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NIKOLA ~....., ÆTHERFORCE
NIKOLA TESLA ON HIS WORK WITH ALTERNATING
ÆTHERFORCE
Second banquet meeting of the Institute of Radio Engineers (now part of the Institute of Electrical Engineers) at Luchow's in
New York City, April 24, 1915.
Photo by C.A. Schere
Smithsonian Institution
Standing at back from left,
George W.
Ferdinand John Stone Jonathan Lee de Nikola Fritz
Alfred N.
Ernst F.W.
Pierce
Braun
Stone
Zenneck Forest Tesla Lowenstein Goldsmith Alexanderson
Tesla refers to these contemporaries in the interview at pages:
not mentioned 103
16, 124
16, 133
100
178, 179 not mentioned
24, 171
ÆTHERFORCE
Tesla Presents Series 1
NIKOLA TESLA ON HIS WORK WITH ALTERNATING CURRENTS AND THEIR APPLICATION TO WIRELESS TELEGRAPHY, AND TRANSMISSION OF POWER
An
Intervievv
Leland
2002
Twenty First Century Books Breckenridge, Colorado
ÆTHERFORCE
Copyright ©
Twenty First
Books
All
reserved. First Published 1992
Printed in the United States of America by Fidlar Doubleday, Inc.
No part of this book may be reproduced in any form or by any means, electronic or mechanical,
or by any information storage and retrieval system,
without
in
from the publisher.
Library of Long!:ess Cataloging-in-Publication Data
Nikola, 1856-1943.
Nikola Tesla on his work with
currents and their
to wireless
telegraphy, telephony, and transmission of power: an extended interview / Leland
U1(lerSOtl. editor.
p. cm.--
Originally published:
1992.
Includes index.
ISBN 1-893817-01-6
2. Tesla, Nikola, 1856-1943--Interviews. 3. Electric
States--Interviews. 4.
systems--United States--Patents. 5.
Electric currents, Alternating. 6. Telegraph, Wireless. 1. Anderson, Leland 1. II. Title.
ill. Series.
TK257 .T48 2002 621.382'092--dc21
2002072006
Originally
&
by Sun uu"uU'I"" Denver a subsidiary of
Colorado
·~--··--Books
Box 2001 .....,U.""""H.L~UJ<,", Colorado 80424
IV
ÆTHERFORCE
This work is dedicated to the late
D. Jordan, Professor emeritus
of American history, University of
who pressed his
to the review of legal records in
historical research.
few
Istc::mans, librarians, and archivists
L¥~'V~H"L.~the
of
materials. . .. Yet the law, in one
way or
is the basis of most
institutions-political, social, cultural,
economic.... It is unfortunately
a truism that graduate students
are seldom introduced to
materials."*
* "In Search of Legal n~~,,,,u,,
American Archivist, Vol. No.4 (Oct. 1970).
v
ÆTHERFORCE
ÆTHERFORCE
Introduction
CONTENTS
I.
High
with Wireless
and
Mechanical
rv. Apparatus
Damped Waves
Oscillators Condenser Discharges;
for Transformation by Continuous Waves
VI.
Energy Transmission
VIII.
IX.
Receiving
of
Remarks
L
.~"'~ ~t-""A of 1915 shipboard LLa,••,,,,.JLlL
spiral
antenna
[Re£ from p.
