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Aether and Gravitation
W.G.Hooper, F. S.S.

1

AETHER AND GRAVITATION

AETHER AND
GRAVITATION BY
WILLIAM GEORGE HOOPER, F.S.S.
G
LONDON CHAPMAN AND HALL, LTD.
1903

QC 177 479

651-14-05-

INTRODUCTORY NOTES
THE author in this work endeavours to solve the greatest scientific problem that has puzzled scientists for the past two hundred years. The question has arisen over and over again, since the discovery of universal gravitation by Sir Isaac Newton, as to what is the physical cause of the attraction of gravitation.
"Action at a distance" has long ceased to be recognized as a possible phenomenon, although up to the present, the medium and method of gravitational attraction have not yet been discovered.
It is, however, generally accepted by scientists, that the only possible medium which can give rise to the phenomena incidental to, and associated with the Law of Gravitation, must be the universal aether, which forms the common medium of all phenomena associated with light, heat, electricity and magnetism .
It is impossible, however, to reconcile gravitational phenomena with the present conception of the universal aether medium, and a new theory is therefore demanded , before the long- sought-for explanation will be forthcoming.
Professor Glazebrook definitely states the necessity for a new. theory in his work on J. C. Maxwell, page 221 , where he writes : "We are waiting for some one to give us a theory of the aether, which shall include the facts of electricity and magnetism , luminous radiation, and it may be gravitation."
A new theory of the aether is also demanded in view of the recent experimental results of Professor Lebedew, and Nichols and Hull of America. It is logically impossible to reconcile a frictionless aether, with their results relative to the pressure of light waves.
In the following pages of this work the author has endeavoured to perfect a theory, which will bring aetherial physics more into harmony with modern observation and experiments ; and by so doing, believes that he has found the key that will unlock the problem not only of the cause of universal gravitation, but also other problems of physical science . The author
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vi

INTRODUCTORY NOTES

has taken Newton's Rules of Philosophy as his guide in the making of the new theory, as he believes that if any man knew
anything of the rules of Philosophy, that man was Sir Isaac Newton. The first chapter therefore deals with the generally recognized rules which govern philosophical reasoning, the same being three in number ; the fundamental rule being, that in making any hypothesis, the results of experience as obtained by observation and experiments must not be violated.
In applying the rules to the present theory of the aether, he found that the theory as at present recognized violated two of the most important rules of Philosophy, because, while aether is supposed to be matter, yet it failed to fulfil the primary property of all matter, that is, it is not subject to the Law of Gravitation. If aether is matter, then, to be strictly logical and philosophical, it must possess the properties of matter as revealed by observation and experiment.
Those properties are given in Chapter III ., where it is shown that they are atomicity, heaviness or weight, elasticity, density, inertia, and compressibility. To be strictly logical and philosophical, the author was compelled to postulate similar properties for the aether, or else his hypotheses would contravert the results of all experience.
The application of these properties to the aether will be found in Chapter IV. , where the author has postulated atomicity, heaviness or weight, density, elasticity, inertia, and compressibility for the aether, and so brought the theory of the aether into perfect harmony with all observation and experiments relative to ordinary matter. It will be shown that Clerk Maxwell also definitely affirms the atomicity of the aether, while Tyndall and Huyghens also use the term "particles of aether" over and over again.
Moreover, in view of the most recent researches in electricity made by Sir William Crookes and Professor J. J. Thomson, we are compelled to accept an atomic basis for electricity, and as Dr. Lodge, in his Modern Views of Electricity, states that "Aether is made up of positive and negative electricity," then, unless we postulate atomicity for the aether, we have to suppose that it is possible for a non-atomic body (aether) to be made up of atoms or corpuscles, which conclusion is absurd, and therefore
must be rejected as illogical and unphilosophical. After postulating atomicity for the aether, we are then able to
apply the Newtonian Law of Gravitation to it, which distinctly affirms that " every particle of matter attracts every other particle," and so we arrive at Thomas Young's fourth hypothesis given in the Philosophical Transactions of 1802, where he asserts that "All material bodies have an attraction for the aetherial

INTRODUCTORY NOTES

vii

medium, by means of which it is accumulated within their substance, and for a small distance around them in a state of greater density." He adds the significant remark that this hypothesis is opposed to that of Newton's. With an atomic and gravitative aether it is shown in Chapter IV. how the elasticity, density, and inertia of the medium are brought into harmony with all observation and experiments.
In the succeeding chapters the new theory is applied to the phenomena of heat, light, electricity, and magnetism , and the principles enunciated therein are then applied to solar and stellar phenomena.
One of the greatest stumbling-blocks to the discovery of the physical cause of gravitation, apart from the unphilosophical theory of the aether medium, lies in the fact that apparently the Law of Gravitation only recognizes a force of one kind. Dr. Lodge refers to this phase of the subject on page 39 of his Modern Views of Matter just published. It is here where scientists have failed to solve the problem of universal gravitation, as there are two forces at work in the solar system and not one ; that is, if we are to accept the results of up-to-date experiments in relation to radiant light and heat as performed by Professor Lebedew, and Nichols and Hull of America. Their experiments conclusively prove that light waves exert a pressure upon all bodies on which they fall, and by no reasoning can this pressure be resolved into an attractive force.
Herschel in his Lectures on Scientific Subjects definitely refers to the existence of a repulsive force in the solar system, and asserts that it offers the most interesting prospect of any future discovery .
The author has therefore attacked the problem of the cause of gravitation, by trying to solve the problem of the cause of the repulsive force which has been experimentally demonstrated to exist by Professor Lebedew and others.
In his efforts to ascertain the physical cause of the Centrifugal Force, he has been assisted by an unknown and original essay written by an unknown writer over twenty years ago. That unknown writer was the author's father, who wrote an essay
on the Complementary Law of Gravitation, and if it had not been for that essay, the present work would never have been attempted .
The main object of the author in Chapters VI., VII . , and VIII ., is to prove beyond the possibility of contradiction, from the phenomena of heat, light, and electricity, the existence of two forces in the solar system ; and by so doing, to bring our philosophy of the aether medium, and all gravitational phenomena, into harmony with all observation and experiments, which at present

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INTRODUCTORY NOTES

is not the case. In seeking to do this he found that the new
theory of the aether harmonized with views given by Faraday and Clerk Maxwell in relation to electric and magnetic phenomena, and by the new theory Maxwell's hypothesis of "Physical Lines of Force " receives a definite and physical basis. In Chapter X. the author endeavours to show what the ElectroKinetic energy is, which term is used by Clerk Maxwell, the term being brought for the first time into harmony with our experience. The Electro- Magnetic Theory of Light also receives fresh light from the new theory of an atomic and gravitating aether.
In the succeeding chapters the theory is applied to Newton's Laws of Motion and Kepler's Laws, and is found to harmonize with all the results given by these laws. Such a result is a distinct advance on the application of a frictionless aether to solar and stellar phenomena, as it is impossible for Kepler's Laws to be reconciled in any way with our present theory of the aether.
In the concluding chapter on the unity of the universe, certain views are suggested as to the ultimate constitution of all matter, upon an aetherial basis, which hypothesis practically resolves itself into an electric basis for all matter. It is suggested that aether and electricity are one and the same medium, both being a form of matter, and both possessing exactly the same properties, viz. atomicity, weight, density, elasticity, inertia, and compressibility. This view of matter harmonizes with the
most " Modern Views of Matter " as suggested by Sir Oliver Lodge in his Romanes Lecture 1903.
The author has accepted Newton's way of spelling " aether " as given in his work on Optics, and has given " aetherial " the same suffix as " material,” in order to differentiate the word from
1 " ethereal," which is too metaphysical a term for a material medium.

Nottingham, Sept. 1903.

CONTENTS

CHAPTER I

PHILOSOPHY OF GRAVITATION

PAGE

ART. I. GRAVITATION

I

99 2. CAUSE OF GRAVITATION

I

33 3. NEWTON'S RULES OF PHILOSOPHY

3

13

4. FIRST RULE OF PHILOSOPHY

3

"9 5. SECOND RULE OF PHILOSOPHY

4

99 6. THIRD RULE OF PHILOSOPHY

7

29 7. APPLICATION OF RULES TO GRAVITATION

9

19 8. ANALYSIS OF LAW OF GRAVITATION

9

32 9. PRIMITIVE IMPULSE

IO

27 IO. CENTRIPETAL FORCE

12

99 II. CENTRIFUGAL FORCE

13

12. NEWTON'S LAWS OF MOTION

15

13. FORCE •

·

16

99 14. FIRST LAW OF MOTION

16

15. SECOND LAW OF MOTION

19

16. THIRD LAW OF MOTION

20

17. SUMMARY OF CHAPTER .

22

36 34 33 35

CHAPTER II

PHILOSOPHY OF GRAVITATION- (continued)

ART. 18. GRAVITATION ATTRACTION

24

93 19. UNIVERSALITY OF GRAVITATION

24

20. DIRECTION OF THE FORCES

26

"9 21. PROPORTION OF THE FORCES

26

99 22. LAW OF INVERSE SQUARES

27

33 wwww

23. TERRESTRIAL GRAVITY •

29

29 24. CENTRIFUGAL FORCE

30

36 36

25. KEPLER'S LAWS

32

26. FIRST LAW OF KEPLER

33

27. SECOND LAW OF KEPLER

36

28. THIRD LAW OF KEPLER

37

X

CONTENTS

CHAPTER III

MATTER

PAGE

ART. 29. WHAT IS MATTER ?.

40

"" 30. CONSERVATION OF MATTER

42

"9 31. MATTER IS ATOMIC

42

99 32. WHAT IS AN ATOM ?

43

99 33. THE ATOMIC THEORY

44

99 34. KINDS OF ATOMS

44

"" 35. ELEMENTS OF MATTER

47

36. THREE KINDS OF MATTER

47

99 37. MATTER IS GRAVITATIVE

50

99 38. MATTER POSSESSES DENSITY

51

"" 39. MATTER POSSESSES ELASTICITY

51

40. MATTER POSSESSES INERTIA

52

CHAPTER IV

AETHER

ART. 42. AETHER IS MATTER

54

99 43. AETHER IS UNIVERSAL .

58

99 44. AETHER IS ATOMIC .

59

99 45. AETHER IS GRAVITATIVE

64

"" 46. AETHER POSSESSES DENSITY

71

39 47. AETHER POSSESSES ELASTICITY .

74

99 48. AETHER POSSESSES INERTIA

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99 49. AETHER IS IMPRESSIBLE

78

"" 50. AETHER AND ITS MOTIONS .

088* 0

CHAPTER V

ENERGY

ART. 51. ENERGY

83

99 52. CONSERVATION OF ENERGY

84

53. TRANSFORMATION OF ENERGY

86

"" 54. POTENTIAL ENERGY

87

"9 55. KINETIC ENERGY

89

99 56. ENERGY AND MOTION

91

99 57. CONSERVATION OF MOTION

92

"" 58. TRANSFORMATION OF MOTION

93

59. MOTION AND WORK

95

‫وو‬ ‫وو‬

36 33

CONTENTS
CHAPTER VI
HEAT, A MODE OF MOTION ART. 60. HEAT, A MODE OF MOTION
"" 61. HEAT AND MATTER 62. RADIATION AND ABSORPTION
22 63. HEAT IS A REPULSIVE MOTION 29 64. RADIANT HEAT • 99 65. DIRECTION OF A RAY OF HEAT "" 66. LAW OF INVERSE SQUARES .
67 FIRST LAW OF THERMODYNAMICS 68. SECOND LAW OF THERMODYNAMICS 69. IDENTITY OF HEAT AND LIGHT
CHAPTER VII
LIGHT, A MODE OF MOTION ART. 70 LIGHT, A MODE OF MOTION
"" 71. TRANSVERSE VIBRATION OF LIGHT 29 72. REFLECTION AND REFRACTION "" 73. THE SOLAR SPECTRUM • "" 74. DIRECTION OF A RAY OF LIGHT 29 75. INTENSITY OF LIGHT 29 76. VELOCITY OF LIGHT "" 77. DYNAMICAL VALUE OF LIGHT 29 78. ELECTRO-MAGNETIC THEORY OF LIGHT
CHAPTER VIII AETHER AND ELECTRICITY ART. 79. ELECTRICITY, A MODE OF MOTION 29 80. ELECTRIC FIELD "" 81. ELECTRIC INDUCTION 82. ELECTRIC ENERGY . 27 83. ELECTRIC RADIATION "" 84. LAW OF INVERSE SQUARES . "" 85. SECOND LAW OF ELECTRICITY

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PAGE 98 100 104 107 109 III 112 114 116 119
122 130 135 139 144 145 148 150 155
162 166 • 174 179 • 182 184 186

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CONTENTS

CHAPTER IX

AETHER AND MAGNETISM

PAGE

ART. 86. ELECTRO-MAGNETISM

192

99 87. THE EARTH A MAGNET . "" 88. THE SUN AN ELECTRO- MAGNET

• 195 199

99 89. FARADAY'S LINES OF FORCE 90. TERRESTRIAL MAGNETISM

• 203 206

91. SOLAR MAGNETS

211

99 92. CAUSE OF ROTATION OF THE EARTH ON ITS AXIS

219

79 93. VORTEX MOTION

•

• 221

99 94. RELATIVE MOTION OF AETHER AND MATTER

224

"" 95. VIBRATIONS IN THE ELECTRO -MAGNETIC THEORY OF

LIGHT .

228

CHAPTER X

AETHER AND NEWTON'S LAWS OF MOTION

ART. 96. AETHER AND CENTRIFUGAL FORCE

232

99 97. AETHER AND CENTRIPETAL FORCE

236

"" 98. AETHER AND NEWTON'S FIRST LAW OF MOTION

239

99 99 AETHER AND NEWTON'S SECOND LAW OF MOTION

244

"" 100 AETHER AND NEWTON'S THIRD LAW OF MOTION

251

"" IOI. WHY PLANETS REVOLVE FROM WEST TO EAST

253

CHAPTER XI
AETHER AND KEPLER'S LAWS
ART. 102. AETHER AND KEPLER'S FIRST LAW • "" 103. AETHER AND KEPLER'S SECOND LAW 99 104. AETHER AND KEPLER'S THIRD LAW 105. ORBITAL MOTION OF PLANETS 97 106. ECCENTRICITY OF THE MOON'S ORBIT . 99 107. THE SUN AND KEPLER'S FIRST LAW 108. THE SUN AND KEPLER'S SECOND LAW 109. AETHER AND THE PLANE OF THE ECLIPTIC 99 110. AETHER AND THE CENTRIPETAL FORCE

256 260
263 266 268
270 274 277 282

CONTENTS
CHAPTER XII AETHER AND COMETS ART. III. WHAT IS A COMET ? 19 112. ORBITS OF COMETS 33 113. KINDS OF COMETS . 37 114. PARTS OF A COMET 115. CENTRIFUGAL FORCE AND COMETS 99 116. FORMATION of Tails •
CHAPTER XIII AETHER AND STARRY WORLD ART. 117. STARRY WORLD • 19 118. STARS AND KEPLER'S LAWS "" 119. AETHER AND NEBULAE • 120. WHAT IS A NEBULA ? • 99 121. AETHER AND NEBULAR HYPOTHESIS 33 122. KINDS OF NEBULAE
CHAPTER XIV AETHER AND THE UNIVERSE ART. 123. THE UNIVERSE · 124. UNITY OF THE UNIVERSE 125. CONSTITUTION OF MATTER 31 126. QUOD ERAT FACIENDUM 99 127. GOD AND THE UNIVERSE
APPENDIX INDEX

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PAGE 291 293 296 298 300 303
306 309 313 314 317 • 319
323 • 326
334 337 342 • 349 351

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AETHER AND GRAVITATION
CHAPTER I
PHILOSOPHY OF GRAVITATION
ART. I. Gravitation.- In the realm of Science, there exists a Force or Law that pervades and influences all Nature, and from the power of which, nothing, not even an atom, is free.
It holds together the component parts of each and every individual world, and in the world's revolving prevents both its inhabitants and its vegetation from being whirled off its surface into space. It exists in each and every central sun, and circles round each sun its associated system of planets. It rolls each satellite around its primary planet, and regulates the comet's mysterious flight into the depths of space, while the pendulation of even the remotest star is accomplished by this same force. Our own rocking world obeys the same mysterious power, that seems to grasp the entire material creation as with the grasp of the Infinite.
It exists in, and influences every atom, whose combinations compose and constitute the entire material creation, or each and every orb that bespangle the blue infinity.
As is readily seen, it weaves as it were around each and all, a mysterious network or chain, that binds star to star, and world to world, blending all into one entire, vast and complete unity. It decides all their orbits and distances, regulates and controls all their motions, from the most simple even to the more complex and intricate, ultimately producing that wondrous and beauteous order, unity and harmony that everywhere pervade and blend all the universe into one grand and harmonious whole.
That Law I need hardly say is the Law of Gravitation. ART. 2. Cause of Gravitation.- Now the question arises, and indeed has arisen a thousand times since the discovery of this law by Sir Isaac Newton over two hundred years ago, as to what is the physical cause, the true explanation of this universal attraction.
B

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AETHER AND GRAVITATION

MacLaurin in his work on the philosophical discoveries of Sir Isaac Newton says : " In all cases when bodies seem to act upon each other at a distance, and tend towards one another without any apparent cause impelling them, this force has been commonly called Attraction, and this term is frequently used by Sir Isaac Newton. But he gives repeated caution that he pretends not by the use of this term to define the nature of the power, or the manner in which it acts. Nor does he ever affirm or insinuate
that a body can act upon another body at a distance, but by the intervention of other bodies."
The results of modern discovery show that action at a distance, without the intervention of any medium, as for example the sun attracting the earth, is not the universal condition which governs all so-called forces.
It is now recognized that light and heat are both forms of energy, and therefore forces, using the term in the same sense that it is applied to Gravitation.
Both light and heat are transmitted through space with finite velocity through the intervention of a medium, the universal Aether. It is therefore only reasonable to suppose, that if one or more particular kinds of energy, or forces, require a medium for their transmission , why not another force, as for example Gravitation ?
Gravitation is an universal force which operates throughout the length and breadth of the entire universe, and if there be a medium which is to Gravitation, what the Aether is to light and heat, the question at once confronts us, as to what are the characteristics, properties, and qualities of that universal medium, which is to form the physical basis of this universal attraction ?
Newton himself suggested that Gravitation was due to an aetherial subtle medium, which filled all space.
In his well-known letter to Bentley, Newton writes as follows : " That Gravity should be innate, inherent, and essential to matter, so that one body can act upon another body at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no man who has any philosophical nature or competent faculty of thinking can ever fall into it."
We also know from his Queries in his book on Optics, that he sought for the explanation of Gravitation in the properties of a subtle, aetherial medium diffused over the universe.
MacLaurin on this point says : " It appears from his letters to Boyle, that this was his opinion early, and if he did not publish his opinion sooner, it proceeded from hence only, that he found he was not able from experiment and observation to give a

RULES OF PHILOSOPHY

3

satisfactory account of this medium , and the manner of its operations in producing the chief phenomena of Nature."
Therefore, if we accept Newton's suggestion, and endeavour to trace the physical cause of Gravitation in the qualities, properties, and motions of this subtle aetherial medium to which he refers, we shall be simply working on the lines laid down by Sir Isaac Newton himself.
I wish therefore to premise, that the future pages of this work will deal with the hypothesis of this aetherial medium, by which will be accounted for, and that on a satisfactory and physical basis, the universal Law of Gravitation.
ART. 3. Rules of Philosophy.- In order that we may rightly understand the making of any hypothesis, I purpose giving some rules laid down by such philosophers as Newton and Herschel, so that we may be guided by right principles in the development of this new hypothesis as to the cause of Gravitation.
The rules that govern the making of any hypotheses, so far as I can discern, may be summed up under the three following heads-
(1 ) Simplicity of conception. (2) Agreement with experience, observation , and experiment. (3) Satisfactorily accounting for, and explaining all phenomena sought to be explained . ART. 4. Ist Rule. Simplicity of Conception.-From this rule we learn that the hypothesis must be simple in conception, and simple in its fundamental principles, and further, that the same characteristic of simplicity must mark each step of its development. This rule of simplicity is distinctly laid down by Sir Isaac Newton in his Principia, Book 3, under the heading " Regulae Philosophandi. " In that work he writes : " Natura simplex est, et rerum causis superfluis non luxuriat."-" Nature is simple, and does not abound in superfluous causes of things." He further states that : "Not more of the natural causes of things ought to be admitted, than those which are true and suffice to explain phenomena. In the nature of Philosophy nothing is done in vain, and by means of many things, it is done in vain when it can be done by fewer. For Nature is simple, and does not abound in superfluous causes." While again in Rule 3, he adds : " Natura simplex est et sibi semper consona."-" Nature is simple, and always agrees with itself."
Whewell also considers simplicity as a fundamental principle of all true hypotheses. On this point he writes : " All the hypotheses should tend to simplicity and harmony. The new

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AETHER AND GRAVITATION

suppositions resolve themselves into the old ones , or at least only require some easy modification of the hypothesis first assumed . In false theories the contrary is the case."
Thus, it is the very essence of philosophy to build upon a foundation of simplicity, combined with the results of experience, observation, and experiment. For example, if we desired to form a hypothesis as to the cause of day and night, two hypotheses might be assigned as to the cause.
First, that the earth revolves on its axis once a day, and so presents each part successively to the light and heat of the sun ; and second, that the sun revolves round the earth once every 24 hours. But such an assumption as the latter would involve the revolution of the sun through an immense orbit at an enormous velocity, in order for the journey to be accomplished in the time. So that it is much simpler to conceive of the earth revolving on its axis once every 24 hours, than it is for the sun to perform this journey in the same period. Hence the rule of simplicity is in favour of day and night being caused by the revolving of the earth on its axis. The same rule might be illustrated in many ways ; but, however illustrated , the principle, according to Newton, always holds good that all effects are produced by the simplest causes, and if there are apparently two causes to the same phenomenon, then the simpler cause is the true and correct one. So that in the making and development of any hypotheses of the physical cause of Gravitation, this rule of simplicity must always be recognized ; and , in conjunction with the other rules, we must seek to make our hypotheses, so as to be able to account and explain all phenomena sought to be explained .
ART. 5. 2nd Rule. Experience. - Newton fully recognized the necessity of experience in Philosophy. He saw the absolute necessity of appealing to experience, observation, and experiment, both as a basis for philosophical reasoning, and further, for the data which were necessary to verify particular applications of the hypotheses suggested .
In his Rules of Philosophy, referring to experience as a guide, he says : " Hoc est fundamentum philosophiae."—" This is the basis of philosophy."
Herschel, writing on the same subject in his Natural Philosophy, writes thus with regard to experience : " We have pointed out that the great, and indeed the only ultimate source of our knowledge of nature, and its laws, is experience. By which I mean, not the experience of one man only, or of one generation, but the accumulated experience of all mankind in all ages registered in books or recorded in tradition. But experience may be
acquired in two ways, either first by noticing facts as they occur

