote instrumentation here on earth today.
PART II. SOVIET BROADCAST RECEIVERS POWERED BY THERMOELECTRIC GENERATORS
The second part of this article addresses receivers that could be powered by thermoelectric generators in lieu of a set of non-rechargeable dry batteries. According to the book Reference Broadcasting Receivers, there are at least 12 Soviet battery-powered receivers that were “plug compatible” with the receptacles of the TGK-3 or TZGK-2-2 generators (see Table 1).16 One of these radios now in my collection is a 4-tube Iskra (Искрa)
radio made in 1958 (see Fig. 10), which presents a proper load for the thermoelectric generator described in Part I. The word Iskra translates to Spark, and Spark (1958) is the designation that will be used for this model in the remainder of the paper. Other than having no tubes, this radio is in very good condition with no obvious modifications. Fortunately, the correct Soviet-made tubes were available at a modest cost.
Table 1. Twelve Soviet battery powered receivers that were “plug compatible” with the TGK-3 or TZGK-2-2 generators.
Radio Model a.k.a. Description
Iskra 49 Spark 49 Stamped metal cabinet
Iskra-53 Spark-53 Molded resin cabinet table model
Iskra (1958) Spark (1958) Molded resin cabinet table model
Nov Molded resin midget mantel set
Voronezh Molded resin cabinet portable
Voronezh Molded resin cabinet table model;
3 and 4 button versions
Rodina Wood cabinet table model:
52, 52A, 52M, 52U, 58
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This Spark (1958) receiver released for mass production in 1958 is the second update to the ARZ-49 reference design released for production as the Spark 49. The first radio series designed to be equipped with Soviet-made, battery-powered, 7-pin miniature, all-glass envelope vacuum tubes commonly referred in Russian slang as “finger lamps.” The reference design identified as “ARZ-49” came from engineers and designers at the Alexandrov Radio Factory of the Ministry of Communications Industry of the USSR under the direction of A. K. Kulesheva with the
help of the Institute of Broadcasting and Acoustics, also known as the IRPA (see Fig. 11).17 The ARZ-49 reference design was released for limited production as the Spark 49, the first entry in Table 1. A detailed description of the Spark 49 and a follow-on description of circuit changes made for the Spark-53 update appear in the Russian magazine Radio.18 At the same time, a new set of standardized batteries with an unusual configuration was developed to provide the most efficient powering of the radio for 1,000 hours, then considered
Fig. 10. This Spark battery-powered receiver was made in 1958. Note plugs for connection to standard batteries. (Author’s collection)
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to be about a year of typical use. A few years later, another standardized set of batteries is configured to power these “finger lamp” sets for 300 hours. These were designated as a “holiday pack.”19
The Spark 49 Receiver
The Spark 49 has a three-piece sheet metal cabinet. The front and rear panel were die stamped, and a single folded sheet formed the top, bottom, and sides. Spot welds are used to attach the front panel to the folded sides and small welded brackets support the chassis. For better acoustic properties a thick wood baffle board provides mounting for the loudspeaker. The cabinet is painted in
a textured lacquer to hide sheet metal blemishes. The four-tube superheterodyne circuit uses a 1A1P (1R5) for the mixer frequency changer, 1K1P (1T4) for the intermediate amplifier, 1B1P (1S5) for the detector, AGC and first audio, and a 2P1P for audio power output. (There is no direct U.S. equivalent for the 2P1P.) The tuning range is in two bands: long wave—150 to 410 kHz (2000 to 732 meters) and medium wave—520 to 1600 kHz (577 to 187 m). The performance of the receiver generally meets the electric and acoustic parameters for battery operated broadcast receivers of the 3rd class (the State standard for broadcast receivers GOST 5651-51 effective January 1, 1952).20 In this classification scheme, the “1st Class” receivers were the best with the most features, usually made in limited quantities and often exported to raise hard currency. The 4th Class receivers were the absolute basic 1- to 3-tube “local” receivers and the only ones not using some form of superheterodyne circuit.
Key Spark 49 Receiver Parameters
■ Sensitivity: better than 400 μV. Selectivity at detuning at 10 kHz: 15-20 dB. Image rejection: 20 dB. ■ Rated power to the speaker: 0.15 watt. ■ Acoustic frequency response of the entire receiver path allows the passage of frequencies between 200 and 3000 Hz at no more than 15 dB variation. ■ Harmonic measured sound pressure is not higher than 15%.
Fig. 11. From left to right: V. M. Khakharev, Chief Designer of Alexander radio factory and Stalin Prize winner; I. A. Averin, chief designer; and A. K. Kuleshov, chief designer of the “Iskra” receiver. (Radio, No. 12, 1950)
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■ The AGC allows the output voltage to change by no more than 10 dB when the input voltage changes 26 dB. ■ Filament current: 0.3 A. Anode current: 6 mA with no signal; average: 12 mA.
Spark 49 Schematic
When choosing a receiver circuit, the main focus was on simplicity and reliability of design as well as obtaining sufficiently high electrical parameters and power efficiency. The receiver is a superheterodyne with a rather low intermediate frequency (IF) of 110 kHz. The IF amplifier has the usual dualcircuit input filter and a single-circuit output filter with aperiodic coupling to the detector. A series resonant circuit is connected to the antenna input to suppress the IF frequency. The local oscillator and IF coils have carbonyl iron cores. Surely the most significant functional feature of this receiver circuit is the provision for a “creeping point” bias voltage for the audio output tube. This is achieved by using a copper oxide diode that rectifies a portion of the audio output obtained from the plate circuit of the output tube. The loudness-dependent audio voltage subtracts from the nominal negative 9-volt “C” bias from the battery pack, allowing maximum amplification while significantly reducing the quiescent plate current of the audio output vacuum tube at low volume. This action significantly reduces the perception of background noise in the receiver because, at low audio signal
levels, the gain of the output tube is reduced. The RC time constant of the circuit is such that distortion caused by having the audio abruptly increase without optimum bias is limited to about 10 milliseconds which is said not to be objectionable. The receiver gives undistorted output power of 0.15 W at rated nominal power supply of 90 volts and 1.2 volts. However, to use the pair of “B” batteries to a final voltage of 60 volts and the filament “A” battery to 0.95 volts at the end of its service life, the listener must be content with much lower power of 80 mW. Therefore, the receiver circuit employs a particularly sensitive dynamic speaker, 1GD-2, which develops an average sound pressure of at least 4 bars at a distance of 1 meter with input power of 0.1 W.21
Design Revisions Made for the Introduction of the Spark 53
According to articles in Radio, the metal cabinet of the Spark 49 was replaced by a compression-molded, single-piece cabinet made of a thermosetting resin similar to Bakelite. This same cabinet was also used for the AC-powered Moskovich and again circa 1956 in a demonstration model of a broadcast receiver using Soviet-made transistors.22 The dial scale previously tilted upwards by about 15 degrees was then mounted in the plane of the cabinet front face. Metal tube shields were eliminated, and a two-pin receptacle was added for connection to the “Cable Radio” local network so that the radio loudspeaker could be used to play the
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network audio. There was no switching arrangement within the radio for this input; the listener simply plugged in or unplugged from the receptacle. The “creeping point” bias circuit was revised to employ a third winding on the output transformer to create a bias voltage dependent on the audio signal level that subtracts from the fixed -9 volt bias supply in a presumably more effective manner (see Fig. 12). There were few other electrical circuit
changes made between the two models. However, between 1956 and 1958, the chassis layout and general construction for the Spark-53 was radically revised. This new chassis version was then simply called Spark (again). While the Spark 49 and Spark-53 used traditional coil formers for the RF and oscillator coils, the new mechanical design made use of self-supporting bobbins wound onto thin plastic spools with an internal thread to accept screwdriver-adjustable,
Fig. 12. In the Spark-53 version, a third winding on the output transformer provides the voltage to control quiescent plate current. Also, note primary winding connections for “cable radio” service. (Spark users manual from author’s collection)
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carbonyl-powdered iron cores. These bobbins are cemented on one side to a die-punched, phenol resin-impregnated, paper board sheet about 1.5mm thick that also serves to hold the wave change switch contacts. The same type of self-supporting coil structure is used for the input and output IF transformers.
Observations of My Spark (1958) Manufactured in 1958
Cabinet
The molded phenol resin cabinet is very similar to the Spark-53 but different in that a top-center, front face crest feature
has been eliminated. Examination of this receiver from the opened back shows little that is very surprising to the American eye other than the apparent uncommon structure of the IF transformer and the lack of a metal shell to contain it (Fig. 13).
Welding of Joints – a Surprising Discovery
What really caught my eye is the underside of the chassis. In order to remove the cotton braid that covers the battery supply cable for cleaning, it was necessary to unsolder the connections on the underside of the chassis. I was surprised to find that the (presumed)
Fig. 13. Back cover removed on 1958 version of Spark receiver. (Author’s collection)

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Instruments of Darkness
Instruments of Darkness
The History of Electronic Warfare, 1939–1945
Dr Alfred Price
Frontline Books
Instruments of Darkness The History of Electronic Warfare, 1939–1945
A Greenhill Book
First published in 1967 by William Kimber & Co., London Expanded edition published in 1977 by Madonald and Jane’s Publishers, London
Revised hardback edition published in 2005 by Greenhill Books, Lionel Leventhal Limited www.greenhillbooks.com
This paperback edition published in 2017 by
Frontline Books an imprint of Pen & Sword Books Ltd, 47 Church Street, Barnsley, S. Yorkshire, S70 2AS
For more information on our books, please visit www.frontline-books.com, email info@frontline-books.com or write to us at the above address.
Copyright © Alfred Price, 1967, 1977, 2005, 2017
ISBN: 978-1-47389-564-5
All rights reserved. No part of this publication may be reproduced, stored in or introduced into a retrieval system, or transmitted, in any form, or by any means (electronic, mechanical, photocopying, recording or otherwise) without the prior written permission of the publisher. Any person who does any unauthorized act in relation to this publication may be liable to criminal prosecution and civil claims for damages.
CIP data records for this title are available from the British Library
Printed and bound by CPI Group (UK) Ltd, Croydon, CR0 4YY
FOR JANE
Contents
List of Illustrations 9
List of Maps and Diagrams 10
Foreword 11
Author’s Acknowledgements 15
Prologue 19
Chapter 1 The Battle of the Beams 21
Chapter 2 The Instruments 51
Chapter 3 Discovery 62
Chapter 4 Towards the Offensive 97
Chapter 5 The Coming of the Yanks 109
Chapter 6 Doubts and Decisions 117
Chapter 7 The ‘Window’ Controversy 124
Chapter 8 The Pace Hots Up 135
Chapter 9 Operation ‘Gomorrah’, and After 155
Chapter 10 Approaching the Climax 179
Chapter 11 In Support of the Invasion 207
Chapter 12 The Final Months of the War in Europe 220
Chapter 13 Climax in the Pacific 240
Chapter 14 In Retrospect 251
Appendix A: Main Types of German Surface Radars 259
Appendix B: Main Types of Japanese Surface Radars 261
Appendix C: Air Forces, Equivalent Ranks 264
Glossary: Code-Names, Equipment Designations
and Unit Terms 265
Index 269
Illustrations
The airship LZ-130 Graf Zeppelin (Breuning) 81 Dr Ernst Breuning (Breuning) 81 Knickebein transmitter (Trenkle) 82 Heinkel 111 with Y-Gerät equipment (von Lossberg) 82 Wing Commander Edward Addison (Addison) 82 Heinkel 111 of Kampfgruppe 100 (Trenkle) 83 X-Gerät beam transmitter (Trenkle) 83 Dr R. V. Jones (Jones) 83 The Graf Spee and its Seetakt radar (IWM) 84 Reconnaissance photo of Auderville radar station (IWM) 84 Freya radars at Auderville (IWM) 84 Messerschmitt Bf 110 with Lichtenstein radar (Trenkle) 85 Wassermann early-warning radar at Bergen aan Zee (Chisholm) 85 Derek Jackson (Jackson) 85 Würzburg radar (Trenkle) 86 Generalmajor Josef Kammhuber (Studiengruppe der Luftwaffe) 86 Bruneval radar station (IWM) 86 Giant Würzburg radar on the island of Walcheren 86 (Crown Copyright)
German radar site with barbed-wire defences 87 (Crown Copyright) Himmelbett station (Heise) 87 H2S radar picture and map of Hamburg (Crown Copyright) 88 H2S indicator on a Lancaster bomber (Crown Copyright) 88 Aerial of a Korfu ground direction-finding station (Cockburn) 89 Generalfeldmarschall Erhard Milch (Milch) 89 Oberst Dietrich Schwenke (Schwenke) 89 Generalmajor Joseph Schmid (Studiengruppe der Luftwaffe) 90 Major Hajo Herrmann, with Hermann Göring (Herrmann) 90 Lancaster bomber over Berlin, 16 December 1944 (IWM) 90 B-17 Flying Fortress jamming escort aircraft (IWM) 91 Dr Robert Cockburn (Cockburn) 91 ‘Jostle’ communications jammer (IWM) 91 Junkers 88 night-fighter with SN-2 radar (Crown Copyright) 92
Upward-firing 20-mm cannon in a Junkers 88 (Chisholm) 92 Tail-mounted aerial for SN-2 radar in a Junkers 88 92 (Crown Copyright)
Jagdschloss fighter-control radar (Trenkle) 93 ‘Mandrel’ jamming on a Jagdschloss radar (Trenkle) 93 B-17 bombers being engaged by a flak battery (USAF) 94 The APQ-9 ‘Carpet III’ jamming equipment (USAF) 94 ‘Tuba’ jamming equipment (USAF) 95 B-29 bombers on one of the Marianas islands (USAF) 95 B-29 ‘Guardian Angel’ jamming escort aircraft (USAF) 96 ‘Little Boy’, the atom bomb dropped on Hiroshima (USAF) 96
Maps and Diagrams
The Lorenz Beam 23 Knickebein beam stations 38 X-Gerät beams during the attack on Coventry 44 The Seeburg Table 57 Himmelbett fighter control stations 60 The ‘Oboe’ system 120 Buck Ryan 128 ‘Serrate’ picture 145 Attack on Hamburg: 24/25 July 1943 159 Attack on Kassel: 3/4 October 1943 180 Attack on Nuremburg: 30/31 March 1944 201 The ‘Ghost Fleet’ 212 Deception operations: night of 5/6 June 1944 215 The Klein Heidelberg system 223 Attack on Bohlen: 20/21 March 1945 234 The Bernhard display 239
10 Illustrations
Foreword
by Sir Robert Cockburn, KBE, CB
(Written in 1967)
World War II was dominated by air power, which permeated every phase of the conflict. The aircraft became a major instrument of offence and defence in the air and a vital weapon in support of ground forces, in maritime warfare, in reconnaissance and in transport. This expansion of air power was stimulated by, and became critically dependent on, a series of remarkable developments in the fields of radar and radio communications. Both sides committed large resources to successive systems of early warning and detection, navigation, target identification and weapon guidance. Under the stimulus of war, technology advanced rapidly and each new system provided greater range, greater precision and greater capacity. Yet by modern standards they were still relatively naïve in concept and were soon found to be vulnerable to interference, deception and manipulation. It was a rude shock to designers to discover how quickly performance demonstrated in the laboratory was nullified in operation against a resourceful enemy; and as the war progressed scientists and engineers pitted their wits against one another to preserve their own systems, and to discover and exploit the weaknesses in those of their opponents. It is this story which Alfred Price describes in Instrument of Darkness.
Alfred Price is a serving officer in the Royal Air Force, at present with Bomber Command; and he has been able to recapture the excitement and drama of a struggle in which new techniques and tactics could have such immediate and catastrophic consequences. But he is also an electronics specialist well qualified to deal with the technical aspects of his subject and to appraise the relative importance of the various countermeasures of World War II. Rarely before or since has it been possible for the scientist in the laboratory to make such a direct impact on military operations. A few black boxes based on a new piece of intelligence, a revealing reconnaissance photograph or observations by a returning bomber
12 Foreword
crew could within a few weeks or months affect the fate of cities and the lives of hundreds of aircrew. Not all black boxes were equally effective; some were at best of psychological value, some were a temporary nuisance, and some were not only useless but positively dangerous. In the heat and fog of war any opportunity, however slight, must be exploited, but in retrospect it is clear that clever devices and adroit tactics were usually of limited value. Trivial weaknesses in a system were easy to exploit but equally easy to remedy, and over-sophisticated jamming and warning methods were incompatible with the nightly holocaust over German targets. Subtle countermeasures like ‘Moonshine’ were effective for special operations where surprise could be exploited, and they played an important part in the spoof invasions of the Pas de Calais. But it was straightforward noise jamming and the massive use of ‘Window’ which was most effective in sustained operations. Alfred Price has profited by the lapse of twenty years to put his story of World War II into perspective. He has gone to a lot of trouble to present at each stage both the British and the German story, and he shows how closely developments on one side were matched on the other. There was, for example, the extraordinary similarity in the evolution of British ‘Window’ and German Düppel. Nowadays it is accepted that major technical advances will occur almost simultaneously in a number of countries, even in highly classified military projects. In peacetime the time scale of development is long enough that a year either way in producing a new weapon may not seriously affect the issue, but in war six months can make the difference between victory and defeat; and it was by such narrow margins that the outcome of the Radio War was determined. Both sides entered the war believing that they possessed in radar a unique advantage over the other; and neither foresaw the profound effect that this scientific breakthrough would have on air operations. In 1940 our own radars were in many respects inferior to the Freya and the Würzburg, and we had no bombing and navigation systems to compare with the Knickebein beams and their successors. At the end of the war the Germans were introducing, well ahead of the Allies, a range of guided weapons, including the pilotless aircraft V-1 and the ballistic missile V-2. But the German High Command did not properly appreciate the pace of development or its inevitable
Foreword 13
impact on operations. For two critical years they failed to maintain the momentum of research in radar, and rapidly lost their initial advantage. By the end of the war British and American equipments were far superior both in performance and in range of application; and the German guided weapons came too late to redress the balance. In particular we were quicker to recognise and exploit the intrinsic vulnerability of radar and radio systems, and the initiative in the jamming war lay firmly in our hands. The importance of the electronic environment not only to aircraft and guided weapons but to the whole range of military operations is now well understood; and one of the most important criteria of any radar or radio system is the ability to discriminate against unwanted and irrelevant information. Vulnerability can be theoretically specified, and allowed for. Nevertheless, jamming and deception are always possible, with sufficient effort. Ideally an economic balance should be struck between complexity and vulnerability, so that the cost of nullifying a system is comparable to the cost of establishing it. But this condition can seldom be met in practice, and Alfred Price’s book is a salutary reminder that the impressive panoply of modern weapons is dependent ultimately on the survival, in war, of their guidance and control systems.