inventory
Xl
1 9 36 48 76 125 148 1 169
181 1 1 237
ÆTHERFORCE
FIGURES
Figure
Page
1 Diagrammatic illustration of first high frequency alternator with 384 poles.
4
2 Photographic view of alternator [shown in Fig. 1].
6
3 Light and motive devices operated from this alternator in novel manner.
7
4 Vacuum tubes lighted in alternating electrostatic field.
8
5 Illustrating various ways of using a high frequency alternator.
10
6 Diagram of the second machine built with no wire on the rotating part.
13
7 Photograph of machine covered by US. Patent No. 447,921.
16
8 Diagrammatic drawing of the third and larger machine with 480 poles.
18
9 Photographic view of alternator covered by US. Patent No. 447,921.
19
10 Small alternator of very high frequency built for purposes of investigation (receivers). 20
11 Small high-frequency alternator of different construction, for the same purposes. 20
12 Diagrammatic illustration of machine with rotating magnetic field excitation.
22
13 Instrument to receive radio waves of 1896-1899 structure.
25
14 Electrical condenser described in US. Patent No. 464,667.
30
15 Electrical condenser described in US. Patent No. 567,818.
31
16 Improved form of electrolyte condenser as used in N.yC.laboratories.
33
17 Form of condenser with air under great pressure as dielectric.
33
18 Apparatus for manufacture of condensers and coils to exclude air.
34
19 Simple mechanical oscillator used in first experiments.
36
20 Mechanical oscillator with air spring combined with electric generator.
37
21 Another mechanical oscillator with controlling electromagnetic system.
38
22 Another type of small mechanical electromagnetically controlled oscillator.
39
23 Large electro-mechanical oscillator for generating isochronous oscillations.
40
24 Diagram of electro-mechanical oscillator for generating isochronous oscillations. 40
25 Double compound electro-mechanical isochronous oscillator.
41
26 Diagram of double compound electro-mechanical isochronous oscillator.
42
27 Large mechanical and electrical isochronous oscillator with four vibrating parts.
43
28 Diagram showing length of section of large mechanical and electrical oscillator.
44
29 Small high frequency mechanical and electrical oscillator used in many investigations.
45
30 Diagram of small high frequency electro-mechanical and electrical oscillator.
46
31 Method of transformation of electrical energy by oscillatory condenser discharges. 49
32 Series quenched spark gap.
50
33 Discharger working in hydrogen rich atmosphere, still further weakened by heat.
51
34 Oscillatory apparatus with interrupter in oil.
53
35 Apparatus with mechanical break as installed on a large scale in the N.yC.labs.
55
36 Isochronous mechanical break used in 35 So. Fifth Avenue laboratory.
57
37 Mechanical break with two oppositely rotating discs.
58
ÆTHERFORCE
with break. ~""J'A""L."un
HH."',llAUJ''-D.J.
by condenser discharges (both
",,+"PIP"" transmitting -.u..........".
illustrating transmission and transformation of
through one
vacuum tubes and lamps.
U.a..l""LLLU"\..U through one wire.
which a
at the of a
88
56
which the coil is not directly \.Vl.lll,,\.
89
57
preceding
were made. 91
with coils
,,,UU,,,,,'VH of energy with
93
60 Application of
transmission messages.
93
61
.U.U""'"'''''''''U):; an eXJJer:tmc~nt
alternator and
62
Striking expenrnen
electrorrlag:net:1c waves.
95
An important experiment in the transmission of energy performed in 1899.
96
65
98
66
101
67
wave arr:~;errlefi1ts.
68
111
69
113
70
electricity set movement.
114
71
",-'.H"''-H"0 were performed.
1
72 Diagram showing general arrarlj;;erneIlt of transmitting and receiving \...U.'.U"'-,,!.
1
Experimental
at Colorado a later phase development.
117
74
at Colorado
investigative structure.
118
75
of a "",-uao,.«'-
transmitter
a pressure of 12
volts.
121
Another discharge remarkable for symmetry at Colorado plant.
IX
ÆTHERFORCE
77
circuits.
123
78
the Houston
79
o f o f LL<l.:Ll"lH''''''U'H
energy.
129
80 Diagram illustrating one many wireless fallacies, from a Marconi patent.
136
81 Diagram illustrating mode of propagation of current from the transmitter.
138
82 Diagram illustrating law gO'ITerruncg iJ;""";~<;::
139
No. 1,119,732.
144
84
of "world telt~gr:itPtlV.
148
85
149
86
view of some the apparatus in the electrical part of the plant.
150
A view from a different direction.
151
88
1
89 Another
some
aplJarattlS which has described.
153
90
telllUtOITlat(Jn, on principles in
3,809.
1
91 Special
measurements, especially
in recemng.
159
92 illustrating some the attachments and mode of using same.
159
as practiced in 1898-1900.
160
94
practiced in 1898-1900.
1
95 illustrating bulbs
to 1900,
1
96 Illustrating bulbs made
to 1900, many
164
97 illustrating bulbs made
to 1900, many used in receiving apparatus.
165
98 illustrating bulbs made prior to 1900, many used in receiving apparatus.
165
99 illustrating bulbs made prior to 1900, many used in receiving apparatus.
166
100
bulbs
prior to 1900,
used in "prp',,-'I"'''' ap}:)ar~ltl
166
101 Static
167
Appendix
Al-1 A
alternator found in Westinghouse L.:..n:;\-U"\-
Company
as
to Tesla.
181
Shipboard quenched-spark transmitter, produced by the Lowenstein Radio Company
and licensed
Nikola Tesla
Scherff
183
Construction detail of Wardenclyffe plant tower.
McChesney
208
Workshop on north side of Wardenclyffe plant building. -William Kolb
222
room of Wardendyffe plant building.
Kelley
230
x
ÆTHERFORCE
against communications companies
PREl'1\CE
by his legal
some now
and
by numerous pending
counsel
of own claims
when called to
as adversaries a plethora of new
judicial
was "Marconi
Company, et \.till"-"' ....VU
Atlantic
proceedings
in 1915 with
Tesla.
SPt:ct(~r of war
who had also
called, was
deadly
",,,,rtr',,,,-,- a
transmission. In this UV'-I.4!'UI..,U used in laboratories at New York
of the
schematic and mechanical drawings
form
drawings extant
five
publication.
almost ....h\.."U""V
discusses
work with alternating currents as applied to WllLH.:';'"
experimental methods,
and
Colorado Springs, and on Long Island.
Although
it is
it was
one time; all references to interruptions
text is
in standard
pica type, unjustified,
proceedings
period.
made in
remarks
typically references to
and
by v,-,_au"v..",,", rambling and A.U'-V~HVH..
additions are provided in brackets []. Helpful notes are also
L.I.A.