RULES OF PHILOSOPHY

5

without any attempt to influence the frequency of their occurrence, or to vary the circumstances under which they occur. This is observation. Second, by putting in action causes and agents over which we have no control, and purposely varying their combination, and then noticing what effects take place. This is experiment. To these two sources we must look as the fountains of all natural science."
Herschel further writes : " Experience once recognized as the fountain of all our knowledge of nature, it follows, that in our study of nature and its laws, we ought at once to make up our minds to dismiss, as idle prejudices, or at least suspend as premature, all preconceived notion of what might , or ought to be the order of nature in any proposed case, and content ourselves as a plain matter of fact with what is. To experience we refer as
the only ground for all physical enquiry. But before experience itself can be used to advantage, there is one preliminary step to make which depends wholly upon ourselves."
" It is the absolute dismissal and clearing the mind of all prejudices from whatever source arising, and the determination to stand or fall by the result of direct appeal to facts in the first instance, and to strict logical deduction from them afterwards."
From extracts like these, from such men as Newton and Herschel, it can at once be seen that experience, and experience alone, should be the chief fountain from whence we draw all our data to form the bases of any hypothesis or theory. If the hypothesis formed is contradicted by the result of any present or future observation or experiment, then such hypothesis will either become untenable, or must be so modified as to take in the new fact furnished by that observation and experiment.
It is a sine qua non of all true philosophy, that philosophy should always agree with experience. To the extent that our Philosophy of Nature fails to agree with our experience, or with the results of observation and experiment, then to that extent it ceases to be philosophy. It may be a hypothesis or even a theory, but certainly it is not true Philosophy.
Now, in the elaboration and development of the theory as to the physical cause of Gravitation , I can premise that nothing will be postulated or supposed, unless such supposition can be directly verified by our own observation and experiments.
Any theory or hypotheses that are contradicted by our own experience in its widest form , will find no place in the development of this work. Further, any present accepted theory in relation to any natural phenomena, which is controverted by experiment, or observation, will be rejected as untenable in the scheme of Natural Philosophy to be submitted to the reader.
Whatever else the theory suggested may, or may not be, one

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thing it certainly shall be, and that is, that it shall be strictly based upon the Philosophical Rules as given by some of the greatest philosophers the world has ever seen. I do not premise that the hypotheses advanced will be strictly correct in every detail.
That would be to assume that my experience of all natural phenomena was perfect. To the extent that our experience is limited, to that extent our hypotheses will be limited and faulty. It would need an Infinite mind to form a perfect theory of the philosophy of the universe, because only an Infinite mind possesses infinite experience . A finite mind can, however, form true philosophical conceptions of natural phenomena, if that mind will only follow the guidance of his own experience, and be willing to accept the teaching that always arises from the results of that experience. In order to do this, however, it must be observed, as Herschel points out, that all old prejudices must be put away, and the question or problem to be considered must be viewed with an open mind. Let me illustrate what I mean. Suppose, for example, that for two hundred years, chalk had always been thought to be a mineral, and then, owing to the development of the microscope, and to the increased magnifying powers of the lenses, it was conclusively demonstrated that chalk
is made up of the shells and remains of certain organisms that lived in the sea ages ago. Would it be philosophical to throw over the results of the microscopical research, and, simply because for two hundred years chalk had been thought to be a mineral, to argue, and still retain the idea that chalk was a mineral?
Such a result would be entirely opposed to all the teaching and principles of philosophy. In a similar way, suppose in the development of the physical cause of Gravitation , a certain conception of the universal Aether has to be put forth in order to account for Gravitation, and that that conception is opposed to some of the theories which have been held relative to the Aether
medium for the past two hundred years ; but that the conception so advanced is supported by the experiments and observation of some of the ablest scientists of the present century, would it be philosophical to reject the newer conception which harmonized with all experiment and observation, and still retain the old conception of the aetherial medium ; or, to accept the newer conception of that medium, and to reject some of the ideas included in the old conception ? From a purely philosophic standpoint, there can only be one reply, which would be in favour of the newer conception, by which our philosophy would be brought into harmony with our experience.
This I premise will be done in this work, and the result will

RULES OF PHILOSOPHY

7

be, that for the first time, our philosophy of the aetherial medium will agree with our experience ; and, as the natural result, several outstanding problems will be explained on a physical basis, which at the present time cannot be satisfactorily explained except from the mathematical standpoint.
ART. 6. 3rd Rule. Satisfactory explanation of the Phenomena sought to be Explained. -The third rule which governs the making of any hypothesis is, that the hypothesis formed in accordance with the first and second rules shall satisfactorily account for all the phenomena sought to be explained.
Newton writes on this point as follows : " No more causes of natural things are to be admitted , than such as are true, and sufficient to explain the phenomena." While again in his fourth rule he states : " In experimental philosophy, propositions collected by induction from phenomena are to be regarded as accurately true, or very nearly true, notwithstanding any contrary hypothesis, till other phenomena occur by which they are made more accurate, or are rendered subject to exceptions." Principia, Book 3. Herschel in his Natural Philosophy points out, that one of the chief requirements of any assumed hypothesis is, that it shall be sufficient to account for the phenomena to
be explained, and that it shall be suggested by analogy. Now the object of this work is to give a physical explanation
of the cause and working of Gravitation, and to show how, by the properties, qualities and motions of the universal Aether, Universal Gravitation may be accounted for on a physical basis. So that every phenomenon, associated with, or included in the Law of Gravitation, should receive a satisfactory physical explanation by the proposed theory.
Thus the physical cause of the centripetal and centrifugal forces should receive for the first time a physical explanation.
Newton's Laws of Motion , in so far as they conform to his own Rules of Philosophy, should also receive a physical explanation.
Kepler's Laws, which govern the motion of planets in their orbits, should also receive a similar physical explanation . Indeed , all phenomena which the Law of Gravitation explains from a mathematical standpoint, ought to receive a physical explanation by the proposed new conception of the Aether medium.
In addition to the outstanding physical cause of Gravitation , there are other physical problems that yet remain to be solved ; as, for example, there is the question as to what is the relative motion of Aether to moving matter. Does the Aether move
with matter through space as suggested by Michelson's and Morley's experiment of America, or does it flow freely through all matter, as it is usually thought to do ? I premise I will give a satisfactory solution of this problem in due course.

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Again, in relation to the Phenomena of Light, there is still outstanding the problem of the physical explanation as to the transverse vibration of light. This problem will also be dealt with from the standpoint of our new conception of the Aether. Whether it will be as satisfactorily solved, as the physical cause of Gravitation, remains to be seen.
Further, there is also the important question yet unsolved, as to what Matter is. Lord Kelvin and Dr. Larmor have recently given to the world certain conceptions as to the origin of Matter, and I shall endeavour to show that such conceptions receive confirmation and support by the proposed new conception of the Aether.
Another problem that will be attacked and solved, will be the cause of the Permanent Magnetism of the earth, with an answer to some of the questions propounded by Professor Schuster at the British Association of 1892 relative to the magnetism of solar bodies.
There is certainly some physical explanation as to the cause of the earth being a magnet, yet up to the present no satisfactory physical theory has been given. I premise that the new conception of the Aether, to be submitted in the after pages , will satisfactorily account, and that on a philosophical basis, for this phenomenon.
Lastly, one of the most interesting discoveries of the present day will receive an added confirmation and explanation in the conception of the Aether medium to be advanced. I refer to the system of Wireless Telegraphy that has been so successfully developed by Signor Marconi, and I premise that new light will be thrown on that discovery by the suggested theory of the Aether.
Now, if all these problems can be partially or wholly solved by the same theory that is advanced to explain the physical cause of Gravitation, it needs no further comment to show that that theory is considerably strengthened and more firmly established .
For it is a rule in Philosophy, that the more problems any suggested theory can solve, the greater are the claims of that theory for acceptance by scientists generally. For, if two rival theories can solve three and ten physical problems respectively, then, in giving a decision as to which is the better theory, the balance of opinion would be overwhelming in favour of that theory which could solve the ten problems. So that, if in addition to the satisfactory explanation of the physical cause of Gravitation, some, if not all of the other problems can be solved, as I premise they can, by the same conception of the Universal Aether, then it follows our third rule of Philosophy will be more than fulfilled, and the theory so advanced will be placed upon

APPLICATION OF RULES TO GRAVITATION 9

such a strong foundation, that it can only be overthrown by proving that it contradicts the results of some undiscovered phenomena.

ART. 7. Application of Rules to Gravitation.- Let us therefore apply Newton's own Rules of Philosophy to the Law of Gravitation, and endeavour to find out if the law, as at present under-

stood, fully satisfies his own Rules of Philosophy. No one can reasonably object to subjecting the Law of Gravitation to the test

of those principles which he lays down as the fundamental Rules of Philosophy.
If it comes through the ordeal with complete success, that is, if it is essentially simple in its conception and development, and if all its details are fully in accord with experience, as revealed by observation and experiment, then there will be no need to alter any of its hypotheses or axioms. If, on the other hand, it

violates any of the rules as laid down by Newton, then, to that extent, an alteration will be necessary, in order that the Law of

Gravitation may be brought into conformity with his own rules, and our Philosophy made to agree with our experience and observation.

ART. 8. Analysis of Law of Gravitation.— In order to accomplish this, let us ask ourselves, " What are the component parts of this Law of Gravitation ? " The Law is not a simple law,

but a compound one. It is compounded primarily of three

parts.

Ist. A Primitive Impulse.

2nd. A Centripetal Force. 3rd. A Centrifugal Force. To these must be added the three Laws of Motion ; although they are not directly part of the Law of Gravitation, yet they are essential to its effectiveness and completion. Without any one of these, the Law of Gravitation would fail to account for

all the phenomena that it does account for.

If there were no Primitive Impulse, then the planets and meteors, sun and stars would for ever remain at rest, and the

Laws of Motion would remain inoperative. If there were no Centripetal Force, then the Centrifugal Force would hurl the planets and comets, asteroids or minor planets away into the depths of space, never to return to their central sun.

If there were no Centrifugal Force, then the Centripetal Force would draw all bodies, i. e. all planets, etc., to their central sun,

and, instead of the planets continually revolving round the sun,
there would be but one immense solitary mass in the centre of the solar system.

If there were no Laws of Motion , with their necessary corollary

the Parallelogram of Forces, the Primitive Impulse would cease

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AETHER AND GRAVITATION

to act, and the Law of Gravitation would again fail in its attempt to account for those phenomena it does account for.
Thus, as it may easily be seen, Gravitation is a compound Law, depending upon at least four hypotheses, and therefore is not essentially a simple Force, or Law.
If, therefore, in giving a physical explanation of the cause of Gravitation, we can reduce all these four elements of the Law into one single physical cause, i. e. the Universal Aether, and show how they may all be explained and accounted for by the properties, qualities and motions of that physical medium , then such a result will be strictly in harmony with the first Rule of Philosophy, as laid down by Newton and others.
We will, therefore, proceed to consider some of these parts of the Law of Gravitation in detail.
ART. 9. Primitive Impulse.-This may be explained as follows. At the creating and launching of each world, Newton supposed that there was given to each world an impulse or tendency to fly off from the controlling centre into space. On this matter MacLaurin writes as follows : " If we had engines of sufficient force, bodies might be projected from them, so as not only to be carried a vast distance away without falling to the earth, but so as to move round the whole earth without touching it ; and, after returning to the first place, commence a new revolution with the same force they first received from the engine ; and after the second revolution, a third, and thus revolve as a moon or satellite round the earth for ever. If this can be effected near
the earth's surface, it may be done higher in the air, or even as high as the moon . By increasing the force or power, a body proportionately larger may be thus projected , and by a power sufficiently great, a heavy body, not inferior to the moon, might be put in motion, which might revolve for ever round the earth. Thus Sir Isaac Newton saw that the curvilineal motion of the
moon in her orbit, and of a projectile at the surface of the earth, were phenomena of the same kind, and might be explained from the same principle extended from the earth so as to reach the moon, and that the moon was only a greater projectile that received its motion in the beginning of things from the Almighty Author of the Universe."
Now what I desire to know is, " What is the nature, the mode of operation, and, above all, the physical cause of this Primitive Impulse ?" Is it in its nature and mode of operation a simple Force, or Cause ? Does it fulfil the condition of Newton's First Rule of Philosophy ? Permit me to suggest several lines of thought which may be made the basis of its analysis.
Astronomers tell us that there are in existence millions of

PRIMITIVE IMPULSE

II

stars, and suns, flooding immensity and space with their light and heat.
Now the question I wish to ask regarding Primitive Impulse in relation to all these stars is this : "Was the Primitive Impulse imparted to each sun, and star, and planet, separately and distinctly ? " If so, then there must have been just as many Primitive Impulses as there are stars and suns and planets, and there would be according to a certain astronomer's estimate at least 800,000,000 Primitive Impulses, which assumption is altogether opposed to, and violates the First Rule of Philosophy.
If, on the other hand, it is affirmed that they all received their motion at one and the same time, then I ask : " What was the physical cause and method adopted to communicate the impulse to each one at the same time ? " If the reply is given, that it was by Universal Gravitation, I have two objections to make to such a reply : first, that Gravitation is altogether inoperative without the Primitive Impulse, otherwise why was it conceived ? and secondly, what is the physical cause of Gravitation ?
Again, scientists inform us that there is every reason for believing, that stars and suns are still being formed in the universe, and that there are certain distinctive phenomena which go to prove that statement. Now, if that be true, and I believe it to be true, I wish to ask if the Primitive Impulse as suggested by Newton, is applicable to the stars and suns already in process of formation in the various nebulae ? and, if so, at what point in the star's history or development is that Impulse applied ?
Personally, I cannot conceive of the Great Creator of all things being so lacking in inventive genius, if I may reverently use that term , as to necessitate a separate Impulse being given to every separate star, or sun, as each one is created or formed during the progress and development of the universe of worlds.
I would much rather believe that which I hold to be the
correct explanation, viz. that He has given to a certain fundamental and primordial medium, certain qualities and properties , by, and through which are originated and perpetuated, all the motions of the heavenly bodies already existent in the universe, or that are ever likely to be existent throughout all time.
The question of separate Primitive Impulses for separate bodies becomes more and more incongruous and inadmissible, as we consider it in its application to such small bodies as meteors and planetoids . Is it not contrary to our fundamental principles of Philosophy, that a separate Impulse should be necessary for all small bodies that exist in their myriads throughout the solar system, not to speak of the universe of which that system forms a part ? Such a conception as Primitive Impulse, to each separate world, is altogether opposed to one's

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AETHER AND GRAVITATION

idea of that simplicity and beauty which govern the universe at large, and violates the first rule of our philosophical reasoning,

and for this reason must be rejected from the System of Philosophy to be propounded in this work.

ART. 10. Centripetal Force.-Let us now look at the Centripetal Force, and ask ourselves what is meant by such a force, and what is its mode of action and working. Centripetal Force,

strictly, may be defined as that force which is always exerted towards the centre of the attracting body.

Taking the earth as an example, Newton points out, that though the gravity of bodies arises from their gravitation towards

several parts of the earth ; yet, because this power acts always

towards the centre of gravity of the earth, it is therefore called the Centripetal Force.

This force, then, is that part of the Law of Gravitation which

corresponds to the Attraction of Gravitation , and is always

exerted in that straight line from the body attracted, to the

centre of the attracting body, which joins the centres of gravity of the two bodies concerned.
The combination and effect of the various forces included in

the Law of Gravitation are illustrated by the familiar illustration of the ball whirled round the hand by a piece of string, or the bucket filled with water, whirled round in the same way. Let

us take the former. A piece of string with a ball attached to one of the ends is held firmly by the hand. An impulse or

motion is imparted to the ball by the hand, that motion being

continued by the movement from the hand. The first impulse given to the ball by the hand represents the Primitive Impulse.

The tension on the string which holds the ball to its controlling centre represents the Centripetal Force, while the opposite force

on the string, which takes up the Primitive Impulse and continues it, is represented by the Centrifugal Force.

The conception of the Centripetal Force is therefore simple, and entirely in accordance with our experience as gathered from observation and experiments. Both in the spheres of electricity,

and magnetism, we find a similar force acting, which tends

towards the centre of the attracting body, and therefore the Centripetal Force satisfies the first two Rules of our Philosophy.

Further, it adequately accounts for certain distinctive pheno-

mena which occur through the Law of Gravitation, as, for

example, the falling of bodies to the earth, and therefore is

entirely in harmony with all the requirements of those principles

!

enunciated by Newton for the successful explanation of any

phenomena. I need hardly point out, therefore, this being so,

any physical cause suggested as the explanation of Gravitation must deal with the Centripetal Force, and be able to give a

CENTRIPETAL FORCE

13

physical explanation of the mode and manner in which the Centripetal Force operates.
The Attraction of Gravitation or the Centripetal Force, however, being, as its name implies, simply a drawing or pulling power to a centre, that is, a force that is ever and ever only drawing matter to matter, or body to body, it could not of, and by itself, accomplish those necessary stellar and planetary motions by which are produced that universal order, unity and harmony which characterize the universe. It is essentially in its operations and influences, a one-sided force, ever tending and influencing towards self, and therefore by itself would only be a detriment and an evil ; and, unless it were accompanied by some companion or complementary and counter force, with which it acts in union
and concert, and which exactly counteracts its pulling power and influence, it would soon draw star to star, and world to world, crashing and heaping them together in ruinous and dire confusion. So that, instead of the infinitude of worlds which now exist, which flash and sparkle in the heavens, and in their intricate, elaborate, and mazy motions move through the vast infinity like stately armies on the march, there would only be one agglomeration of matter, a silent and solitary mass existing in the vast abyss of space.
Therefore, as soon as Sir Isaac Newton had discovered and demonstrated the existence of the power of Attraction, as repre-
sented by the Centripetal Force, and its association with the universe at large, there was seen at once the necessity of another Force, of an opposite character, which would form the companion and complementary force to Attraction ; a repulsive, repellent force, one tending or repelling from a centre, so as to counterbalance the influence of the Centripetal Force which ever tends towards the centre.
To fill up the blank, there was conceived to exist what is called a Centrifugal Force, that is, literally, a Force acting, and ever acting from a centre, and with that Force we will now deal.
ART. II . Centrifugal Force.- In applying our Rules of Philosophy to this Force, if by Centrifugal Force is simply meant that Force which is the exact opposite of the Centripetal Force, that is, a Force which acts from a centre, instead of to a centre, then such a Force is strictly in harmony with, and satisfies all the conditions of the two first Rules of Philosophy.
Not only is such a conception simple, but it is also in accordance with experience and observation. Professor Hicks in his address to the British Association in 1895 said : " What is called Centrifugal Force is an apparent bodily Force directed outwards from the centre of curvature of the body's path, and

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AETHER AND GRAVITATION

having an intensity equal to the distance from the centre multiplied by the square of the absolute angular velocity."
In the sphere of magnetism and electricity, the operation of two equal and opposite forces prevails. The attractive force of electricity, which is exerted to the centre, is always accompanied by the generation and development of a repulsive force, it being one of the fundamental rules of electricity that equal and opposite quantities of electricity are always generated at one and the same time. So that if the Centrifugal Force is viewed as being simply the exact opposite of the Centripetal Force, it fully satisfies the test when the first two rules laid down by Newton are applied to it.
If, on the other hand, Centrifugal Force implies and embodies the idea of continuance of the Primitive Impulse, as I believe it is supposed to do, then to that extent it is not conformable to the principles of our Philosophy, as embodied in the rules given by
F Newton.
Simply because, while it supposes a source or origin of its activity at the first, it goes on to suppose a continuance of that activity, without recognizing a continuing source or cause. It
only recognizes and supposes the one original impulse given at the beginning, to account for the cause of the continually existing, and exerted power of the Centrifugal Force. I do not for a moment suggest, that the Divine Creator of all things, and the Ordainer and Upholder of all powers, forces and laws could not, had He chosen to give such a force, have given it and for ever operating. With that aspect of the question I have nothing to do, and of it nothing to say. I am dealing, and only wish to deal, with scientific facts, and scientific teaching from the purely philosophical standpoint.
Such an idea of a continuing effect, without a continuing cause, is altogether opposed to experience and observation, and is a violation of the second Rule of Philosophy.
Look where we will, or at what we will, and not only effects and causes are seen on every side, and in every thing , linked together inseparably, but wherever, and in whatever phenomena there is found a continuance of effect or effects, there is always and without exception found also a continuing source or cause.
Wherever Nature, therefore, gives us a continuous effect of any kind or sort, she always gives us a continuing cause, that can be both proved and demonstrated to exist. Nowhere in Nature, amid all her powers, principles and laws, is there to be found an effect without a cause, and in all continuing effects, a continuing and perpetuating cause also, and that effect exists just as long as the cause exists.
If the effect is perpetual, then the source and cause is perpetual