Author’s Acknowledgements
First Edition
In writing Instruments of Darkness I have been greatly helped and encouraged by the many busy men who have unhesitatingly given me their valuable time: to all of them I tender my grateful thanks. Space does not allow me to mention each one by name, but I am particularly indebted to Sir Robert Cockburn, Professor R. V. Jones, Professor D. A. Jackson, Air Marshal Sir Robert Saundby, Air ViceMarshal E. B. Addison, Air Commodore Chisholm, Dr B. G. Dickins and Mr J. B. Supper and, in Germany, the Studiengruppe der Luftwaffe, the Telefunken Company and Herr Hans Ring. I should like to thank Sir Donald MacDougall for allowing me access to Lord Cherwell’s papers and Mr. R. Bruce and Mr. C. Moore for allowing me to examine documents under their control. Also I am indebted to Mr. L. A. Jackets and the staff of the Air Historical Branch for much of the material I have used. I must stress, however, that I alone am responsible for the opinions expressed. My thanks go to Her Majesty’s Stationery Office for permission to quote from The Strategic Air Offensive Against Germany 1939–1945 by Sir Charles Webster and Noble Frankland. I should also like to thank Messrs. Cassell and Co. for allowing me to quote from Winston Churchill’s The Second World War; Messrs. Methuen and Co. for permission to quote from The First and the Last by Adolf Galland; Group Captain J. R. D. Braham for the use of the passage from his autobiography Scramble; and the proprietors of the Daily Mirror for permission to reproduce the Buck Ryan cartoon strip. I should like to record my debt to my wife, who gave valuable support when the going was tough, and my mother, who helped with the German translations.
16 Author’s Acknowledgements
This Edition
In the thirty-seven years since the initial appearance of this book, important additional material has become available. This completely revised edition takes the story up to the time of the Japanese surrender in August 1945, and details the huge US efforts in this area in both the European and the Pacific theatres of operations. I am grateful to the Association of Old Crows, Washington DC, for permission to use material from Volume 1 of The History of US Electronic Warfare, which I wrote to their commission. On a sad note, I must mention that almost all of the men and women I interviewed for this book are no longer alive. Let these pages serve as a memorial to their achievements.
‘The instruments of darkness tell us truths,
Win us with honest trifles, to betray’s
In deepest consequence.’
Shakespeare, Macbeth
Prologue
On the evening of 2 August 1939 the giant airship LZ130 Graf Zeppelin lifted off from her base at Frankfurt-am-Main and climbed slowly into the night sky. Leaving the German coast near Cuxhaven, she rumbled out over the North Sea heading for a designated search area off the coast of Great Britain. The LZ130, last of the long line of rigid airships built in Germany, had been designed to fly on the trans-Atlantic passenger service in conjunction with her sister ship, the LZ129 Hindenburg. Before the new airship was completed, however, Hindenburg came to a fiery end. With her died the notion of the airship as a passenger-carrying vehicle. For a time, Graf Zeppelin had no formally assigned role. Then, in the spring of 1939, she was modified for a quite different task. If war came, Luftwaffe intelligence officers would need to know the use potential enemies made of the radio spectrum for communications, navigation and even radar systems. Without such knowledge, and the method of operation and location of these systems, countermeasures would be impossible. Graf Zeppelin’s luxurious passenger compartments now carried a battery of radio receivers and a team of signals experts to operate them. The airship was the world’s first airborne electronic intelligence, or Elint, collector. From April 1939 the Graf Zeppelin flew a series of missions along Germany’s eastern and western frontiers, hunting for radio and other signals of interest emanating from neighbouring countries. On 12 July she ventured over the North Sea, and reached a point about a hundred miles off Middlesborough before turning for home. The mission on 2 August was a more determined attempt to examine the radio spectrum in the skies around Great Britain. For that mission the airship carried a crew of forty-eight, who included a twenty-five-strong team of radio specialists under the command of Dr Ernst Breuning. The airship crossed the North Sea and flew close to the east coast of Scotland, taking care to remain outside territorial waters. She then turned around and flew southeast down the coast to a point abeam Lowestoft, before returning to Germany.
While the Zeppelin was within their cover, Britain’s newly erected line of ‘Chain Home’ radars reported her every move. When she passed Aberdeen an RAF Magister training plane took off to get a closer look at the airship, and for a time flew in formation with her. Given the amount of British radar activity over the North Sea, it is surprising that the radio operators aboard the Zeppelin failed to identify British radar signals. Interviewed in 1969, Ernst Breuning told the writer that his team had concentrated their search on the radio spectrum above 100 MHz. That was where early German radars operated, and it seemed reasonable to expect that British radars might do the same. In that part of the spectrum the listeners found none of the expected pulsed radar signals. They did, however, hear transmissions from the new VHF radios being developed in Britain for the RAF. Breuning and his team did make a cursory search in the 20–50 MHz band – which was in fact that part of the spectrum where the early British radars operated. There the listeners found some pulsed signals, but these were discounted. The transmissions sounded just like those picked up during earlier flights, identified as coming from a station in Germany conducting experiments to measure the altitudes of the layers of ionised gas that surround the earth. Missing the British radar signals was an easy enough mistake, given that the German radio operators were learning the rudiments of Elint ‘on the job’ and their receivers had not been designed for this task. Graf Zeppelin’s marathon flight lasted 48 hours and covered a distance of 2,600 miles. It was the longest she would ever make. Less than a month after she returned from her sortie, on 1 September 1939, Germany invaded Poland. Within a couple of days, Great Britain and France entered the conflict in support of their eastern ally. With a major war on its hands, the Luftwaffe saw no further role for the big airship and she was scrapped. Graf Zeppelin’s unsuccessful missions off the coast of Great Britain are of historical interest only, for they achieved little of military value. Yet the notion of searching the radio spectrum for enemy or potential enemy signals, as a prelude to countering them, was an idea whose time had come. The airship’s flights marked the first tentative steps in a completely new form of warfare, one whose significance both sides would quickly learn.
20 Instruments of Darkness
Chapter 1
The Battle of the Beams
‘During the human struggle between the British and German air forces, between pilot and pilot, between AA batteries and aircraft, between ruthless bombing and the fortitude of the British people, another conflict was going on step by step, month by month. This was a secret war, whose battles were lost or won unknown to the public; and only with difficulty is it comprehended, even now, by those outside the small high scientific circles concerned.’
Winston Churchill, Their Finest Hour
The truth about military intelligence work is that much of its success depends on chance, and much upon tenacity. Little of it is glamorous in the way that readers of espionage thrillers would believe. In the case of a secret device to guide bombers to targets, for example, in time of war it is usually only a matter of time before an aircraft carrying it is shot down and falls in hostile territory. Then, a diligent examination of the wreckage should reveal its existence and survivors, perhaps still shaken after narrow escapes, may be induced to talk under interrogation. Aircrew cannot be expected to memorise detailed lists of radio frequencies, callsigns and the geographical positions of beacons. If that information is to be used in the stress of action, it has to be written down and taken on the sortie. Sooner or later, one of those briefing sheets is bound to be captured. If the system involves radio beams, those investigating it have another clear advantage: such beams cannot be concealed. One has only to look carefully enough and they will be found. Once the transmissions are found, they can be analysed and their purpose deduced. Thus, a handful of intelligence officers can have a bearing on the conflict that is out of all proportion to their numbers. This was why, on the night of 21 June 1940, Flight Lieutenant Harold Bufton came to be patrolling in the darkness over East Anglia in a twin-engined Anson aircraft. In the rear cabin his wireless
operator, Corporal Dennis Mackey, carefully searched the ether with his radio receiver. Suddenly Mackey found what he was looking for: a series of Morse dots, sixty to the minute, piercingly clear in his headphones. As the Anson continued on its heading, the dots merged into one steady note. A little later, the steady note broke up, not into ‘dots’ but into Morse ‘dashes’ at the same steady rate of sixty to the minute. Later in the flight, a second radio beam was located. After he landed at his base at Wyton, Bufton reported:
1. There is a narrow beam approximately 400–500 yards wide, passing through a position one mile south of Spalding, having dots to the south and dashes to the north, on a bearing of 104° to 284° True. 2. That the carrier frequency on the night of 21st–22nd June was 31.5 mc/s, modulated at 1,150 c/s and similar to Lorenz in characteristics. 3. That there is a second beam having similar characteristics but with dots to the north and dashes to the south synchronised with the southern beam, apparently passing through a point near Beeston on a bearing lying between 60° and less than 104°.
In terms of the effort involved, the flight of the Anson with the two-man crew was far removed from the Graf Zeppelin’s abortive Elint collection mission off the coast of Great Britain almost a year earlier. Yet in intelligence collection, success is often unrelated to effort involved. The Anson had located a couple of radio beams emanating from Germany, which intersected over the important Rolls-Royce aeroengine factory at Derby. It was a highly significant discovery.
***
To observe the background of that discovery, we need to look briefly at some scientific developments that had taken place in Germany in the early 1930s. There the Lorenz Company had developed a blindapproach system to help aircraft find airfields in bad weather. The so-called ‘Lorenz System’ used two adjacent radio beams to mark a path extending up to thirty miles from the airfield. In the lefthand beam Morse dots were transmitted, and in the right-hand beam Morse dashes. The signals interlocked, so that where the two beams overlapped a listener heard a steady note. Aircraft navigated
Instruments of Darkness
22
by flying down the steady-note zone until they came to the beams’ transmitter. By the mid-1930s the Lorenz system was in widespread use by civil airlines and some air forces. The Royal Air Force used it, as did the Luftwaffe. In Germany Dr Hans Plendl, a specialist in radiowave propagation, then adapted the Lorenz system to assist aircraft to attack accurately at night or in bad weather. This system became the X-Gerät (‘X-device’) which employed six Lorenz-type beams. Marking the approach to the target were three such beams, one coarse and two fine, all transmitted on different frequencies and all pointing straight at the target. The other three beams crossed the approach beams at three points leading up to the bomb-release point. The X-Gerät radio beams were transmitted on frequencies between 66 and 75 MHz (see map on p. 44).
A bomber using X-Gerät followed the approach beam to the target. When it was 50 km (30 miles) from the bomb-release point, the aircraft flew through the first crossbeam. That served as a warning that it was time to line up accurately in the approach beam. When it was 20 km (12 miles) from the bomb-release point, the aircraft flew through a second crossbeam. As it did so, the navigator pressed a button to start one hand of a special clock, similar to a stopwatch but with two hands that rotated independently. When the bomber was 5 km (3 miles) from the bomb-release point, it passed the third and final crossbeam. When he heard the steady-note signals from
The Battle of the Beams 23
The Lorenz Beam
that beam, the navigator pressed the button on his special clock a second time. The hand which had been moving stopped, and the other hand started rotating to catch it up. The distance from the second crossbeam to the third crossbeam was three times that from the third crossbeam to the bomb-release point (5 km or 3 miles), so the second hand on the clock travelled three times faster than the first. When the hands coincided, a pair of electrical contacts closed and the bombs were released automatically. All in all this was a sophisticated system, considering that it had been produced before World War II. The combination of the clock and the beams provided accurate data on the bomber’s speed over the ground, one of the most important facts to be known for accurate bombing once an aircraft was routed correctly over the target. The Luftwaffe established a special unit to operate with X-Gerät, No. 100 Air Signals Battalion (Luftnachrichten Abteilung 100) based at Köthen near Dessau and equipped with Junkers 52s and Heinkel 111s. Meanwhile Telefunken, a competitor of Lorenz, had produced another blind-bombing system for the Luftwaffe. Called Knickebein (‘Crooked Leg’) this system was much simpler than X-Gerät and it employed only two Lorenz beams. One beam marked the approach to the target, the other crossed the first beam at the bomb-release point. The system was less accurate than the X-Gerät, but it had two major advantages over it. Firstly, the device used the same frequencies – 30, 31.5 and 33.3 MHz – as the Lorenz airfieldapproach receiver fitted as standard in all German twin-engined bombers, so that receiver could pick up the Knickebein signals, and there was no need for the bomber to carry specialised equipment. Secondly, crews trained in the use of the Lorenz airfield-approach receiver could fly the Knickebein beams without further training. Thus Knickebein could be used by the entire Luftwaffe bomber force and not just part of it. The aerial array necessary at the Knickebein ground transmitter was a huge structure, more than 100 feet high and 315 feet wide. The whole thing rested on railway bogies running on a circular track, to allow the beam to be aligned accurately on the distant target. The system’s range depended on the altitude of the receiver aircraft: a bomber at 20,000 feet could receive the signals from a transmitter 270 miles away. The steady-note lane was one-third of
Instruments of Darkness
24
a degree wide, giving a theoretical accuracy of one mile at a distance of 180 miles. By the end of 1939, the Luftwaffe had erected three Knickebein transmitters to cover potential targets in Great Britain and western Europe. One was at Kleve close to the Dutch frontier, a second was at Stollberg in Schleswig-Holstein, and a third was at Lörrach in the southwest corner of Germany. Towards the end of 1939, No. 100 Air Signals Battalion was redesignated Kampfgruppe 100 (KGr 100) and now possessed twentyfive He 111s fitted with X-Gerät. During the campaigns in Norway and France, however, the unit did not use its night precision-attack capability and operated as a normal day-bombing unit. However, soon after the Allied evacuation from Dunkirk in June 1940, Luftwaffe signals personnel began erecting Knickebein and X-Gerät transmitters in Holland and northern France as part of the preparations for attacks on Great Britain.
***
Until the spring of 1940, the RAF had not considered it likely that German night bombing attacks would prove a serious threat. The general view was that the darkness that hid the bombers from the defences would also hide the targets from the bombers. Dr R. V. Jones, a scientist who a few months earlier had taken up a post at the Directorate of Intelligence at the Air Ministry, had a wide remit. His task was to determine which scientific developments taking place in Germany might affect the air war. He began receiving clues from various sources which suggested that the Luftwaffe possessed, or would soon possess, a radio system to guide bombers to their targets at night or in bad weather. In March 1940, an He 111 bomber crashed in England. In the wreckage, searchers found a scrap of paper which stated:
Navigational aid: radio beacons working on Beacon Plan A. Additionally from 0600 hours Beacon ‘Dunhen’. Light beacon after dark. Radio beacon ‘Knickebein’ from 0600 hours on 315°.
At about the same time, a prisoner admitted under interrogation that Knickebein was ‘something like the X-Gerät’, about which he assumed his captors already knew. He said that a beam was sent from Germany which was so narrow that it could reach London with
The Battle of the Beams 25
divergence of no more than one kilometre (the prisoner had exaggerated the fineness of the beam, though Jones had no way of knowing this). Two months later, the diary of a German airman was found in the wreckage of another He 111. Under 5 March it carried the significant entry:
Two-thirds of the Staffel on leave. In the afternoon we studied Knickebein, collapsible boats, etc.
From these snippets of information Jones deduced that Knickebein – and the X-Gerät which was ‘something like’ it – might be some sort of directional radio beam. The bearing of 315 degrees might point from the northwest coast of Germany to Scapa Flow, an area where Luftwaffe bombers had been active. What seemed unbelievable was the prisoner’s assertion that a radio beam from Germany to London – a minimum distance of 260 miles – could have a divergence of only one kilometre. In fact the prisoner had exaggerated: the beam’s divergence at that distance would have been nearly 11⁄2 miles. By now the Government Code and Cipher School at Bletchley Park was starting to produce a useful stream of decrypts of German radio signals transmitted in high-level Enigma ciphers. One such signal, picked up on 5 June and decrypted four days later, stated: ‘Knickebein at Kleve is confirmed [or established] at point 53° 21' N, 1° W.’ The signal had come from the Chief Signals Officer of Fliegerkorps IV and it seemed that the position, near Retford in Nottinghamshire, might be the location of an illicit radio beacon. A search of the area produced nothing but, significantly, the signal gave the location of a Knickebein. For, apart from being the home of the fourth wife of King Henry VIII, the town of Kleve lay at the part of Germany closest to Great Britain. The next logical step was to examine the radio equipments carried by the He 111 bomber, since this aircraft was linked with each intelligence report on Knickebein. Did it carry any device that could receive beam signals at long range? In October 1939, an He 111 had crash-landed near Edinburgh. At Farnborough, technicians had carefully dissected and analysed each item of the plane’s equipment. At the time they noted that the plane’s Lorenz blind-approach
Instruments of Darkness
26
receiver was far more sensitive than its British counterpart. Might this be the device that picked up the long-range beam signals? At first sight it might seem a simple matter to find out whether the Luftwaffe possessed a long-range radio-beam system. A few flights by aircraft carrying search receivers would settle the matter. But Jones was young and recently appointed and had no such aircraft under his control. Also, he knew he had to play his cards carefully. Jones saw his position as being analogous to that of a watchdog. He had to bark when he saw danger, but if he barked at the first whiff of trouble and none was subsequently revealed, people would learn to disregard his cries. On the other hand if he barked too late, the Luftwaffe could strike unhindered. There could be no mistaking the gravity of the situation, if the Luftwaffe really did possess an accurate method for attacking targets by night at a time when Britain’s air defences were ineffective. There was one man who could secure for Jones the influential backing he needed, and upon whom he could rely for a sympathetic hearing: his tutor at Oxford before the war, Professor Frederick Lindemann. Frederick Lindemann and Winston Churchill had been close friends since 1919, and when Churchill became prime minister in May 1940 the association continued. For all his superlative qualities as a war leader, Churchill had little grasp of scientific matters and he relied heavily on Lindemann to explain these to him. Clearly, if Jones could convince Lindemann of the possible danger of the Luftwaffe radio beams, his battle would be half won. On 12 June Lindemann sent for Jones to discuss another matter. At the end of the conversation, Jones steered the discussion round to Knickebein. Lindemann was unimpressed, however. He said he could not believe that a long-range beam on a frequency of around 30 MHz – the part of the spectrum covered by the Lorenz blindapproach receiver – would bend to follow the curvature of the earth. At that time such signals were thought to travel almost in a straight line, which limited their effective range to about 180 miles if the receiving aircraft was flying at 20,000 feet. That fell far short of the 260-mile range necessary to reach London from the nearest point in Germany. On the day after the unsuccessful encounter, Jones returned to Lindemann’s office carrying an unpublished paper he had discovered. Its author was Thomas Eckersley, scientific advisor to
The Battle of the Beams 27
the Marconi Company and a leading authority on the propagation of radio waves. The paper contained a series of graphs to illustrate the maximum ranges at which radio signals on various frequencies could be received. By taking the extreme end of one of the curves, it looked as if signals on 30 MHz might be picked up by an aircraft flying at 20,000 feet over much of England, provided the transmitter was situated on high ground in Germany. That satisfied Lindemann, who immediately wrote to the Prime Minister:
There seems to be some reason to suppose that the Luftwaffe have some type of radio device with which they hope to find their targets. Whether this is some form of RDF [radar] . . . or some other invention, it is vital to investigate and especially to seek to discover what the wavelength is. If we knew this, we could devise means to mislead them; if they use it to shadow our ships there are various possible answers . . . If they use a sharp beam this can be made ineffective. With your approval I will take this up with the Air Ministry and try to stimulate action.