ÆTHERFORCE
ÆTHERFORCE
What]
INTRODUCTION
to showyou) step 1?Y step) is how dream. . . .
are holding in your hands one Seldom, in technical
historical documentation U"-''-HA.F, the technical Archimedes. It describes yet to be replicated.
history of electrical commentary
J."'-'"''' ••''' stone for deciphering engineering scientists 100 years ago-but
are its contents it
one's breath away!
Tesla's own
ntf:rp:retlit1()flS (couched in the
of 19th century physics)
ele:Ctl:1C~U phenomena
lack satisfactory "'lI.iJl"'H"'Ll'-'ll~ the
t"n("),;,'r"., technical analysis.
you how to
transmitter" (that
arcane instrument for global
transmission),* but it will
what instruments
was employing, what his LL".....'''-LU.C> were, how he conceptualized
he proceeded,
perto>ttIled his historic
when key results were
how he L""''-'''"'-U
himself, was
results of his
He
asserts is experimentally
Listen to
electrical phenomena to his attorney: "magnificent,"
" "glorious,"
Edmund Spencer or a
once said,
me
even in a legal briefing. He weaves
imagination and
us
words!
gossamer web of encnanrrrler.I(--~;n yet
our
nearly 80 years
a stenographer recorded
Who was Nikola Tesla?
Philadelphia, Lord to his Society discovery.
was one of the
waves.
* It may just be that magnifying
is enough information reader will have to
to solve the puzzle himself.
ÆTHERFORCE
It is commonly understood by power
rotating
field
AC polyphase power distribution
throughout
However, most electrical engineers are unaware that, as late as 1943, he (not Marconit) was
by the U.S.
Court as having priority
of"
are aware that, when
attempted to patent
digital logic gates World War II, U.S. Parent Office
Tesla's
priority the electrical implementation of logic
secure communications, control systems,
As a
a monopoly on digital logic
in
was unable to
Tesia served the electrical engineering profession in its highest offices. In the early 1890s, was
as \.,'\.,... L.... U
of the
Institute of
now
of
Electrical and
At
Graham Bell was
its president. Tesla
two
as
and, a
one his
laboratory technicians at the Colorado Springs experiments served as first vice-president of the
Institute of Radio
when it was formed 1903. This was the now, famous consulting
the grid biased
amplifier (for
1918),4 the
and
two
with comments on the propagation of
£enn,~ck and sky waves by Austin, appeared in February and June issues of
this
It
be
that
of the
professional
..pr'p",,,.,; over 13 honorary
from such as Columbia, £in;,p...,,,. H':>Wll .... '..lUl
1"""''''11,1''''' of Paris,
Prague, and Sofia.
Recently,
fascinating fact about
has come to
all
it is now
known that was nominated for an undivided Nobel
physics in 1937.5 Tesla's nominator,
Ehernhaft, of Vienna, had
Einstein for the Nobel
*
E. Scott,
of
has said,
evolution
power from the discovery of Faraday in 1831 to the initial great installation of the
polyphase system in 1896 Niagara
is undoubtedly the most tremendous
all
history." [Electrical
1943 (Vol. 62, 8),
pp.
t
Although it took the courts
decades to figure out, the facts were well
understood by
technical men of the day. Robert H, Marriott,
once said that Marconi had, " ... played the of a
sales engineer. A money getting company was formed, which in attempting to obtain
a monopoly, set out to
to everybody that Marconi was inventor and that
they
that patent on
to a monopoly." [Radio oro'aat'aST.
1 (Vol. 8, No.2),
XIV
ÆTHERFORCE
and """"""'u.. ,,"'.>.u;:;:. his admirers
1893,
published a remarkable
century
now it will still
along with
electric waves,
wrote,
and fellows, and university prt:SlGlenrS scientific and engineering world.
(1888-1889), edited and It is in print today, and a
"""'~H"HH" u,-""-aLYU... to
progress of is descriptive
Tesla
Unlike most
aforementioned
no financial ;:'UIJIJ'.J.L to fall back on
themselves
in the
felt no compulsion to
these must dig (and
to make it to one "skilled
Dr~
so it is ",..,........",,..,...,
a faculty position or res,eaJrCh ~H~""","'\"'.
marketplace. It is not surprising,
in the open
literature
day. For
literature,
only enough is U~c''-i'j''''U
art."
influence scientists simply did not
10 L<VUUVU
instrumentalities, everything that is
man puts in a kind ofgap.
is about same as that
a 30-year
have "'''-"'....u ...,'-
me [the Tesla
was
with hv(jro,s;reJn: employs all
but calls it a new wireless
a Nobelprizefor it. ...
is capable." (p. 48)
xv
ÆTHERFORCE
Electrical History
in technical evaluation of historic
research, it is a source of
intense frustration and shattering disappointment to find "a new book" or even have a television
appear, only to
that the authors (a) didn't
the technical
subject sufficiently to understand the
were, and (b) '-'-'...............
unsubstantiated popularized assertions,
and
errors
at U1r'rr.'''T
not at the scene
battle. This is especially true
addressing topics in the realm
antennas, and distributed circuits (i.e., radio)
merely an academic knowledge of electronics
or Maxwell's
to
livelihood
It leads
one to conclude no reliable history of
can
technical training and
their time and
But this
IS a
incongruous for over
start an immediate
replicate apparatus,
and missing pieces, clarify issues, and execute a technical analysis.