LAWS OF MOTION

15

also, both in its existence and energy. Hence if the Centrifugal Force embodies the idea of continuance of the Primitive Impulse, without showing how that Primitive Impulse is continued, then such an idea is an anomaly in the universe, is altogether opposed to the teaching of Nature and science, and violates the most fundamental principles of our Philosophy.
The philosophic explanation, therefore, of the Centrifugal Force, is that Force which flows from a centre, and which is the exact opposite and counterpart of the Centripetal Force. Further, as the Centripetal Force is an attractive Force ever attracting to a centre, so the Centrifugal Force, being its exact opposite, is a repulsive Force, which fulfils all the laws and conditions which govern the Centripetal Force, as it is in every phase and aspect the exact opposite, being indeed its complement and counterpart.
Any physical explanation of the Law of Gravitation, therefore, must also give a satisfactory physical explanation of this Force, and show its mode of operation and working. This I premise I will do without the faintest shadow of doubt or failure ; that is, if we are to accept the evidence of some of the most delicate experiments of modern times relative to aetherial physics.
ART. 12. Laws of Motion.- One of the most important factors in the successful application of the Attraction of Gravitation to the universe at large, are the Laws of Motion enunciated by Sir Isaac Newton. These are three in number, and are as follows-
Ist. Every body continues in its state of rest, or of uniform motion in a straight line, except in so far as it may be compelled by impressed Forces to change that state.
2nd. Change of motion is proportionate to the impressed Force, and takes place in the direction of the straight line in which the Force acts.
3rd. To every action there is always an equal and contrary reaction.
Corollary.- To these must be added the first Corollary of the three laws which is commonly known as the Parallelogram of Forces, which is as follows : " That when a body is acted upon by two Forces at the same time, it will describe a diagonal , by the motion resulting from their composition, in the same time that it would describe the sides of the parallelogram."
Now let us apply Newton's Rules of Philosophy to these laws, and see if they fulfil the conditions laid down therein.
In the first place, there being three laws necessary to cover all the motions involved, there is not that simplicity of conception which is a primary factor in the making of any hypothesis. Then it will be observed that even after postulating the three

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laws, Newton was unable to account for the elliptic orbits of the planets, until he had added a Corollary known as the Parallelogram of Forces.
ART. 13. Force.-The question has arisen also, as to the meaning of the term Force which Newton uses. What is a Force, its cause and mode of operation ? The idea of Force is conveyed to us by our " muscular sense," which gives us the idea of pressure, as for example when we push or pull a body along the ground.
We must not, however, limit our idea of Force to that narrow circle. It has now been fully established that Sound and Heat, Light, Magnetism, and Electricity are Forces, and therefore capable of doing work, as will be shown later on. Newton's use of the term Force is therefore somewhat vague ; he does not definitely say what the Force is which causes the change of position, of the body, or of the rate of motion of that body. That it is something to do with Gravitation is obvious, but its exact nature or character is not revealed .
Since Newton's time we have made an advance in the definition of Force, and have come to consider Force as a kind of energy ; the application of Force being the application of energy. Such terms as Mechanical Force, Chemical Force, Vital Force, are therefore out of date, and in their place the more definite ideas of energy are substituted. Instead, therefore, of getting such terms as Transformation of Forces , we now get Transformations of Energy. In the chapter on Energy, I hope to show that even that is not a satisfactory solution of the definition of a Force . If we are to make our Philosophy agree with our experience, then Force is due to motion, and motion alone.
So that Centrifugal Force will imply a motion from the centre ; Centripetal Force a motion whose effect is ever towards the centre of gravity of any body.
ART. 14. First Law of Motion.-This may naturally be divided into two parts for the purpose of applying the Rules of Philosophy.
(1 ) Every body continues in a state of rest, except in so far as it is compelled by impressed Forces to change that state. To what extent is this statement conformable to our experience and observation ? If I place a body, as for example a weight, on a table, will it remain in that state until it is moved by some other Force ? I think that it will so remain, and to that extent the law conforms to experiment.
Wider observation, and all experience, also prove the conformity of this part of the First Law of Motion to the second Rule
of Philosophy, as all experience testifies to the fact that a body remains at rest, until some other power or force moves it from

LAWS OF MOTION

17

the position of rest. The application of this position of rest to any of the planets is, however, very difficult to conceive. MacLaurin, in relation to this fact, states : "This perseverance of
a body in a state of rest can only take place in absolute space, and can then only be intelligible by admitting it." In dealing with the physical cause of Gravitation, I hope to be able to show that it can not only be admitted as a mathematical proposition, but that it can be made intelligible from the physical standpoint.
The second part of the First Law of Motion may be stated as follows : " Every body continues in a state of uniform motion in a straight line, except in so far as it is compelled by impressed forces to change that state."
Now what is the testimony of observation and experiment in regard to this part of the First Law of Motion ? Let us test the question by the results of our experience. If a ball is sent rolling along the ground, its motion is gradually reduced until it comes to rest. If the ground is very rough indeed, as for example a ploughed field, then its speed will be very soon reduced , and the ball quickly comes to a standstill. If, however, the ground is smooth and level, like a well-kept cricket-field, then the motion of the ball will be reduced more slowly, and it will travel further before being brought to rest ; while, if the ball is thrown along a very smooth surface of ice, it will travel a much longer distance before it is finally brought to rest.
Thus we learn, that the more we can get rid of all resistances to the motion of any body, the greater distance will the body travel, and the less diminution there is in the uniform motion of the body. So that, if it were possible to obtain a medium which offered no resistance at all to a moving body, then it would be a legitimate inference to infer that a body in such a medium, when once set in motion, would move with uniform motion for ever. Under such conditions, therefore, this part of Newton's First Law of Motion is physically conceivable. The crux of the whole matter, therefore, lies in the problem as to whether there is, or there is not, in existence, such a thing as a frictionless medium. We
will therefore consider the problem of the existence of a frictionless medium from the philosophical standpoint.
Professor Lodge, in Modern Views ofElectricity, p. 331 , writes : " Now, if there is one thing with which the human race has been more conversant than another, and concerning which more experience has been unconsciously accumulated than about almost anything else that can be mentioned, it is the action of one body upon another ; the exertion of Force by one body on another, the transfer of motion and energy from one body to another, any kind of effect, no matter what, which can be produced in one
C

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body by means of another, whether the bodies be animate or inanimate."
" Now I wish to appeal to this mass of experience, and to ask, Is not the direct action of one body on another across empty
space, and with no means of communication whatever, is not this absolutely unthinkable ? We must not answer the question offhand, but must give it due consideration, and we shall find, I think, that wherever one body acts on another body by obvious contact, we are satisfied and have a feeling that the phenomena is simple and intelligible, and that, whenever one body apparently acts on another body at a distance, we are irresistibly impelled to look for the connecting medium."
Again, on p. 333 of the same work, he adds : " Remember then, that whenever we see a thing being moved, we must look for the rope. It may be visible, or it may be invisible, but unless there is either a push or a pull, there can be no action."
Now, in relation to celestial phenomena, we are confronted with the fact of bodies acting on one another, and yet apparently they do not act upon one another by or through a medium, and to that extent according to the above extracts, such phenomena are opposed to universal experience. Again, we find planets and satellites moving through space with more or less uniform speed , and yet apparently there is no physical medium that acts upon them with either a push or a pull, as the present conception of the Aether is that of a frictionless medium, so that experience in its widest form seems altogether opposed to the existence of a frictionless medium.
Again, Tait in his Natural Philosophy says : " The greater masses, planets and comets moving in a less resisting medium, show less indications of resistance. Indeed it cannot be said that observations upon any one of these bodies, with the exception of Encke's Comet, has demonstrated resistance. The greater masses, planets and comets moving in a less resisting medium, show less indications. No motion in Nature can take place without meeting resistance due to some if not all of these influences. The analogies of Nature and the ascertained facts of physical science forbid us to doubt that every one of them, every star, and every body of every kind has its relative motion impeded by the air, gas, vapour, medium, or whatever we choose to call the substance occupying the space around it, just as the motion of a rifle-bullet is impeded by the resistance of the air."
What is the testimony of our own personal observation and experiments to such an impossible entity as a frictionless medium ? Can any of the readers tell me of any medium, be it solid, liquid, or gaseous, that they have ever heard of, or read of, or experimented with, that possesses the quality of being

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frictionless ? The answer is unanimously in the negative. But a frictionless medium was absolutely imperative to the success ofthe Newtonian aspect of the Law of Gravitation . Ifthe Aether had not been frictionless, then the First Law of Motion would have been violated, and a body, as for example a planet set in motion, would not then have moved with uniform motion, but would have been brought to a standstill by the resistance of the Aether. Accepting therefore experience as a guide, as we are bound to do if we wish to be strictly philosophical, as Newton pointed out. then we are compelled to come to the conclusion that there is no such thing in the entire universe as a frictionless medium. Such a hypothesis is contrary to all laws and rules of Philosophy, and to continue to advocate its claims is to remain where we are in relation to the cause of Gravitation, and in complete ignorance of the beauty and harmony of the wonderful physical mechanism that underlies the whole of the universe. Of course, if experience
and observation are no guide to Philosophy, then we will let imagination run riot, and postulate the most extravagant explanations for the varied phenomena of the heavens. With experience of no account, we will affirm that the moon is made of green cheese, that the earth is flat, that the sun revolves round the moon, and a host of other absurd hypotheses that require no correction by experience and observation. But there, a truce to such absurd imaginations. Experience is a guide to Philosophy, its claims are recognized by the greatest Philosopher the world has ever known, and therefore as either experience or a frictionless medium has to go, we will part with the frictionless medium, and endeavour to make a hypothesis of the Aether that is in greater harmony with our Rules of Philosophy.
ART. 15. Second Law ofMotion.-The application of Newton's Rules of Philosophy to the Second Law of Motion is attended with greater success than was the case with his First Law. " Change of motion," he states, " is proportionate to the impressed Force, and takes place in the direction of the straight line in which the Force acts."
Newton adds this explanation to his Second Law : " If a Force generates any motion, a double Force will generate double motion, and a triple Force triple motion, whether they are applied simultaneously or gradually and successively. And this motion, if the body were already moving, is either added to the previous motion, if it is in the same direction, or subtracted from it if directly opposed to it, or is compounded with the previous motion if the two are inclined at an angle.”
According to that, a force which presses or pushes with a four-pound pressure per square inch, if doubled, would press with a force of eight pounds per square inch, which fact agrees with

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experience. If the force is applied gradually, then the change of motion would be gradual ; if applied suddenly, then the resultant motion would be sudden and violent.
The impressed force, therefore, always produces a definite and corresponding effect on any moving body, however that force
may be originated , and however it may be applied . The effect so produced is always a change of motion, or, in present scientific terms, a change of momentum in the moving body. If the impressed force is halved, by an alteration in the mass of the body which exerts the impressed force, then the resultant momentum produced is halved also. If the impressed force is doubled, through any alteration in the velocity of the body which exerts the force, ther. the momentum produced in the moving body will be doubled also. So that the impressed force is equal to the change of momentum in the moving body upon which it is impressed.
When similar forces are impressed upon exactly similar bodies, the velocities produced are exactly the same ; but, if similar forces act on dissimilar bodies, then the velocities produced in the different bodies are not the same ; yet the total motion produced on all bodies, according to the Second Law of Motion, must always be proportionate to the impressed force . So that when we compare the effect of similar forces on different bodies, we find that there are two factors involved, viz. , the mass and velocity of the moving body. The product of these two quantities is termed the momentum of the body.
When we apply the Second Law of Motion to the theory of aetherial dynamics, as suggested in this work, we shall seek to show that Newton's Second Law of Motion holds good in its application to the new theory. With the present conception of a frictionless Aether, however, it is philosophically impossible for the Aether to exert force on any body that may exist in it. Because, to the extent that it is frictionless, to that extent it ceases to possess mass. If it does possess mass, then it cannot be frictionless. Such an assumption violates all the Rules of Philosophy.
Yet the Aether is supposed, in some unknown manner, to possess inertia, which property is also dependent on mass. If the Aether really possesses inertia, then it must possess mass, and possessing mass it ceases to be a frictionless medium. So that if it possesses mass, then it can exert force the same as any other body, and Newton's Second Law of Motion is applicable to it.
ART. 16. Third Law of Motion.-Newton's Third Law of Motion reads as follows-
"Action and re-action are equal and opposite, or, to every action there is always an equal and contrary re-action." This

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law is also conformable to experience ; for, by experiment, it has been proved to hold good for electric and magnetic action. As MacLaurin points out, the Third Law of Motion may be extended to all sorts of powers that take place in Nature, and belongs to attraction and repulsion of all kinds, and must not be considered as being arbitrarily introduced by Newton.
The mutual action between any two bodies has, therefore, a double action. Thus a piece of stretched string must be conceived as pulling at both ends ; the pull at the one end being exactly equal and opposite to the pull on the other end.
A magnet will attract a piece of iron with a certain force, but it is equally true that the iron attracts the magnet with an exactly equal and opposite force. We might even extend the application of this Third Law to a falling stone in its relation to the earth. Thus, if a stone is dropped from a high altitude to the surface of the earth, although the motion seems to be all in one direction, yet if the Third Law holds good, then the earth is attracted by the stone in exactly an equal, but opposite direction, to that in which the earth attracts the stone.
As, however, the mass of the earth is very great compared with that of the stone, it follows that the velocity of the stone compared with the velocity of the earth, must be very much greater, in order that the forces shall be equal.
The application of this Third Rule of Motion to planetary and celestial phenomena is therefore philosophical, in that its conception agrees with experience and observation.
Thus, while it is true that the sun attracts each of the planets in his system, it is equally true that the planets, in their turn, attract the sun with an exactly equal and opposite force. But the velocity of motion induced by the earth's attractive power upon the sun, would be less than the velocity of motion induced
by the sun's attractive power upon the earth, although the two forces would be equal and opposite, simply because force , being a compound quantity , is dependent upon the mass of a body as well as upon its velocity.
Not only, however, is it true that the sun and all the planets jointly attract each other, but it is equally true that the planets attract each other also, with an exactly equal and opposite effect. Indeed, as Gravitation is universal, it has to be conceived that there are no two bodies existing,but what the Third Law of Motion
equally applies to those two bodies ; so that equality of action and re-action is as universal as the Law of Gravitation itself.
In coming to a conclusion with reference to Philosophy and the Laws of Motion, I wish to say that I am strongly of the opinion that the day has come, or will soon come, when they will pass away and give place to a more direct and simple method of

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AETHER AND GRAVITATION

working of the great Law of Gravitation. I look upon the Laws of Motion as part of the scaffolding which has been used to build up the Law of Gravitation. That Law has now been erected, and stands firm and secure in its position in the universe. Whatever changes may take place in its scaffolding, the Law itself will stand out with greater beauty and clearness, if we could but see the perfected structure, apart from the props and helps which have assisted in its successful erection and completion. As Dr. Larmor said , in his address to the British Association, 1900 : " There has even appeared a disposition to consider that the Newtonian principles, which have formed the basis of physical phenomena for nearly two centuries, must be replaced in these deeper subjects by a method of more direct description of the cause of the phenomena. The question has arisen, as to how far the new methods of aetherial physics are to be considered as an independent departure ; or how far they form the natural development of existing dynamical science."
I hope, therefore, to be able in this work to do something towards clearing the completed Law from some of the outside props, which have long hidden the simplicity, beauty and harmony of the physical working of Gravitation from the eyes of those who feign would see its wonderful mechanism.
In the elaboration and development, therefore, of the physical cause of Gravitation, it will be necessary to conceive a medium , whose properties and motions shall be able to account for all the movements of the planets, comets, suns and stars that the Laws of Motion now account for. Instead, however, of there being several Laws purely and simply mathematical in their application, there will be one physical medium, which will by its properties and motions account for-and that in a satisfactory manner- all the motions of the heavenly bodies. That such a medium is required in the scientific world is proved by the statement made by Professor Glazebrook, in his work on J. C. Maxwell, page 221 ,
where he says : " We are still waiting for some one to give us a theory of the Aether, which shall include the facts of electricity and magnetism, luminous radiation, and it may be Gravitation."
ART. 17. Summary of the Chapter.- In summing up the contents of this chapter, we find therefrom, that there is a Universal Law in existence that is known as the Law of Gravita-
tion. The physical cause of this Law, however, is unknown ; Newton suggesting that it was due to the properties of an aetherial medium that pervaded the universe.
To form a right conception of this medium , and to develop the hypotheses of the same on strictly philosophical lines, it is essential for us to know the rules which govern the making of any hypothesis.

SUMMARY OF THE CHAPTER

23

Those rules, according to Newton, and other philosophers, are chiefly three in number, and form the very essence of any philosophical reasoning. Any departure from those rules will entail partial or entire failure in the success of the undertaking.
The application of Newton's rules to parts of the great Law of Gravitation show that some of those parts are not fully in harmony with the rules which Newton laid down in his Principia.
Any physical theory that may be hereafter suggested as the physical basis for the Law of Gravitation, must itself not only account for the various forces already referred to, but must itself fulfil the Rules of Philosophy laid down by Newton. That is to say, the conception of the physical medium must be simple in character, its properties and motions must agree with all our experience, as given by observation, and experiments ; and the properties and motions postulated for it must satisfactorily account for, and explain all the phenomena that are presented to us by the Universal Law of Gravitation.
If all this be done, then from the standpoint of strict philosophical reasoning, the physical medium so suggested, and the theory so made, will be incapable of being overthrown or disproved .

CHAPTER II
PHILOSOPHY OF GRAVITATION
ART. 18. Gravitation Attraction.-The Law of Gravitation being a compound law, and not a simple law (Art. 8), it is necessary that the principles which govern universal attraction should now be considered.
The law which governs Gravitation Attraction may be defined as follows : Every particle of matter in the universe attracts every other particle with a force whose direction is that of a line
joining the centre of their masses, whose magnitude is directly as the product of their masses, and inversely as the square of the distance between them.
This may be divided into four parts. (1) The Universality of Gravitation. (2) The Direction of the Forces involved. (3) The Proportion of these Forces. (4) The Law of Inverse Squares.
The theory of the Aether, therefore, which will be perfected in this work, must not only satisfactorily account for the Attraction of Gravitation on a strictly philosophical basis, but the laws, governing the pressures or tensions of that physical medium, must harmonize with each of the parts of the complex Law of Gravitation into which it has been resolved.
ART. 19. Universality of the Attractive Force.- The principle upon which Universal Attraction rests is found in the words : " Every particle of matter in the universe attracts every other particle." It must, however, be admitted that this statement has never actually been proved . The smallest body that Newton used to prove his Law of Attraction was our satellite the moon.
Cavendish, however, in 1798, by a series of experiments, conclusively demonstrated that the force of Gravitation existed in small bodies. He took two small leaden balls of a certain weight, and fixed them at the ends of a rod about six feet long, the rod being suspended by a piece of wire in the air. Large leaden balls were then brought near the small ones, and great care was taken to see if there were any twist in the wire by which they were suspended. It was found that the wire had become
24

UNIVERSALITY OF THE ATTRACTIVE FORCE 25
twisted on the approach of the large leaden balls, and thus he was able to prove that every particle of the attracted and attracting body are mutually concerned in the Attraction of Gravitation. There is abundant evidence of the application of this force in relation to our earth, as we shall see later on.
The universality of the Attraction of Gravitation is a fact that has been proved in a thousand ways, and a thousand times. All stars and suns, and all planets, satellites and comets and nebulae are subject to this universal law. Astronomy teaches us that its power extends across the vast abysses of space, and that stars situated at distances that cannot possibly be measured, are subject to this world-wide law. Some of the greatest discoveries in astronomical science were due to the operations of this wonderful law, the gravitating influences of certain planets indicating their existence, although their discovery had not yet been made.
The discovery of Neptune through the mathematical calculations of Le Verrier and Mr. Adams in 1846 was the crowning proof of the Law of Gravitation. Mr. Adams in England had noticed that the planet Uranus was being pulled out of the course by some unknown power, and so set to work to calculate the position of the body which thus influenced the motion of Uranus in its orbit. He located the position of the supposed influencing body strictly by mathematical calculations, and then took his results to the Astronomer Royal. Delay, however, occurred in the search for the supposed new planet, and nothing was done further in the matter for many months. Meanwhile Le Verrier in France, unknown to Mr. Adams, had been making similar calculations with reference to the perturbations of Uranus, and had arrived at similar results.
These results were sent to the Berlin astronomers, and the heavens were searched for the supposed new planet. After a time, the planet was discovered in that part of the heavens indicated by Le Verrier, and for a time his name stood out as the sole discoverer. Gradually, however, the claims of Adams were admitted and recognized , and to-day his claims to participate in the honour ofthe wonderful achievement are generally admitted . Thus the discovery of Neptune gave to the Law of Gravitation a stability and proof that perhaps it had never received before.
Further evidence of the existence of the universality of the attractive force, is to be found in a certain system of stars known as binary stars, which revolve around each other, while they gravitate around a common centre. Recent researches in astronomy only seek more and more to confirm the universality and effectiveness of this grand law, that seems to hold the entire universe in its sway.
Any medium, therefore, which is postulated as the physical

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AETHER AND GRAVITATION

cause of Gravitation, must itself be as universal as Gravitation, in order for it to be able to fulfil this condition of universality. We shall find, as we proceed, that the only possible medium which can fulfil this condition, is the universal Aether, whose qualities and properties are already partly known and partly understood .
ART. 20. Direction ofthe Forces.-The attraction of Gravitation is always directed along the straight line which joins the centres of masses of the attracting and attracted bodies. Thus, if the earth and moon are taken as examples, an imaginary straight line drawn from the centre of the earth's mass to the centre of the mass of the moon would be the direction in which the gravitative force would be exerted. Now a line which joins the central body to its satellite we shall see when we come to deal with Kepler's Laws is known as the Radius Vector. Thus the path of the attraction between the two bodies is along the Radius Vector. It is a singular coincidence that the path of a ray of light from the sun also coincides with the Radius Vector, as it is one of the laws of light that the path of a ray always follows a straight line.
It must not, however, be assumed, that while the attractive power is being exerted along any one straight line joining the centres of two bodies, therefore the attractive power is not operative in relation to any other part of the space, around the body. If our earth, for example, had four moons instead of one, and they were each in different positions in relation to the earth, then the law as to the direction of the forces would still hold
good . We have examples of this in the case of Jupiter with his five moons, and Saturn with his eight moons. So that the attractive force of Gravitation is again like light, it operates on all sides equally at one and the same time. A lamp in the middle of a room sends its light waves on every side at one and the same time, so that while each ray has for its path a straight line, yet those rays are emitted equally on every side. In like manner, though the direction of the forces between two attracting bodies is that of a straight line, yet the law of universal attraction is equally exerted on every side of the planet at one and the same time.
In the theory of the Aether, therefore, to be developed in this work, it will have to be demonstrated that the direction of the forces, which are originated and transmitted by that physical medium, must philosophically fulfil the conditions which govern the direction of the forces, as observed in gravitational phenomena.
ART. 21. Proportion of the Forces.-Newton proved that the attraction is proportional to the product of the masses of the bodies concerned.