Before passing the note to Sir Archibald Sinclair, his Secretary of State for Air, Mr Churchill jotted a brief comment at the bottom: ‘This seems most intriguing and I hope you will have it thoroughly examined.’ Now Jones had the big guns firing for him. Sinclair acted promptly and on the following day, 14 June, he placed Air Marshal Sir Philip Joubert in charge of the investigation. On that very day RAF interrogators were questioning another prisoner, who stated that Knickebein was a bombing device involving two intersecting radio beams which could be picked up by the aircraft’s Lorenz receiver. He added that bombers had to fly very high to pick up the beam signals at long ranges. For example, to receive the signals over Scapa Flow the aircraft had to be above 20,000 feet. Jones observed that from Scapa Flow to the nearest point in German-controlled territory – in western Norway – was 260 miles. That was exactly the same distance as from London to the nearest point in Germany. This intelligence was available in time for a meeting Air Marshal Joubert had called for 15 June, attended by Lindemann and Jones. Now there was sufficient evidence to justify bringing more people into the picture, and Joubert summoned a further meeting for the
Instruments of Darkness
28
following afternoon. In addition to Jones the attendees included Air Chief Marshal Sir Hugh Dowding, C-in-C Fighter Command, and Air Commodore Charles Nutting, the RAF Director of Signals. Jones recounted the available evidence, and it was decided to fit special radio receivers to aircraft to hunt for the beams. Three Avro Anson general-purpose aircraft would be made available, and work began immediately to fit them with the necessary radio receivers. Squadron Leader Rowley Scott-Farnie, representing the RAF signals intelligence service at the meeting, opined that the beams would probably be found on a frequency of 30, 31.5 or 33.3 MHz. He said that every Lorenz receiver found in a wrecked Luftwaffe aircraft was tuned to one of those three frequencies. On the following Tuesday, 18 June, fresh evidence arrived in a miscellany of papers salvaged from a German aircraft shot down in France some weeks earlier. On one of them was written:
Long-range radio beacon = VHF 1. Knickebein (near Bredstedt, north-east of Husum) 54° 39' 8° 57' 2. Knickebein (near Kleve) 51° 47' 5" 6° 6'
That served to confirm some of the earlier pieces of information on Knickebein. If those were the locations of two Knickebein transmitters, that would make sense. Those positions were at points in Germany among the closest to England, but they were well separated to give the greatest possible ‘angle of cut’ between a pair of beams. Jones noted that Scapa Flow lay on a bearing of 315 degrees from Bredstedt, which explained the earlier reference. As if more proof were needed, a wrecked Heinkel provided a further clue. The wireless operator’s log had been recovered intact and it included a list of known radio beacons. At the head of the list was a jotted entry: ‘Knickebein Kleve 31.5’. Each of the other beacons was followed by a radio frequency, and the RAF listening service confirmed that the list was correct for the night in question. It was therefore reasonable to assume that the Knickebein at Kleve had on that night been radiating on 31.5 MHz. That fitted in with Scott-Farnie’s prediction.
The Battle of the Beams 29
That evening, 19 June, an Anson took off on the first flight to search for beam transmissions; its receiver developed a fault, however, and the radio operator heard nothing. On the next night, the 20th, another Anson flew a patrol to look for beams but found nothing – the Luftwaffe had stayed at home. Even as that aircraft was airborne, however, an RAF intelligence officer was literally piecing together another clue. A Luftwaffe wireless operator had baled out of his crippled aircraft over England. Soon after landing the airman, more conscientious than many of his compatriots, realised he still had his notebook. He carefully tore it into more than a thousand pieces, but as he attempted to bury them he was captured and the pieces were recovered. The reward of much hard work was a table of data, which confirmed the positions of the Kleve and Bredstedt transmitters and the operating frequency of the former; it also gave the frequency of the latter as 30 MHz. Thus, by the morning of 21 June, R. V. Jones had established the positions and frequencies of two of the Knickebein transmitters. The findings were timely, for that very morning Churchill decided to summon a top-level meeting at No. 10 Downing Street to discuss the latest intelligence on the German radio beams. Among those present were Sir Archibald Sinclair (Air Minister), Lord Beaverbrook (Minister of Aircraft Production), Professor Lindemann, Sir Cyril Newall (Chief of Air Staff), Sir Hugh Dowding and Sir Henry Tizard (Scientific Advisor to the Air Staff). When Jones arrived, the meeting had already started. He arrived to find a discussion in progress on whether aircraft could in fact be guided by long-range radio beams. Both in rank and age, Jones was by far the most junior person present. He sat there waiting to be asked to speak, and after a few minutes the Prime Minister questioned him on a technical point. That was the excuse Jones had been waiting for and he asked ‘Would it help, sir, if I told you the story from the start?’ Churchill said it would, and Jones recounted various pieces of evidence supporting the theory that the Luftwaffe possessed a system of radio beams to direct bombers on to targets. That convinced the meeting that here was a matter worthy of further investigation. The axis of the discussion shifted from ‘Do the German radio beams exist?’ to ‘How can we find out more about them?’ That afternoon Air Commodore Nutting summoned Jones and Eckersley to his office, to discuss the technical details of the beam
Instruments of Darkness
30
transmissions that might be used by Luftwaffe bombers over England. Then Eckersley dropped his bombshell: despite the series of graphs he had previously drawn, he said he could not agree with the widely held explanation of Knickebein. He said he did not believe that radio signals on 30 MHz would bend to follow the curvature of the earth. Jones pressed Eckersley to explain why he had produced the set of graphs upon which he, Jones, had relied so heavily in the Cabinet Room that morning. Eckersley renounced them, saying they applied to a different case when he had tried to stretch his theory. The feelings of Jones can be imagined more readily than described, since he had used Eckersley’s graphs to convince Lindemann that a long-range beam following the curvature of the earth was a possibility. Obviously someone was barking up the wrong tree; Jones could only hope it was not himself. (In fact partial bending to conform with the earth’s curvature does occur with transmissions on 30 MHz, but its extent was not realised in Britain at the time.) While Jones pondered on this unexpected development, the hunt for the beam signals continued. That very night, the patrol by Bufton and Mackey picked up the German beam transmissions over the Midlands, as described at the beginning of this chapter. Appropriately, given the seriousness of the new threat, the RAF code-named the beam system ‘Headache’. It fell to Air Commodore O. G. Lywood to initiate countermeasures. Wing Commander Edward Addison, one of Lywood’s staff officers, latter recalled:
One day he [Lywood] called me in and told me that a young fellow from scientific Intelligence called Jones had produced an extraordinary story of the Luftwaffe using a beam over this country to bomb London. It was known as Knickebein. He said: ‘I can’t tell you how he came by this information, but he has. It looks extremely dangerous. What do you think we ought to do?’
Addison suggested the formation of a specialised organisation to counter the German beams. Lywood agreed, and placed Addison in charge. Addison’s new unit, No. 80 Wing, was hastily established and set up its headquarters at Garston near Radlett in Hertfordshire. Thing were now moving ahead rapidly, but one further element of the defences was required. There needed to be an organisation
The Battle of the Beams 31
to build the specialised jamming devices to render the German beams unusable. That task fell to Dr Robert Cockburn, a young physicist who had recently joined the Telecommunications Research Establishment (TRE) at Swanage. He and a small team began work to design and build tailor-made jammers to counter Knickebein. The process of building specialised jammers would take time, however, and time was short; an all-out bombing offensive on Great Britain might begin any day. Accordingly, Addison requisitioned several diathermy sets (devices used in hospitals to cauterise wounds) and had these modified into crude spark transmitters to transmit a ‘mush’ of radio noise on the Knickebein frequencies. RAF personnel installed the diathermy jammers in selected police stations, where the duty constable had instructions to switch them on when instructed to do so from No. 80 Wing headquarters. Addison also secured some RAF Lorenz airfield beam-approach transmitters and modified these to radiate a beam similar to that put out by Knickebein. His idea was to produce a fake beam that could be laid across the German beam, in the hope that the German bombers might wander off course without the crews noticing it. Monitoring flights revealed that the deviation produced by the lowpowered device was negligible. Nevertheless, in the interests of getting countermeasures up and running as soon as possible, a few of these systems went into service with No. 80 Wing. An important component of the new wing was the flight of Anson aircraft commanded by Squadron Leader R. Blucke, which now flew patrols each night to determine the directions and crossing points of the German beams. Initially this unit operated under the cover name of the Blind Approach Training and Development Unit (BATDU for short). In September 1940 the unit was renamed the Wireless Intelligence Development Unit (WIDU), but its work continued exactly as before. Soon after the Anson aircraft had first picked up Knickebein signals, the RAF listening service discovered that suitably equipped ground stations could also receive these signals. Several outstations were now set up, which passed information on the beams’ frequencies and of their dot or dash transmissions to No. 80 Wing headquarters where they were plotted out on a special map. Those ground stations alone could not provide an exact picture of the German beam patterns. Yet they provided a useful cue for the Ansons
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to get airborne, and greatly narrowed the search area for their crews to hunt for the beams’ steady-note lanes. To underline the increasing potency of the new threat, during August RAF listening posts picked up signals that were traced to two new Knickebein transmitters erected on the north coast of France. One was at Greny near Dieppe, only 120 miles from the centre of London. The other was at Beaumont-Hague near Cherbourg, 150 miles from the capital. While Addison requisitioned equipment for his makeshift jamming organisation to begin operating, there was another commodity he urgently needed: capable personnel. With the highly technical war that was now in the offing, he had no use for other units’ misfits and throw-outs. He needed the best material available. Fortunately, interest in the wing’s well-being extended from the prime minister down, and Addison had free reign to choose people for his unit. A particularly useful source of recruits was the community of peacetime amateur radio enthusiasts.
***
At the same time as the wing began its improvised countermeasures to Knickebein, it took control of another jamming commitment that had been initiated some months earlier. Luftwaffe aircraft made considerable use of radio beacons set up in friendly territory, to assist navigation. Each German radio beacon transmitted its identification letters in Morse code, then a 50-second tone to allow aircraft radio operators to take bearings on the beacon. At that time in Britain there were fears that German agents might plant radio beacons near targets, to guide in their bombers. To counter the beacons, Post Office engineers had devised a clever device known as the Masking Beacon, or ‘Meacon’. The device comprised a receiver and a transmitter located about 12 miles apart. The receiver was linked to a directional aerial, aligned on the German beacon it was to counter. The receiver picked up the German beacon’s emissions, amplified them and fed them by landline to the ‘Meacon’ transmitter. The transmitter then radiated an exact replica of the German beacon signal, with the same Morse identification letters and 50-second tone, exactly in step with the German signals. But the ‘Meacon’ transmitter was, of course, in a quite different position.
The Battle of the Beams 33
Professor Lindemann explained the operation of the Meacons in a paper he wrote for the Prime Minister early in August. The Luftwaffe, he said, had nearly eighty radio beacons in Germany, Norway and northern France, operating on the medium and long wave bands. Not more than twelve of these beacons were in use at any one time, the remainder being held in reserve. Different groups were used on different days. Lindemann continued:
There are two ways of dealing with such beacons. The first is to jam them, i.e. to make so much disturbance in the ether that their signals cannot be received. If one compares them with lighthouses, it is like turning on the sunlight so that they would become invisible. This method is difficult because they operate on so many different wavelengths that we must produce very strong signals in each band to cover the lot... Further, each lighthouse has its own colour (wavelength) which has to be outmatched, so that the general glare must be produced over the whole spectrum, ranging from 30 metres to 1,800 metres. In order to cover this range eight very powerful stations would be required, but this leads us to another difficulty. If we had eight such stations, the Luftwaffe would soon get to know where they were and could use them as lighthouses to guide them to their targets. It is much easier to fly towards a beacon than to navigate away from it on back bearings. In order to prevent this it would be essential to link our jamming stations in groups of three, making each group of three flash simultaneously. If this is done (though there is no exact optic analogy), the radio receiver cannot tell from whence the beam comes, so these could not be used as homing stations. On the other hand, this would imply the use of 3 x 8, i.e. 24 powerful stations, which would mean that all our home wireless had to be sacrificed for this purpose. By giving up the BBC and all other transmitters, this arrangement could possibly be made in four to six weeks. Even then we should have difficulty if the Luftwaffe chose to use, instead of their normal beacons, the super high-power stations normally used for wireless purposes in France and Holland. This brings us to the second method, called ‘Masking’. For this purpose, we require a number of small stations in England which
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pick up and repeat the German signals exactly in phase. If this is done, the wireless operator in the German machine cannot distinguish between the signals from his beacon and the echo signal from our station, and his direction finding is completely set to nought. Since these echo stations are in exact phase with the ground stations it is impossible to home on them, so that they cannot be used as a navigational aid by the enemy as a German station could. They are admittedly slightly more complicated to set up, but we have already six in action and a further nine will be operating within a week. Providing the Luftwaffe do not use more than twelve stations at a time we can mask them completely with these fifteen stations so this method of navigating will be nullified. All masking beacons are being provided as rapidly as possible and it is hoped in a few weeks to be able to cope with any possible German orchestra of beacons. Obviously, if we had eighty, we could deal with them if they turned on all their eighty beacons. On the other hand it is unlikely that they will use too many at a time as it would certainly confuse their own pilots very much. Thirty stations would probably suffice for anything the Luftwaffe are likely to do.
***
By 18 August 1940, No. 80 Wing had nine ‘Meacon’ stations in operation. Two days later, the strange assortment of hastily erected ‘Headache’ stations – modified diathermy sets and Lorenz transmitters – was ready to begin radiating on the Knickebein frequencies. It was a close-run thing for, on 28 August, a force of 160 bombers delivered the first heavy night attack on a British city, Liverpool. The bombers returned to the port in similar strength on each of the following three nights. The expected night onslaught had opened. On 7 September, the bombers shifted their night attacks to London. From then until 13 November an average of 160 aircraft raided the capital each night, except for one occasion when bad weather prevented operations. This assault coincided with the deployment of the first of the jammers which Robert Cockburn and his team had designed to counter Knickebein. The RAF code-name for the German beam system was ‘Headache’, so the code-name for the antidote system – the jammer – was ‘Aspirin’. The latter
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transmitted Morse dashes on the beam frequencies. Those dashes were not synchronised with the beam signals, rather they were superimposed on them. The intention was that when a bomber pilot heard the Morse dashes, he would turn in the required direction. But when he reached what should have been the central steady-note lane he continued to hear dashes and so tended to overshoot. When in the ‘dot zone’, he heard a mixture of dots and dashes which did not resolve themselves into a clear note. The ‘Aspirins’ were prescribed for the more important sites, where they replaced the less efficient modified diathermy sets and Lorenz transmitters. Both of the older types of equipment were then moved to new sites, to increase the area where jamming cover was available. Throughout this period there was discussion as to whether it might be possible to design a countermeasures system to ‘bend’ the German beams, to push the bombers off course without their crews realising it was happening. Technically speaking, such a device was feasible. Such an elegant countermeasure would have taken time to design and build, however, and Addison had to meet a major threat to Britain’s cities; he did not have time to develop subtle approaches to the problem. In the event there was never any deliberate bending of the German beams, though it is widely believed that this was the case. Possibly the story began as a ‘plant’ by British intelligence, to weaken Luftwaffe confidence in Knickebein. As Addison told this writer:
Whenever anything unusual happened, people thought it was us. At the time we worked in such secrecy that when these funny ideas got around we had no means of correcting them – even had we wanted to. On one occasion a German aircraft unloaded its bombs in the castle grounds at Windsor. The next morning, the Comptroller of the King’s Household rang me; he was very cross, and wanted to know why we had bent the beams over Windsor – His Majesty might have been killed. It was the usual case of a lost German getting rid of his bombs – and we got the credit or the blame, depending on where they fell.
Dr Robert Cockburn voiced similar views during an interview with this writer. He commented:
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The myth has been established that we bent the beams. In fact we didn’t. I did rig up a system using a receiver at Worth Travers, near Swanage, and a transmitter at Beacon Hill, near Salisbury. I was going to pick up the modulation of the Knickebein, retransmit it, and thus push the beam over. In other words, my transmitter would have produced a beam similar to the German ground station but pointing to where I wanted it to. It was all very nice, but it didn’t happen. By the time the system was ready, the other jamming methods were in full swing and we could not spare the time or the effort to bring out a new system to supplement the old. So the deliberate bending of the German beams, which I had worked out, never happened.
When No. 80 Wing took over the Beacon Hill jamming station the unit used it to transmit unsynchronised Morse dashes, just like the other ‘Aspirins’. In October 1940, Edward Addison was promoted to group captain. No. 80 Wing now comprised twenty officers and 200 men and women, and operated fifteen ‘Aspirin’ sites to jam the Knickebein beams. How effective was this effort? The British ‘official line’, published in several books including the earlier editions of this one, was that the jamming was so effective in disrupting the Knickebein beams that the system fell soon out of use. The truth of the matter is rather different, though the outcome was the same. The Knickebein transmitter at Greny, 120 miles from London, often provided the main beam to the British capital. The BeaumontHague transmitter, 150 miles from the capital, was well placed to provide the necessary crossbeam. If those two transmitters trained their beams on London they could mark out a diamond-shaped patch of sky with sides measuring about 900 yards and 1,600 yards. The threat of over a hundred German night raiders delivering bombs to that degree of accuracy was a fearful prospect, but it never happened. Luftwaffe bomber crewmen who flew over Britain at that time have told the writer that usually they could easily hear the beam signals through the early jamming. Yet, even if it was not fully effective, the presence of the jamming was unsettling to the attackers because it indicated that the defenders were aware of the beams’
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existence and probably knew their location. One Luftwaffe bomber pilot told this writer:
At first we were very excited about Knickebein, a fine new method of navigation and a big help to find our targets. But after we had used it on operations once or twice, we realised that the British were interfering with it. Initially the jamming was weak and it hardly concealed the beam signals at all. But that fact that our enemy obviously knew that the beams existed and that they were pointing towards the target for the night, was very disconcerting. For all we knew, night-fighters might be concentrating all the way along the beam to the target. More and more crews used the Knickebein beams only for range, and kept out of them on the run up to the target.