We
document will
considerable
along
as
well by a broad c ....~·rh·n of investigators.
introduction is not an
to
discuss such pursuits. Instead, we invite the reader to consider the wonderful personal narrative
which will be
him.
pathos in
as
famous
Every wireless message that has ever been transmitted to af!J distance has been transmitted Iry this apparatus;
there is no other way. Twenty-seven more years would pass
the highest courts
echo in
proceedings would emlenre
any radio
For
the title inventor of radio.
"innovation" and
are those that still don't understand
Surprises from Tesla
never lost the magical touch.
Royal
(London), careful
a technical
was unexpected from
in
is a
of his life's work. Those us that have toiled with RF technology, and electromagnetic
radiation and propagation owe a
debt to Anderson, one of the world's leading
on Tesla, publishing this
It is absolutely
We no doubt
It IS
to join lvfy Inventions;
Patents, and Articles; Und Sein
Inventions}
Researches and Writings, Colorado Springs Notes as a member of the historic "canonical Tesla
publications." Anyone doing a serious technical evaluation
must turn to
works.
ÆTHERFORCE
It is important to to the era of 1916. A
Lusitania has been 100,000 young
......"'~ULU to 1916
of this interview. In mind's eye, return
Woodrow
same age as
18 months.
and more than
loved ones.
produced his millionth
and electricity
Mount Wilson, California, the new lOa-inch telescope is
completion. In Europe,
Albert Einstein has introduced the general
of relativity, and astronomer Arthur Stanley
Eddington is quietly
expeditions to
off the coast
and Brazil to test
the theory during a
eclipse. Consultant
Stone Stone has completed his term as
president of the
Harvard Professor Kennelly has stepped into the position-he had
I-'.."'.,.u'....u. of the AlEE
The IRE now
1,000 H,,-""L',,,
At Bell Labs, John
has just shown
possible. The transcontinental telephone
Bell in
and Thomas A.
U.S. and
amateur station.
L.L"-U"<LU",,LV'U is mathematically between "l-.."j-p·rl
is populated AM broadcasting,
just an
has recently proposed that the 'Pt-"P'~"
he publishes an and W.M.
mathematics."
"Some
in
American.
of Defense create a Defense Science
Looking toward
called, "The
World to be Created by Electricity." E. Taylor
published,
Philosophical MagaiJ'ne
erroneous ""UI-"'-',,",-
Nineteen
one of E.O.
the P0sical
Tesla coils
Tesla prophesies
radio-controlled
and missiles
soon expose the 1"."",''''L''-'
population, not just military, to the
of war. In 1916, Scientific American """,\..u:,,,,••,,
Tesla's new
speedometer, tower at Shoreham
Island) will pass
hands, and Hugo
magazine, ElectricalExperimenterwill contemplate his
Springs experiments.
Lwoff-Parlaghy entertains Tesla
New York .:>V'-,J",.ull\."
in The
I t will
Guly 20, 1931).
XVll
ÆTHERFORCE
A Visit to a Law Office
have been ushered into an oal:e-d.ec()rated law office New
Tesla, now 60 years old,
bushy black hair, slight
U.L\.''''''','-' his piercing light blue-grey
possesses a winning smile
wears no jewelry or watch
a somewhat
voice, and
'.II"",",,,"lY and convincingly. He is
the cosmopolitan
in his speech, manner,
He
numerous drawings, mUJcr:s.
Across a wooden
attorney. His demeanor is tJ.L\JU;;""'.LUU41 and serious, his
are penetrating, manner is deliberate. He is aware
professional reputation
international regard
esteemed gentleman that
him, and he is
understanding every
that he can turn to his
in the dramatic contests at law
which will soon occur.
present is a stenographer,
providing the
an accurate written tralrlS(:rll=lticln of every thought which
soon unfold. The L>JL.LU''''.uLL....''
over, the counselor
and
References:
(1) Martin,
Inventions} Researches and Writings ofNikola Tesla, The Electrical J...jU~HJ."",",l.
York, 1893;
pp. 123 and 198-293,
with Alternate Currents
Potential and
Frequency" by Tesla,
book has been H ..'"' ... UU,Ul........
and is available
several sources.
(2)
Nikolik, N"
Yugoslavia, 1956;
Frequency"
(3)
with Alternate
Potential and High Frequenry,
1904, 162 pp.
(4) Discussion Comments by 1254, 1256.
of Some Foundations .L'.L'JU~•.LH Radio-Electronic
Espenschied, Proceedings of
July, 1959 (Vol. 47, No.7),
(5) Crawford,
J.L., and Ullrich, R.,
California, 1987.
(6) Martin, 1919,
The Story
Electricity
*
t
Battelle,
Thornton,
XVlll
ÆTHERFORCE
Counsel
Please recount the history of your work with alternating currents and their application to wireless telegraphy, telephony, and wireless transmission of power.