PROPORTION OF THE FORCES

27

Hence it is that the sun, which is the centre of the solar system, is capable of attracting the most remote planets, because the mass of the sun is greater than the mass of all the planets put together. Or take another illustration. Suppose that the sun and the earth are at equal distances from Saturn. Now the sun's mass is about 300,000 times that of our earth. Therefore if the earth draws Saturn through a certain distance in one second, the sun would draw Saturn through a distance which is 300,000 greater than the earth in the same period.
The governing principle, therefore, which decides the proportion of the attractive forces between two bodies is mass, and not
simply density or volume. The mass of a body is a property which remains the same, as long as the inertia of the body remains constant. Mass is really a measure of the inertia of a body, or that property of a body by which it continues in its state of motion or of rest.
Mass is therefore a compound quantity, being equal to volume multiplied by density, so that if the volume of any body is halved , the density is doubled . Thus, the proportion of the attractive force between any two bodies ever remains the same, so long as the masses of the two bodies remain the same. Through all the changes of volume and density of any body, its attractive force remains constant, as long as the mass remains constant ; for the simple reason, that as the volume of a body is increased, the density is proportionately decreased ; or, as the volume is decreased , the density is increased .
For example, the volume of the sun as compared with the volume of the earth, is about 1,300,000 times greater, but the proportion of the attractive forces between the two bodies, is about 324,000 to 1. This difference is accounted for by the fact, that the density of the sun is about one quarter the mean density of the earth, hence their masses are in the proportion of 324,000
to 1. Thus the proportion of the attractive forces between any two bodies is dependent upon their masses, and not simply upon their volume or density.
ART. 22. Law of Inverse Squares.-The Law of Inverse Squares which is applicable to Gravitation is equally true of Sound, Light, Heat and Electricity, the Law being that Gravitation acts inversely as the square of distance. That is to say, if the distance of any body from the sun, for example, be doubled, then the force of Gravitation is diminished to one quarter of
the intensity which would be exerted on the body in the first position.
Thus the further a body is from its controlling centre, the weaker the Attraction of Gravitation upon it becomes. Taking therefore Mercury and the earth as examples, we find that their

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AETHER AND GRAVITATION

mean distances are respectively 35,000,000 miles and 92,000,000, which is a proportion of about 1 to 24. So that the intensity of the sun's attraction on the earth is about four-twenty-fifths of what it is on Mercury, that being the inverse square of the relative distances of the two bodies.
Now the intensity of Light and Heat received by the earth is regulated by the same law of inverse squares, so that the earth would receive about four-twenty-fifths the intensity of light and heat which Mercury receives when they are both at their mean distances.
This law of inverse squares is applicable to every body which acts as a gravitating source throughout the whole of the universe, whether that body be small or large, and whether it be in the form of meteor, satellite, planet, sun or star.
Each satellite, planet or sun exerts an attractive influence upon every body that exists , that attractive influence being regulated by the masses of the respective bodies, and decreasing inversely as the square of the distance from the body viewed as the centre of attraction. So that, the further the attracted body is from the attracting body, the less is the intensity of the mutual attracting forces, though that intensity does not vary simply as the distance, but rather as the square of the distance, and that in its inverse ratio. Thus if we take two masses of any kind or sort, and place them at various distances as represented by the numbers 1 , 2, 3 , 4, 5 , 6, the intensity of the attracting forces between the same masses at the relative distances will be
represented by the numbers 1 , 1, 16, 25, 36, which are the inverse squares of the respective numbers representing their distances. As we shall see, the same law holds good in relation to heat, light and electricity, and indeed to all forms of energy which radiate out from a centre equally in all directions.
There is no need to apply Newton's Rules of Philosophy to this Attraction of Gravitation, as it has been demonstrated to exist, times without number. Moreover its laws are exactly the same as those governing the phenomena of sound, light, heat, and electricity, so that apart from being proved by actual experiments in relation to the gravity of the earth, we have a wider experience of the application of the same ruling principles of the law in other departments of science.
The Law of Universal Attraction, which is strictly the Centripetal Force of the compound Law of Gravitation , fully satisfies the three governing rules of Newton's Philosophy. Not only is it simple in its conception, but it is borne out by experience, and adequately accounts for the distinctive phenomena which it seeks to explain. By it, astronomical observations can be taken with a precision and certainty that defy error or failure. The motion

TERRESTRIAL GRAVITY

29

of a planet in its orbit can be so perfectly calculated, that its position in space in relation to other planets can be foretold years in advance. The theory of the Aether, therefore, which is to be perfected in this work, must philosophically show that the pressures or tensions of that medium, which are postulated as the cause of Gravitation Attraction, must themselves fulfil the laws of inverse squares, which govern light, heat, electricity and the Attraction of Gravitation . I premise that this will be done in the theory of the Aether to be submitted to the reader in the after pages of this work.
ART. 23. Terrestrial Gravity.— Before passing from this phase of the subject, I should like briefly to look at the question of the Attraction of Gravitation from the standpoint of our own earth, as by so doing we shall notice some facts regarding the same, hitherto unnoticed, in the preceding articles.
Terrestrial Gravity is but a phase of Universal Gravitation. One of the most familiar facts and phenomena of everyday life is, that when a body, such as a stone or stick or bullet, is thrown or projected into the air, it always falls to the earth again. This is due to the attraction of the earth and the stone for each other.
It has been proved experimentally that if a stone and a weight are let fall from a height of 16 feet, they would reach the earth in one second of time. Again, a feather, or cork, or even a piece of iron would take exactly the same time falling through the same space, provided that the feather or cork could be screened from the resistance of the air.
The distance, however, through which a body falls in one second varies at different parts of the earth's surface, being least at the equator, and greatest at the North and South Poles. This is accounted for by the fact that the polar diameter is only 7899 miles, while the equatorial diameter is 7925 miles, thus the distance from the centre of the earth to either pole is about 3950 miles, or 13 miles less than the equatorial radius of the earth. Now the force of gravity decreases upwards from the earth's surface inversely as the square of the distance from the earth's centre of gravity, but decreases downwards simply as the distance from the centre decreases. Thus if a ball were taken down 2000 miles, that is half the distance to the centre, it would only weigh half-a-pound, while if it were taken to the centre of the earth, it would have no weight at all ; while a pound weight at the equator would not weigh one pound at the poles, because it would be nearer the centre of the earth by 13 miles.
Thus a pound weight is not always a pound weight. It varies as we carry it to different parts of the earth's surface, depending upon its relation to the centre of the earth for its exact weight. The point which I wish to make perfectly clear,

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AETHER AND GRAVITATION

as it will be necessary for future reference, is, that there is no such thing as weight apart from the gravity of the earth ; or, if we apply the principle to the solar system, there is no gravitating force in that system apart from the gravitating force of the central body, the sun, or the planets and other bodies which form the solar system .
Let us look at this matter from another standpoint, in order to prove this truth and make the same perfectly clear. If a pound weight were put in a spring-balance, then at the surface of the earth it would weigh one pound . Now, we will suppose
that we have taken the weight to a height of 4000 miles above the surface of the earth, that is exactly double the distance from the centre of the earth, the radius of the earth being approximately 4000 miles. According to the law of inverse squares, the force of Gravitation decreases inversely as the square of the distance. The distance having been doubled, the proportion of the forces at the two places, i. e. the earth's surface and 4000 miles above it, are as I to
Thus at a distance of 4000 miles the weight which weighed one pound at the earth's surface, now only weighs a quarter of a pound. At a distance of 8000 miles, the distance would be trebled, therefore the force of Gravitation is one-ninth, and the weight would weigh one-ninth of a pound. If we could take the pound weight to the moon, the attractive force of the earth would be reduced to 1-3600, as the moon is 240,000 miles distant, that is sixty times the earth's radius. The square of 60 is 3600, and if we invert that we get 1-3600, so that the weight which weighs a pound at the earth's surface, would only weigh 1-3600 part of a pound at the distance of the moon. This again proves, that apart from the Attraction of Gravitation , there is no such thing as weight, and that the weight so called of any body, such as a planet or satellite, increases or decreases as its distance increases or decreases from its central attracting body.
ART. 24. Centrifugal Force.- I have already shown in Art. 10 that the Centripetal Force and Universal Attraction are one and the same ; as the Centripetal Force always acts towards the centre, and must therefore be in its operation and influence a gravitating or attractive power.
I have also pointed out in the same article, the necessity of another force, which is to be the complement, and the counter part of Gravitation Attraction. That complement and counter force was conceived by Newton, and called by him the Centrifugal Force. The very nature of the Centripetal Force demands and necessitates a force which in its mode of operation is exactly the opposite of the Centripetal Force. Unless there
were such a force, a repellent and repulsive force, then instead

CENTRIFUGAL FORCE

31

of there being that harmonious working of the universe that now exists, there must inevitably be a gradual drawing together of all planets and satellites, of all stars and suns, into one vast, solitary, and ruinous body.
There are also other phenomena which demand a Centrifugal Force in the universe. It is a well-known fact, that there exist between the orbits of Jupiter and Mars, what are called planetoids, about 500 in number, which are supposed to be the remnants of a broken or shattered world. As may be expected from such an accumulation, they present the most extraordinary diversities and eccentricities in the orbits that can possibly be conceived. They are of all shapes and sizes, and besides their orbits round the sun, have orbits among themselves. They are so clustered together that their orbits intersect each other at numerous points, and when in conjunction are said to suffer great perturbations, being pulled great distances this way and that by each other's attractive influence. It is further stated that their orbits so intersect each other, that if they were imagined to be material rings, they would be inseparable, and the whole could be suspended by taking any one of them up at random. Here, then, is presented to us a kind or order of celestial phenomena for whose well-being and effectual working the Centripetal Force or the Attraction of Gravitation cannot possibly account. In their case another force is demanded which shall be the exact complement and counterpart of the Centripetal Force. There needs therefore a force, not an
imagined one, simply conceived to fill a want, but a real Force, as real and as plainly to be understood as the Centripetal Force. A force existing in each world just like the Attraction of Gravitation, only the reverse of Gravitation, a repellent, repulsive Force, acting in the reverse mode, and way, to universal attraction. This Force must be governed by the same rules and laws that govern the Centripetal Force, if it is to work in harmony with the same. It must be universal in its character, having
a proportion of forces equal to the product of the masses of the two bodies which are concerned, and its path must coincide with the path of gravitational attraction, that is, in the straight line which joins the centres of gravity of the two bodies. Further, and what is perhaps the most important of all, it must act as a repelling or repulsive force which shall be in the same proportion in regard to distance, as the law governing Centripetal Force, that is, inversely as the square of the distance.
Again, and briefly, there are also in existence small bodies called meteors, which are said to exist by myriads, which float in space, and circle round the sun. They are of all shapes and sizes, from one ounce to a ton or even tons, thousands of them

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coming into contact with our earth's atmosphere every year, especially in August and November. All of these small bodies have orbits among themselves , and gravitate round one another, as they revolve round the sun. Now if the orbits of the planetoids be such an entangled mass, what must be the orbits of these meteors ? What an indescribable, unimaginable mass of labyrinthian motions must exist among these myriads of little bodies ! How they must intersect, cross and intermingle each other's orbits ! What attraction and counter-attraction they must exert upon each other ! Let me ask any man to sit down and try to imagine how the present recognized Centripetal and Centrifugal Forces can account for the effectual working of these meteors. As illustrating the necessity of a real and physical Centrifugal Force which is to be the exact counterpart of the Centripetal Force, I would call the attention of the reader to Herschel's view of this matter. In dealing with the phenomena of comets' tails he writes : 1 " Beyond a doubt, the widest and most interesting prospect of future discovery, which this study holds out to us, is, that distinction between gravitating and levitating matter, that positive and irrefutable demonstration in nature of a repulsive force, co - extensive with, but enormously more powerful than the attractive force we call gravity which the phenomena of their tails afford." I premise that this prophecy of Herschel's will be fully demonstrated and proved in the succeeding pages of this work. For, in the theory of the Aether that is to be afterwards perfected, it will be philosophically proved that the physical medium so conceived will satisfactorily account for a force or motion from the centre of all bodies ; which motions fulfil all the conditions required by that Centrifugal Force, which is the complement and counterpart of the Attraction of Gravitation. At the present time, with the conception of a frictionless Aether, it is impossible to harmonize the existence of such a force or motion with our theory of the Aether. Yet Professor Lebedew of Moscow, and Nichols and Hull of America,
have incontrovertibly demonstrated by actual experiments the existence of such a force. Therefore it follows, that if our present theory of the Aether fails to agree with experimental evidence, such a theory must be reconstructed in order that our philosophy may be made to agree with our experiments and our experience.
ART. 25. Kepler's Laws.- A long time before Newton had discovered the Law of Gravitation , Kepler had found out that the motions of the planets were governed by certain laws, and these came to be known as Kepler's Laws.
These laws which were given to the world by Kepler, simply 1 Lectures on Scientific Subjects.

KEPLER'S LAWS

33

represented facts or phenomena which had been discovered by observation, as Kepler was unable to account for them, or to give any mathematical basis for the same.
On the discovery, however, of Universal Gravitation , Newton saw at once that these laws were simply the outcome of the application of the Law of Gravitation to the planets, and that they could be accounted for on a mathematical basis by the Law of Gravitation, as they seemed to flow naturally from that law.
Kepler's Laws are three in number and may be thus stated— 1st Law. Each planet revolves round the sun in an elliptic orbit, with the sun occupying one of the Foci. 2nd Law. In the revolution of a planet round the sun, the Radius Vector describes equal areas in equal times. 3rd Law. The squares of the periodic times of planets are proportional to the cubes of their mean distances. Now the question arises, whether it is possible to form a theory of the Aether which shall satisfactorily and philosophically account for all the phenomena associated with Kepler's Laws in their relation to the motions of planets, satellites, or other solar bodies ? On the present conception of the Aether such a result is an absolute impossibility. With the theory of the Aether, however, to be submitted to the reader in this work, the result is possible and attainable. If, therefore, such a result is philosophically proved, as I submit will be done, then we shall have greater evidence still that the theory so propounded is a more perfect theory than the one at present recognized by scientists generally.
ART. 26. Kepler's First Law.--Each planet revolves round the sun in an elliptic orbit, the sun occupying one of the Foci.
The ancients thought that the paths of the planets around the sun were circular in form, because they held that circular motion was perfect. A system of circular orbits for the paths of the planets round the sun would be very simple in its conception, and would be full of beauty and harmony. But exact calculations reveal to us that the path of a planet is not exactly that of a circle, as the distance of a planet from the sun in various parts of its orbit is sometimes greater, and sometimes less, than its mean distance.
The planet Venus has the nearest approach to a circular orbit, as there are only 500,000 miles between the mean, and greatest and least distances, but both Mercury and Mars show great differences between their greatest and least distances from the sun.
If, therefore, the orbits of a planet are not exactly circular, what is their exact shape ? Kepler solved this problem, and
D

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proved that the exact path of a planet round its central body the sun was that of an ellipse, or an elongated circle. Thus he gave to the world the first of his famous laws which stated that each planet revolves round the sun in an orbit which has an elliptic form, the sun occupying one of the Foci.
Not only is the orbit of a planet round the sun elliptic in form , but the path of the moon round the earth, or the path of any satellite, as for example a satellite of Mars or Jupiter or Saturn , is also that of an ellipse, the planet round which it revolves occupying one of the Foci.
It has also been found that certain comets have orbits which
cannot be distinguished from that of an elongated ellipse, the sun occupying one of the Foci.
Now let us apply the Law of Gravitation to Kepler's First Law, and note carefully its application.

E

H

B

S.

D

Fig: 1.
Let A, B, C, D be an ellipse representing the orbit of the earth, and let S represent the sun situated at one of the Foci.
We will suppose that the earth is projected into space at the point A, then according to the First Law of Motion, it would proceed in a straight line in the direction of A E, if there were no other force acting upon the earth. But it is acted upon by the attraction of the sun , that is the Centripetal Force which is exerted along the straight line S A (Art. 20), which continues to act upon it according to the principle already explained in Arts. 21 and 22.
Now, according to the Second Law of Motion and the Parallelogram of Forces, instead of the earth going off at a tangent in the direction of A E, it will take a mean path in the direction of A B, its path being curved instead of being a straight line.
If the sun were stationary in space, then the mean distance, that is, the length of the imaginary straight line joining the sun SA to the earth, would remain unaltered. The Radius Vector SA, or the straight line referred to, would then be perpendicular

KEPLER'S LAWS

35

to the tangent, and the velocity of the earth round the sun would be uniform, its path being that of a circle.
The Radius Vector SA, however, is not always perpendicular to the tangent F E, and therefore the velocity of the earth is not always uniform in its motion in its orbit, as sometimes it travels at a lesser or greater speed than its average speed , which is about 18 miles per second.
It has to be remembered that the sun itself is in motion, having a velocity through space of about 4 miles per second, so that, while the earth is travelling from A to Bthe sun is also travelling in the direction of S B. Thus the orbital velocity of the earth, and the orbital velocity of the sun, together with the Centripetal Force or universal Gravitation Attraction , are all acting in the same direction when the earth is travelling from A to B, that is, in the direction of the orbit situated at B. This point of the orbit is known as the perihelion, and at that point the velocity of the earth is at its greatest, because the earth is then nearest the sun.
According to Newton, the planet when at B would still have a tendency to fly off into space owing to its Centrifugal Force, but it is held in check by the Centripetal Force, so that instead of it flying off into space, it is whirled round and starts off on its journey away from the sun in the direction of B, C. The sun, however, is still continuing its journey in the direction of S, H, so that not only is the increased orbital velocity of the earth , which it obtained at its perihelion, urging the earth away from the sun, but the sun itself in its advance through space is leaving the earth behind it. The combined effect of the two motions, the advancing motion of the sun, and the receding motion of the earth, due to its increased orbital velocity, drives the earth towards the aphelion, where its distance from the sun is greatest, and its orbital velocity is the least.
By the time the planet has arrived at point C, its motion through space has gradually decreased, and the Centripetal Force begins to re-assert itself, with the result that the earth is
slowly made to proceed towards the point D of the ellipse, at which point its motion is the slowest in orbital velocity, only travelling about 16 miles per second, while the distance of the
earth from the sun is the greatest and has increased from 91,000,000 miles at the perihelion to 94,500,000. This point of the orbit is known as its aphelion.
After rounding this point, the orbital velocity of the earth begins to increase again, owing to the diminishing distance of the earth from the sun, which according to the law of inverse squares (Art. 22) gives an added intensity to the Centripetal Force.

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Thus by the combination of the Laws of Motion and the Law of Gravitation discovered by Newton, he was able to satisfactorily account for and explain on a mathematical basis, the reason why the earth and all the other planets move round the sun in elliptic orbits, according to Kepler's First Law.
In the development of the physical cause of gravitation, therefore, the same physical medium, which accounts for that law, must also give a satisfactory explanation of the first of Kepler's Laws.

ART. 27. Kepler's Second Law.-This law states that the Radius Vector describes equal areas in equal times. The Radius Vector is the imaginary straight line joining the centres of the sun and the earth or planet. While the First Law shows us the kind of path which a planet takes in revolving round the sun, the Second Law describes how the velocity of the planet varies in different parts of its orbit.
If the earth's orbit were a circle, it can be readily seen that equal areas would be traversed in equal times, as the distance from the sun would always be the same, so that the Radius Vector being of uniform length, the rate of motion would be uniform, and consequently equal areas would be traversed in equal times. Take as an illustration the earth, which describes its revolution round the sun in 365 days. Now if the orbit of the earth were circular, then equal parts of the earth's orbit would be traversed by the Radius Vector in equal times. So that with a perfectly circular orbit, one half of the orbit would be traversed by the Radius Vector in half a year, one quarter in one quarter of a year, one-eighth in one-eighth of a year, and so on ; the area covered by the Radius Vector being always exactly proportionate to the time.