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Knickebein Beam Stations
The eleven beam stations used during the attacks on Britain are shown. The map also shows attacks made by a Ju 88 pilot with III/KG 1, flying from Roye/Amy. A: raids on Cardiff on the nights of 1 and 3 March 1941, picking up the Beaumont-Hague beam at the coast and flying from there straight to the target. B: Plymouth 21, 28 and 29 April, again using Beaumont-Hague. C: Birmingham 16 May; this time he flew north to pick up the Kleve beam then northwest to find the Stollberg beam and the route to the target. During March and April the bombers often used the same route for repeat attacks. By May it was considered prudent to make a wide detour to avoid the defences in southeast England.
Other German aircrew echoed those sentiments, which became progressively stronger as the jamming became more powerful and the night defences became more effective. The primary effect of the jamming had therefore been its effect on the morale of the bomber crews, rather than the disruption it caused to the Knickebein signals. Yet the ‘bottom line’ of the makeshift efforts of No. 80 Wing and Dr Cockburn’s team was that they had successfully neutralised the German beam system. That gave a considerable boost to their prestige both in the RAF and in the corridors of power at Whitehall. It was also a triumph for Dr R. V. Jones and the cause of scientific intelligence; the next time the watchdog started to bark, people would listen. That would soon happen, for the Luftwaffe still had its other beam system.
***
On 13 August 1940 the Luftwaffe began its large-scale aerial bombardment of targets in Great Britain. On that day the first of the hard-fought daylight battles took place over southern England. After darkness fell, twenty-one He 111 bombers attacked the Nuffield factory at Castle Bromwich producing Spitfire fighters, and the nearby Dunlop tyre factory in Birmingham. The unusual feature of this attack was the inordinately high degree of concentration for a night raid – eleven bombs hit the sprawling collection of factory buildings at Castle Bromwich. The aircraft involved belonged to the special beam-flying unit Kampfgruppe 100, and carried the complex X-Gerät beam system. After its impressive start, KGr 100 delivered night attacks on several other small targets. The high degree of bombing accuracy achieved during the initial attack was not repeated often, however, and usually the attacks were not so effective. Halfway through August, the RAF monitoring service picked up unexplained signals on 74 MHz which appeared to originate from a point on the French coast. Jones code-named the new system ‘Ruffian’. By the end of the month the monitors had noted signals on nearby frequencies, and ground direction finders pinpointed their sources to the Calais and Cherbourg areas. The signals differed from those of Knickebein in their frequency and the keying rate, but they were sufficiently similar to identify them as an aid to navigation. During the following month Jones added further items
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to his file on ‘Ruffian’ and after his success with Knickebein, his new fears found ready ears. At the end of the third week in September his report, passed via Professor Lindemann, reached the prime minister’s desk:
It appears that the Luftwaffe are making great efforts to improve the accuracy of their night bombing. A number of new beams on a shorter wavelength than before have appeared. . . One Kampfgeschwader, KG 100 consisting of about forty machines [sic – in fact it was a Kampfgruppe, though the unit’s strength was given correctly], has been equipped with special new apparatus to exploit these beams with which apparently accuracies of the order of 20 yards are expected. With the technique they seem to be developing such a result does not seem impossible. We know the exact location of the sources of the beams in question. The parent beam is on the very tip of the Cherbourg peninsula; the crossbeams are in the Calais region. They will probably not reach much beyond London. Apart from attacks on the machines using the beams, our possible lines of defence would be: 1. to try to destroy the specially fitted KG 100 machines which are stationed at Vannes; home station Lüneburg and reserve station at Köthen; 2. to try to destroy the beam stations (a) by bombing, which would be very difficult since they are almost invisible targets (b) by a special [i.e. commando] operation; 3. to employ radio-countermeasures.
Early on in the investigation, RAF intelligence identified the distinctive footprint of the new series of attacks: great accuracy along a line running from Cherbourg, with a somewhat lower accuracy in range. The heaviest bombs used were 550-pounders. From the early summer of 1940 Luftwaffe signals personnel had worked hard to establish landline connections between each of the major bases and airfields in France, and that service’s main communications network in Germany. Starting in eastern France, they gradually worked their way westwards. As each airfield came on line it ceased using wireless for ground-to-ground communications, a move which deprived the cipher crackers at
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Bletchley Park of the opportunity to read their traffic. As luck would have it, however, KGr 100’s base at Vannes lay in the extreme west and so was one of the last to be connected to the network. Thus, from the autumn of 1940 until well into 1941, Bletchley Park was able to deliver to Jones’s office a steady stream of decrypted signals on KGr 100’s activities. On occasions the intercepted signals listed the beam frequencies and alignments for a night’s attack. Yet, at that stage of the war, the painstaking task of decryption often took several days. Although the raids were therefore over long before Jones read the signals, the information they contained was invaluable to build up a general picture of how the system worked. He noted that the beams were aligned to within five seconds of arc, which implied a maximum accuracy of the order of twelve feet at a distance of 100 miles from the beam transmitter. From this, Jones estimated accuracy of the new system to be ‘of the order of twenty yards’. In fact his report exaggerated the accuracy of the system by a factor of about six, but even so it represented a potent threat. To counter the X-beams Dr Cockburn and his team hastily modified the transmitter from an Army gunlaying radar to jam the beam frequencies, and code-named the device ‘Bromide’. When the prototype appeared to work satisfactorily, Cockburn’s section began a crash programme to build sufficient ‘Bromides’ to provide cover for potential targets. The immediate plan was to install these jammers at ground stations between Cherbourg – the source of the approach beams – and the Midland towns, Manchester and London. By the end of September KGr 100 had taken part in more than thirty attacks, more than half of which were on London. For the rest of the attacks the unit usually visited targets alone, attempting precision attacks using the beams. Early in October, RAF intelligence noted that KGr 100 had started dropping 1-kg stick-shaped incendiary bombs during some of its attacks. On the face of it that was a strange development; these small weapons scattered over a large area and could not be aimed accurately, which seemed to nullify the major advantage of the X-beam system. There seemed only one reasonable explanation for the change: KGr 100 was practising to lead the rest of the Luftwaffe bomber force to its targets. Apprised of the new information, Lindemann advised Mr Churchill on 24 October:
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There is some reason to believe that the method adopted is to send a few KG 100 aircraft fitted with special devices to assist in blind bombing on these expeditions, in order to start fires on the target which any subsequent machines without special apparatus can use.
The note accurately predicted the course the Luftwaffe would adopt a few weeks later. In the meantime, fate played into the hands of British intelligence in one of the more inept episodes of the secret war. Early on the morning of 6 November, a raiding Heinkel bomber suffered a compass failure over England. After tuning their radio compass to the beacon at Saint-Malo in Brittany, the crew turned for home. When the radio compass indicated that the aircraft had passed over the beacon, the aircraft descended but as it broke the cloud the pilot saw he was still over the sea. This had to be the Bay of Biscay, so he reversed his course and headed back to the beacon. By now his fuel was almost exhausted and, when a coastline came into view, he decided to set the bomber down on the beach. The pilot misjudged his approach, however, and in the resultant crash one crewman was killed and two were injured. The survivors scrambled up the shingle beach where, to their great surprise, they were immediately surrounded by soldiers in khaki uniforms. The beacon in which the airmen had misplaced their trust had been covered by a No. 80 Wing ‘Meacon’ transmitter at Templecombe in Somerset. What the crew had thought to be the southwest coast of Brittany, was in fact the beach at West Bay near Bridport. Some soldiers waded out to the wreckage and secured a rope round it, and all would have been well had a Royal Navy vessel not arrived. The ship’s captain pointed out that, since the bomber was in the sea, its salvage was technically a Navy matter. After some wrangling, the Army grudgingly agreed. The sailors took the line aboard their ship and solemnly towed the aircraft out into deeper water, preparatory to lifting it out. Unfortunately, in the course of that operation, the rope snapped and the Heinkel sank to the bottom. Dawn broke to reveal the upper part of the wrecked bomber protruding from the waves, looking rather like a stranded whale. As the tide receded, the plane’s markings gradually came into view; painted on the rear fuselage in characters nearly four feet high were
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the identfication markings 6N+BH. And 6N was the unit code for KGr 100. Professor Lindemann was understandably bitter when he learned what had happened. A week later, he wrote to the prime minister:
The KG 100 squadron is the only one known to be fitted with the special apparatus with which the Luftwaffe hope to do accurate night bombing using their very fine beams. As it is important to discover as much as possible about this apparatus and its mode of working, it is a very great pity that inter-Service squabbles resulted in the loss of this machine, which is the first of its kind to come within our grasp.
All was not lost, however. RAF technicians removed the invaluable X-beam receivers from the waterlogged hulk and, looking somewhat the worse for their immersion, they went to Farnborough for examination. Any last doubts regarding the advanced nature of German radio-beam technique were dispelled by the dates on some of the receivers’ inspection-stamps. They went back to 1938. In the second week of November, the Luftwaffe shifted the burden of its attack from London to the Midlands cities. In the first of these attacks KGr 100 was to lead the bomber force to its target, Coventry. On the afternoon of 14 November the Boulogne headquarters of 6th Air Signals Company – the unit which operated the X-beam transmitters – received its orders on beam alignments from KGr 100’s headquarters at Vannes. It relayed these instructions to transmitters Elbe, Oder and Rhein nearby, and to Weser, the ‘approach-beam’ transmitter, on the Cherbourg peninsula. The approach-beam crossed the English coast near Christchurch, ran to the east of Salisbury and Swindon, and passed over Leamington and Coventry. Shortly before the target city the three ‘crossbeams’ intersected it. That night KGr 100 sent thirteen He 111s to mark Coventry. Soon after 1900 hours, the leading aircraft crossed the Thames. Six minutes later it flew through the first of the crossbeams, and moved into the centre of the main approach beam aligned on the city. On that night, only four ‘Bromide’ transmitters were available to counter the X-beams. One of these, at Kenilworth, lay almost directly beneath the bombers’ run in. Yet the jammers caused the raiders little trouble; the system had been conceived in haste at a
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time when too little had been known about X-Gerät. Consequently, although the jammers probably emitted on the correct frequency, the radiated note was modulated at 1,500 cycles instead of 2,000 cycles. The difference – between a whistle and a shriek – is just perceptible to the human ear; but the filter circuits in the German receivers were sensitive enough to pick the beam signals out of the jamming with ease.
The leading Heinkel continued on its northerly course undisturbed and at 1906 hours, three miles south of Leamington, it flew through the second crossbeam. The observer started the automatic bomb-release clock and two and a half minutes later, about a mile east of Bagington, the aircraft flew through the third and final crossbeam. The second pointer on the clock began moving rapidly to catch up with the first. Fifty seconds later the two pointers
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Layout of the X-Beams over Coventry, Night of 14 November 1940
overlapped, the pair of electrical contacts closed and the bombs were released. The time was 1920 hours. During the next 45 minutes, the twelve remaining Heinkels from KGr 100 dropped their bombs on the city, starting some fires. By then the first of the main force of bombers had arrived, and in the hours to follow their loads reinforced the destruction already caused. Yet, even without the assistance of KGr 100, it is likely that the main force of bombers would have found the target with little difficulty. It was a bright moonlight night, with clear skies. Feldwebel Günther Unger of Kampfgeschwader 76 (KG 76), piloting a Dornier 17, attacked later that night. He recalled:
While we were still over the Channel on the way in we caught sight of a small pinpoint of white light in front of us, looking rather like a hand torch seen from two hundred yards. My crew and I speculated as to what it might be – some form of beacon to guide British night-fighters, perhaps. As we drew closer to our target the light gradually became larger until suddenly it dawned on us: we were looking at the burning city of Coventry.
One stream of bombers came in over the Wash, another over the Isle of Wight and a third over Brighton. Altogether 449 bombers hit Coventry during the ten hours of the attack. Between them they dropped 56 tons of incendiaries, 394 tons of high-explosive bombs and 127 parachute mines. The city was hit heavily and several factories were forced to cease production, albeit temporarily. Nearly 400 people were killed and a further 800 were seriously injured. The attackers had the rare benefit of a combination of perfectly clear skies, a full moon, a combustible target (there were many old timbered buildings), and weak anti-aircraft defences. Although the X-Gerät beams played a part in the raid’s success, this should not be exaggerated. Crews in the follow-up bomber units, including Günther Unger, have said the night was so bright that they would have found the city even without the assistance of marking by KGr 100. Meanwhile, examination of the captured X-Gerät receiver had revealed the weakness of the ‘Bromide’ jammer, and within a few days of the attack they had all been modified to transmit the correct jamming note. With modified ‘Bromides’ emerging from Cockburn’s workshop at an encouraging rate, it seemed that a much
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more effective No. 80 Wing was ready to counter KGr 100’s next major pathfinder marking effort. Birmingham came under attack on the night of 19 November (by thirteen bombers from KGr 100 and 344 aircraft in the followup force), on the 20th (eleven and 105) and the 22nd (nine and 195). Yet that city suffered nothing like the concentrated damage inflicted on its neighbour. Nor, during the months to follow, would any other British city. At the time British intelligence attributed the sudden deterioration in the effectiveness of KGr 100-led attacks to the improvements made to the ‘Bromide’ jammer. With the benefit of hindsight, however, it is possible to offer a quite different explanation for the failure to repeat the destruction inflicted on Coventry. The steady improvement in Britain’s night air defences during the winter of 1940 forced the Luftwaffe to cease large-scale attacks when there was a full moon. Also, during that period, the raiders had to contend with frequent spells of bad weather. So, when Kampfgruppe 100 led attacks on nights when there was little or no moon and poor weather, against targets that were better defended than Coventry and less combustible, it is not surprising that the results were less impressive. Although other cities suffered damage comparable with that suffered by Coventry in relation to their size – notably Liverpool and Plymouth – in their case it was the cumulative effect of several attacks and not just one. Even when X-Gerät worked perfectly, the weak system of target marking usually mitigated against an effective attack. The Luftwaffe was evolving its technique from scratch, and it still had a lot to learn. For one thing, it employed far too few pathfinder aircraft. Sending ten or a dozen bombers mark the target, for a follow-up attack that might last six hours or more, was not enough. Moreover, the 1-kg ‘stick’ incendiary bomb dropped by KGr 100 to start fires had poor ballistics and was a relatively inaccurate weapon. Even if the initial fires were accurately laid, the pathfinder marking rapidly became diluted as bombers in the follow-up force dropped much greater numbers of incendiary bombs with varying degrees of accuracy. Since the bombers all carried more or less the same types of high explosive and incendiary bombs, it was impossible to tell which fires had been started by pathfinders and which by the follow-up bombers. If there was cloud cover, the follow-up bombers often
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failed to find their target even if the initial marking had been accurate. In a later chapter we shall observe how the RAF applied the lessons it learned from the Luftwaffe attacks in 1940 and 1941. In the autumn of 1940, No. 80 Wing took control of a special unit to counter the Luftwaffe pathfinder tactics. If the follow-up raiders aimed their bombs at fires on the ground, why not light fires in the countryside for them to bomb? The job of establishing the necessary decoy fires – known as ‘Starfish’ – fell to a section headed by Colonel J. Turner, one-time head of the RAF Works Department. Since the decoys needed to look plausibly like cities under attack, timing was critical. The fires had to be well alight in time to catch the follow-up attackers, and ideally the bombers should need to fly over a decoy to reach the real target. That called for careful control and good communications. The ‘Starfish’ operation was an integral part of No. 80 Wing’s activities, directed from its headquarters. By the end of November twenty-seven decoy sites were ready for action. The first two ‘Starfish’ were ignited on the night of 2 December 1940, just over two weeks after the Coventry attack, during a raid on Bristol. In the course of that action the sites collected sixty-six high-explosive bombs. From then on, the ‘Starfish’ were a regular feature of Britain’s passive defences. If the local fire and civil defence services were able to extinguish the pathfinders’ fires promptly, decoy fires often drew away a large proportion of the bombs intended for city targets. By February 1941, No. 80 Wing had sufficient ‘Bromide’ transmitters to jam all of the approach and crossbeam frequencies. That brought about a significant improvement in jamming effectiveness, and a resultant deterioration in the performance of X-Gerät. Now, when KGr 100 delivered an attack on its own, the unit’s ‘bomb signature’ often showed that a large proportion of its bombs had fallen outside the target area.
***
In November 1940 the RAF monitoring service noticed more unusual signals on frequencies in the 42–48 MHz band, and R. V. Jones allocated these the code-name ‘Benito’. The new system, called Y-Gerät by the Germans, was another brainchild of Dr Hans Plendl. This employed a single beam made up of 180 directional signals per minute, which was aligned on the target. That was too
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fast for human interpretation, and the aircraft carried an electronic analyser to determine its position relative to the beam. To measure the aircraft’s range from the ground station, the ground station transmitted additional signals which the aircraft picked up and re-radiated on a different frequency. The ground station then measured the range using normal radar methods. When the aircraft arrived at the pre-computed bomb-release point, the ground station transmitted the bomb-release signal. Since it used only one ground station, Y-Gerät was more flexible than either of the predecessor systems. It was more accurate than X-Gerät, though it was also a great deal more complex. General Wolfgang Martini, head of the Luftwaffe signals service, later recounted how he tried to explain the operation of Y-Gerät to Hermann Göring. The Reichsmarschall listened for about two hours, then asked a few questions which showed he was none the wiser. Göring, a World War I fighter ace, had little time for such things. He thought wars should be fought by brave men with guns, not like this. He is said to have commented on another occasion, ‘Radio aids contain boxes with coils, and I don’t like boxes with coils.’ It is hard not to feel for him. After a false start in the summer of 1940, Plendl’s new system resumed operations at the end of the year. The Y-Gerät was fitted to the He 111 bombers of III Gruppe of KG 26 (III/KG 26) based at Poix near Amiens, and beam transmitters were situated at Poix, Cherbourg and Cassel in France. When he examined the Y-Gerät signals, Dr Cockburn noted that there were separate transmissions to fix the aircraft’s bearing and range from the ground beacon. To counter the system, therefore, he worked out a separate jamming method for each. At the time it was discovered the new beam system was still at the working-up stage, so Cockburn was under no great pressure to rush his jammers into operation. He even had time to introduce subtlety into his countermeasures. The prototype of Dr Cockburn’s new jammer for Y-Gerät code-named ‘Domino’ – employed a receiver at Highgate and the BBC’s dormant television transmitter at Alexandra Palace north of London. The receiver picked up the ranging signal from the bomber’s transmitter and passed it to Alexandra Palace, where the powerful equipment there returned the ‘echo’ to the German
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ground station to produce an erroneous range indication. The first ‘Domino’ went on the air in February 1941, soon followed by another at Beacon Hill near Salisbury. It soon became obvious that the ‘Domino’ transmitters were causing embarrassment to bomber crews relying on the Y-Gerät. On 9 March, the Y-beam signals changed frequency in the middle of an operation in an attempt – unsuccessful – to shrug off the jamming. Two nights later a small force of bombers attacked the Beacon Hill jammer, and one scored a near miss which put the station out of action for a few days. On the following night that jammer was still off the air, when III/KG 26 operated once more. The Alexandra Palace jammer covered the transmitter at Cassel, and none of those crews received the bomb release signal. There was no ‘Domino’ cover for the Beaumont-Hague transmitter, however, and crews using that ground station made accurate attacks. On the next night the Beacon Hill station was back on the air, and full jamming cover returned. Of eighty-nine Y-Gerät sorties flown over England during the first two weeks of March 1941, only eighteen aircraft received the bombrelease instruction. On the night of 3 May 1941, during an attack on Liverpool and Birkenhead, the Y-beam unit lost three Heinkels shot down. In each case the Y-Gerät equipment was removed from the wreckage and sent to Farnborough for examination. This revealed that between each pair of direction signals there was a short gap, which locked the electronic bearing-analyser to the beam. Later Dr Cockburn commented:
Unlocking the Y-beam was a piece of cake: they had fallen into the trap of making things automatic, and when you make things automatic they are more vulnerable. All one had to do was radiate a continuous note on the beam’s frequency. This filled in the gap between the signals, unlocked the beam analyser and sent the whole thing haywire.