I. High Frequency Alternators
Tesla
Work on high frequency alternators was begun by me in 1888, in my laboratory at 89 Liberty Street. I had just completed my system of power transmission, which is now universally adopted, but several problems yet remained to be solved. One was to run my induction motors at very high speeds; another one was to adapt them to the then existing alternating circuits of supply of 133 cycles. These two problems, although they were diametrically opposite, both required the use of laminated structures with a great many poles or polar projections, and I constructed quite a number of these with the object of improving along the lines indicated.
Among these was an alternator with 24 poles, which gave me 12 cycles per revolution. This I used originally in running some small induction motors at speeds up to 200 [revolutions] per second. Occasionally, however, I would use this alternator in other experiments, with transformers, etc., and condensers, and then by running it at high speed (10,000 RPM) developing something like 2,000 cycles [per second], which phenomena were entirely new. This, of course, interested me very much, but the work was interrupted in 1888 when I had to go to Pittsburgh to attend to the manufacture of the motors.
On my return to New York the next year, that was early in 1889, I engaged a laboratory at 175 Grand Street, close to Center Street, and there is where I undertook to design and construct the first high frequency machines.
I had at that time already perceived enough to get the idea that energy could be transmitted without wires. It was of no consequence to me at that time whether it was to be used for telegraphy, or telephony, or power transmission. I was on the problem of transmitting energy without wires; and as it is my custom always to analyze scientifically every problem that I undertake to solve, I devoted a great deal of thought to how to attack that problem, and the following crystallized out.
ÆTHERFORCE
2
Work With Alternating Currents
It was evident to me that wireless transmission of energy, if it could ever be accomplished, is not an invention; it is an art. Bell's telephone, Edison's phonograph, or my induction motor were inventions, but the wireless transmission of energy is an art that requires a great many inventions in combination.
We are living on a planet that is rushing through space; this planet is partly conducting and partly insulating. If it were all conducting, or if it were all insulating, we could not transmit energy without wire. It is only because it is partly conducting and partly insulating that a glorious future for man is reserved through the application of this art.
The steps to be taken which I recognized then as absolutely necessary were, first, that I had to produce electric oscillations of the required character. Now, granted that I had them, it still remained to be shown how these oscillations could be transformed into some sort of vibratory energy capable of penetrating into the distance. Therefore, the second step was the transformation of these oscillations into such form of energy as would go to a distance. To develop methods of and apparatus for reception, to collect the energy at any point, was the third step. The fourth step was to isolate the energy. If I simply transmitted energy in all directions without regard to its use, then that energy would be simply lost in space, and it would be no economical system. Consequently, I had to devise means to isolate that energy, and this problem again presented itself in two aspects, active and passive; that is, I had to make the transmitter noninterfering, and I had to make it noninterferable. Those are not two identical problems, but both had to be solved. Finally, as to the fifth step, I found that we could never transmit energy, or construct our machines and apply them with understanding, unless we discovered the laws according to which this energy flows through the planet, laws which would enable us to calculate accurately the energy we are to receive at any point, and to design our machines to suit the work.
In reviewing these objectives, what I am going to show you, step by step, is how I proceeded until I finally realized my dream, and, in 1899, produced a transmitter of greater power than probably all the combined transmitters put up today, and, furthermore, perfected an apparatus by which unlimited energy can be transmitted very economically, thousands of horsepower if necessary, from one small, compact plant, much smaller than that at Sayville or Tuckerton. [*]
* Editorial note: The large German-owned radio station at Sayville, Long Island, was constructed by Telefunken (Geselleschaft fur Drahtlose Telegraphie) a few years prior to WWI for communication with a station at Nauen, near Berlin. Suspected of rendering non-neutral service at the outbreak of hostilities, it was taken over by the U.S. Navy Department in July, 1915. The great Tuckerton, New Jersey, radio station was built by the Homag Company (Hochfrequenz-Maschinen
ÆTHERFORCE
Frequency Alternators -
3
The drawing [ . 1] shows the first s toward the
evolution of a generator, or transmitter, which
be used to
flash energy to distances, under practical and economical con-
ditions. This machine was described me in U.S. Patent
447, 0, of March 10, 89.
It was the first
alternator that was ex-
h
, and with ch tests were made
c, although I
alternators of
frequency, as I said before, as
far back as 1888. This was a machine from which I could
from 10,000 to 20,000 cycles. We used to say, in old times,
"alternations"; this term has been loose
that my early
machines were rather
i but as a matter of fact,
the des
of machines was my specialty and,
had spent e
years in doing
Therefore, the results
I
machine, and which I
before the world
in 1891, are results
a machine that I could not, with all
my present
and experience, and all the devices of
the art, improve one-half of one percent. And any other en-
, no matter who he be, would have that same hard time as
myself because in this
I embodied every little device
that was available. I utilized to the full and
the maxi-
mum out of the materials. I had the lowest armature resis
which could be obta , I had the lowest self-induc-
T I had the
t periphery
I had the greatest
, far
than any alternator that has ever been
since that time. In fact, I united this machine fea-
tures which no other that has been des
since has ever
Furthermore, the currents I deve
were
ly
sinu
1. That
have been known to other
, that
the currents should be sinusoidal, because that follows from
certain theoretical researches; but remember that I had in-
vented the "rotat
ic field,"
the very product
of that field was based on the use of
ities which wax and
wane alternately in accordance with the law of the sine as, I
have
out in a paper read before the American Institute
of Electrical
1888, when I presented my
motor before that
Therefore,
ng was done in
this machine that could be done to secure
by every
possible device known to
Aktiengesellschaft fur Drahtlose Telegraphie) for the
Generale de
Te
sans Fil of France, but the German firm
after the outbreak of hostilities. It, too, was
Department, September, 1915. (See: Howeth, L.S.,
U.S.
ing
,
; pp.