From Kepler's First Law, however, we know that the planet's

I

distance does vary from the sun, and therefore the Radius Vector

is sometimes longer and sometimes shorter than when the earth

is at its mean distance ; the Radius Vector being shortest at

the perihelion of the orbit, and longest at the aphelion . We

learn from Kepler's Second Law that when the Radius Vector is

shortest, that is, when the planet is nearest the sun, it acquires its greatest orbital velocity ; and when the Radius Vector is

longest, that is, when the planet is farthest from the sun, the orbital velocity of a planet is the slowest.
Let A, B, D, C represent the elliptic orbit of a planet, with S sun at one of the Foci, and let the triangles A, S, B and D, S, C be triangles of equal area. Then, according to Kepler's Second Law, the time taken for the Radius Vector to traverse the area A, S, B is equal to the time that the Radius Vector takes to traverse the area D, S, C. So that the planet would take an

KEPLER'S LAWS

37

C
S
B
Fig: 2 .
equal time in going from A to B of its orbit, as it would take in going from D to C. Thus the nearer the planet is to the sun, the greater is its orbital velocity, and the farther it is away from the sun the slower is its velocity, the velocity being regulated by the distance. The manner in which the difference of velocity is accounted for by the Law of Gravitation has already been explained in the preceding article. Thus Newton proved that Kepler's Second Law was capable of being mathematically explained, and accounted for, by the universal Law of Gravitation .
If, therefore, a physical cause can be given for Newton's Law of Gravitation, then such physical cause must also be able to account for, and that on a strictly philosophical basis, the second of Kepler's Laws as well as the first.
ART. 28. Kepler's Third Law.- The Third Law of Kepler gives the relation between the periodic time of a planet, and its distance from the sun. The periodic time of any planet is the time which it takes to go once round the sun. Thus the periodic time of the earth is 365 days. The periodic time of Venus is 224'7 days, while that of Mars is 6869 days.
Kepler had found out that different planets had different periodic times ; he also found out that the greater the mean distance of the planet, the greater was the time which the planet took to perform its journey round the sun, and so he set to work to find out the relationship of the periodic time to the planet's mean distance.
After many trials and many failures he arrived at the right conclusion, and at last discovered the true law which is known as Kepler's Third Law, which states that for each and every planet, the squares of their periodic times are proportional to the cubes of their mean distances.
For purposes of illustration let us take the earth and the planet Venus and compare these two. The periodic time of the earth is 365 days, omitting the quarter day. The periodic time of Venus is 224 days approximately. Now, according to Kepler's

38

AETHER AND GRAVITATION

Third Law, the square of 365 is to the square of 224, as the cube of the earth's mean distance is to the cube of Venus's mean distance, which are 92.7 millions of miles and 67 millions of miles respectively. The problem may be thus stated-
As 3652 2242 : 92.73 : 67³ : This worked out gives— 133,225 50,176 : 796,597:982 : cube of Venus's mean distance.
So that by Kepler's Third Law, if we have the periodic time of any two planets, and the mean distance of either, we can find out the mean distance of the other by simple proportion .
In making astronomical calculations, the distances of the planets are generally obtained by means of Kepler's Third Law, as the periodic time of the planet is a calculation that may be made by astronomers with great certainty, and when once the periodic times are found, and the mean distance of a planet, as our earth for example, is known, the mean distances of all the other planets in the solar system may soon be obtained.
In like manner this Third Law of Kepler's is equally applicable to the satellites of any planet. For example, when the periodic time of both of Mars' satellites, Phobos and Deimos, are known, being about 8 hours and 30 hours respectively, and the distance of either is known , as Phobos with a mean distance of 5800 miles, then the mean distance of Deimos can easily be calculated by this law, and is found to be 14,500 miles.
As discovered by Kepler, the Third Law was simply the result of observation. He was unable to give any mathematical basis for its existence. The Laws as they were given to the world by Kepler were simply three great truths which had been discovered by observation. It rested with Newton to show how these laws could be accounted for on a mathematical basis, and to show how they all sprang from one and the same source, namely the universal Law of Gravitation. In his Principia he proved that all Kepler's Laws were fully expounded and explained by his great discovery of Universal Gravitation.
Now what Newton has done for Kepler's Laws from the mathematical standpoint, we propose to do from the physical standpoint. In the development of the physical agency or cause of Gravitation, therefore, among the phenomena and laws, which have to be satisfactorily accounted for on a physical basis, are these three Laws of Kepler's just referred to.
So that in addition to the satisfactory explanation of a physical cause for the Laws of Motion, and the Centripetal and Centrifugal Forces, the hypothesis of a physical cause of Gravitation must fully and satisfactorily account for the Laws of Kepler, whose mathematical explanation was given by Newton.
Further, and what is as equally important, the explanation so

KEPLER'S LAWS

39

given must be strictly in harmony with the Rules of Philosophy as laid down in Art. 3. That is, the explanation must be simple in character, must not be contrary to experience or observation, and must satisfactorily account for the laws which the hypothesis of the physical cause of Gravitation seeks to explain. This I premise we will do as we pass from stage to stage in the development of the theory.
I can safely premise that it will be simple in character and conception, that it will be entirely in harmony with all experience and observation, and that the physical cause so advanced will give as physical a basis to Kepler's Laws as Newton's mathematical calculations gave them a mathematical basis.
In summing up, I need hardly point out, that if all that I have premised in this and the preceding chapter is accomplished in the after chapters of this book, then for the first time since the discovery of Universal Gravitation by Sir Isaac Newton, his great discovery will have received the long-expected and long-desired physical explanation, that explanation and cause being founded on his own Rules of Philosophy given in his immortal Principia, and for the first time our Philosophy will be brought strictly into harmony with our universal experience.

CHAPTER III
MATTER
ART. 29. What is Matter ?-The law of Universal Attraction states that "Every particle of matter attracts every other particle," etc., and the question at once arises as to what is meant by the term Matter, what are its properties and its constitution ? Tait, in his Natural Philosophy, gives the following as the definition : "Matter is that which can be perceived by the senses, or is that which can be acted upon by, or can exert force."
It has already been pointed out in Art. 13 that force is due to motion, and that wherever we get motion of any kind or sort, there we get energy, or what used to be termed force. The consideration of this phase of the question will be more fully dealt with in the chapter on Energy and Motion. Suffice to say, that all experience teaches us that force is the outcome of motion.
Accepting this definition therefore of force, Tait's definition of matter will read thus, if brought up to date : " Matter is that which can be perceived by the senses, or is that which can be acted upon by motion, or which can exert motion."
The common idea that matter can only be that which can be seen or actually felt, is not large enough for a definition of Matter. There are numbers of things in Nature which cannot either be seen or felt, yet which are included in the term Matter. Let us take one or two examples. Every one admits that nitrogen and oxygen are matter, yet I venture to say that no one has actually seen or felt either of these gases. Both of these gases are colourless and invisible, and are both tasteless. You may open your mouth and inspire both gases, and yet if they are pure, you cannot taste either of them. They are only matter, in the sense that they appeal to our sense of force through the motion which they may acquire.
Or again, take air, which is a mechanical mixture of several gases. Can you see air ? If it be free from vapour and smoke, air is invisible, and on a clear day you may look for miles across the sea, or from the top of a mountain, and yet not have your sight impeded in any way by the atmosphere. Neither can it
40

WHAT IS MATTER ?

41

be felt by the sense of touch. Open and shut your hand, and see if you can feel the air while you do so. In similar ways it
may be demonstrated that the air is tasteless. So that it is not necessary for us to see, or feel , or taste, or even smell that which we term Matter, in order for it to be included in that term . So long as that which we term Matter is able to accept motion in any manner from any body that is either moving, or in a state of vibration, and not only accepts, but also transmits the vibratory, or the kinetic motion so called of the moving body, then that which accepts the motion is legitimately termed Matter.
It becomes perfectly clear, therefore, why air, aether, oxygen, and hydrogen are termed Matter. Because they can be all acted upon by motion, and after being so acted upon, they can exert motion upon some other body. Heat is a form of motion, and when heat acts upon the air, the latter is set in motion, and we have what are commonly known as winds. It is unnecessary for me to prove that the motion of winds can be transmitted to other matter, as we have numerous examples from our observation and experience, in the case of windmills driven by the motive power of the winds, and also balloons urged along by the same cause ; apart from the devastating effect produced in towns and country by a hurricane or storm.
The point which I wish to emphasize is, that Matter, strictly defined, is that which can be acted upon by motion, such as heat or electricity, both being forms of motion, and which can exert the motion so derived upon some other body.
Wherever, therefore, in the universe we find any body, whether it be solid, liquid or gaseous, or any medium which can be acted upon by motion, and after being so acted upon, can exert motion, that body or medium may legitimately be included in the term Matter, although it may be absolutely invisible to the eyes, or insensible to the sense of touch, or taste, or smell. In the same work,¹ Tait states that in the physical universe there are but two classes of things, " Matter and Energy," and then goes on to give examples of both. He adds that a stone, piece of brass, water, air, aether, are particles of matter, while springs, water-power, wind , waves, heat and electric currents are examples of energy associated with Matter.
Now I may add here, that within these two statements is to be found the germ of the physical cause of Gravitation, together with the satisfactory explanation of all phenomena that the universe reveals to us, either by observation or by experiments. I purpose therefore, before giving any detailed accounts of that medium which is to formthe physical basis for the cause of
1 Tait, Natural Philosophy.

42

AETHER AND GRAVITATION

Gravitation, to look at the term Matter in all its aspects, in order that we may get a right conception of the universe, and of the part that Matter plays in the same.
ART. 30. Conservation of Matter.-The Theory of the Indestructibility of Matter was first introduced by Lavoisier in 1789. This theory may be thus summed up ; that Matter which fills the universe is unchangeable in quantity, so that the total quantity ever remains the same. Changes may take place in regard to the state of the Matter, but the sum-total of Matter throughout all the changes remains unaltered . Thus when we burn coal, it is changed into carbonic acid by combination with the oxygen of the atmosphere ; when sugar is put into water, it simply passes from the solid to the liquid condition. If a piece of iron or steel is allowed to rust, the surface of the iron has entered into combination with the oxygen and water of the atmosphere, and formed a new substance. So that a body may change from solid to liquid , as for example from ice to water, or from liquid to a gaseous condition , as from water to steam , and probably from a gaseous condition to an aetherial condition as we shall see later on, but the sum-total of Matter throughout all these changes ever remains the same. Thus, throughout all the physical and chemical changes that Matter may undergo in the universe, there is no actual loss in weight or quantity. Throughout the whole realm of Nature we do not find a single instance of the production of absolutely new Matter. We may, and can produce new combinations of the forms of Matter. The substance so formed by chemical combination may be different from anything that has ever been seen or produced before, but the elements of which it is formed must have existed in some other form before its production.
This principle is the great underlying principle of all chemical investigation and research, and may be proved at any time by means of the scales or balance in the laboratory. Lavoisier first made the experiment with the scales and proved this truth by actual demonstration.
ART. 31. Matter is Atomic.-The hypothesis that Matter is made up of infinitely small particles which are termed atoms, was first proposed by the Grecian philosophers. This hypothesis has gradually taken definite shape, but it remained for Dalton to first put the hypothesis into a connected form, and that form is now known as Dalton's Atomic Theory.
According to this theory, an atom of hydrogen was the lightest atom known, but comparatively recent researches by Sir W. Crookes have shown that there are possibly in existence minute particles which are even lighter than an atom of hydrogen. Thus Sir W. Crookes has suggested that there are certain

WHAT IS AN ATOM ?

43

particles associated with an atom of hydrogen which are 700 times less in weight than the atom itself.
Professor J. J. Thompson has further suggested that if we could divide an atom into a thousand parts, and could take one of those parts, we should find that this corpuscle, as he has termed it, would be the carrier of the charges in an electric current, so that it will be seen that we are moving into the direction of the continuity of Matter. Let us now look at the question as to what is meant by an atom more fully.
ART. 32. What is an Atom ?-Clerk Maxwell's definition of an 66
atom is, a body that cannot be cut in two." An atom is the smallest part of a simple substance which can enter into combination with another element, and is incapable of being further subdivided.
An atom of hydrogen is the smallest part of that particular gas which can enter into combination with any other element, as oxygen, to form a chemical compound as water, which is com-
posed of two atoms of hydrogen and one of oxygen. Further, an atom of any kind or sort, retains its identity and
remains the same throughout all chemical combinations or
physical changes which it may undergo. By spectroscopic analysis, it has been ascertained, for example, that hydrogen exists in the sun and stars, and the conclusion is arrived at in connection therewith, that an atom of hydrogen in any sun or star is the same as an atom of hydrogen in our atmosphere, or in any of the compounds, as water, in which it is found. Thus it has come to be received as an accepted fact, that every atom of any substance, as oxygen, nitrogen, and hydrogen, whether they exist in the earth or sun, in meteorites or the farthest stars or nebulae, wherever they are found, possesses the same identity and the same physical properties.
Atoms attract one another, and this atomic attraction is known as affinity. There is not the least possible doubt that affinity is a form of universal attraction , except that the affinity of atoms is selective. This affinity of atoms for each other gives rise to the combination of atoms known as molecules and chemical compounds.
Size of Atoms.- It has been computed by Lord Kelvin and others, that an atom may be as small as 50.000.000 of an inch in diameter, so that if 50,000,000 of them were put side by side, they would just measure one inch in length. Atoms are not all of the same size or weight. An atom of oxygen weighs 16 times as much as an atom of hydrogen. It has been proved by Kirchhoff and Bunsen, that the 1.000.000 part of a milligramme of sodium chloride is sufficient to give a yellow colour to a gasjet. Faraday prepared some sheets of gold, so thin that he

44

AETHER AND GRAVITATION

estimated they only measured the

part of the length of a

light-wave. We have to remember that each sheet of gold must have contained molecules of gold composed of atoms. What

must have been the size of the atoms therefore of which the

sheet was composed ? ART. 33. The Atomic Theory.-The Atomic Theory was

revived by Dalton in 1804, in order to account for the fact that elements unite in certain definite proportions. From that time to the present, the theory has grown and developed until at

the present time it is looked upon as a well-established theory. It is, however, simply a theory, and from the very nature of the hypothesis is incapable of proof. No one has ever seen an atom of hydrogen or oxygen, or an atom of any solid , liquid , or gaseous matter. The Atomic Theory suggests, therefore, that there is a limit to the divisibility of matter. All chemical experiments lend support to the theory, and by it we are able to give an intelligible and easy method of expression to what would otherwise be difficult phenomena to explain.

Ancient philosophers were divided on the question of the infinite divisibility of matter. The Epicureans were of the opinion that matter was incapable of infinite division, and that

even if we were able to make the smallest possible division, it would be impossible for us to reach the smallest particle termed " Atom ."

ART. 34. Kinds of Atoms.-Various forms of atoms have

been conceived by philosophers from time to time, ranging from the Hard Atom , and the simple point-centres of Boscovitch, until we come to the more modern Vortex Atom of Lord Kelvin, or the Strain Atom of Dr. Larmor, which will be looked at separ-

ately. Democritus conceived a hard atom as long ago as 500 B.C., while the notion of a hard atom is not absent from the

works of Newton himself. We find that Newton suggested that

the particles of air might be hard spherical bodies, at a distance from one another of about nine times their diameter.

The hard atom, however, seems to be refuted by spectroscopic analysis, which reveals to us in a manner that has never been revealed before, something of the sizes and vibrations of atoms.
From the phenomenon of heat, which is simply matter in motion, we feel compelled to accept the fact that an atom is not a hard particle, but that it is something which is more closely allied to the Vortex Atom, or the Strain Atom of Dr. Larmor.

Boscovitch Atom.-According to Boscovitch's theory, each atom is simply an indivisible point in space capable of motion, and possessing a certain mass whereby a certain amount of energy is required to produce a certain change of motion. In

addition to this, any two atoms could attract or repel each other

LORD KELVIN'S VORTEX ATOM

45

with a force depending upon their distance apart. The Law which regulates these forces for all distances greater than todo of an inch is an attraction varying inversely as the square of the distance, and a repulsion for less distances.
We have, therefore, to suppose that in place of the hard atom, there is merely a geometrical point which can exert attractive or repulsive forces to, or from, the central point. So far as external particles are concerned, they would behave just the same as a hard atom would do. This conception was largely entertained in recent times by Faraday. It is more a mathematical explanation than a physical one, but has been found convenient in explaining what takes place in the interior of bodies in their three states, namely : solid, liquid, and gaseous.
Lord Kelvin's Vortex Atom.-Another hypothesis which has been suggested for the constitution of an atom, is that known as the Vortex Atom, which received its birth at the hands of Lord Kelvin. The underlying principle of this Vortex Atom is, that matter may be entirely due to the rotating parts of a fundamental medium, the Aether, which fills all space.
The properties of vortex motion were first mathematically calculated by Helmholtz, but it was left to Sir Wm. Thompson, now Lord Kelvin, to give a physical idea of the Vortex Atom .
Before entering further into the question of the Vortex Atom, it may be as well to explain how vortex smoke rings may be made .

A

B

BA

о

0

Fig.3.

All that is required is a wooden box, about one cubic foot in size, with a round hole perforated in one of the sides, and the opposite side covered with a piece of linen in place of the wooden side. The bottom of the box should then be covered
with some strong solution of ammonia, and some hydrochloric acid poured into a saucer and put into the box. The combination of these two will cause thick clouds to form in the box, and if the linen is sharply tapped by the hand, a ring of this cloud will be forced through the hole on the opposite side of the box. The ring so formed will be circular in shape, and will go sailing through the room in which it is made.

46

AETHER AND GRAVITATION

When the hole is circular, the rings will be found circular also, but if the hole is square, then the rings will be irregular in shape. One remarkable characteristic about these rings is, that when two of the rings are travelling in the same straight line, the one behind will overtake the front one, and while so doing, the diameter of the front one is enlarged, while that of the one behind contracts. The front one will also travel slower, while the one behind travels faster until it has caught up the former, and then the latter, having contracted sufficiently, will pass through the diameter of the former as illustrated in the figure. This alternation of contraction and expansion is continued as long as the two rings move in the same plane and until they are destroyed. When, however, the two rings are moving in opposite directions, and meeting each other in the same straight line, they will repel one another, instead of attracting each other.
Their rate of progress is gradually reduced as they approach together, and they begin to expand and enlarge, but they never touch each other. Another peculiar feature about the rings consists in the fact, that the central core of air in the ring remains the same all the time the ring is in motion through the room , so that it has the same core of air at the end of its journey as it had when it left the box.
As Lord Kelvin pointed out, if there were no friction of the air, the ring once created would rotate for ever. If, therefore, there were such a thing as a perfect fluid, and there were vortex rings in it, nothing could destroy these rings when once they were created, and this is one of the most striking suggestions with reference to the Vortex Atom theory of matter. It remains to be seen whether in the universe we have such a medium as a perfect fluid.
Sir Wm. Thompson has applied the Vortex Atom theory of matter to the Aether, but from mathematical calculation he was unable to arrive at a satisfactory conclusion as to the Aether being composed of vortex atoms.
Another remarkable property belonging to these rings, lies in the fact that they cannot be cut in two. It will be found that when the knife is brought near to them, they seem to recoil from the knife. In that sense, it is literally an atom, a thing which cannot be cut in two.
The Vortex Atom has many recommendations in its favour. Many of the most important properties of matter are possessed by it, as for example indestructibility, elasticity, inertia, compressibility, and its incapability to be cut in two. Further, it may be linked with another ring, and so give the basis to the combining properties of atomic weights.

ELEMENTS OF MATTER

47

The Vortex Atom theory is simple in character, as it does not postulate any extravagant hypothesis, but makes use of the Aether as the common basis for all matter, simply stating that this property of rotation may be the basis of all that we call matter. We shall further consider the relation of the Vortex Atom to matter, when we deal with the constitution of matter and the unity of the universe.
ART. 35. Elements of Matter.-As is well known, modern chemistry has succeeded in reducing all the complex forms of matter in Nature into a number of simple substances, which are called elements. Of these elements about seventy are at present known, some of which, however, are very rare. An element
therefore is a simple substance which cannot be decomposed by any known force or process, as heat or electricity, into other elements .
There are, however, only about fourteen of these elements that enter largely into the constitution of the earth, the most common being oxygen and silicon. By the use of the spectroscope, it has been proved that many of these elements, as for example oxygen, hydrogen, sodium and calcium, exist in the sun and stars, as well as in the most distant nebulae. Most of the elementary bodies are to be found in a gaseous form as hydrogen, oxygen, fluorine and chlorine, though it has been found possible to liquefy even these gases. Thus we see that matter may be roughly divided into three states, viz. solid, liquid, or gaseous.
The condition in which the substance is found depends upon its temperature and pressure. An example of matter in its three stages is best shown in the case of water, where in the solid condition we have it as ice, in the liquid condition as water, and in the gaseous condition as steam .
By recent researches it has been found possible to liquefy gases at a very low temperature and increased pressure, with the result that now nearly all known gases as hydrogen, oxygen, and carbonic acid are to be obtained in liquid form. By still more recent experiments made by Professor Dewar, it has even become possible to liquefy the air we breathe, with the result that at a temperature of about 270 degrees below freezing- point and at an increased pressure, the otherwise invisible and gaseous air may be changed into a liquid, and poured out from one vessel into another in the same way that water can be poured out. A vessel, however, at the ordinary temperature into which such liquid air is poured, would be so hot compared with the coldness of the liquid air, that as soon as the exceedingly cold liquid air came into contact with the vessel, the comparatively hot vessel would make the liquid air to boil.
ART. 36. Three Divisions of Matter.- Matter has been divided

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AETHER AND GRAVITATION

into three divisions, viz. solid, liquid, and gaseous. These
divisions are each known by characteristic qualities, which separate the one division from another. At the same time, it is possible for matter to pass from one division into another, as for example in the case of water, which may exist in solid, liquid, and gaseous form. In view of the recent researches of Sir. Wm. Crookes and Professor J. J. Thompson, it is very probable that before long we shall have to add a fourth division to matter, which we should have to call ultra-gaseous form, or it may possibly be the aetherial form. If it should prove to be true that Aether is matter, and possesses the essential qualities of matter as suggested by Lord Kelvin, then certainly we shall have reached the boundary of another great division of matter, and our conception of the divisions of matter will have to be enlarged to take in that form, so that matter would then be divided into four great divisions, viz. solid, liquid, gaseous, and aetherial.
We will now consider the three groups as at present recognized.
Solid.-Examples of solid bodies are common and familiar, and are typified by such things as iron, silver, copper, and lead. The chief characteristic of this condition of matter is that its condition or state is fixed , and cannot be altered without the
expenditure of heat or electricity or some other form of energy.
All solid elementary substances, with the exception of carbon, can be melted or reduced to a molten condition, although some of them require a very high temperature to effect this reduction, as, for example, platinum. When a still higher temperature is applied, the metals may be vaporized, or reduced from a molten
state to that of a vaporous condition. In the case of solids, the atoms have not a free path in which to move. It must not be thought, however, that the atoms of a solid are motionless, as there is nothing absolutely motionless in the universe. In the
case of the solid, the molecules which compose it, preserve their relative position and are linked together in relation to each other by the force of Cohesion.
Liquid.-When matter is in a liquid condition, as, for example, water and oil, the condition of its molecules are not so fixed and stable as they are in the solid state. The molecules can move freely about one another, and their freedom is increased compared with their condition when in the solid state.
As already indicated, the reduction of a solid body to a liquid or molten state may be effected by heat. When heat is applied to a solid body, several results follow, each of which is the outcome of the other.