Dr Cockburn’s new jammer, code-named ‘Benjamin’, first went on the air on 27 May 1941. By then, however, a major development in the German war strategy had brought about a profound change in the air war over Great Britain. During May 1941 the bulk of the Luftwaffe bomber force moved to bases in eastern Europe, in preparation for the long
The Battle of the Beams 49
planned attack on the Soviet Union. On 21 June the offensive began, and the intensity of the night Blitz suddenly gave way to the boredom of waiting for an enemy who rarely came. An air of almost unreal calm descended on Great Britain, but Group Captain Addison could not rely on the respite lasting for long. If German forces achieved a rapid victory in the east, the Luftwaffe would resume its onslaught on Great Britain. During the summer and autumn of 1941 No. 80 Wing continued its build-up, and replaced the last of the makeshift jammers with purpose-built systems. By September the unit had a strength of some 2,000 men and women of all ranks. It operated eighty-five ground stations scattered throughout the British Isles, and controlled more than 150 ‘Starfish’ decoys.
***
So ended the first-ever electronic warfare action. Knickebein had surrendered almost without a fight. X-Gerät proved more difficult to jam, but in the time available its capabilities were not exploited sufficiently to provide effective target-marking for Luftwaffe bombers. Y-Gerät played only a minor role, its effectiveness much reduced by jamming, before the bombing campaign ended. We now know that the jamming of Knickebein and X-Gerät was less disruptive than had been thought at the time. Yet, although the initial jamming of Knickebein was insufficiently powerful to conceal the beam signals, it dissuaded Luftwaffe crews from using their beams when flying over England. Although the Luftwaffe reaction to the various countermeasures had been slow in coming, it would unwise to conclude that Luftwaffe technicians could not have modified their radio aids to operate more effectively in the face of the jamming. In fact, before they could do so, the night bombing offensive against Britain had come to a halt. As we shall see, the Luftwaffe could do much better than this.
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Chapter 2
The Instruments
‘I have done my best during the past few years to make our air force the largest and most powerful in the world. The creation of the Greater German Reich has been made possible largely by the strength and constant readiness of the air force. Born of the spirit of the German airmen in the First World War, inspired by its faith in our Führer and Commander-in-Chief – thus stands the German Luftwaffe today, ready to carry out every command of the Führer with lightning speed and undreamed-of might.’
Order of the Day from Hermann Göring to the Luftwaffe, August 1939
Radar, like many major inventions in the twentieth century, did not result from a sudden and inspired line of thought pushed to the point of fulfilment by a single inventor. As with many innovations, the basic idea preceded the invention by several decades. Only when each of the major components had been developed, could its realisation become practicable. Again, as with many other inventions, once the background work was complete, development of the device proceeded independently in several nations simultaneously. In the case of radar, by the early 1930s the major components necessary to assemble such a system already existed. These were: a high powered pulsed transmitter; a very sensitive receiver; a device for measuring small time differences very accurately (the cathoderay tube); and a highly directional aerial system. During that decade scientists working independently in Great Britain, the USA, France, Germany, the Netherlands, Japan and the Soviet Union all produced working radars. Each nation claimed the device as its own, and in each the fighting services believed that it offered them a unique advantage. Since they would be the target systems in the next phase of the electronic warfare battle, however, the account that follows will concentrate on radar developments in Germany.
***
When World War II began in September 1939 the German armed forces had two separate types of radar in service and a third was at the advanced testing stage. For early warning against air attack the Gema Company had produced the Freya radar operating on frequencies around 120 MHz, initially with a maximum range of about seventy-five miles. Gema also produced the Seetakt radar operating on 370 MHz, for installation in warships and at shore batteries. This radar provided surface-search and also accurate range information to assist naval gunnery. Late in the 1930s the rival Telefunken Company also entered the field of radar, and its Würzburg equipment was the impressive result. When the war began this equipment was still in the trials stage. The small, highly mobile set operated on what was then the extremely high frequency of 560 MHz, and could plot the position of aircraft to within fine limits at ranges up to twenty-five miles. The Würzburg was the first radar in the world with the precision to allow anti-aircraft gunners to engage targets accurately at night or through cloud. Also at this time, Telefunken had commenced testing a small airborne radar. How well did the German radars compare with their British equivalents at the outbreak of World War II? The Freya, the only German early-warning equipment, had a maximum range of seventyfive miles, its rotating aerial array gave it full 360-degree cover and its wheeled carriage allowed a high degree of mobility. Yet, it could not measure the altitude of approaching aircraft. Its nearest British equivalent, the ‘Chain Home’ operating on the far lower frequencies between 20 and 52 MHz, had a maximum range of 120 miles and could determine the altitude of approaching planes. But the ‘Chain Home’ stations gazed out to sea with a fixed 120-degree angle of look, and for technical reasons the radar could not give reliable plots on aircraft flying over land. Moreover, the four 300-foot high towers – each twice the height of Nelson’s column – supporting each station’s transmitter aerials precluded mobility. It was not in its radar hardware that the RAF had established a lead, but rather in the way in which the information was exploited. Only in Fighter Command could reliable and up-to-date information based on radar plots be passed to fighter pilots by radio. By September 1939 the RAF had nineteen ‘Chain Home’ radars operational, covering the approaches to the east coasts of England
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and Scotland. Its system of fighter control had been developed and tested during scores of exercises. The Luftwaffe had made no attempt to perfect such a system of its own before the war. Since it had little to fear from hostile bombers, that service had logically concentrated its energies on offensive developments – like the radio beams. The Seetakt and Würzburg precision radars were the most advanced equipments in the world in their respective categories. When war broke out, the Royal Navy had no equivalent of the Seetakt for its ships nor would it have one for another two years, and the Würzburg was considerably in advance of its nearest British equivalent in both range and plotting accuracy. But Britain had established a lead in the development of radar sets small enough to be carried in aircraft; there were two types on the point of entering service, one for coastal patrol aircraft and one for night-fighters.
***
In the autumn of 1939 the Luftwaffe had eight Freya stations operating on the chain of islands along the northwest coast of Germany: two on Heligoland, two on Sylt, two on Wangerooge, one on Borkum and one on Norderney. At that time the RAF was prohibited from attacking targets on the German mainland, because this would endanger civilian lives. It therefore sent bombers in probing attacks, to feel out the defences with attacks on German warships in the Heligoland Bight. The first three daylight bombing attacks were inconclusive. Then, on 18 December 1939, twenty-four Wellingtons of Nos. 9, 37 and 149 Squadrons set out from their bases in East Anglia to patrol the Schilling Roads, Wilhelmshaven and the Jade Roads. Two of the Wellingtons turned back early with technical problems, the rest continued with the mission. Just after midday, a Freya radar on the pre-war holiday island of Wangerooge picked up the approaching Wellingtons at a range of seventy miles. The operator reported the formation to the nearby fighter station at Jever and, after a delay, the defending fighters, sixteen Messerschmitt Bf 110s and thirty-four Messerschmitt Bf 109s, took off to engage. By then, having found no warships at sea, the bombers had turned around and were heading for home. It was a clear winter’s day and the fighter pilots could see the RAF formation from several miles away. They quickly caught up with the
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raiders and, in the heated engagement that followed, bomber after bomber went down. Of the twenty-two bombers involved in the action, only ten regained friendly territory. So the RAF had learned the hard way, as the Luftwaffe was to learn during the Battle of Britain and the US Army Air Force would learn in 1943, that formations of bombers operating over enemy territory by day without fighter escort risked heavy losses. The lesson was clear, and throughout most of the conflict that followed RAF Bomber Command sought to avoid the German defences by delivering attacks under cover of darkness. On 14 May 1940, following the destructive Luftwaffe attack on the city of Rotterdam, Prime Minister Winston Churchill lifted the ban on air attacks on the German mainland. By 4 June, RAF bombers had flown some 1,700 night sorties over Germany at a cost of thirtynine aircraft, most of them lost in accidents. Compared with what Bomber Command would achieve later in the war, those early operations were no more than gestures of defiance. Yet they caused a degree of consternation in Germany. Had not Hermann Göring declared that the Ruhr industrial area would not be exposed to a single bomb from an enemy aircraft? After inspecting the AA gun defences in the Essen area in August 1939, Göring’s imagination had been captivated by the Würzburg radar. Here was a device to enable the gunners to engage enemy planes even through the thickest cloud or at night. It was the success of the early Würzburg trials that had inspired him to make his muchquoted declaration regarding the invulnerability of the Ruhr. Yet the introduction of Würzburg into service took somewhat longer than anticipated, and the first sets did not become operational until the summer of 1940. Lacking radar, the gunners sought out the night raiders using searchlights and largely ineffective sound locators, with poor results. Göring was not at all satisfied by this – while his reputation had suffered, the raiders had not. Since the AA guns alone could not inflict losses sufficient to deter the night raiders, he decided to form a specialised night-fighter force. Up to that time a few intrepid pilots had flown night patrols in single-seat Bf 109 fighters, and on occasions they had shot down raiding bombers. Yet, lacking any formal system of ground control, an interception at night remained a matter of chance.
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In July 1940 Göring summoned Oberst Josef Kammhuber to his headquarters, and ordered him to set up a specialist night-fighter unit and a ground-control system to support it. Kammhuber was forty-three when he took on his new appointment. In his previous posts he had demonstrated that he was a methodical worker, displaying great drive tempered by sound judgement. He was to use these qualities to the full in his new post. Kammhuber worked fast. By mid-August 1940 the first specialised night-fighter unit, Nachtjagdgeschwader 1 (NJG 1), had a strength of seventy Bf 110s, seventeen Ju 88s and ten Do 17s. None of these planes carried radar or other specific equipment for their new role, however. Backing these fighters, on the ground, was a regiment of searchlights and a few Freya early-warning radar sets. Kammhuber was promoted to Generalmajor and established his headquarters in a seventeenth-century castle at Zeist near Utrecht. The night-fighter organisation was subordinated to Generaloberst Hubert Weise, responsible for overall command of the air defence of the Reich. During the summer and autumn of 1940, radar-directed nightfighting was in its infancy. Usually fighters were scrambled when early-warning radar stations on the coast reported approaching raiders. After take-off the night-fighters flew to assigned radio beacons, which they orbited until searchlights nearby illuminated an enemy bomber. Then, with his target in sight, the night-fighter pilot closed in for the kill. Known as ‘illuminated night-fighting’ (Helle Nachtjagd), this system achieved some success. The early engagements revealed an important weakness in the system, however. The searchlights were positioned around the bombers’ potential targets, as were the AA guns. There was no effective system of identification, with the result that night-fighters often came under fire from the ground. Quite apart from the loss of men killed or wounded, and in aircraft destroyed or damaged, that made the system manifestly inefficient. The gunners were shooting at fighters, and the fighter pilots had to manoeuvre to avoid the shells, at a time when both should have been engaging enemy bombers. To prevent such ‘friendly fire’ incidents, Kammhuber saw that it was important to designate separate engagement zones for AA guns and night-fighters. He therefore moved his searchlight batteries into
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the countryside, well clear of the AA gun defences, to form a defensive belt that ran parallel to the coast from Schleswig-Holstein to Liège in Belgium. Raiding aircraft would have to pass through that belt, to reach their targets in Germany. Kammhuber subdivided his searchlight belt into a series of ‘boxes’ about twenty miles wide, each with a radio beacon where a night-fighter would orbit while waiting for the enemy raiders to appear. Having formed his defensive line, Kammhuber set about improving its effectiveness. He saw that any system that relied on searchlights was a slave to the weather. The answer was to use a precision radar on the ground to direct a night-fighter into an attacking position behind an enemy bomber. The Freya was too imprecise for that task, for the ‘blips’ from the night-fighter and the bomber usually merged on the radar screen long before the nightfighter pilot had his quarry in visual range. The Würzburg flakcontrol radar, with its very much higher frequency and superior resolving power, offered a much better prospect. By the end of 1940, production of this radar was getting into its stride and Kammhuber secured a few to direct experimental night interceptions. The initial trials with Würzburg demonstrated the advantages of using radar to direct night-fighters, and Kammhuber requested more sets to equip his defensive line. This now comprised a series of contiguous boxes, forming a barrier which raiding bombers had to cross to reach their targets and again on their return flights. Each night-fighter box was equipped with a Freya and two Würzburg radars, a radio beacon and a ground-control station. The Freya directed one short-range narrow-beam Würzburg to track the nightfighter, while the other tracked the incoming bomber. The Würzburg equipment been designed to direct AA guns and its form of presentation – giving raw range, bearing and elevation information – made it impossible to direct night-fighters from the radar screen. To convert the Würzburg information into a form in which it could be used by the fighter controller, the Luftwaffe developed the so-called ‘Seeburg table’. Located in the headquarters building of each ground-control station, the device looked like a large dais with two flights of steps leading up to a ‘table’ at the centre. The ‘tabletop’ consisted of a horizontal frosted glass screen, bearing an outline map of the area and the Luftwaffe fighter grid.
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Directly beneath this glass screen sat two operators for the lightprojectors. Each received telephoned plots on the aircraft he or she was tracking, from the appropriate Würzburg. One operator projected onto the screen above a red light to indicate the bomber’s position, the other projected a blue spot to indicate the fighter’s position. As the coloured spots of light moved across the frosted glass screen, plotters at the top of the ‘dais’ marked the planes’ respective tracks using a coloured wax crayon. The fighter controller stood over the frosted glass screen, passing radio directions to the fighter pilot to bring him into a position to engage the bomber. The ‘Seeburg table’ became a standard item of equipment at each fighter-control station. This method of close controlled night interceptions was code-named Himmelbett.
Initially Kammhuber positioned his Würzburg radars immediately in front of the searchlight belt. That allowed night-fighter pilots to attempt a radar-controlled interception first. If that failed, they could then resort to the tried and tested ‘illuminated night-fighting’ tactics. The radars thus increased the effective ‘depth’ of the searchlight belt, allowing Kammhuber to redeploy searchlights to extend the line from eastern France to the middle of Denmark.
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The Seeburg Plotting Table
Yet, although the Würzburg radar gave a useful improvement in the effectiveness of the defensive line, it soon became clear that the device’s range performance fell short of what was needed. All too often, Allied bombers emerged from the line and passed out of Würzburg range before the night-fighter could make a successful interception. After prompting from Kammhuber, Telefunken modified the Würzburg to overcome this deficiency. In the spring of 1941, the company produced a variant of the radar with the diameter of the reflector-dish increased from ten feet to twenty-five feet. That narrowed the width of the radar beam, and enabled the equipment to track aircraft up to forty miles away. The new Telefunken radar was called the Giant Würzburg (Würzburg Riese). Apart from its larger reflector and static mounting, electronically it was little different from the smaller version. During the second half of 1941, the first Giant Würzburg radars entered service to replace the standard sets used for night-fighter control. Following a reorganisation of the night air defences early in 1942, it was decided that, with this influx of new electronic equipment, Kammhuber no longer needed the searchlights in his defensive line. At the time he contested the decision, though later he would admit it was for the best. It forced night-fighter crews to trust their ground controllers to guide them to their targets and, when the crews became accustomed to it the system was more effective than ‘illuminated night-fighting’ could ever have been. During the spring of 1942, Kammhuber’s line was strengthened by the introduction of three new radar devices. The formula of using a larger aerial reflector to narrow the radar beam and increase range, which had worked so well in the case of Würzburg, also succeeded with Freya. The result was the Mammut (‘Mammoth’) built by the I. G. Farben company. This was essentially a Freya with a greatly enlarged reflector ninety feet wide and thirty-five feet high – about the size of a tennis court on its side. The structure was fixed on supporting pylons, and determined the azimuth of aircraft by ‘swinging’ the beam electronically through a limited arc of 100 degrees. The enlarged reflector squashed the radar beam into a narrow pencil, which reached out to aircraft up to 185 miles away. Like its smaller predecessor, Mammut could not measure altitude. The second new radar, the Wassermann, built by the Gema company,
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gave accurate height, range and bearing readings on aircraft up to 175 miles away. This set employed a reflector 130 feet high and 20 feet wide, mounted on a rotating tower. Wassermann was the finest early-warning radar to be produced by either side during World War II. The Luftwaffe installed Mammut and Wassermann sets along the coast of occupied Europe, to extend the range of its earlywarning cover. Those two new sets were both early-warning systems. The third new radar was of an entirely different character: the Lichtenstein lightweight airborne radar, designed for installation in night-fighters. Another Telefunken product, the Lichtenstein operated on frequencies in the 490 MHz band. It had a maximum range of two miles and a minimum range of about 200 yards. That minimum range figure was an important parameter in a night-fighter radar. While the radar transmitted each high powered pulse, the sensitive receiver had to be ‘switched off’ or it would suffer severe damage. That meant the receiver could not pick up echoes from the nearest targets. That dead distance, between the fighter and the closest target that could be seen on radar, was proportional to the length of the transmitted pulse. In fact, the 200-yard minimum range was low for a first-generation airborne radar. The new airborne radar went into production and the first four night-fighters fitted with Lichtenstein arrived at the operational airfield at Leeuwarden in the Netherlands in February 1942. In ser vice, the shortcomings of the device became clear. The entanglement of aerials and reflectors on the aircraft’s nose increased the drag, impaired handling and reduced the top speed of the Ju 88, for example, by 6 mph. Initially, pilots were unwilling to accept those penalties for the privilege of carrying a radar of uncertain reliability. Paradoxically, the main reason for their conservative attitude was the high quality of the ground control using the Giant Würzburg, which usually placed the fighter within visual range of its target. Hauptmann Ludwig Becker and his crew persevered with the Lichtenstein equipment, however. They found that when the set could be coaxed into working properly – and it had its share of teething troubles – it offered considerable advantages, particularly when engaging the British bombers on moonless nights. As Becker’s score of kills accordingly mounted, other crews began to accept the device.