•
consultant to the Tuckerton
station and received monthl
until it was
taken over by the U.S. Navy
ÆTHERFORCE
4
Work With Alternating Currents
(No Model.)
N. TESLA.
METHOD OF OPERATING ARC LAMPS.
No. 447.920.
Patented Mar. 10.1891.
-99'S
.R
Figure 1. Diagrammatic illustration of first high frequency alternator with 384 poles, patent application filed October 1, 1890, also in book ~Inventions, Researches and Writings of Nikola Tesla" by T.e. Martin, published by the Electrical Engineer, New York, 1893, Figs. 199-203, pp. 375-376.
ÆTHERFORCE
ernators ~
5
Re
to the
. 1J, I employed a ring of
the finest iron, and a steel disc with a
r,
of rotat at 1,400 feet per second, safely.
No such veloci has ever been
in any alternator.
I had, furthermore, an armature resistance in this
of
only 0.5 ohm. If I would have had, say, 6 ohms, which is
of such an alternator, the machine would have been
burned out. Even at 0.5 ohm, I had a hard time to
it
when I really had the
resonant rise.
I used a trick [in this
] which enabled me to
a
f and you will see how I accomplished
I con-
structed my rotor with just one
of thin wire, and by a
special process I baked this wire so that it formed a sol
mass with the rotor, and the
force, no matter how
h the
, could not tear it off. Then I made my field
very small. The result of this was that I had a tremendous
ventilation which enabled me to put
the field a cur-
rent of 25 or 30 amperes per square millimeter, and out of the
armature I could easily take 30 amperes per square millimeter.
You know, in
des, if you take out four to four-and-
f amperes per square mill
, that is a
per-
formance. I defy anyone to take out of the conductor [of
these conventional machines] more than five or six amperes per
square millimeter. But, I des
this
so that I
could have 30 amperes per
llimeter in the armature
and
30 amperes per
millimeter in the field on
account of the
So, therefore, when I show this
, I have shown the
most
ne in wireless that has ever been
up to this date. People, of
to use a
, but that is a
If I had had a
turbine to
s
done much better.
Later on, however, I will show you a machine which I des
fically for the turbine. I have recently heard that, as
a result of
[emphasis Tesla,
[*]
reported that
to just
the same machine which
I exhibited in
1893, with which I showed
s
to Helmholtz, and which was a
of
s known all the
world over from pictures;
have been
for
years and years but exper
this particular field.
This machine
2] was exh ted before the American
Institute of Electrical
, where I showed my first ex-
Sf and these experiments, as I shall state in a few
* Editorial note: Reference is to John V.L.
I at that time chief research
engineer, National Electric
was one of the driving forces
in the
of the Institute of
I later
its
ident
in 920. The
refers to the
General Electric
Steinmetz, Berg
and
in collaboration with Fes
of the
National Elect Signaling
to the production of successful
alternators operating to
ÆTHERFORCE
6
Work With Alternating Currents
words, I obtained some striking results, which were the starting point of this whole development.
Figure 2. Photographic view of alternator [shown in Fig. 1]. Illustration from Martin book, Fig. 97, p. 153.
Fw. 97.
Unfortunately, that [Fig. 2] is a reproduction from the only picture I have. This machine was destroyed in the fire that annihilated my laboratory in the Spring of 1895, and I had nothing left of it but a little piece. That photograph [was] taken from an old, very poor print; but it shows the general arrangement of the machine.
This machine I operated at Columbia College with about 5,000 cycles; later on I attained 23,000 cycles running it at a higher speed, and it was in every way a most satisfactory piece of apparatus. It was used by me in experiments with wireless telephony, telegraphy, and all sorts of experiments until it was destroyed.
When I published the results with this machine, I did not have the courage to run it as high as I wanted to so I operated only at about 3,000 or 3,600 revolutions and then I could get out of it approximately 4 kilowatts. But I could easily get out of it 12 or 13 kilowatts later on. This large output was only made possible through the tremendous ventilation. I remember that at Columbia College, Mr. [Gano] Dunn, who is now Vice-President of the White Company, I believe, and who was assisting me in the lecture, forgot to turn off the current in the field when the machine was stopped, and if I had not shut it off, the field would have burned out. This high output I could only get through this artifice.
It was a fine machine, and I really do not see how anybody could produce a better device for the purposes of
ÆTHERFORCE
High Frequency Alternators ~
7
radio telegraphy. There is no such thing. I have designed other machines which are, perhaps, better in some respects. This machine is extremely serviceable.
There were two striking results which I showed in my lecture at Columbia College, and I will illustrate them because I wish to show these various ideas from their starting point.