THREE DIVISIONS OF MATTER

49

I. There is an increase of temperature which is due to the increased energy of the molecules, through the added heat.
2. There is an enlargement of the volume or size of the body, and if the addition of heat be continued, the molecular forces which hold the molecules together are broken down, and then the molecules, loosened from those forces which in the solid state have bound them together, begin to move about with greater freedom , and thus give rise to the molten condition of metals, or liquid condition of water. Thus, it is the heat which has set the atoms which compose the molecules in motion. The atoms of the solid have absorbed the heat, and the heat which has thus been absorbed has imparted vibratory energy to the atoms, which they did not possess before. Now when a substance is in the liquid state, the atoms of that substance have not only a vibratory motion, but have also a translatory motion, so that they can move in and out among one another. This is proved by the phenomenon of diffusion, where we have the case of two different-coloured liquids, for example, intermingling with each other, which is conclusive evidence of the translatory motion of the atoms in liquids.
Gaseous.- The third state in which matter is found is the gaseous state. In this condition, the particles of matter which form the gas have the greatest possible freedom of movement, and are able to move about with inconceivable velocity. There is abundant evidence to prove that gases consist of particles of matter which are perfectly free, and are able to fly about in all directions. The simplest proof is obtained by mixing two gases together, as, for example, when any gaseous substance is allowed to mix with the air of a room, when we find that the particular gas soon mixes itself thoroughly with all the air in the room . This process of mixing is known as Diffusion, and the
lighter a gas is, the more quickly does it diffuse itself. The rate of movement of the various particles is varied, by reason of the encounters which each particle undergoes from time to time. Through experiments made by Joule, he arrived at the conclusion that particles of hydrogen attained a velocity of 6055 feet ! per second at o° C., which is a velocity much greater than that of a cannon-ball. In spite of the enormous velocity with which a particle of hydrogen would move, there are such a large number of particles in a single cubic inch of space, that no one particle has an absolutely free path from the one side of the enclosed space to the other. To this constant movement of the individual particles is due the elasticity or pressure of gases . The outward pressure which they exert on any body which encloses the gas is caused by the total effect of the impact of the particles, and is proportional to the sum of their masses multiplied into the
E

50

AETHER AND GRAVITATION

square of their velocities. If we halve the enclosed space, then we should double the number of impacts in a given time, so that the number of impacts is inversely as the volume of the gas. This is equivalent to the statement, that the pressure of a gas varies inversely as its volume, which is Boyle and Marriotte's Law.
ART. 37. Matter is Gravitative.- If there is one property which is essentially characteristic to all matter, it is that all matter is gravitative. To this rule there is no exception, as the universal Law of Attraction states that " every particle of matter attracts every other particle." Thus, wherever in the whole universe
there is a particle of matter of any kind or sort, whether such matter be solid, liquid, or gaseous, there the force of attraction will be exerted with a force proportionate to the mass of the particle, and inversely as the square of the distance between the attracted particles.
Gravitation, then, is a property which is essentially inherent in matter, and any substance which is termed matter, or fulfils the conditions that govern matter, must be gravitative, whatever other property it may, or may not, possess. Unless this be so, we should have a violation of the universal Law of Gravitation, which would cease at once to be a universal law, for instead of reading " every particle of matter attracts every other particle," we should have to say that " some particles of matter attract some other particles," which would be a violation of that universal law which, through the genius of Newton, has given to the universe an unity from the philosophical standpoint that it did not possess before.
Some matter may, or may not be elastic ; it may, or may not be solid, or liquid, or gaseous ; but there is this fact regarding matter which is absolutely undeniable, and that is, " All matter is gravitative."
That this is true of each and all kinds of matter has been
proved by direct experiment times without number, and the constant application of the law to all forms of matter is a fact observable from the phenomena incidental to every-day life. Astronomical observation teaches us also, that all stars, suns,
planets, satellites, and comets are subject to this great Law of Gravitation, as indeed they must be if they are composed of matter. That they are all composed of exactly similar elements of which the earth is composed, has been proved again and again by spectroscopic analysis, which teaches that hydrogen, iron, and calcium, etc., are to be found in distant stars and nebulae, as they are equally to be found in the composition of the earth. Thus throughout the wide universe so far as observation and experiment can teach us, we learn that without any exception,

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everything that is termed matter is subject to this universal Law of Gravitation.
ART. 38. Matter possesses Density.-Density is that property of matter which decides the weight of a body per unit of volume.
The density of any substance may be shown in several ways. It may denote, first of all, the number of molecules in a given body. Let us take as an illustration, the case of air being forced into a vessel of a given size, say one cubic foot capacity. We will suppose that in such a vessel there are 1,000,000 molecules. If we pump in a quantity of air equal to the amount it contained at first, then it is obvious that we have doubled the number of molecules in the same vessel, and therefore we say we have doubled the density. Not only so, but the weight of the air in the vessel will have been doubled. Looked at from this standpoint, density means the number of molecules in unit volume such as a cubic inch, or cubic centimetre.
Again, as has already been shown in Art. 35, the different elements have different atomic weights. Thus an atom of carbon weighs twelve times as much as an atom of hydrogen, that is to say, there are twelve times as much matter by weight in an atom of carbon as there is in an atom of hydrogen, so that it would take twelve times as many hydrogen atoms to weigh a pound as compared with the number of atoms of carbon. This is only another way of stating that carbon has twelve times the density of hydrogen. If we compare lead and silver with hydrogen in the same way, we find that the density is 206 times and 107 times greater than that of hydrogen.
Thus, it may be seen, that all matter possesses density, and that that density depends partly upon its atomic constitution. If the molecule of matter is composed of atoms whose atomic weights are very large compared with that of hydrogen, as iron, silver, lead and gold, then the molecules will have a much greater density, than a molecule formed of oxygen and hydrogen, i.e. water. This property of the density of matter plays a most
important part in the transmission of any kind of wave- motion.
ART. 39. Matter possesses Elasticity.-Matter possesses elasticity. Elasticity is that property of matter which enables all bodies to resume their original shape, when the pressure which has caused the alteration of shape has been removed.
For example, suppose an ivory ball be dropped upon a marble table, or any other hard surface. It will then rebound, and rise
almost to the same height from which it was dropped. If the surface upon which it fell was first covered with blacklead, a circular spot of lead will be found on the ivory ball. From this fact, we arrive at the conclusion that when the ball came into

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contact with the table, at the moment of contact it was flattened , and then owing to its elasticity it rebounded into the air again.
Now the measure of the elasticity of a body is proportionate to the velocity of the wave-motion which it can transmit. A
good illustration of the transmission of wave- motion may be shown with a number of ivory bagatelle or billiard balls. If eight or more of these be put in a row, all touching each other, and a single ball be placed about an inch or so away from the others in a straight line with them , then when the single ball is struck with a cue against the other eight, the motion of the single ball is transmitted by each one of the eight successively with such rapidity, that the end ball would be set in motion in a quicker time than a single ball would take to reach the end ball, if it had been free to move along without encountering any opposition.
It is a fact capable of demonstration, that the smaller the particle of matter, the greater will be its vibratory motion. Thus the particles of air are very, very small, and consequently air is found to be very elastic, and allows sound to be transmitted through it with comparatively great velocity, some sounds travelling at the rate of over 1000 feet per second.
A most important factor in determining the propagation of any wave-motion, through a gas or solid, is the relationship of the elasticity of the gas or solid to its density. Suffice to say, that the velocity of any wave-motion is determined by the relation of the elasticity to the density. For example, sound, which is a wave-motion of the air, can not only be transmitted through gaseous bodies as air, but also through liquids and solids. Sound travels faster through solids than through liquids, and faster through liquids than through gases. In liquids, the relation of the elasticity to density is greater than in air, and in solids the relation is greater still. Therefore sound travels much faster in liquids than in gases, and faster in solids than in liquids.
This is the reason why a train can be heard coming if the ear is put to the railway-line, when no indication of its approach is given to the ear by the atmosphere. Some examples of the velocities of sound through different substances are as follows-

GASES O. C. FEET
Air 1090 per sec. Oxygen 1040

LIQUIDS. FEET
Water 4708 per sec. (8 ° C. ). Alcohol 4218 99 99 (20° C.).

SOLIDS. FEET
Gold 5717 per sec. Silver 8553 ", 99

ART. 40. Matter possesses Inertia.-Inertia is that property of matter, by which matter cannot of itself alter, or change its state of motion, or of rest.
Newton's first law of motion states that a body at rest remains

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at rest until some force or motion acts upon it. If a stone be
dropped from a balloon, the stone does not fall because of any property which it possesses, but because the force of gravity acts upon it. If it were possible to eliminate this force of gravity, then if there were no other force which could act upon the stone, it would remain suspended in space.
The inertia of a body is equal to the mass of that body, or the amount of matter in the body as measured by gravity, so that if a body is halved, its inertia will be halved also, and if doubled, its inertia will be doubled also. As the inertia of matter opposes all kinds of motion , the amount of force required to overcome the inertia of a body is proportionate to its mass. So that if the mass of a body is doubled, then twice the force would be required to move it, while if the body were halved, half the force would suffice to do it.
Inertia is possessed quite as much by a moving body as a body at rest. The definition given points this out, as it states that matter cannot of itself change its state of motion. If a body therefore is in motion, it requires a certain amount of resistance to bring the body to a state of rest, or the loss of an equal amount of energy, by friction or otherwise, equal to the quantity which it absorbed in order for it to be set in motion.
We get numerous examples of this property of the inertia of bodies in our daily experience. Many of the accidents that befall people in various ways are due to this property of the
inertia of matter. A cyclist is riding a machine down-hill, and loses control over his machine, with the result that he runs into a wall , and is killed. Now what has happened ? The cyclist has participated in the motion of the machine, with the result that
when the machine has been suddenly stopped, the body has been thrown forward owing to the momentum it had acquired.
We are constantly being affected by the property of inertia of matter, in tram and train and bus. Whenever any of these are suddenly stopped, or suddenly started , we are thrown either backward or forward, owing to the body either not having acquired the motion of the train, or, having acquired it, is unable to lose its motion as quickly as the train, and is therefore thrown forward.

CHAPTER IV
AETHER IS MATTER
ART. 42. Aether is Matter.-The hypothesis of an Aether which fills all space was made in order that scientists might be able to account for certain phenomena of Light, which otherwise were difficult to account for. Its existence is demanded not only for the phenomena of Light, and Heat, but, in view of the comparatively recent researches of Hertz on " Electric Waves," of Electricity also.
The Aetherial Medium is generally assumed to be that fundamental medium, by means of which possibly all the properties of matter, and all the phenomena of motion of the universe are to be explained. Light and Heat have been proved to be due to the periodic wave-motion of this universal Aether, while from the investigations and researches of such men as Clerk Maxwell, Poynting, Thompson and Hertz, it has been proved that electro-magnetic phenomena are due to this same medium .
Several different forms of Aether have been postulated by various philosophers from time to time, but the only Aether that has survived, is that which was first conceived by Huyghens to explain the phenomena of Light, though it was Thomas Young who finally succeeded in placing the conception of the Aether on a sound basis. Each discovery of science has only strengthened the hypothesis and existence of the Aether, the latest discovery, that of wireless telegraphy so successfully developed by Signor Marconi, being attributed to the electro-magnetic properties of this self-same Aether.
It has already been pointed out that Newton endeavoured to account for Gravitation by the pressure of the Aether. If, therefore, Gravitation be really due to this universal medium it becomes necessary to ask ourselves, What are the properties and characteristic qualities of this wonderful medium ? What then is Aether, and what its properties ?
It has already been pointed out in Art. 29 that Aether is matter. Such an assumption is strictly in accordance with the Rules of Philosophy, quoted in Chap. I.
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55

Not only is this hypothesis a simple one, but it is also in accord with all our experience and observation.
It is a simple supposition, because, unless Aether is assumed to be matter, then, instead of the universe being composed of two classes of things, matter and motion, we have to add a third class, which we call Aether. It can be readily seen, that by the introduction of a third class into the composition of the universe, such an addition, instead of simplifying the constitution of the universe, adds greater complexity to the same.
By accepting the hypothesis that Aether is matter, we do away with the third class of essentials in the universe, and so reduce the number to two classes. If we could go one step further, and prove that instead of there being two classes of things in the universe, there was only one group, and show that all material things, and all phenomena could come under the head of either matter, or motion, then we should have reduced the universe to the simplest conception possible. As, however, it is not possible, at least in our present state of knowledge, for us to come to this fundamental and simple hypothesis of unity for the entire universe, we must accept the next simpler solution, and affirm that the universe is composed of two classes of things, viz. matter and motion, and this as I have already shown is a simpler classification than by putting Aether into a class by itself, and therefore is in accord with our first Rule of Philosophy.
Again, it is entirely in accord with our second Rule of Philosophy, as it in no way violates the results of experiment, experience, or observation. Look where we will, or at what we will, whatever we see, touch, taste, or smell is termed matter. The burning sun, the glowing star, the flying meteor, the glowing comet, the earth, our own island home, the towering rock, the wide ocean, the running river, the green trees of the forest, the tiny insect, the lordly elephant, all animals, plants, and our own physical body, all are composed of matter, either in solid , liquid or gaseous form . Therefore when we affirm that Aether is matter, the affirmation is strictly in accordance with the elementary principles of Philosophy, and in no way violates their rules or laws. To affirm that Aether is not matter, is to affirm something contrary to all experience , unless it be affirmed that Aether is motion, for which assumption the evidence is not nearly so strong or conclusive as that it is matter. Therefore the objector to this assumption is himself unphilosophical, in that he postulates or supposes that the Aether is a medium, with qualities which lie altogether outside the range of our experience and observation.
There is a growing conviction in the minds of scientific men, that Aether belongs to that group of things which we describe

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by the term matter. Lord Kelvin in giving an address to the British Association , 1901 , on " Clustering of Gravitational Matter in any part ofthe Universe," said : "We are all convinced with our President (Professor Rucker) that Aether is Matter. Aether we relegate to a distinct species of matter which has inertia, rigidity, elasticity, compressibility, but not heaviness."
Dr. Larmor in Aether and Matter writes : " Matter must be constituted of isolated portions, each of which is of necessity a permanent nucleus belonging to the Aether, of some such type as is represented for example by a minute vortex ring in a perfect fluid."
Faraday in relation to this subject writes (Exp. Res., vol. ii.) : " The view now stated of the composition of matter would seem to involve the conclusion that matter fills all space, or at least all space to which Gravitation extends, including the sun and its system, for Gravitation is a property of matter dependable on a certain Force, and it is this Force which constitutes matter." As the Aether fills all space, including the solar system, therefore, according to Faraday, " Aether must also be Matter."
By the hypothesis that Aether is matter, with all the properties that such a hypothesis logically gives to Aether, I venture to premise that the third Rule of Philosophy will be fulfilled , and that there is no phenomenon of the astronomical world, and no part of the universal Law of Gravitation which such a hypothesis will fail to account for on a satisfactory physical basis. For the first time a physical explanation will be given to Newton's Laws of Motion, at least to those laws which are strictly in accordance with the first and second Rules of Philosophy. For the first time a physical conception will be given to all Kepler's Laws, and what the mathematical Laws of Gravitation have done to Kepler's Laws, in giving them a mathematical basis, the simple hypothesis that Aether is matter, with all that is logically involved therein, will do for the same laws from the physical standpoint. For the first time a physical conception will be given to the Centrifugal and Centripetal Forces, which are the complement and the counterpart of each other, that physical conception being the outcome of the same hypothesis that Aether is matter.
In addition to this, light is thrown upon such problems as are referred to by Lord Kelvin (Phil. Mag., July 1902) in his paper on "Clouds on the Undulatory Theory of Light," and further light is given to some theories of Electricity advanced by such men as Faraday, Clerk Maxwell, and Professor Thompson. I venture to think, therefore, that the hypothesis advanced, and the conception put forward that Aether is matter, is philosophically correct, and is warranted by the results that arise out of such a hypothesis.

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It may be thought by some that the hypothesis that I have advanced is already conceded, and that the fact that Aether is matter is already admitted by scientists and advanced thinkers generally. But such an idea is only partly correct. It is already admitted by some of our most advanced scientists that Aether is matter, but that admission is only carried partially to its logical conclusion .
Lord Kelvin in an address to the British Association, 1901, gave utterance to the following remarks on the relation of Aether to Matter : " We are convinced with our President (Professor Rucker) that Aether is Matter, but we are forced to say that the properties of Matter are not to be looked for in Aether, as generally known to us by action resulting from force between atoms of Matter and atoms of Aether. Here I am ILLOGICAL when I say between Matter and Aether, as if Aether were not Matter. Aether we relegate to a distinct species of Matter which has inertia, rigidity, elasticity, compressibility, but NOT HEAVINESS ."
From a quotation of this kind, which is from the lips of one of the keenest intellects of the present time, I think I am justified when I make the statement, that it is not conceded that Aether is matter, with all that that concession logically involves. Because, as Lord Kelvin points out, though it is admitted that Aether is matter, yet that admission is only a qualified admission, and not one which carries with it all the properties that essentially belong to matter, or an admission which includes the fact that Aether is gravitative, that is, subject to Gravitation. To be strictly logical and philosophical, in the statement that Aether is matter, it must be conceded not only that Aether is subject to such properties as elasticity, inertia, and compressibility, but that it is also gravitative or possesses weight. For either Aether is matter, or it is not matter.
It cannot be both at one and the same time. Such a conception is altogether opposed to that simplicity which is the chief characteristic of Nature as pointed out by Newton.
If therefore Aether be matter, then, to be strictly logical and philosophical, it must be conceded that Aether is gravitative, as well as having the other properties of matter, as elasticity and inertia, etc. Unless this is conceded, then we have the anomaly in Nature of matter, which is not matter, because it violates the very principles which above all others decide what is matter, viz., "That every particle of matter attracts every other particle," etc., that is, that it is gravitative. Thus by supposing that the Aether is matter, and yet not being gravitative, all the Rules of Philosophy are violated, as such a hypothesis is opposed to both the first and second Rules of Philosophy, and is contrary to all

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observation and experience. If Aether therefore be matter, as is conceded by the most advanced thinkers of the time, then it follows that the only logical and philosophical conclusion that can be arrived at is, that it is also subject to those properties which are the chief characteristics of all matter. These properties may be classified as follows : atomicity, gravitation, density, elasticity, inertia, and compressibility.
ART. 43. Aether is Universal.- Young in his first Hypothesis on the Aether medium states that, " A Luminiferous Aether
pervades the Universe rare and elastic in a high degree " (Phil. Tran., 1802).
As Young points out, this invisible and elastic Aether fills all space and floods the universe at large. In it suns blaze, stars shine, worlds and planets roll, meteors flash, and comets rush in their mysterious flight. In it all material and physical things exist, for it is to them not only the primary medium of their existence, but, just as the infinite and ever-active energy of the Divine is to the universe in its entirety and fulness, the exciting
and stimulating spirit of its energies and powers, so this aetherial ocean is to the material and physical universe, the exciting and stimulating medium of all its activities, energies, and powers ; and without which, though all material and physical things were endowed with the varied capacities of their kind or life, yet they could neither exert nor exercise them, nor even exhibit the simple activity of motion. Hence everywhere, where material and physical things are, there, as the medium of their existence and energy, the Aether is ; and where the Aether is not, no material or physical thing is, or can be. That the Aether is universal is proved by the phenomena of light. Light-waves have a velocity of about 186,000 miles per second. Now the distance of the sun from the earth is about 92,000,000 of miles,
so that light takes about eight minutes and a half to travel from the sun to the earth.
A ray of light from the nearest fixed star takes about three and a half years to reach the earth, while there are some stars so far away that astronomers tell us, that though light travels with so great a velocity, yet it would take several thousand years to reach the earth. This fact implies that throughout boundless space there is to be found this aetherial medium. Thus inter-
planetary and interstellar space is not empty, but is filled with this ever-present, all- pervading Aether ; and not only so, but every particle of matter in the universe is surrounded by this universal Aether, which forms the exciting and stimulating medium of all the activities, energies, and motions of all Matter. Thus the Aether is both universal and infinite in its extent.
Clerk Maxwell, in his paper on " Action at a Distance "

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(Collected Works, by Niven), with reference to the universality of the Aether, writes : " The vast interplanetary and interstellar regions will no longer be regarded as waste places in the universe, which the Creator has not seen fit to fill with the symbols of the manifold order of His Kingdom. We shall find them to be full of this wonderful medium, so full, that no human power can remove it from the smallest portion of space, or produce the slightest flaw in its infinite continuity. It extends unbroken from star to star, and when a molecule of hydrogen vibrates in the Dog Star, the medium receives the impulses of those vibrations, and transmits them to distant worlds. But the medium has other functions besides bearing light from world to world, and giving evidence of the absolute unity of the material system of the universe. Its minute parts may have rotatory as well as vibratory motions , and the axes of rotation form those lines of magnetic force which extend in unbroken continuity into regions which no eye has seen, and which, by their action on our magnets, are telling us in language not yet interpreted what is going on in the hidden world from century to century." Now I premise, that in the theory of the Aether to be submitted in this work, the physical interpretation of this statement of Maxwell's will receive its literal fulfilment.
ART. 44. Aether is Atomic.-If there is one fundamental truth which is applicable to all matter, it is, that all matter is atomic.
Professor Rucker, in his Presidential Address to the British Association of 1901 , in dealing with this question, said : " The believer in the atomic theory asserts that matter exists in a particular state, that it consists of parts which are separate and distinct from one another, and as such are capable of independent movement. It is certain that matter consists of discrete
parts in a state of motion, which can penetrate into spaces between the corresponding parts of surrounding bodies. Every great advance in chemical knowledge during the last ninety years finds its interpretation in Dalton's Atomic Theory."
From such an authority as this, and from the facts which he gave in his dealing with the question, we are bound to admit that all matter is atomic. That being granted, when the statement is made, therefore, that Aether is matter, the only logical conclusion that can be arrived at, with reference to the question of the atomicity of the Aether, is, that Aether is also atomic. Unless this be conceded, we have the first and second rules of our Philosophy violated, as an atomless Aether is opposed to that simplicity of conception, which is an essential requirement of all hypotheses, and is moreover contrary to that presumptive evidence gathered from observation and experiment, which teaches us that