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By March 1942, the German defences were destroying an average of four bombers out of every hundred attacking Germany by night. Of these the fighter defences were responsible for about two-thirds, while AA guns accounted for most of the remainder. By now there were four Geschwader of night-fighters with 265 aircraft, of which 140 might be available on any one night. The force continued its expansion. During April it accepted thirty-three Bf 110s, twenty Ju 88s and thirty Do 217s. Telefunken had already manufactured 275 Lichtenstein radars, and production was running at about sixty sets per month.
On the ground-radar side as well, there was a steady strengthening of Kammhuber’s line. To equip the whole of the defensive line as it then stood, he needed 185 Giant Würzburg sets. By the end of March 1942, Telefunken had delivered about half that number, and the rest were following at the rate of about 30 per month. Although the defences were taking a steadily mounting toll of the British night raiders, Kammhuber’s system of fighter control had an obvious Achilles’ heel. For its success it depended on the Lichtenstein, Freya, Mammut, Wassermann and Giant Würzburg radars, and on effective communications between the fighter pilots
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Himmelbett fighter-control stations at the end of 1942
Interception zone covered by original Himmelbett chain Himmelbett stations
Night-fighter aerodromes
Approximate limit of German early-warning radar cover, against aircraft flying at 10,000 ft
and their ground controllers. In some degree, all these systems were vulnerable to interference. In the next chapter we shall observe how the British intelligence service stripped away the veil of secrecy surrounding that organisation.
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Chapter 3
Discovery
‘The relief offensive for which Britain’s badly harassed Allies have been begging for such a long time has confined itself to the landing of a few parachutists on the coast of northern France. The parachutists were soon forced to make a glorious retreat across the ocean, without having achieved any useful purpose.’
German News Broadcast, 28 February 1942
Throughout 1941 and 1942, RAF Bomber Command was losing a steadily increasing proportion of the planes dispatched against targets in Germany. Yet, until there was detailed knowledge on how the air defences operated, it was impossible to devise appropriate countermeasures. The intelligence sources that had been so useful during the ‘Battle of the Beams’ – the crashed German aircraft, captured aircrew and the analysis of the beams themselves – were now denied, for the RAF bombers were destroyed over enemy territory. Moreover, because the more sensitive items of information concerning the air defence system were usually communicated via landlines, there was little radio traffic on this subject for Bletchley Park to decipher. In consequence, it took many months of hard work to expose the workings of the system Josef Kammhuber had created. In the absence of firm evidence before the war, British scientists had regarded with scepticism the possibility that their German counterparts might also be working on radar, though there was little doubt that they could build such systems once they had the basic idea, since they were known to be advanced in high-frequency radio techniques. In mounting the listening operation with the Graf Zeppelin, the Luftwaffe had concentrated its search for signals on the frequencies used by its radar systems; now British intelligence was taking much the same approach, with a similar lack of success. The first clue that the Germans were working on radar came from the so-called Oslo Report, received via the British Embassy in Oslo in November 1939. Probably sent by a disaffected German scientist,
the document mentioned several military technical systems then under development in Germany. There were references to a remotely-controlled glider carrying an explosive warhead, homing torpedoes and remotely-controlled shells. There was a short description of a warning system able to detect aircraft out to a range of 120 km (75 miles) using ‘pulses reflected by the aircraft’. The report added that, during one of the British air attacks on Wilhelmshaven, the stations covering the northwest coast of Germany had detected the RAF bombers at a range of 120 km. That last statement was greeted with some disbelief. The German fighters’ reaction to these attacks seemed very slow, if there had been such a long advance warning (in fact that was due to other weaknesses in the control and reporting system). Certainly, the RAF fighter reaction would have been much faster.
***
One available source could certainly have confirmed to RAF officers the existence of German radar at this time, had not inter-service secrecy prevented it. In December 1939, the German pocket battleship Graf Spee was scuttled off Montevideo in Uruguay. Five days earlier, the warship had suffered several hits in a battle with Royal Navy cruisers. The German captain had thought his ship could not fight her way back to a friendly port, so to prevent further loss of life he ordered her destruction. The estuary of the River Plate is shallow, however, and when the demolition charges went off the warship sank only about ten feet before she came to rest on the seabed. At first light next morning, a flotilla of sightseeing boats put out from Montevideo to look at the shattered warship. Scores of photographs were taken, to be flashed round the world by news agencies. Most people failed to notice a strange feature on the close-up photographs of the smoking hulk: a structure rather like a bedstead on its side, mounted above the bridge. British naval intelligence sent its own sightseer to Montevideo to look over the warship, radar expert L. Bainbridge Bell. He boarded the wreck and climbed up to the ‘bedstead’ structure – a feat requiring some agility, since the Graf Spee had developed a list. Afterwards, Bainbridge Bell reported that the structure was almost certainly the aerial system for a radar set, probably used for ranging
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the ship’s guns. In this assumption he was correct, this was a Seetakt radar. Armed with that information, naval intelligence officers in London examined other photographs of Graf Spee and observed that the structure was present, though hidden under a canvas cover, on photographs taken as early as 1938. That was a discomforting discovery, for even at the start of 1940 Royal Navy warships had no gun-ranging radars, and no British ship would receive one for well over a year. Bainbridge Bell’s report was pigeonholed in the naval intelligence files, however, and R. V. Jones would not learn of it until 1941.
***
During the early months of 1940, the RAF scientific intelligence service picked up little information that could be connected with Luftwaffe radar systems. Although we now know that these were technically efficient, they were in limited use at that time. At that stage of the war the German strategy was primarily offensive, and the Luftwaffe therefore concentrated on systems like the navigational beams to aid bombers. Radar, as a purely defensive device at that time, had a lower priority. The British forces, being on the defensive, were compelled to adopt the opposite course. In May 1940, as the RAF night bombing offensive against Germany began, a prisoner mentioned that the German Navy had experimented with a ‘radio echo’ device for measuring the range and bearing of distant objects. He said the Luftwaffe was working on similar systems, though these were not so far advanced. From the description, it seemed that the German system bore unmistakable similarities to the British coastal radar chain. There was much here that agreed with the statements made in the Oslo Report. On 5 July, shortly after the reception of the first Knickebein beam signals by a British aircraft, one of R. V. Jones’s intelligence sources passed him the gist of a secret Luftwaffe report dated a week earlier. This stated that German fighter aircraft had been able to intercept British reconnaissance planes on that day because of information from the ‘Freya Meldung’ – the Freya warning. That seemed to confirm that the Germans had some form of aircraft detection system. On learning of Jones’s interest, the source mentioned that a Freya site was operating at Lannion protected by a battery of light
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anti-aircraft guns. Lannion was a small village on the northern coast of Brittany. The report seemed to underline the importance of Freya, for German troops had entered the area only three weeks earlier. There were two obvious ways to follow up: the site should be photographed from the air; also, a listening watch should be maintained for signals that could be traced to the site. Jones also tried a further approach, typical of the methods adopted in the strange craft of military intelligence: he researched the mythological background of the code-name, Freya. Freya was the Nordic goddess of beauty, love and fertility. Her most prized possession was an exquisite necklace called Brisingamen; to acquire this, she had sacrificed her honour and been unfaithful to the husband she loved. Heimdal, watchman of the Nordic gods, guarded Brisingamen. And Heimdal could see a hundred miles in every direction, by day or night. Jones cautiously reported to the Chiefs of Staff:
It is unwise to lay too much stress on this evidence, but these are the only facts that seem to have any relation to our previous knowledge. Actually Heimdal himself would have seemed the best choice for a code-name for RDF [radar] but perhaps it would have been too obvious . . . It is difficult to escape the conclusion therefore that the Freya-Gerät is a form of portable RDF.
This was all good stuff, but it awakened a nagging suspicion in the minds of the War Cabinet. Might the Germans have captured intact a radar set left behind by the British Expeditionary Force in France? How else could the Germans have developed an operational radar system so quickly? On 7 July, Churchill minuted General Ismay, his chief of staff, about the matter:
Ask the Air Ministry whether any RDF [radar] stations fell intact into the hands of the enemy in France. I understand there were two or three. Can I be assured that they were effectively destroyed before the evacuation?
General Ismay made the necessary inquiries, and replied that one radar transmitter had been left behind by the RAF at Boulogne, but this had been thoroughly destroyed. It was doubtful that the Germans could extract useful information from it. One of the Army’s gun-laying radar sets might have been captured in a damaged state, but the others were carefully destroyed. The evacuation ship Crested
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Eagle had been carrying an Army gun-laying radar when she ran ashore near Dunkirk, but a naval party had been put on board to destroy the set. From German sources, we know that their forces had captured a nearly intact British mobile air-warning radar near Boulogne. Far from being impressed with the find, they regarded it as extremely crude and much inferior to the Freya. It was a fair assessment, for at that time the mobile British radars were considerably less effective than their static counterparts. On 14 July, Jones received an intelligence report of a second Freya station in operation, this time at Cap de la Hague on the Cherbourg peninsula. Nine days later, the station played an important part in the operation in which dive-bombers sank the destroyer HMS Delight. At the time, Delight was about twenty miles south of Portland Bill. As she had never been closer than sixty miles from the Freya, and had neither fighter support nor balloons to reveal her position, the action showed that the radar gave cover on lowlevel targets at least as good as that from the latest British equipments. In the second week in August, as the Battle of Britain was about to begin, Jones received the text of a secret Luftwaffe report which stated that Freya was designed to work in conjunction with the fighter defences. Attempts to locate Freya on aerial photographs of the two sites now reported, at Cap de la Hague and at Lannion, met with no success. Photographs were taken from reconnaissance Spitfires flying at 30,000 feet and gave a definition just sufficient to enable the 300foot Knickebein turntables to be picked out. All that could be said for certain was that the Freya had to be smaller than that. In the meantime a radar expert from the TRE, Derek Garrard, set out on a radar hunt on his own account. He filled his car with borrowed receiving equipment, and drove to points along the south coast to look for unusual transmissions. The initiative was rewarded, though his first intercept was not connected with Freya. From a point near Dover he picked up radar transmissions on a frequency of 375 MHz, which could be linked with the shelling of British convoys passing through the Straits of Dover, from gun batteries situated near Calais. In fact, the signals came from a Seetakt radar – the same type as that examined on the Graf Spee many months before.
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Garrard’s find caused a commotion among radar experts in Britain; of those prepared to admit the possibility of the Germans having developed radar, few would accept that they had sets superior to those built in Britain. Yet, here was a German radar, working on a frequency so high as to be almost unusable in Britain, directing coastal gun batteries. If the Germans had learned their radar techniques from a British set captured in France, they had applied their new-found knowledge with remarkable despatch. In the autumn of 1940 the introduction of improved reconnaissance cameras brought a great improvement in the quality of RAF aerial photography. The effect on the hunt for the German radar stations was immediate; on 22 November, a high-flying Spitfire returned with photographs of unprecedented clarity showing the village of Auderville near Cap de la Hague. Just to the west of the village were two unexplained circles side by side, each measuring some twenty feet across, looking like a pair of opera glasses laid lenses down. Dr Charles Frank, a physicist who had recently joined Jones’s staff, examined the photographs through a stereoscope and saw that two consecutive frames did not form a perfect stereo pair, as they should have. A shadow associated with one ‘circle’ had changed slightly in the nine seconds between the first exposure and the second. During that time, a thin wide object on top of one circle had rotated through ninety degrees. In each case the shadow was about two millimetres long, but whereas in the first about a tenth of a millimetre wide, the second was two millimetres wide. The difference was hardly greater than the resolving power of the photographs, but it was enough to establish that here was something worth closer examination. The next obvious move would be to lay on a low-level reconnaissance sortie to photograph the ‘opera glasses’ at Auderville. However, with Britain still under imminent threat of invasion, there were demands with a higher priority on the small force of photographic reconnaissance Spitfires. In the interval, Jones received an Ultra decrypt which mentioned another German aircraft detection device called Würzburg. It appeared that one Freya and one – perhaps two – Würzburg sets were earmarked to go to Romania; also, two Würzburg sets were to be sent to Bulgaria. All had been allocated for coastal defence units. Perhaps, Jones reasoned, this represented the minimum
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number of radars necessary to provide continuous cover along the two nations’ coastlines with the Black Sea. If that was so, he calculated that the range of Freya had to be at least fifty-seven miles, and the range of Würzburg to be at least twenty-three miles. At that time Jones did not know that the two radar systems complemented each other, but although his initial premise was wrong the maximum ranges he had postulated for the two systems were remarkably accurate. He now had clues on two distinct types of aircraft-detection apparatus used by the German forces, though neither had yet been clearly seen or heard. Not until 6 February 1941 was a reconnaissance Spitfire available to take a low-level look at the ‘opera glasses’ at Auderville. The first mission was a failure, however. As the Spitfire sped through the area, the circular objects were missed in the gap between two successive frames of the oblique camera. The second low-level sortie, flown by Flying Officer W. Manifould six days later, was more successful. He returned with a magnificent close-up photograph, which showed that each circle was surmounted by a rotatable aerial-array. Unquestionably, this was a radar station (in fact it was a Freya). Even as Manifould’s photographs were being processed, a listening station in southern England identified pulsed signals coming from the direction of Auderville on 120 MHz. Signals on that frequency had been picked up earlier, but the listeners assumed that they came from the new VHF radios fitted to RAF fighters. Only when Derek Garrard examined the signals on a cathode-ray tube was their true significance recognised. Garrard plotted the bearings on their source, and found that these signals originated not only from Auderville, but also from transmitters situated near Dieppe and Calais. Within four hours of each other, Jones received the low-level photographs and the report of the intercepted radar signals, after a hunt that had lasted more than a year.
***
Within a month of the recognition of the Freya signals, new pulsed signals were picked up on 570 MHz. In the spring of 1941 a special radio-reconnaissance unit, No. 109 Squadron, had begun flying sorties over occupied Europe looking for German radar transmissions. After dark on 8 May one of the unit’s ‘ferret’
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Wellingtons flew a circuitous route taking in the Cherbourg peninsula and Brittany. In the course of the sortie, the plane’s crew obtained rough fixes on nine radar sites. In the months to follow, information on Freya stations came in thick and fast. By the end of October 1941 no fewer than twentyseven of these radars had been located, strung out along the coast between Bordeaux in France and Bodö in Norway. No. 109 Squadron aircraft also brought back scores of fixes on 570 MHz transmitters. Yet the sources of these signals were evidently very small, for they defied all attempts to photograph an example. One spectacular piece of intelligence obtained at this time was a strip of cine film showing a Freya station in operation, with the German crew tracking aircraft targets. Less spectacular, but far more important from the intelligence viewpoint, was the discovery that wireless plots from the Freya units could be overheard in England. When tracking an aircraft, the radar station passed distance-andbearing reports by radio to a central air-defence headquarters. The ‘code’ used to pass the information was relatively simple, and easily broken. For example, on 10 October a listening station in England picked up a Morse transmission which read:
MXF = 114011 = 14E = X =254 = 36 = +
MXF was the radio call-sign of the Freya station; 114011 was the time of the plot in hours, minutes and seconds; 14E was the serial number of the plot. X indicated the number of aircraft present (X meant one, Y meant several and Z meant many); 254 was the bearing from the radar station, and 36 was the range in kilometres British intelligence tapped this source for all it was worth. Reconnaissance aircraft, maintaining an accurate record of their flight path by photographing the ground directly below, flew over German-held territory so that the Freya stations would track them. Listeners in England then recorded the plots on the aircraft’s progress. Afterwards, the bearings and ranges were back-plotted on maps. Several Freya stations were located and identified in this way. Once the various radar stations had been located and identified, the German plotting reports were used to provide up-to-date information on the movements of RAF raiding forces flying over German-held territory and beyond the range of radar stations in Great Britain.