FIG. 114.
FIG. 11.-..
Figure 3. Light and motive devices operated from this alternator in novel manner. Illustration from Martin book, Figs. 114 and 115, p. 177.
The first result [Fig. 3] was one of the experiments which I at that time showed in a public lecture, motive devices operated by merely connecting them to one terminal of a source of oscillations -- a high frequency coil. I have often been told that my most important results in invention was the demonstration of the practicability of transmitting energy over one wire; because, once we can transmit energy over one wire we can use also the earth, for the earth is equivalent to a large conductor -- a better conductor than copper wire. This was one of the results I got, but the most striking one I will show you now.
This second result [Fig. 4] shows how energy goes through space without any wire. That was a most striking experiment which was repeated all the world over and was published in thousands and thousands of papers. There is a field produced -- of high frequency -- and in this field I hold two tubes of glass in my hands. These glass tubes spring into powerful light. That was an experiment which carried the whole world by storm; but to me it was the first evidence that I was conveying energy to a distance, and it was a tremendous spur to my imagination and to my energy to develop what I had started.
ÆTHERFORCE
8
Work With Alternating Currents
Figure 4. Most striking results obtained -- vacuum tubes lighted in alternating electrostatic field. Illustrated in Martin book, Fig. 125, p. 188 .
ÆTHERFORCE
II. Experiments with Wireless
and Telephony
Tesla
[Diag. 1 of have des
but they were a different way.
I used this machine which I wireless. These exon Grand Streett and carried on in
Counsel
What date was that?
Tesla
That was in 1891,
to my
to
and to lecture
before the s
societies there, the
Institution
and the Institution of Electrical
I had a wire run
out through the
t and
on the roof all sorts of
to const
this capacity [shown in the diagrams as
an elevated squareJ The first s was to connect this al-
ternator [shown the agrams as a rcleJ with one terminal
to the water p
and the other end to the antenna.
I had already
my lecture at Columbia Col
that I
could transmit energy through one wire; therefore, I was pre-
to find that a current of cons
strength could be
passed through this wire here
the alternator to
the elevated
,
was insulated.
at that time was that I would disturb the
in the
ions of the earth, and the
disturbed, this could then be
ized to bring into
in any way some instrument. That was what we
now call, s
y,
ssing forced
ions of very
on an antenna. We have introduced the term
"antenna" since that time.
The second
was as shown [in
. 2 of Fig. 5J. You
will notice that I have inserted a coil in the circu
The
for that
arose from the fact that I could not
to tune the
prope to the
alternator. I had
in the
a very large
and you will note that in my exposi-
tions of that
f from 1891 to 1893, I insisted on the
very largest capac that could be
because, accord-
to my
which has since, of course, been con
the amount of current that flows
such a system is
proportionate to that capacity. Therefore, as the effect in
the distance is
to that current, I had to use a
b capacity; but not having a
in the bui
I introduced an
coil to tune the s
down to the
of the
that from the ground connection
this circuit,
, the coil, and
ÆTHERFORCE
10
Work With Al
ng Currents
antenna, would have the natural
of the
zed the necess of introducing a means of
and it is this [shown in Diag. 3 of
. 5].
Next I usting,
ways of ~~O~1~1m~~,tg a t the
a high frequency a1ternator in street Laboratory: 1891-1893.
NOw, I found that notwi
I tuned this system
successfully, I could not
this antenna or these "cans," as
we called them at that time,
su
high. But
it occurred to me that if I transformed the current and raised
the tension of the dynamo in
could then
the antenna to a
splacement of electri
like this [
. 4 of
in
I have
dynamo
supply a
a second current of higher
aI, and tune
and ust the conditions so
that this conductor [connecting the antenna to the transfor-
mer],
the secondary of the
,is aga tuned to
the
the
was a fine
; it is
s
that
is absolutely essential, because on
in the fewest instances can the power of a
or be taken
up without transformation.
ÆTHERFORCE
E
Wi Wire ss
y
Telephony -
11
Then, of course, I [an adjustable
That was the fifth
convenience the im-
in
. 5, Fig. 5].
r to increase the current in the primary, I
ed an
liary condenser ci
t [shown in Diag. 6,
. 5].
This auxiliary circuit I have,
the way, already illustrated
in a
which was
to me in 1891 [U.S. Pat. No.
454,622]. The condenser has the effect of magnifying very
much the current, this magnification being proportionate to
the ratio of the inductance to the resistance of the circuit,
and that rat was very great so I
a strong current which
the current in the antenna .
the next step
7,
. 5], I have
f
s
, but it was not drawn up
. [*] I put a con-
denser in se s with the
That is exactly the way
at Columbia Col
At Columbia Col
I had an
ustable condenser,
from W. Marshall, with very
small
, which I used in
with an inductance
coil, and the secondary I was then operating exhibited all the
which have been described in the lecture.
In [Diag. 8, Fig. 5] I show another modification which
has certain virtues. I introduced ustable condensers here,
with which I could, first, counteract the self-inductance of
the dynamo in one circuit, then raise the tension in the reso
nant
circuit, and then tune the secondary of the sys
tem to the same vibration.