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all matter is atomic. If it be argued , that it is impossible to decide upon a question as to the atomicity of the Aether, my reply is that the same argument may reasonably be applied to all matter. But, as Professor Rucker stated, all the evidence on matter points out and supports the theory of its atomicity, and , therefore, the only logical and philosophical conclusion is, that Aether is atomic also. Again, it may be suggested that we cannot see or touch an atom of Aether, and that it is not only invisible, but apparently incapable of being made sensible to our senses. In reply to that, as I have already shown in Art. 31,
that objection can be equally used against an atom of hydrogen, or an atom of oxygen. Does any one doubt the existence of the hydrogen atom or the atom of oxygen, because it is invisible to the sense of sight, or cannot be revealed to the limited sense of touch ? Certainly not ! By the same reasoning, it is just as illogical to deny the existence of an atom of Aether because it cannot be seen or felt, as it is to deny the existence of an atom of hydrogen or oxygen. An atom of Aether reveals itself to the
senses in the same way that an atom of hydrogen or oxygen does, that is, by the force or energy which it exerts. Its vibrations can be manifested to the body in the form of heat, while the undulatory motion which the aetherial atoms transmit in the form of light, reveal the presence of the aetherial atom to the sense of sight. The question at once arises as to what constitutes an aetherial atom , what are its properties and motions ?
Now, in order for us to enter successfully into this speculative region, it is essential that we should, as far as possible, conform to the Rules of Philosophy, and endeavour to gain some conception of an aetherial atom from the results of experience and observation. In doing this, we are at once confronted with the difficulty, that no one has ever seen an atom, or analyzed the properties of one. Actual experiment has revealed , nothing absolutely certain as to the ultimate character of an atom, and if this be true of the atoms of matter, then it must also be true of an aetherial atom . It would seem at first, therefore, that we have no results of experiment, or observation, by which we may be guided in formulating a right conception as to the constitution of an aetherial atom, and therefore we are thrown simply into the regions of speculation as to its constitution and properties.
But I venture to suggest, that there is a method which is strictly philosophical in its application , by which we may possibly arrive at a clear conception of an aetherial atom. All great discoveries of science have been the outcome of applying the principle, that what is true of the visible and seen, is true of the invisible and unseen ; that what is true of the known , is true

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of the unknown ; that the principles and laws which govern the small also govern the large and the great. It was thus that Newton discovered his great Law of Gravitation, as he was able from the falling of an apple, to rise to the application of the same principle to our satellite the moon, and this led him on to the discovery of the Law of Gravitation.
If, therefore, in Philosophy, the laws governing the small things are also applicable to the great things, then the converse equally holds good, that the laws governing great things are the reflex of the laws which govern the small things. For example, the laws which govern the light and heat of the sun are the same which govern the light and heat of a candle or a glow- worm ; and the laws which govern a planet or world are the same as those which govern an atom. Thus a planet or world, which is simply an agglomeration of atoms, may reveal to us in its motions and laws, what are the motions and laws which govern the atomic world.
In looking at the properties and motions of a planet, therefore, as our earth for example, we find that a planet is a sphere, or more correctly an oblate spheroid ; that the earth or planet is a magnet possessing polarity, having a north and south pole ; that it has rotation on an axis, in addition to translation in an orbit, and that it is subject to the universal Law of Gravitation.
If, therefore, it holds good in Philosophy, that the small things are the index to the greater, and that the laws governing the small things also govern the greater, then the converse holds good, that what is true of the large is true of the small , and that the laws governing the great also govern the small.
So that gathering up those chief properties of the earth to which I have already referred , and applying them to an aetherial atom , or any other atom if necessary, we arrive at the conclusion that an atom must be spherical in shape, must possess rotation, and must have an orbit, must possess polarity, and also be subject to the universal Law of Gravitation.
Here, then, we have given to us certain data by which we are enabled to form our conception of an atom , aetherial or otherwise. The question arises, whether, among the forms of atoms which have been devised by scientists, any of the atoms so conceived fulfil all, or nearly all of these requirements. We have Boscovitch's Atom, the Hard Atom of Lucretius, and the more recent conception of the Vortex Atom of Lord Kelvin. Of all the hypotheses in regard to the ultimate nature and constitution of an atom , the Vortex Theory probably is the one which offers to
the mind the simplest conception of an aetherial atom. The Vortex Ring Atom, however, which has been so fully
developed by Lord Kelvin, hardly fulfils all the requirements of

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an aetherial atom. In the first place it is not spherical in shape, and I hold that to be one of the fundamental bases of the aetherial atom. Then, in the next place it does not, so far as I can read, possess polarity ; that is, it does not possess a north and south pole, through being a magnet in the same way as the earth is a magnet. We must therefore look for a modification ofthevortex ring to discover the constitution of our aetherial atom, and I venture to think that such a modification is to be found
in Professor Hill's conception of a Spherical Vortex Atom (Phil. Trans., 1894).
In the conception there put forward, and mathematically worked out, Professor Hill showed that his spherical vortex atom possessed similar properties and characteristics to the vortex rings of Lord Kelvin. So that the spherical vortex atom would possess rotation on an axis, and it would be a magnet, as I shall prove later on, because it rotates in an electro-
magnetic medium. It would possess elasticity, compressibility, inertia, and, further, would possess a certain amount of mass. That mass might be infinitely small, but nevertheless it would possess mass of an infinitesimal order.
Further, if we are to be strictly correct, in our analogy between the earth and the aetherial atom, its polar diameter must be shorter than its equatorial diameter, as that is one of the facts observable regarding the shape of our earth, so that the shape of the aetherial atom will not be strictly spherical, but its actual shape would be that of an oblate spheroid, being flatter at the poles, and bulging out in the equatorial regions.
This exact analogy between the earth and an aetherial atom may not at present seem of very great importance, but its importance will be seen later on, when we come to deal with the phenomena of heat, light, and electricity.
Here, then, is our conception of an aetherial atom in the rough, based not upon any imaginative hypothesis, but rather upon that strict conformity to observation and experience, which is the very groundwork of all true Philosophy.
For, after all, what is the earth but an atom on a large scale ? In comparison with illimitable space, with its infinite distances, that can alone be measured by the velocity of light, our own earth is but a speck of dust, a very atom that helps to make up the universe, and, as such, should teach us the shape and properties of other atoms of which the same universe is composed.
We have therefore to conceive of the all -space-pervading Aether as being composed of infinitesimal portions of Aether, which are nearly spherical in shape, and ever in a state of rotation ; this state of rotation differentiating the atom of Aether from the free Aether, if such an entity exists. So that an atom

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of Aether would simply be an infinitesimal portion of the Aether in a state of rotation.
If, by any means, we could stop the rotation , we should at once destroy the atom , in the same way that the smoke vortex ring would cease to be a ring, if its rotation were stopped. The cessation of the rotation I , however, believe to be impossible. So that even in the ultimate atom of that universal medium the Aether, we have an illustration of the combination of those two forms which are inseparably connected throughout the whole universe, viz. matter and motion, and it is the combination of these two that gives to the aetherial atom its form, and its very existence, without which it has no life, and ceases to exist.
It may be necessary in the development of this work as we proceed, to slightly modify our conception of the aetherial atom, but that modification will rather be of a constructive character, than a destructive one. There may also be certain objections to meet and explain away when we deal with the phenomena of light, heat, and electricity, and Gravitation , and the part which the aetherial atom plays in those phenomena, but these objections I hope to meet and answer as they arise.
The atomicity of the Aether has already been suggested by such scientists as Clerk Maxwell, Lord Kelvin, Dr. Larmor, and Professors Lodge and J. J. Thompson. Clerk Maxwell, in an article on " Action at a Distance," I referring to the atomicity of the Aether, writes : " Its minute parts may have rotatory as well as vibratory motions, and the axes of rotation may form those lines of magnetic force which extend in unbroken continuity into regions which no eye has seen." I premise that I will conclusively prove that this statement finds its literal fulfilment in the theory of the Aether that will be developed in this work.
Lord Kelvin, in several articles on " Vortex Motion " in the
Philosophical Magazines of recent years, has mathematically dealt with the Aether from the atomic standpoint, and has endeavoured to prove that the Aether medium is composed of vortex rings, but he was unable to come to any satisfactory conclusion. With the theory that Aether is matter, and therefore possesses mass, his conception is now brought within the range of physical explanation, as well as mathematical calculation.
Dr. Larmor, in his Aether and Matter, has successfully applied the principle of the atomicity to the Aether, on what is termed the " Electron basis. He states that an electron is
nothing more or less than " a point singularity in the electrodynamic and optical Aether." So that our aetherial atom is practically synonymous with Dr. Larmor's electron. Again, Dr. Larmor, in the same work, states that " the atomicity of
1 Collected Works, by Niven.

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electricity is coming within the scope of direct experiment. " 1 But Professor Lodge, in his Modern Views of Electricity, states that "the Aether is composed of positive and negative electricity, the combination of these two forming the Aether
2 medium." Now, if the Aether is composed of positive and negative electricity, and the atomicity of electricity is coming within the scope of direct experiment, it follows as a matter of necessity that the atomicity of Aether and the atomicity of electricity are one and the same, and therefore the atomicity of Aether is coming within the scope of direct experiment. Professor J. J. Thompson, who has also attacked the problem of the atomicity of electricity, speaks of " corpuscles " which are the actual carriers of the positive and negative electricity, in the atoms of the various elements . These corpuscles therefore
indicate the fact that electricity has an atomic basis. Now if there is any such identity between Aether and elec-
tricity, as there undoubtedly is, and electricity has an atomic basis, then the atomicity of the Aether follows as a matter of course, otherwise we shall have a medium composed of atoms which is itself not atomic, which conclusion is absurd and therefore unphilosophical. So that the most recent researches into electricity confirm and establish the atomicity ofthe Aether.
ART. 45. Aether is Gravitative.-Young, in the Philosophical Trans. of 1802, in regard to this question , states in his Fourth Hypothesis : "All material bodies have an attraction for the aetherial medium, by means of which it is accumulated within their substance, and for a small distance around them, in a state
of greater density, but not greater elasticity." He adds that "this fourth hypothesis is opposed to that of Newton's."
Scientific research has justified the conception of his first three hypotheses with respect to the universality, elasticity and vibrations of the aetherial medium, but up to the present I am not aware that science has accepted his fourth hypothesis.
I propose to show how, from a strictly philosophical and logical standpoint, his fourth hypothesis is just as true as his first three hypotheses, and that it henceforth passes out of the realm of the hypothetical into the realms of fact and science, not only by philosophical reasoning, but by actual experiment made by some of the most advanced scientists of the present time.
Let us consider the question first from the standpoint of the Rules of Philosophy. Our first Rule of Philosophy states, that any hypothesis must be simple in connection. Now I put it to any intelligent man, and ask him which is the simpler conception of Acther ? To affirm that Aether is matter, and therefore
1 Preface to Aether and Matter. 2 Page 348.

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subject to the properties of matter, as elasticity, density, inertia and Gravitation, or to affirm that Aether is matter, but while it is subject to some of the properties of matter, as elasticity, density and inertia, it is not subject to the very property which of all properties is the most fundamental, viz . Gravitation . There can, in my opinion, only be one answer to the question, so that, when we affirm that Aether is matter, we are compelled to affirm, in order to conform to the first Rule of Philosophy, that it is gravitative also. Faraday was also of the opinion that Aether was subject to the Law of Gravity, for, writing in Experimental Researches, he states : " The view now stated of the constitution of matter, would seem to involve the conclusion, that matter fills all space, or at least all space to which Gravitation extends, INCLUDING THE SUN AND ITS SYSTEM. For Gravitation is a property of matter, dependable on a certain force, and it is this force which constitutes matter."
Let us also test the question by our second Rule of Philosophy, and we shall find greater evidence still for the statement that Aether is gravitative. What do experience and observation teach us with reference to matter ? As we have already seen
(Art. 37), if there is one truth that they teach us regarding matter, it is that it is gravitative.
There is not the slightest evidence throughout the universe, as far as our observation can lead us to form an opinion, that there is any kind of matter which is not subject to the Law of Gravitation. Therefore to assume that Aether is matter, and yet not to assume that it is also subject to Gravitation, is to assume that which is directly opposed to the most fundamental principle of all philosophical teaching and scientific research. If Aether be matter, therefore, and yet is not gravitative, we shall have an anomaly in an otherwise universal law, as we shall have some kind of matter which fails to come within the scope of the universal Law of Gravitation.
To be consistent, therefore, we must either cease to call Aether matter, or else admit that Aether, like all other matter, is gravitative. It is absolutely impossible to be strictly logical and admit that Aether is matter, and not to admit that it is subject to the most universal law that governs matter, as the Law of Gravitation distinctly states that " every particle or atom of matter attracts every other particle." This universal law in view of a gravitationless Aether would have to be amended to "Some particles of matter attract some other particles." Thus the universal Law of Gravitation ceases at once to be a universal
law, and such a result is opposed to all experience and experiment. Again, let us apply our third Rule of Philosophy to this supposed gravitationless Aether, and see what the result is.
F

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Our third rule states, that any hypothesis put forward must satisfactorily account for the phenomena sought to be explained and accounted for. The Aether was conceived in order to explain the phenomena of light, and one of the properties it was conceived to possess was elasticity, yet that very conception was devoid of the most fundamental property of matter, without which there is no elasticity, that is, that it was not atomic.
I have already shown in Art. 44, that Aether is atomic, and therefore there is given to the Aether a structure which is capable of exhibiting elasticity , inertia, density, and even Gravitation, while at the same time, the conception is fully in harmony with philosophical reasoning and Newton's Rules of Philosophy.
Let us consider the question whether Aether is, or is not gravitative, from another aspect. For several hundred years,
the physical cause of Gravitation has been outstanding, while the world has held the conception that Aether is a gravitationless and frictionless medium. The earth has been rolling on in her orbit year in, year out, together with all the other planets in their annual march round the sun, and yet through all that time no one has been able to suggest, or give any satisfactory or adequate physical explanation, as to what moves the earth along.
I am fully aware that Newton suggested and proved, that it was because of the Law of Gravitation. But I look upon that as a mathematical explanation and not as a physical one.
Now I venture to predict this, that on the assumption of a gravitationless medium, the physical explanation so longed for will always be outstanding, as a gravitationless Aether is synonymous with a frictionless medium, and so long as we admit that there is a frictionless medium, so long will the physical cause of Gravitation, and therefore the physical cause of all the movements of the planets and comets, be outstanding and unexplained.
If, however, instead of being illogical in our reasoning, we become logical, and affirm that Aether is matter, and because all matter is gravitative, therefore Aether is gravitative ; and if, instead of being unphilosophical, we become philosophical, and affirm that because a gravitationless Aether violates both the first and second Rules of Philosophy, such a conception must be put away, and in its place a more philosophical conception must be forthcoming, which is that Aether is gravitative ; then, upon such a logical and philosophical basis, I venture to premise that the great problem which is still outstanding of the cause of Gravitation, will remain outstanding no longer, and the physical cause of all the movements of all celestial bodies will be put upon a physical basis, in addition to a mathematical one.

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If such a result can be arrived at by the logical and philosophical conception of a gravitative Aether, then the three Rules of Philosophy are fully satisfied, and the assumption of a gravitative Aether is warranted on a strictly philosophical basis.
So that Thomas Young is strictly correct from a philosophical standpoint in his fourth hypothesis, when he states : " That all material bodies have an attraction for the aetherial medium, by means of which it is accumulated within their substance and for a small distance around them in a state of greater density but not greater elasticity." He is not, however, correct when he states that though there is a greater density near the body, there is not a greater elasticity, as such an assumption is opposed to experiment and observation in relation to perfect gases, as I shall show when dealing with the elasticity of the Aether.
Again, in view of the fact that the Aether is atomic, it can now be easily understood how it may be subject to Gravitation . The very essence of Gravitation is that atoms, or particles, attract each other. If there were no particles, or atoms, it is obvious that there would be no attraction, and therefore no Gravitation. Wherever, therefore, there are to be found atoms of any kind or sort, whether they be atoms of hydrogen, oxygen, silver or aetherial atoms, there the Law of Gravitation holds good, and attraction between these atoms is to be found. In other
words, any substance which is atomic, is also gravitative. Now Aether is atomic as has been shown, and therefore from that standpoint it is also gravitative. It may, however, be objected that the assumption of gravitative properties for the Aether is after all but a speculation, and that Young's fourth hypothesis was only a hypothesis, and that the gravitating properties of the aetherial medium have never come within the scope of direct experiment, without which no hypothesis can be fully accepted .
If such an argument be advanced against a gravitating Aether, then I must differ from those scientists who advance such an
objection. My contention is that the gravitating properties of the Aether have already been made the subject of some of the most refined and delicate experiments that have been made during the past few years.
I refer to the experiments of Michelson and Morley of America.
For an outline and explanation of such experiments I must refer the reader to the Phil. Mag. of December 1887.
Now what is the result of these experiments ? I believe it is almost unanimously conceded by all scientists, that their experiments prove that the Aether is carried along by the earth. Let us carefully look at this conclusion and see what it implies in relation to the question at issue.

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If the Aether is carried along by the earth, it necessarily follows that there is some governing law or principle which holds it to the earth, while the earth moves through space with its velocity of 68,000 miles per hour.
Now what is that governing principle or law, which is capable of holding such an aetherial atmosphere to its central body ? If we wish to be strictly philosophical, it is necessary, according to our second Rule of Philosophy, that we should not go outside experience and the analogy of Nature.
Where is there a similar analogy in Nature to that of the Aether being carried along through space by the earth ? I know of only one analogy which can be used, and that is the analogy of the atmosphere, which is also carried along by the earth through space, as it rushes on in its orbit round the sun.
That being so, the question arises, what principle or law holds the atmosphere to the earth ? for, whatever be the law which governs the atmosphere, to be consistent with the second Rule of Philosophy, we must infer that the same law also holds the Aether in its place. There is only one answer to the latter question, and that is the Law of Gravitation. If it were not for that law, and the fact that the atmosphere is subject to that law, the atmosphere would simply be swept off from its central body, the earth, as the latter rushed through space with its comparatively enormous velocity.
The only legitimate and philosophical conclusion that we can arrive at, therefore, is that the Aether must be carried along with its central body, the earth, through being acted upon by the selfsame Law of Gravitation, and for it to be so acted upon it must obviously be gravitative. It would be unphilosophical to suggest that it was held in its place by any other force, as that would be introducing a new force or law into Nature, contrary to our experience in relation to an exactly similar phenomenon of Nature.
We have therefore, it seems to me, direct proof by actual experiment that Young's fourth hypothesis was correct, and that not only in relation to the atomic world, but also in relation to the planetary world, and the stellar world, all bodies exert an attractive influence upon the surrounding Aether, by means of which the Aether is accumulated near the surfaces of all bodies
in a state of greater density, and therefore of greater elasticity. Let us apply this truth to the solar system, and see what we
get. If it is true that the earth exerts an attractive influence upon the surrounding Aether by means of which it is held in its
place relatively to the earth, then it is equally true that Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune also exert gravitating or attractive influences upon the surrounding Aether, in the same way that they do upon their own atmospheres. So

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that in their cases also, the surrounding Aether is carried along by them through space. Professor Stokes has suggested that this is so, in order to account for the aberration of light, as we shall see later on.
Not only so, but the sun also would have an attractive power over the Aether by means of which its aetherial atmosphere would be carried through space, as it moved along in its progress at an estimated rate of 17,000 or 18,000 miles per hour.
I would like to point out here, that this explanation of the effect of the planets' attractive power over the surrounding Aether is only a partial one, as there are other effects directly involved in the fact that the Aether is subject to the gravitating influence of all satellites and planets.
This is not the place, however, to go fuller into the matter, the consideration of the subject being taken up in a later chapter.
Thus I have tried to show a gravitating Aether is strictly in accord with the three Rules of Philosophy, for it is simple in conception, is not contrary to experience, and by it I premise that it is possible to explain the physical cause of Gravitation, with all that is involved in that law.
Once more, if Aether is gravitative, then every atom and particle in the universe, as well as every planet, and sun, and star, exert an attractive power over the Aether, so that every atom is enveloped in an atmosphere of Aether, in the same way that every planet, and sun, and star is enveloped by the aetherial atmosphere.
The Aether, however, while it may flow through the spaces that exist between the molecules of bodies, yet is held bound to those molecules in the same way, and by exactly the same force, that holds the atmosphere to a planet or world.
Further, if the atoms possess different masses or weights, as they do, then each atom would possess an aetherial atmosphere proportionate to its mass, with the result that an atom of carbon, with its atomic weight of 12, ought to possess a denser aetherial atmosphere than an atom of hydrogen, and so on right through the atomic scale. I need hardly point out that this conception of the Aether in relation to atoms, and molecules of bodies, will solve certain problems relating to the density of Aether in connection with matter, which problem up to the present cannot be solved by the present conception of a frictionless medium.
That problem may be stated as follows : Does the presence of matter affect the Aether in any way, so as to load or make it denser ? Professor Lodge, in Modern Views of Electricity, in relation to the density of the Aether, writes : " The neighbourhood of gross matter seems to render Aether more dense. It is difficult to suppose that it can really condense an incompressible fluid,