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While this was going on, No. 109 Squadron continued to bring back fixes on the sources of the 570 MHz transmissions. Yet still the device defied all attempts to photograph it. Clearly, it was much smaller than Freya. From agents’ reports, Jones learned that these transmissions were connected with a fire-control device known as the FMG. Towards the end of 1941, news arrived that four FMG sets were operating in the area of Vienna, of all places. Unless Vienna – a city of great beauty but comparatively little military importance – was a radar equipment depot, it seemed reasonable to infer that the FMG device existed in considerable numbers. Another important photographic clue came from the United States, at that time still neutral. The US Embassy in Berlin overlooked the Berlin Zoo district, where a couple of huge concrete flak towers had been built. A photograph arrived on Jones’s desk showing the top of one of the towers; clearly visible was a large dishshaped open-work radar reflector, of a type not seen before. Unfortunately there was nothing nearby to give scale to the object. A few weeks later, a Chinese scientist reported seeing the same device, which he described as paraboloid more than twenty feet in diameter, that could be rotated and elevated. He thought it might be used to direct the anti-aircraft guns. Jones saw that the new radar could not possibly be the 570 MHz radar known to exist in such profusion in German-occupied Europe. Otherwise, its large reflector would have been spotted on aerial photographs long before this. In fact, the Berlin Zoo photograph showed one of the first Giant Würzburg radars to enter service. Still Jones had no picture of the small Würzburg equipment, but the hunt for one was nearing its end. Late in November 1941, Charles Frank was examining a medium-level photograph of the Freya station at Bruneval near Le Havre on the north coast of France. There he saw that a track had been trodden out along the cliff-edge: it ran from the Freya towards a large house, which seemed to serve as a headquarters. Just before it reached the building, the track swung to the right. It ended at a small black object about halfway between the house and the cliff top. Several people had considered it worth their while to tread out a path from the main radar station to the ‘small black object’. Might that object play some part in the working of the Freya? On 3 December Flight Lieutenant Tony Hill, a reconnaissance
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pilot, visited the interpretation centre at Medmenham in Buckinghamshire to discuss the photography of German radar sites. Squadron Leader Claude Wavell knew of Charles Frank’s special interest in the Bruneval radar, and mentioned the mysterious black object to Hill. On the following day, on his own initiative, Hill took off in a Spitfire to look at Bruneval. He swept in low over the cliffs, and was past the emplacement before the startled defenders knew what had happened. On his return, Hill discovered that his camera had failed to function properly. It was a cruel blow – but he had seen the device clearly, and was able to say that it looked ‘like an electric bowl-fire and was about ten feet across’. If Hill was right, this might be the elusive source of the 570 MHz transmissions. On the following day, Hill bravely repeated the performance. This time the camera worked perfectly and the photographs he brought back were among the classics of the war. They showed the device exactly as he had described it, like an electric bowl-fire about ten feet across. Although it now seemed highly probable, the evidence was still not conclusive that this was the source of the 570 MHz signals. Until that was certain, countermeasures could not begin. It is difficult to establish who first suggested the idea of pilfering the device at Bruneval. The notion was so obvious – it lay within 200 yards of the coast – that it might have occurred to several people. At all events, by the beginning of January 1942 such an operation was in the detailed planning stage. Clearly a commando raid launched from the sea would be doomed to failure; the device was situated at the top of high cliffs, protected by a sizeable German garrison. Even if the troops could fight their way to the top of the cliffs without suffering serious casualties, it was unlikely they could do so before the defenders had destroyed the radar. The naval commodore in charge of Combined Operations, Lord Louis Mountbatten, suggested that parachute troops should be used instead. On 21 January the Chiefs of Staff agreed to this, and assigned C Company of the 2nd Parachute Battalion to the operation. An operational squadron of Whitley bombers would transport them to the target area, and a force of light naval craft would evacuate the raiders from the nearby beach when the mission was over. Intensive training began for what the men were told would be ‘a special demonstration exercise’ to be watched by the whole
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of the War Cabinet. The venture received the code-name ‘Biting’. Once the device had been captured, the task of dismembering it was to be undertaken by seven men of the Royal Engineers, commanded by Lieutenant D. Vernon. The eighth man in the team was from the RAF: Flight Sergeant C. Cox, a radar mechanic, who was to go along should his specialist knowledge be required. The dismantling party was given a British gun-laying radar – the nearest available equivalent to the expected German system – on which to practise its dismantling skills. Vernon and Cox then received a special briefing on the anticipated layout of the German set. According to the planned time-table, they would have half an hour with the apparatus; in that time they were asked to make sketches and take photographs of the equipment, then dismantle it systematically starting at the aerial and working backwards through the receiver to the presentation gear. The operating frequency could be established beyond doubt by removing the aerial element from the centre of the ‘bowl’, and measuring it. The next target was the receiver and its associated presentation equipment. These would reveal whether any anti-jamming circuitry was built into the set. The transmitter was also wanted, so British scientists could examine German techniques for generating high powered pulses on ultra-high frequencies. Dr Jones also asked that a couple of prisoners be taken, radar operators if possible. These might be persuaded to reveal information on the methods of operating the radar and aircraft reporting. All German signals equipment bore informative labels and inspection-stamps, and useful general intelligence could be obtained from these. Should the various units prove impossible to dislodge, Jones asked that the labels be torn off and brought back. By the fourth week in February Jones had confirmation from other sources that the ‘bowl-fire’ was a radar code-named Würzburg, and that one of these sets was situated near the Freya station at Bruneval. By then all the military preparations for the operation were complete, but now the weather intervened. On the evening of the 24th the weather was unsuitable, as it was on the next two nights. The timing of the raid was critical; the attack had to take place on the night of a full moon, but also when the tide was on the rise so the assault craft would not be left stranded on the beach. The 27th was the last possible date for the operation for a month or more.
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That evening the forecast was favourable and the Commander-inChief Portsmouth, Admiral Sir William James, signalled: ‘Carry out operation Biting tonight 27th February.’ The twelve converted Whitley bombers of No. 51 Squadron took off from Thruxton near Andover. On board were 119 paratroops and the RAF flight sergeant, sitting huddled together and trussed up in their uncomfortable parachute harnesses. One soldier later wrote: ‘The mugs of hot tea (well laced with rum) we had drunk before taking off began to scream to be let out. In that restricted space and encumbered as we were there was, alas, no way.’ Shortly after midnight on the morning of the 28th, the first sticks of paratroops leapt from their aircraft. Some ten seconds later the men tumbled on to the carpet of virgin snow some 600 yards to the south of the radar site. They hastily shed their parachute harnesses and cocked their weapons, ready to fight for their lives. But the halfexpected rattle of German small-arms fire did not come. Their arrival had passed unnoticed. The sound of the Whitleys’ engines faded into the night, leaving the men feeling very lonely and vulnerable. As the men assembled into their small groups, their next move was not at all warlike: that tea just had to go. Major John Frost, the force commander, later wrote that this ‘was certainly not good drill, as now was the time when a stick of parachutists was most vulnerable . . . but at least it was a gesture of defiance!’ The assault parties now moved on their assigned targets. One, led by Frost himself and comprising fifty men including the dismantling party, crept towards the radar site and the house nearby. A second party, under Lieutenant Timothy, took up covering positions to screen the force from attack from the landward side. The remainder made off to secure the beach and the escape route. Frost’s men silently surrounded the Würzburg, whose silhouette stood out sharply in the moonlight, and the nearby house. If the house was some kind of headquarters, it might be a centre for resistance. Frost himself stole round to the front door with a small party. Satisfied that all was ready, he gave the signal for battle to begin – a long shrill blast on his whistle. With four men at his heels, Frost burst into the house and began searching each room in turn. It proved something of an anti-climax, the only German present died trying to defend one of the upstairs rooms. Outside, a fierce battle was in progress with almost continuous
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automatic fire punctuated by the bangs from exploding handgrenades. Within minutes, all resistance around the Würzburg had been overcome. But, as that fight ceased, another began. There were about a hundred German troops stationed in the vicinity, and Lieutenant Timothy’s covering force found itself being hotly engaged. In the fight to seize the Würzburg, five of its six operators had been killed. The sixth man made off into the darkness, but in his haste he lost his sense of direction and stumbled over the cliff. Fortunately he managed to grab a projecting rock, and with some difficulty he climbed back to the top. He then found himself being helped over the edge by a British paratrooper. In no position to offer resistance, the man quietly surrendered. With the Würzburg secured, Lieutenant Vernon climbed on top of the operating cabin and examined the aerial with the aid of a hand torch. He then photographed the aerial from each angle – an action no sooner made than regretted, for the light from the flashbulbs attracted bullets from several directions. Vernon then summoned his team and ordered one sapper to saw off the aerial element, while the remainder sought to remove the boxed components in the operating cabin. The aerial came away easily, but the boxes defied all attempts to dislodge them using screwdrivers. This was no time for finesse, for the bullets ricocheting off the cabin’s walls were real enough. The men then brought into play their crowbars, and the equipment gave up the unequal struggle. One by one, the units were ripped from the console. The dismantlers had been at work for barely ten minutes out of the planned thirty, when Major Frost saw three lorries approaching with headlights full on. Almost certainly, these were German reinforcements. If the defenders brought into action weapons heavier than the rifles and machine guns they were already using, the raiding force would be at a severe disadvantage. Frost decided to settle for whatever the dismantling party had already secured, and ordered his force to withdraw to the beach. But now he learned that the shoreline was still in German hands. What had gone wrong? Of the forty men detailed to secure the escape route, half had landed more than two miles from the planned dropping-zone. The senior officer present, Lieutenant E. Charteris, took a quick bearing on the lighthouse at Cap d’Antifer and worked
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out his position. He then led his men towards the radar site at a brisk trot, and arrived at the clifftop just as Frost was organising his own force to storm the beach. The combined assault teams rushed the German positions in their path. Now the beach was in British hands and on it lay the wounded, the German prisoners and the items stripped from the Würzburg. Frost told his signallers to call in the naval craft to evacuate the force. It was high time to leave, for on the cliffs on either side of the beach the German forces were becoming increasingly active. After a few minutes, the signallers reported they had had no success in contacting the boats. Frost fired red distress flares, but to no effect. Then, he later wrote, ‘I moved off the beach with my officers to rearrange our defences. It looked as though we were going to be left high and dry, and the thought was hard to bear.’ Just as his troops had begun to take up positions for a final stand, Frost heard a cry: ‘Sir, the boats are coming in!’ He looked back and saw six snub-nosed assault craft sliding to a stop on the beach. With a sigh of relief he ordered his men to embark, while the boats’ crews put down covering fire on the German troops at the top of the cliffs. With the roar of accelerating engines the landing craft backed away from the shore, while the brisk exchange of gunfire continued until the boats were well clear. Safe aboard an assault craft, Major Frost learned the reason for the delay. While he had been signalling, a German destroyer and two patrol boats had passed within a mile of the small British flotilla but noticed nothing. Frost also learned that the pieces of the radar secured by his men were almost exactly what were needed. Mr D. H. Priest, a Telecommunications Research Establishment engineer who had received a temporary commission as a flight lieutenant for the occasion, examined the booty on the boat. Had the coast been clear, he would have landed and climbed to the radar site to look over the Würzburg, but this was not possible. When dawn broke, several Spitfires arrived over the craft and escorted them back to England. The Bruneval operation was successful on almost every count. The raiders had captured most of the radar. Of the three prisoners, one was a radar operator. The paratroops suffered fifteen casualties – two dead, seven wounded and six missing. The dismantling party had done extremely well in the brief time available. The units it brought back included the receiver, the receiver amplifier, the
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modulator – which controlled the timing within the radar – and the transmitter. In addition, there was the sawn-off aerial element. The only unit which Jones had requested and not received was the presentation equipment. If – as had nearly happened – the boxes had proved impossible to tear from their mountings, Jones might have had to make do with the labels alone. So it is interesting to see what could be learned from these. The labels indicated that the manufacturer was Telefunken, a company with factories in the Berlin area. The works numbers were particularly interesting. From previous experience with German serial numbers, Jones had deduced that the number allocated to the first production model of each component was 40,000. The earliest number found on the captured units was 40,144, the latest was 41,093. This suggested that the number of sets of components produced by the date of manufacture of the last item, was 1,093. The earliest inspection date, early November 1940, was stamped on a part of the transmitter; the latest, 19 August 1941, was on the aerial. This did not necessarily mean that 1,093 complete Würzburg sets had been turned out by the latter date, since a proportion of the component units would have served as spares. It was a principle of German design that servicing was facilitated by replacing component units, while the defective ones were returned to a central depot for repair. Assuming that about half the production went into spares, Jones reckoned that around 500 of these radars were available by August 1941, and production was probably running at about 100 sets per month. For him the raid was particularly satisfying, since the intelligence gleaned either confirmed or added to the previous picture. No part of the picture had to be modified or discarded. An important side effect of the raid was that it gave British intelligence added confidence in the accuracy of the information it was receiving. Scientists at the Telecommunications Research Establishment at Swanage made a thorough examination of the Würzburg units. In their view the equipment was considered ‘straightforward and in no respect is it brilliant . . . On the other hand, it must be remembered that the equipment was made in 1940 and designed in 1939 or earlier.’ In 1940, British radar techniques had not been sufficiently advanced to build a set working on 570 MHz with a range of twenty-five miles. While the German radar carried no
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specific anti-jamming circuitry, it could be re-tuned over a narrow range of frequencies to overcome electronic jamming. After the Bruneval horse had been ‘rustled’, the German local defence commanders along the French coast made sure that the stable door was well and truly bolted. The remains of the Würzburg were removed, and a new set was installed in the main Freya compound. Within a few weeks, a dense barbed wire entanglement surrounded the compound. Other radar stations followed this lead. Every German radar station near the coast now became conscious of its vulnerability, and surrounded itself with barbed wire. That greatly helped Jones and his staff; there were several sites which were suspected to contain Würzburg sets, but in each case the existing aerial photographs had failed to show them. Now these sites obligingly ringed themselves with barbed wire – which showed up well on aerial photographs – to confirm the suspicions. Not only in Germany were there repercussions of the Bruneval operation. The success of the raid highlighted a golden opportunity for a retaliatory attack on the Telecommunications Research Establishment, hub of British work on radar and situated near Swanage on the south coast of England. In the spring of 1942 the establishment made a rapid move to Malvern College, well clear of the coast.
***
Two weeks after the Bruneval raid came an event that was to have even greater significance to the development of countermeasures systems in Great Britain. On 11–13 February 1942 the German battlecruisers Scharnhorst and Gneisenau, and a flotilla of smaller ships, had left their temporary base at Brest, run the gauntlet of the defences covering the Straits of Dover, and successfully reached ports in Germany. In doing so they had inflicted a major blow to Britain’s reputation as a naval power. The operation had taken place under the noses of powerful British forces and was a masterpiece of boldness, careful planning and tight security. An important element in the success of the operation was the large scale use of ground jammers. As the warships came within range of the British coastal radars at the eastern end of the Channel, these jammers were switched on simultaneously. Many of the best British radar operators were now serving in the
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Mediterranean theatre, where the heaviest fighting was taking place. Those who replaced them at radars along the south coast of England were less experienced and they reported the clutter on their screens as ‘equipment failure’ or ‘local interference’. As a result commanders did not appreciate the significance of the radar operators’ difficulties until it was too late. This all came out during the far-reaching official inquiry after the event. The escape of the German warships would have significant effects. At the beginning of 1942 several important British radars – those for coast watching, ground-controlled interception, airborne interception, AA gun-control and searchlight-control – all operated on frequencies in the 200 MHz band. A heavy German jamming effort in that part of the spectrum would pay rich dividends if there was a resumption of the night Blitz. Thus, by highlighting that fundamental weakness, the escape of the German warships greatly assisted the British cause. Work began immediately to develop new types of radar that worked in widely different parts of the spectrum. Once those were in place, the Germans would never again have the chance to knock out the radar system with so little effort.
***
During the spring of 1942, British intelligence gradually improved its picture of the Luftwaffe night air defence system. In March, news arrived of an inland Freya station at Nieuwekerken in Belgium, just to the north of the important night-fighter airfield at Saint-Trond. By this time many coastal Freya stations had been located, but inland stations were thought to be a rarity. A high-flying reconnaissance Spitfire was sent to investigate. The photographs it brought back showed a Freya radar set and a cluster of searchlights, but the latter were grouped round a radar with a large circular open-work bowl – like that photographed in the Berlin Zoo. The proximity to the airfield at Saint-Trond strongly suggested that this was some sort of night-fighter control centre. Shortly afterwards this was confirmed. Then an agent reported a night-fighter control centre at Domburg on the Dutch island of Walcheren. And the subsequent high-level photographic reconnaissance revealed a Freya and two ‘Berlin Zoo’ radars there. A more detailed study of the Nieuwekerken site showed there were two ‘Berlin Zoo’ radars there, also. This called
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for a closer look at the new type of radar. On 2 May, a reconnaissance Spitfire ran in fast and low along the Dutch coast and past the Domburg site. Yet again Flight Lieutenant Tony Hill had pulled off a low-level scoop, for he returned with clear photographs of both ‘Berlin Zoo’ type radars. As the Spitfire swept past them, the two radars were pointing in different directions. So Hill’s pictures showed the radar from two quite different angles. Equally important, at one of the sets an operator had been about to climb the ladder to the cabin. He stood watching, helpless, to become a human yardstick when the photographs were analysed. One night two weeks later, a further ploy was adopted to elicit information about the range of this radar. An RAF Beaufighter night-fighter flew towards the Domburg area, closely watched by the British radar station on North Foreland. A German night-fighter rose to intercept, and a long and inconclusive engagement followed. Throughout it, the RAF monitoring service recorded the orders passed to the Luftwaffe pilot. In particular, they noted that he was not permitted to move more than forty miles from the radar station. This was a strong pointer to its maximum range. Soon afterwards, the ‘Berlin Zoo’ radar was identified as the Giant Würzburg. The next major item of intelligence came from a Belgian agent. He had managed to steal from a German headquarters a map showing the deployment of an entire regiment of searchlights. As luck would have it, the map covered the area around Saint-Trond. Marking the station at Nieuwekerken was a lightning flash, as were two more at Zonhoven and Jodoigne, some twenty miles on either side. Might these be fighter-control stations too? And if they were, was twenty miles the standard distance between adjacent sites? Reconnaissance photographs revealed that this was the case. By extrapolating the line, Jones and his staff soon picked out five further night-fighter control stations, strung out at regular intervals along an almost straight line. During the summer of 1942, the clump of flags on the wall map in Jones’s office sprouted shoots to either side of its original starting point in southern Belgium. The great radar hunt was on. Charles Frank christened the defensive belt the ‘Kammhuber Line’, and that appellation caught on in the RAF. Agents were sent to areas previously calculated, to seek out the radar stations. Their catch was good; a paraboloid the size of a
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suburban house could hardly escape being the object of wonder and speculation by the local population. It should be remembered that at this time the ‘man in the street’ had never heard of radar. As a result the descriptive vocabulary of the inhabitants of the Low Countries was seriously strained; ‘inverted umbrella’ and ‘magic mirror’ were typical of the terms used. One Giant Würzburg was talked about so much that it became known as ‘le fameux miroir d’Arsimont’. During their flights over Belgium, Holland and northern France, RAF bombers dropped caged carrier pigeons. The birds’ legs bore labels asking the finder to write in details of any large dish-like structures seen in the area, and then release the pigeons. This method alone assisted in locating three sites previously unknown to Dr Jones. In the next chapter, we shall observe how this information was used to develop the first countermeasures to the Luftwaffe night air defence system.
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The rigid airship LZ-130 Graf Zeppelin, the last of these craft to be built, flew an electronic intelligence gathering mission along the east coasts of England and Scotland in August 1939.
Dr Ernst Breuning (right) led the listening team
aboard the Graf Zeppelin. He described to the author how his team picked up signals from the newly erected British radar chain, but misidentified them as coming from a research station in Germany which was conducting experiments to measure the altitude of the ionised layers surrounding the earth.
The huge Knickebein beam-transmitter at Stollberg in Schleswig-Holstein. The aerial array was about 100 feet high, and was supported by railway bogies which ran on a circular track 315 feet in diameter to align the beam on the target.
Heinkel 111 bomber of III/KG 26, the unit which employed the Y-Gerät beam system over Britain in 1940–41. Note the additional aerial for the system, mounted above the fuselage behind the cabin.
Wing Commander Edward Addison commanded No. 80 Wing during the ‘Battle of the Beams’. Later he led No. 100 Group, which provided countermeasures support for bomber operations.
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Heinkel 111 of Kampfgruppe 100 on the compass swinging base. Note the two additional aerial masts on the rear fuselage, belonging to the X-Gerät beam attack system.
X-Gerät beam transmitter. Dr R. V. Jones played a major role in uncovering the beam systems used by the Luftwaffe during attacks on Great Britain.
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Left: The first photo to reach Britain showing that the Germans had radar in service. The Graf Spee, pictured in December 1939 after she had been scuttled off Montevideo. The aerial array of the Seetakt radar can be seen (circled) above the bridge.
Below: In November 1940 a reconnaissance aircraft took this photo of two unusual tub-shaped structures (circled and inset) at Auderville near Cherbourg. In February 1941 a Spitfire flew a risky low-altitude mission to get this close-up of the ‘tubs’, each of which was found to house a Freya radar.
85
Messerschmitt Bf 110 night-fighter, with the drag-producing aerial array of the Lichtenstein radar on the nose.
Above: Flight Lieutenant, later Wing Commander, Derek Jackson played a major role in the development of ‘Window’ metal foil strips to jam enemy radars including the Lichtenstein.
Left: Wassermann early
warning radar at Bergen aan Zee in the Netherlands. The surrounding houses give scale to the huge 130-foothigh aerial array.
Above: Generalmajor Josef Kammhuber, architect of the Himmelbett system. Left: Close-up of the Würzburg radar. Designed for use by flak and searchlight batteries, this radar was also used for a short time to direct nightfighters into action.
Reconnaissance photograph of the Würzburg at Bruneval, taken three months before the famous raid.
Low-altitude photo of the Giant Würzburg radar on the island of Walcheren, taken in May 1942.
Following the Bruneval raid, German radar sites were surrounded with dense barbed-wire entanglements, which made them highly conspicuous on aerial photographs. Below: Himmelbett station with a Freya radar (foreground) for long-range search and two narrow-beam Giant Würzburg radars (left and right) to track the movements of the British bomber and the intercepting night-fighter respectively.
H2S indicator in the navigator’s position of a Lancaster bomber.
H2S radar picture of Hamburg (right) compared with a map of the same area. The wide estuary of the River Elbe, pointing at the city from the west, served as a prominent navigation feature on radar.
89
Aerial of a Korfu ground direction-finding station, which tracked RAF bombers by picking up the radiations from H2S.
Generalfeldmarschall Erhard Milch held frequent conferences to discuss each step in the countermeasures battle as it appeared on the German side.
Oberst Dietrich Schwenke headed the Luftwaffe intelligence section responsible for monitoring technical developments by the Western Allies.
90
Generalmajor Joseph Schmid (right) took control of Luftwaffe night-fighter operations after General Kammhuber was ousted from that post following the ‘Window’ debacle in July 1943.
Major Hajo Herrmann (centre) seen with Reichsmarschall Herrmann Göring during an inspection of ‘Wild Boar’ night-fighter pilots. Major Herrmann had been instigator of those new tactics.
Ideal ‘Wild Boar’ conditions. Seen from above, a Lancaster bomber silhouetted against a cloud background by searchlights and fires on the ground, photographed over Berlin during the raid on 16 December 1944.
91
Dr Robert Cockburn led the countermeasures team which designed and put into production many of the British jamming systems.
B-17 Flying Fortress modified as a jamming escort aircraft, before issue to No. 214 Squadron, RAF. The radome under the nose housed the scanner for the H2S radar.
Above right: The 600-pound cylinder of the ‘Jostle’ highpowered VHF communications jammer, mounted on the rear of its special transporting truck. This jammer was fitted to the jamming escort Liberators and Flying Fortresses of No. 100 Group.
92
From the autumn of 1944 Luftwaffe night-fighters needed to be equipped to avoid RAF intruders, as well as engage bombers. This Ju 88 night-fighter carries the nose-mounted aerial array for the SN-2 radar. The blister on top of the cockpit canopy houses the rotating aerial for the Naxos radar-homing and warning receiver . . .
Note the two upward-firing 20-mm cannon fitted in the fuselage . . .
Also the tail mounted aerial for SN-2 to provide warning of Allied intruders closing in from behind.
93
Above: The Jagdschloss fighter-control radar was the first German radar to employ the plan position indicator type of display. To avoid electronic jamming, the radar had provision for the operator to select one of four separate operating frequencies.
Left: Effect of ‘Mandrel’ jamming on the screen of a Jagdschloss radar. The screen is north-aligned. The three large ‘spokes’ in the northwest quadrant point to three aircraft jamming as part of a ‘Mandrel’ screen. The caterpillar-shaped return heading south-southeast has the appearance of a bomber stream, though in fact it is ‘Window’ spoof. The scattered returns in the southeast quadrant come from Luftwaffe night-fighters and No. 100 Group Mosquitoes.
Above: Formation of B-17 bombers being engaged by a flak battery firing though an overcast. Note the effect probably caused by ‘Carpet’ jamming of the fire-control radars: although the bursts appear to be accurate in line, the shells have detonated at the incorrect range and well below the raiders’ altitude. Left: The APQ-9 ‘Carpet III’ jamming equipment, used in large numbers to counter the German Würzburg and Mannheim flak-control radars.
Right: B-29 bombers pictured at one of the islands on the Marianas group. With assistance from radio-countermeasures, these aircraft made devastating attacks on Japanese cities and industrial targets for minimal losses in the spring and summer of 1945.
95
Above: The ‘Tuba’ equipment, designed and built at the Radio Research Laboratory at Harvard, was the largest and most powerful jamming system produced during World War II. The man standing at the base of the aerial gives scale to the special directional array developed for the jammer. ‘Tuba’ became operational too late to have any effect, however.
96
‘Little Boy’, the atomic bomb which devastated the Japanese city of Hiroshima. The aerial elements of two of the four radar airburst fuses can be seen mounted on the side of the weapon.
‘Guardian Angel’ B-29, which served as a jamming escort aircraft to provide cover for bombers attacking Japan. Eight jamming aerials are visible on this view of the aircraft.
Chapter 4
Towards the Offensive
‘If you know the enemy and know yourself you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory you will suffer a defeat. If you know neither you will always be beaten.’
General Sun-Tzu
As German troops advanced deeper into the Soviet Union in the summer of 1941, it became clear in Britain that, after almost a year on the defensive, it was time to seize the initiative in the West. Clearly, an invasion of the continent was out of the question in the foreseeable future. For the time being the only readily available means of striking at the German homeland was through RAF Bomber Command. Prime Minister Churchill assured Russian Premier Josef Stalin that, when the weather improved in the spring of 1942, the RAF would launch a heavy air offensive against Germany and: ‘We are continuing to study other measures for taking some of the weight off you.’ Those ‘other measures’ would not materialise for a long time. At that time, however, Bomber Command was going through a period of soul-searching. The fact that the Luftwaffe had found it necessary to develop radio aids to assist accurate navigation and bombing at night had led to some scepticism concerning the results the British bomber crews might themselves be achieving. After all, they had no such aids. One of the doubters was Air Vice-Marshal Robert Saundby, who took up an appointment as Senior Air Staff Officer at Bomber Command headquarters at the end of 1940. He told his staff that, when a force of bombers claimed to have dropped 300 tons of bombs on a certain target, all they could be certain of was that they had ‘exported 300 tons of bombs in its direction’. Professor Lindemann conducted his own investigation into the results of the RAF bombing, based on the photographs brought back by reconnaissance aircraft. The findings were highly disquieting: of the crews who thought they had hit the target, only one in three
had in fact placed their bombs within five miles of it. In the case of targets in the Ruhr industrial area, the figure was as low as one crew in ten. After receiving the report in September 1941, Mr Churchill taxed the Chief of Air Staff with this:
It is an awful thought that perhaps three-quarters of our bombs go astray . . . If we could make it half and half, we should virtually have doubled our bombing power.
As a long-term investment, development began on two radio devices to improve bombing accuracy: Oboe and H2S. These will be described in later chapters. For the moment, the most urgent requirement was for a less ambitious radio aid that would improve basic navigational accuracy at night. Fortunately work on such an aid was well advanced at the Telecommunications Research Establishment and the device, codenamed ‘Gee’, was nearing the service trials stage. The ‘Gee’ (or Grid) system of navigation had been conceived in 1938, and work on the device had begun in earnest in the spring of 1940. ‘Gee’ employed three ground transmitters situated about a hundred miles from each other. These transmitters acted in unison to radiate a train of pulses in a set order. The aircraft carried a special radar receiver, which enabled the navigator to measure the minute time differences between the reception of the various signal pulses. By referring those time differences to a special ‘Gee’ map, the navigator could determine his position to within six miles, while flying up to 400 miles from the furthest transmitter. Closer to the transmitters, the accuracy was even better. In its concept ‘Gee’ was a great improvement over that of Knickebein, its nearest German equivalent. The latter gave an accurate positional fix only at the crossing point for a pair of Lorenz-type beams, whereas ‘Gee’ provided fixes for aircraft anywhere within its area of cover. By the beginning of March 1942, sufficient ‘Gee’ receivers existed to equip about one-third of Bomber Command’s aircraft. The device immediately became popular with crews, who affectionately nicknamed it the ‘Goon box’. The Luftwaffe captured its first ‘Gee’ receiver on 29 March, recovered from the wreckage of a Wellington bomber which came down in the sea off Wilhelmshaven. The device had suffered some salt-water damage, but that water had saved it from complete
Instruments of Darkness
98
destruction. As the crew had abandoned the Wellington, one of them initiated the explosive detonator intended to destroy the box. The system had a built-in delay to give everyone time to get clear, and before it went off the water had smothered the charges. The procedure adopted by Luftwaffe intelligence from this point on was similar to that used by R. V. Jones and his team in Britain. Intelligence officers and radio experts hunted for any further scraps of information relating to the new British system. Oberst Dietrich Schwenke, the intelligence officer in charge of the Luftwaffe section dealing with equipment captured in the West, discussed the find at a high-level conference held in Berlin on 26 May. He said the remains of this equipment had been recognised in several shot-down British aircraft, but in every case except the Wilhelmshaven incident and a second aircraft which had also crashed in the sea, the units had been smashed beyond repair when the demolition charge went off. Schwenke continued:
The British [have developed] a new system which gives the pilot [sic] his position at all times. The equipment for this is the receiver I have just described. Tests have been carried out on it by Telefunken, but the set was unfortunately not received in good condition. Our experts are still not in complete agreement concerning the technical working of the equipment.
Schwenke went on to describe the working principle of ‘Gee’, and the way it was used. He added that the equipment was being installed as standard in the each of the RAF’s principal heavy-bomber types – the Wellington, the Lancaster, the Stirling and the Halifax. He continued: ‘I think it is being used not so much to find pinpoint targets, as to improve dead-reckoning navigation.’ Once a working receiver became available, Schwenke planned to install it in a Luftwaffe aircraft. It would then be possible to establish the accuracy of the system over Germany, using the British transmissions. The transmitters were known to be located in southeastern England, in positions where they could cover the Ruhr industrial district. Schwenke said the possibility of jamming was under investigation, but first it was necessary to find out exactly how the system worked and the frequencies it used. He said the ground transmissions were fairly powerful, but he thought they could be jammed if more powerful jamming transmitters radiated
Towards the Offensive 99

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"abstractNote": "Research implications – We argue that events such as the G-20 meetings provide protesters with opportunities to gain temporary “standing” with the media. During such times, activists can use tactics and frames to alter the balance of power in relations with the media and the state and to attract positive media coverage, particularly when activists develop strategies that are not exclusively focused on the media. We argue that a combination of political opportunities and activist media strategies enabled protest organizers to position themselves as central figures in the G-20 news story and leverage that position to build media interest, develop relationships with reporters, and influence newspaper coverage.", "abstractNote": "Purpose – Movements typically have great difficulty using the mass media to spread their messages to the public, given the media's greater power to impose their frames on movement activities and goals. In this paper, we look at the impact of the political context and media strategies of protesters against the 2009 G-20 meetings in Pittsburgh on media coverage of the protests.Methodology – We employ field observations, interviews with activists and reporters, and a content analysis of print coverage of the demonstrations by the two local daily newspapers, the Pittsburgh Post-Gazette and the Pittsburgh Tribune-Review.Findings – We find that protesters were relatively successful in influencing how they were portrayed in local newspaper stories and in developing a sympathetic image of their groups’ members. Specifically, we find that activist frames were present in newspaper coverage and activists were quoted as frequently as city officials.Research implications – We argue that events such as the G-20 meetings provide protesters with opportunities to gain temporary “standing” with the media. During such times, activists can use tactics and frames to alter the balance of power in relations with the media and the state and to attract positive media coverage, particularly when activists develop strategies that are not exclusively focused on the media. We argue that a combination of political opportunities and activist media strategies enabled protest organizers to position themselves as central figures in the G-20 news story and leverage that position to build media interest, develop relationships with reporters, and influence newspaper coverage.",
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"firstName": "Laura K.",
"lastName": "Taylor",
"creatorType": "author"
},
{
"firstName": "Celia",
"lastName": "Bähr",
"creatorType": "author"
}
],
"date": "2023-01-01",
"DOI": "10.1108/JACPR-02-2022-0685",
"ISSN": "1759-6599",
"abstractNote": "Purpose Over 60% of armed conflicts re-occur; the seed of future conflict is sown even as a peace agreement is signed. The cyclical nature of war calls for a focus on youth who can disrupt this pattern over time. Addressing this concern, the developmental peace-building model calls for a dynamic, multi-level and longitudinal approach. Using an innovative statistical approach, this study aims to investigate the associations among four youth peace-building dimensions and quality peace. Design/methodology/approach Multi-level time-series network analysis of a data set containing 193 countries and spanning the years between 2011 and 2020 was performed. This statistical approach allows for complex modelling that can reveal new patterns of how different youth peace-building dimensions (i.e. education, engagement, information, inclusion), identified through rapid evidence assessment, promote quality peace over time. Such a methodology not only assesses between-country differences but also within-country change. Findings While the within-country contemporaneous network shows positive links for education, the temporal network shows significant lagged effects for all four dimensions on quality peace. The between-country network indicates significant direct effects of education and information, on average, and indirect effects of inclusion and engagement, on quality peace. Originality/value This approach demonstrates a novel application of multi-level time-series network analysis to explore the dynamic development of quality peace, capturing both stability and change. The analysis illustrates how youth peace-building dimensions impact quality peace in the macro-system globally. This investigation of quality peace thus illustrates that the science of peace does not necessitate violent conflict.",
"issue": "2",
"libraryCatalog": "Emerald Insight",
"pages": "109-123",
"publicationTitle": "Journal of Aggression, Conflict and Peace Research",
"url": "https://doi.org/10.1108/JACPR-02-2022-0685",
"volume": "15",
"attachments": [
{
"title": "Full Text PDF",
"mimeType": "application/pdf"
}
],
"tags": [
{
"tag": "Developmental peace-building model"
},
{
"tag": "Education"
},
{
"tag": "Engagement"
},
{
"tag": "Inclusion"
},
{
"tag": "Information"
},
{
"tag": "Quality peace"
},
{
"tag": "Time-series network analysis"
},
{
"tag": "Youth peacebuilding"
}
],
"notes": [],
"seeAlso": []
}
]
} }
] ]
/** END TEST CASES **/ /** END TEST CASES **/

69
translators/Queensland State Archives.js
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@ -9,7 +9,7 @@
"priority": 100, "priority": 100,
"inRepository": true, "inRepository": true,
"browserSupport": "gcsibv", "browserSupport": "gcsibv",
"lastUpdated": "2024-08-21 19:45:00" "lastUpdated": "2024-09-03 15:30:00"
} }
/* /*
@ -88,7 +88,10 @@ async function scrape(url) {
let item = new Zotero.Item("manuscript"); let item = new Zotero.Item("manuscript");
item.title = data.title; item.title = data.title;
if ("record_type" in data.subject_terms) { if ("record_type" in data.subject_terms) {
item.type = data.subject_terms.record_type.join("; "); let recordTypes = data.subject_terms.record_type.map(
term => term.term
);
item.type = recordTypes.join("; ");
} }
item.archive = "Queensland State Archives"; item.archive = "Queensland State Archives";
item.archiveLocation = data.qsa_id_prefixed; item.archiveLocation = data.qsa_id_prefixed;
@ -115,8 +118,7 @@ async function scrape(url) {
}); });
} }
// Add digital representation // Add digital representation
if (data.digital_representations.length > 0) { for (let image of data.digital_representations) {
let image = data.digital_representations[0];
let imageID = image.qsa_id_prefixed; let imageID = image.qsa_id_prefixed;
let mimeType, imageTitle; let mimeType, imageTitle;
if (image.file_type == "JPEG") { if (image.file_type == "JPEG") {
@ -127,12 +129,12 @@ async function scrape(url) {
mimeType = "application/pdf"; mimeType = "application/pdf";
imageTitle = "PDF " + imageID; imageTitle = "PDF " + imageID;
} }
item.attachments = [{ item.attachments.push({
title: imageTitle, title: imageTitle,
url: "https://www.archivessearch.qld.gov.au/api/download_file/" + imageID, url: "https://www.archivessearch.qld.gov.au/api/download_file/" + imageID,
mimeType: mimeType, mimeType: mimeType,
snapshot: true snapshot: true
}]; });
} }
item.complete(); item.complete();
} }
@ -240,7 +242,62 @@ var testCases = [
{ {
"type": "web", "type": "web",
"url": "https://www.archivessearch.qld.gov.au/search?f[]=keywords&has_digital=false&op[]=AND&open=false&q[]=wragge&sort=relevance&type[]=archival_object", "url": "https://www.archivessearch.qld.gov.au/search?f[]=keywords&has_digital=false&op[]=AND&open=false&q[]=wragge&sort=relevance&type[]=archival_object",
"defer": true,
"items": "multiple" "items": "multiple"
},
{
"type": "web",
"url": "https://www.archivessearch.qld.gov.au/items/ITM276520",
"items": [
{
"itemType": "manuscript",
"title": "Criminal files - Supreme Court, Northern District, Townsville",
"creators": [
{
"lastName": "A267, Supreme Court, Northern District, Townsville",
"creatorType": "contributor",
"fieldMode": 1
}
],
"archive": "Queensland State Archives",
"archiveLocation": "ITM276520",
"extra": "Issued: 1875/1876\nArchive Collection: S7833, Criminal Files - Supreme Court, Northern District, Townsville",
"libraryCatalog": "Queensland State Archives",
"manuscriptType": "Depositions and indictments",
"rights": "Copyright State of Queensland",
"url": "https://www.archivessearch.qld.gov.au/items/ITM276520",
"attachments": [
{
"title": "PDF DR87978",
"mimeType": "application/pdf",
"snapshot": true
},
{
"title": "PDF DR87979",
"mimeType": "application/pdf",
"snapshot": true
},
{
"title": "PDF DR87980",
"mimeType": "application/pdf",
"snapshot": true
},
{
"title": "PDF DR87981",
"mimeType": "application/pdf",
"snapshot": true
},
{
"title": "PDF DR87982",
"mimeType": "application/pdf",
"snapshot": true
}
],
"tags": [],
"notes": [],
"seeAlso": []
}
]
} }
] ]
/** END TEST CASES **/ /** END TEST CASES **/

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