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but it may load it, or otherwise modify it, so as to produce the effect of increased density."
In view of the fact that Aether is gravitative, the reply is to be found in the Law of Gravitation, "Every particle of matter attracts every other particle of matter, etc.," and as Aether is matter, it will be attracted by the other matter irrespective of whether that matter be in the atomic, molecular, or planetary or stellar form. We shall see that this is so when we come to deal with the density of the Aether.
It may be objected in relation to this aspect of Aether, that Young also asserted that the Aether flows as freely through matter, as the air flows through the trees of the forest, and that such a statement therefore contradicts his fourth proposition regarding the gravitating properties of Aether. A little reflection will, however, put a different construction on this objection.
Let us consider the analogy from the standpoint of experience, and see what that analogy teaches us. From experience we learn that the air is gravitative, but we also learn that it is possible to be moved from place to place as winds, and that as such it can move freely between the trees of the forest, causing their boughs and leaves to tremble and bend beneath its energy and power.
I have yet to learn, however, that while it moves between the trees as separate and distinct objects, such a movement militates or destroys its gravitating properties.
Does the air cease to be any less gravitative , or subject to the Law of Gravity, when it is subject to certain movements, which give rise to certain currents as winds ? Such an assumption is altogether opposed to philosophical reasoning.
Whether the air is stationary or in motion, it is ever subject to the great Law of Gravitation, and accepting that as an analogy, the apparent contradiction between the oft-quoted simile of Young and his fourth hypothesis is at once removed, and from analogy we learn that it is quite possible for Aether to move between bodies because of certain currents which may be originated by heat, light or electricity, yet at the same time the existence of such currents does not violate its gravitating tendency.
Young's fourth hypothesis is therefore in perfect harmony with his oft-quoted simile, that the Aether flows through the interstices of bodies as the wind flows through a group of trees, but like the air-currents it does not so flow unless the currents are generated by some form of energy, as heat or light, electricity or magnetism.
From these considerations therefore we are compelled to come to the conclusion that Aether, like all other matter, is subject to the same universal Law of Gravitation. If further evidence ofthe

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gravitating tendency of the Aether were required, I would refer the reader to Lord Kelvin's utterance on this subject.
Lord Kelvin, Phil. Mag., November 1899, in relation to the Aether writes : "We are accustomed to call Aether imponderable. How do we know that it is imponderable ? If we had never dealt with air except by our senses, air would be imponderable to us, but we know by experiment that a vacuum glass tube shows an increased weight when air is allowed to flow into it. We have not the slightest reason to believe that Aether is imponderable. It is just as likely to be attracted by the sun as air is. At all events the onus ofproof rests with those who assert it is imponderable. I think we shall have to modify our ideas of what Gravitation is, if we have a mass spreading through space
with mutual attraction between its parts, without being attracted by other bodies."
We have already seen in the previous article that Faraday was of opinion that the Law of Gravitation extended throughout the whole of the solar system, and as Aether fills the solar system, then obviously Aether must also be subject to the Law of Gravitation.
ART. 46. Aether possesses Density.-That matter possesses density has already been shown in Art. 38, and on the hypothesis that Aether is matter, Aether must possess density also. This property has already been postulated for the Aether, in order to account for certain phenomena in connection with the reflection and refraction of light. Young assumed different densities for the Aether near bodies owing to its being attracted by those bodies (Art. 45 ). Reflection and refraction of light are produced by a change of density of the Aether. It is now generally accepted that the optical difference of bodies depends mainly on the different densities of Aether in association with those bodies. Professor Tyndall, in his Lectures on Light, writes on the density of the Aether as follows: " The density of the Aether is greater in liquids and solids than in gases, and greater in gases than in vacuo. A compressing force seems to be exerted on the Aether by the molecules of these bodies."
Apart, however, from the atomicity and gravitative properties of the Aether, it is difficult to understand how there can be density of the medium, and still more difficult to give a satisfactory explanation of different degrees of density for the same medium , which some scientists assume it to have.
If, however, all that is logically included in the statement that Aether is matter, and therefore is atomic and gravitative, is conceded, then, from the analogy of our own atmosphere in relation to the earth, the density of the Aether, and different degrees of density also, is at once put upon a logical and philo-

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sophical basis, as it is brought into harmony with all experience and observation, and is simple in its conception.
On the other hand, an Aether which is not atomic or gravitative cannot possess different degrees of density, except by assuming the existence of some unknown law of which we have no know-
ledge, which conception is altogether opposed to the fundamental principles of simplicity, observation, and experiment as laid down not only by Newton but by every true philosopher.
Therefore, that Aether can possess different degrees of density, is only the logical outcome of the statement that Aether is matter, seeing that such a statement without the shadow of a doubt must at least imply that it is gravitative.
I need hardly point out, that it is much more philosophical to be able to account for the density of the Aether in a reasonable and philosophical manner, than simply to postulate for the Aether certain properties and qualities, because certain phenomena demand the existence of such properties.
The Aether has been such a hypothetical medium, that it has been easy to postulate for it certain properties, if certain phenomena have demanded the existence of those properties.
Thus if the Aether were required to be elastic, then elasticity was postulated for it ; if more elastic, then greater elasticity was added . If density were demanded, then density was postulated, and if less or more density, less or more density was given to it.
That method of speculation may be satisfactory up to a certain point, but no one will admit that such a method is wholly philosophical. It will be a far better method to adopt, if, in dealing with the universal Aether, we can make it conform to certain recognized laws and principles, and from the application of those well-known laws, be able to infer the exact constitution of this space-filling Aether medium.
Now the question arises, if Aether is gravitative , what effect has the Gravitation of any body, be it an atom , or a meteor or planet, sun or star, upon the Aether in which it moves, and which surrounds it ?
That we may have some light thrown upon the matter, I would like now to take the reader to Newton's Optics, in order that he may give us his opinion as to this property of density of the Aether. In his nineteenth query Newton ( Optics) asks this question-
" Is not this medium much rarer within the dense bodies of
the sun, stars, planets and comets than in the empty spaces between them, and in passing from them to great distances , doth it not grow denser and denser perpetually, and thereby cause the gravity of those great bodies towards one another, and of their

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part towards the bodies, every body endeavouring to go from the denser parts of the medium towards the rarer ? "
Here then we have given to us an indication of what is the possible state of things in relation to the gravitation of the Aether, and all bodies in solar and stellar space. The only mistake that Newton made, was in inverting the right order of comparatively dense and rarer parts of the aetherial medium, by putting the rarer parts of the medium near to the bodies, and supposing the denser parts to be farther away in space.
As a matter of fact, the correct view is exactly the opposite, that is, if we are to form our conception by following out those philosophical rules that Newton laid down. For either the rules are right, or his supposition is right. They cannot both be right, as his supposition is contrary to the second Rule of Philosophy, as all experience and observation from the analogy of Nature teach us that a medium enveloping any body, as planet, star or sun, is densest nearest to the body, becoming rarer the further that medium gets away from the central body. Let us take for our illustration the best example, that experience and observation afford, that of the atmosphere surrounding the earth. The analogy is so perfect, that one is almost tempted to believe that the atmosphere and the Aether are in some way intimately associated with each other. Some years ago Lord Kelvin was of the opinion that the Aether was but an extension of the atmosphere, though I am not certain whether he holds that view
at the present time. Clerk Maxwell, writing in the Phil. Mag. in May 1861 , writes : " I have deduced from this result the relation between statical or dynamical electricity, and have shown that the elasticity of the magnetic medium in air is the same as that of the luminiferous medium, if these two coexistent, coextensive, and equally elastic media are not rather one medium ."
Now for the comparison . Both the atmosphere and Aether are matter. Both are atomic, both are gravitative, both possess elasticity, and both possess density. The atmosphere also possesses different degrees of density, so does the Aether. In
the case of the atmosphere, however, experience and experiment teach us that the atmosphere is denser nearer the earth than farther away.
When we ascend mountains, it is a matter of common knowledge that the higher we ascend, that is the further we get from the earth, the rarer the atmosphere becomes. When we ascend in balloons, we find that the air becomes so rare and so light, that the blood will flow from the nose, on account of the reduced pressure exerted on it, the pressure inside the body being greater than that outside. Now in accordance with our second Rule of Philosophy, if experience is to be any guide at all, then it most

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conclusively teaches us that the Aether being subject to the same laws as the atmosphere, the same results inevitably follow. Therefore the Aether nearest the earth is denser than any layer immediately above it, and that layer denser than the one above it, and so on for great distances, with the result that the only conclusion we can come to in regard to the density and rarity of Aether in relation to all gravitating bodies is, that the densest part of the Aether is nearest to them , and the rarest, the farthest away from them. So that while Newton's suggestion in his
nineteenth query is correct in principle, it is incorrect in application to space.
I would like to point out here, that what is true of the earth in relation to the density of the surrounding Aether, must also be true, according to our second Rule of Philosophy, of every other planet, or sun, or star. So that every planet, satellite, every sun or star has its atmosphere, if I may so term it, of Aether, which obeys and follows the same laws as the earth's atmosphere does.
This is a most important fact, and has a most important bearing upon the physical cause of Gravitation as applied to each planet, and sun and star, as I shall afterwards show.
I wish now to bring the reader into contact with a Theory of Gravitation that was given to the world by Professor Challis of Cambridge, 1872. In the Philosophical Magazine of June of that year he writes : " I assume that all the active forces of Nature are different modes of pressure under different circumstances of a universal elastic Aether, which presses always proportionately to its density."
Now what I wish to point out is, that while Prof. Challis admits the density of the Aether, and also varying degrees of density, as he states that the Aether presses proportionately to the density, he does not show how that varying density is accounted for. If there is this varying density, then there must be some underlying principle which governs the variation in density, and I know of only one principle or law which can regulate that variation in density, and that is that Aether is gravitative, and being gravitative it not only possesses density, but also variations in density.
Thus by admitting that Aether is gravitative, because it is matter, we have at once a satisfactory explanation for the density of the Aether and also for different degrees of density both in the atomic world, and in the planetary and stellar world.
ART. 47. Aether is Elastic.- In Art. 39, matter was shown to be elastic, and on the assumption that Aether is matter, the elasticity of the Aether, which has been postulated for it by various scientists, can be logically and philosophically accounted for.

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In view of the transmission of light through space with a definite and finite velocity, we are compelled to regard Aether as possessing elasticity, similar to that of an elastic solid body.
If we take the analogy of sound, we find that sound is transmitted and propagated through matter, by waves of alternate condensation and rarefaction, and that transmission is regulated by the relation of the density of the medium to its elasticity. Light has been proved to be due to the undulatory wave-motions of the Aether, and in order to account for the transmission of the wave-motion, it is essential that the Aether should possess the property of elasticity.
As Young points out in his First Hypothesis,¹ the Aether possesses this property of elasticity, but with the advance of
scientific knowledge and research, the elasticity of the Aether may be said to have passed out of the hypothetical stage, into the state of actual fact and experiment. Both McCullagh and Fresnel have assumed this property of elasticity for the aetherial medium in order to account for certain phenomena of light.
Apart, however, from the atomicity of the Aether, it is exceedingly difficult to understand how such a property can belong to it. Atoms are exceedingly small particles, possessing the property of elasticity, or the power to recover their original shape after distortion or change of shape. If the Aether therefore be atomic, as is pointed out in Art. 44, it can at once be readily understood how the Aether as a whole can possess the property
of elasticity. The atoms of the Aether must be inconceivably small, as the light-waves travel with the enormous velocity of 186,000 miles per second.
What must therefore be the atomic vibration which such a
statement implies ? If, on the other hand , the Aether is assumed to be continuous and non-atomic, it must be seen how exceedingly difficult it is to account for the elasticity of the Aether, as it seems absolutely impossible for a medium which is continuous, and non-atomic, to be able to transmit the waves of light with a finite velocity.
Apart, therefore, from atomicity of some kind or other, elasticity of the Aether is an assumption philosophically incorrect, as it is contrary to that simplicity of conception laid down by Newton, and is also contrary to all experience, and thus violates the second Rule of Philosophy.
Aether therefore must be said to be perfectly elastic ; so perfectly elastic, that it is susceptible to the least touch of any natural thing, so that even an atom, so small that it cannot be seen with the most powerful microscope, yet so elastic is this Aether medium, that the least motion or vibration of one of
1 ¹ Phil. Trans. , 1802.

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these atoms, though the motion did not exceed the 20- or 40millionth part of an inch, yet even this would create in the aetherial ocean, Aether-waves, just as a body moving in water creates water-waves, which, radiating from the place of their birth, beget and create others, the process continuing until they reach the margin of the water in which they were generated. It is precisely so with these Aether-waves, when once generated and set in motion. They create others, the process being continued and perpetuated ; and, unless arrested in their course, may continue until they reach the very limits and confines of material immensity and space.
It is, perhaps, only necessary to say, regarding the perfection of the elasticity of the Aether medium , that though it takes from 40,000 to 69,000 waves to complete the space of one inch in extent, yet it is done with such miraculous rapidity, as to speed the distance of 186,000 miles in the short space of a second of time ; or, taking the number of Aether-waves to complete an inch as 50,000, its elasticity is such that it makes 50,000 x 186,000 X 12 X 5280 vibrations in one second of time.
We have already seen in Art. 39, that according to Boyle and Marriotte's Law, the velocity of a wave- motion, as sound in the air, is determined by the relation of the elasticity of the medium to its density. If the temperature of the atmosphere remains the same, then the elasticity varies in the same proportion as its density.
According to Art. 45, Aether is gravitative, and that fact produces different degrees of density in the aetherial atmosphere of an atom or planet or meteor, sun or star ; that part of the Aether being densest nearest the central body, and rarer the further we go away from that body.
Now the question at once arises, what is the effect of the increased density of the Aether near the body upon the elasticity of the Aether ?
From the analogy of sound in air, we arrive at the conclusion that Boyle and Marriotte's Law equally applies to the Aether, as it does to the atmosphere of any planet. That is, if the temperature of any stratum or layer of the Aether remains the same, then the elasticity of the aetherial medium in that layer is proportionate to its density, so that while the gravitating property of the Aether makes it denser nearest the central body, the fact that the elasticity is proportionate to the density, does not affect the transmission of any wave-motion.
ART. 48. Aether possesses Inertia. From Art. 40 we have seen that all matter possesses inertia, inertia being that property of matter by which it cannot of itself change its state of motion or of rest.

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If Aether be matter, therefore, then it must also possess inertia. This property of inertia is already postulated for Aether by scientists, and to that extent is conformable to the Rules of Philosophy. Professor Tyndall, with reference to the inertia of the Aether, writes : "The motion of Aether communicated to material substances throws them into motion . It must be therefore itself a substance. Aether is a substance endowed with inertia, and capable, in accordance with the established laws of motion, of imparting its motion to other substances ." 1
Again, Lord Kelvin in his Address to the British Association, 1901 , on the " Clustering of Gravitational Matter in any part of the Universe," states : " Aether we relegate to a distinct species of matter which has inertia, etc." Aether, therefore, according to Tyndall, " is a substance or medium endowed with inertia, and capable, in accordance with Newton's Laws of Motion, of imparting its motion to other substances."
If, however, the Aether is frictionless, as has generally been supposed, then it cannot possess inertia, because to the extent that a body possesses inertia, to that extent it is opposed to being frictionless.
Inertia is really the equivalent of mass, or the amount of matter measured by gravity, and if Aether possesses mass in any sense at all, as it must do if it is matter, then, possessing mass or weight, it must offer resistance to any body moving through it, and to that extent cannot be frictionless. To suppose that the Aether is frictionless, and yet possesses inertia, is to suppose
something altogether opposed to all the Rules of Philosophy and therefore of experience.
I have already shown that a frictionless medium is opposed to all philosophy and experience, and is an anomaly in the universe.
On the strictly philosophical assumption that Aether is matter, and therefore atomic and gravitative, the whole question of the inertia of the Aether is reduced to one of common experience. It is, at least to my mind, difficult to conceive of mass without weight or without atomicity, and yet that is the unphilosophical position of the present state of science in relation to the Aether. In other words, while the Aether is supposed to possess inertia, which is dependent upon mass, as measured by gravity, yet it is supposed not to be gravitative, that is, that the mass of the Aether has no weight at all, and therefore is not mass, which assumption contradicts itself. From Arts. 44 and 45, however, we have seen, to be strictly philosophical, that Aether must be atomic and also gravitative. It can now be easily understood how it can possess inertia like any other matter, and is therefore
1 Lectures on Light.

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capable of receiving motion from other matter, and also of imparting that motion to other matter.
So that, wherever there is motion of any kind in the Aether, either in the form of vibratory motion as heat, or undulatory motion as light, or rotatory motion as electricity, those motions will affect adjoining matter in the same way that the motion of any other moving matter affects any body with which it comes into contact.
From the fact that Aether possesses inertia, and is also gravitative, we have now to alter our conception of this universal space-filling medium, and in place of a frictionless medium , which is incapable of imparting motion to any body, we have now to remember henceforth that the Aether is matter, which possesses inertia, and therefore has the capacity not only of offering resistance to any body moving through it, as a comet or meteor, but also of imparting the motion which it may receive in any manner to any other matter, as a planet, satellite, or sun, that may be floating in it.
With this philosophical view of the Aether, which is entirely in harmony with our first and second Rules of Philosophy, we shall be able to give a physical explanation of the Law of Gravitation, as we have now a physical medium existing in all atomic, solar, and stellar space, which can both accept motion, and transmit that motion to other bodies. In other words, we have a medium which can both push and pull.
ART. 49. Aether is Impressible.-Another characteristic property of this Aether medium is, that it is as perfectly impressible as it is elastic. So perfectly impressible, that it receives, retains, and perpetuates for thousands of years, and for distances to human mind incalculable, every impression given to it of light, form , colour, tint, and shade ; and that, too , with a perfect fidelity that nothing mars, even to the least and most infinitesimal detail.
Therefore, irrespective of distance, wherever there is matter to arrest and reflect the impressions received , there those impressions of light (and all that in the luminosity is involved and contained) become visible and revealed, and wherever there is power of vision to receive and concentrate these Aether- or lightwaves, there, not only luminosity or light, but all that constitutes and is involved in that luminosity, becomes at once visible and seen.
It is by this means we see the colour, tints, shades, and forms of suns and planets ; of stars, constellations, etc. , with all the varied forms, configurations, and movements of the celestial phenomena. Each and every one, small or great, glittering or blazing, sun or planet, are ever creating or generating Aether-

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waves, and impressing them with all the details and particulars of their nature and existence ; and these Aether-waves ever bear upon their mystic wings the impressions received , carrying the information given with lightning speed to the very confines and limits of infinite space or the material universe ; beyond which exists nothing but the ever-living and active energy of the Divine, the only unlimited, unbounded, and absolute infinitive.
It is by the interception and concentration of these waves by our perceptive powers, aided with the giant powers of the telescope, that we obtain the information given, or become cognizant of the nature and existence of the varied lights, colours, tints, and shades of the celestial bodies.
The vision, assisted by the giant power of the telescope, collects and concentrates these Aether-waves into a perfect image of those things that gave them birth, and by this means reveals to us the knowledge of things afar, their existence, nature, characteristics, properties, and powers.
Thus it is we see the solar orb, with its huge fires all aglow, obtain a knowledge of its character and powers, see its huge spots, its quivering fringe of flame, and high-leaping prominences, or watch its slowly revolving form.
Thus we see the planets that around it sweep and roll ; swiftfooted Mercury with his wondrous speed, and dazzling Venus with her silver sheen ; Mars the god of war with his ruddy glow, and mighty Jupiter with his orange hue, and the yellow Saturn with her mysterious rings, the blue Uranus, and the more distant Neptune, with all the satellites that to it belong .
Then far far away the brilliant Sirius- the Dog Star, Cygnet, Centauri, the Great Bear, and a thousand others.
The Pleiades and the twenty millions of suns that form our own galaxy and the Milky Way, with all their varied colours, tints, and hues of white, golden, orange, ruby, red and blue, green and grey, silver, purple and yellow, buff and fawn, emerald and green, lilac and coppery. Thus we see the distant Orion, so far away that swift-footed Light, with its speed of more than eleven million miles per minute, has to travel for more than thirty thousand years before it spans the gulf that intervenes between it and us, and brings to us the news of its existence there.
Then the spectroscope with its revealing power literally tears asunder wave from wave, and reveals the mystic message which each doth bear, of the distant things from which they come, of each and every sort and kind.
Thus we know, that in the solar fires there ever burn such things as hydrogen, oxygen and nitrogen , and also, in a vaporous state, aluminium, sodium, iron, magnesium, cobalt, calcium , chromium, copper, manganese, zinc, and others.

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Thus light-waves are speeding everywhere, and from all material things. They come from our own sun, and rush in, and flood the earth's aerial veil, the atmosphere ; and " Each little atom of matter, like a mirror, reflects and re-reflects them
as if in sport, buffeting each luminous ray from one to another, "7
increasing and amplifying it by an infinity of repercussions (Herschel), and then in their entirety and whole, like a huge multi-mirror, so blend and mingle them that they come to earth's surface in that soft radiance we call Light, and bathe it as in a sea of mellowed glory.
ART. 50. Aether: its Motions.-The question of the exact motions of the Aether is a question which has involved the attention of scientific men for many years, and which is at the present time receiving the attention of some of our most advanced scientists, not only in this country but in other countries also.
Whether the Aether in space is at rest, or is moving along with all the bodies that float in it, so to speak, is a question of the greatest importance to scientists and philosophers generally, as the particular character of the motions of the Aether, which are either suggested or ascribed to it from the analogies of Nature, are sure to have a most important bearing not only on the motions of all the planets and satellites, but also upon such questions as the aberration of light, and such difficulties as presented by Lord Kelvin in his paper on " Clouds on the Undulatory Theory of Light " (Phil. Mag., July 1902).
I need hardly point out that the hypothesis that Aether is gravitative, is bound to play a most important part in the consideration and development of this phase of the study of the universal aetherial medium. It is not my intention, however,
at this stage of the work to go fully into the development of this aspect of the subject.
The application of this principle will be considered at the right time, and in the right place. It is, however, generally assumed, that the Aether is at rest in space, and that the earth, the planets, and the sun and all stars, move through it with varying velocity, although, as Lord Kelvin points out, such an assumption is covered with a cloud which up to the present is
as dense as ever." Of course, if the Aether be at rest, and the planets and other heavenly bodies move through it with varying velocity, then the only assumption regarding the Aether is, that it is frictionless, but, as I have shown in Art. 45, this is opposed to all philosophical reasoning, and therefore to experience and observation.
We have, therefore, to postulate for the Aether such motions as shall fulfil all the Rules of Philosophy, that is, shall be simple in conception , shall be in harmony with our experience