In [
. 9, Fig. 5], as you see, I came to this arrange
ment where I have an ustable inductance and adjustable con-
denser in the primary, and an ustable coil in the
or antenna circuit. That is now a
arrange-
ment, and it is very
and
In the meantime, as I was deve
all this, I had al-
struck a new line of effort toward producing vibrations;
namely, I had developed a system
ing me to take
or-
current of any
and transform it into any
of
vibrations I desired, either
or undamped. I will dwe I
on this [later], but I want to say now that I also
as shown here [Diag. 10, Fig. 5]. I bri
with an air gap. This I did in studying harmonics.
I found that sometimes I could
a very strong harmon ,
for instance, the third harmonic was often very
this
I
work with the fundamental
with a harmonic, and I made some interest
which later on led me to very
* Editorial note: Tesla refers
adj table primary inductance rather than
an adjustable secondary inductance as shown.
ÆTHERFORCE
12
Work
te
Currents
[Diag. 11,
. 5 is a similar sposition in which I
introduced
ustable condenser, and had the same arrange-
ment in
And
lly, [Diag. 12,
5]
one of the most common
ans which I have been us later in other laboratories -
an ustable inductance in the antenna circuit, and an ad-
justable condenser and ustable
in the pr
circuit.
1
Will you describe, Mr. Tesla, just how far these went
into use, and how far they were shown and
to others?
Te la
At the
on] Grand
Street, I had in
following men: Mr.
Sz
, a
electrician and wire man who
had been a
France and came over in 1884
or 1885, I do not recall now. Then there was Mr. F.W. Clark,
a very skilled mechanic, formerly in the
of Brown &
Sharpe. Bes s these were Mr.
Leonhardt, a young
an
Paul Noyes, a former employee of
the Gordon Press
where I
him while I
was
my arc 1
was
by the
There was also a man by the name of David
sell, a German-American
s blower.
At the time I made these experiments, there were very few
of the el
that since made a success with
in
, who would have known much
They had seen me run the
up
had seen me operate continuous with those machines.
I had shown them wonderful results, and had told them all the
that I was going to
energy without wire
, te
, run cars and 1 s at any distance
that these were the
toward s end. How
much these men could tell, in the 1
of the present
, that, of course, I am unable to say; but, cer-
y, I had
of witnesses to follow my
and to
know what I had been doing.
This
. 6] I was buil
while I was
carrying on
the first
As you will
note, I had s
the wire from the armature. I had
taken the f st steel I could
and constructed a machine
with oppos poles, with what we call a" ff" field, and
had done away
all moving wire. I intended to connect a
turbine and run s machine at a very
, which I
be up to 20,000 revolutions. The armature con-
ductors were sposed in this f
and the
I that was
ÆTHERFORCE
Experiments With Wireless Telegraphy and Telephony -
13
(No Model.)
N. TESLA.
~ Sbeets':""Sbeet 1.
ALTERNATING ELECTRIC CURRENT GENERATOR.
No. 447,921.
Patented Mar. 1_0, 1891.
-.!/
/IlIilne.r.se,s :
~=*~~ .ff~tS~.
Figure 6. Diagrammatic illustration of the second machine built with no wire on the rotating part, designed for turbine drive, taken from U.S. Patent No. 447,921 of March 10, 1891. Application filed November 15, 1890.
ÆTHERFORCE
14
Work th Alternating Currents
the
was
the conductors,
as
this
, I had two wires for the
and two
wires for the conductors. Usually, however, I had six binding
posts because I had two
ts splaced
in
the armature.
I have
and years in des
and I
have never
It one machine but that the
saw
it complimented me on its
ss and the
s of
my design.
men were students;
not know how to
do it.
made a machine which had an internal resistance
of 6 ohms and
to raise the tension one hundred fold.
the resistance of my
ne was 1/40 of an ohm on
wanted to make a short conductor and made a conductor
many feet
The wire in my machine was but 4 feet
So, you see, I had
in this machine the
t
thoughts of design. It could not be
any more because
I had gone to the I
ngi limit of tensile
st
, limit of air space, limit of copper, I
of every
other material. This
ne I have used for many years with
success, and I have discovered many,
facts in con-
nection
wireless by its means, and some of these facts I
will tell you.
Counsel
What has
to that
?
Tesla
I used it for years and years; used it
I
That machine must still be in existence, but with
fference that I have
the number of
s. It was to
do away with the spark gap. That was an idea that I conceived
1892, but it dragged on
I a later period. My
idea was to construct a machine with a
n small number of
s, rotate it at an enormous
, and thus
ch would
the same effect as the arc dis-
my so-called "Tesla transformer."
ly,
s
machine had 64 poles. Then [in 1901] I reduced them to 32,
and
to 16, and that form I have
with it
any osci lations, continuous trains or undamped oscillations
of
I desired. That is done a process not yet
well
only so far that electri ans have
cs from low fundamentals; but in that
have
a very small energy. Now, I have
me to take, for
,
s
give me 3,000 or 4,000 oscillations, and from
s
100,000 [oscillations], and there
s train of
waves.
ÆTHERFORCE
riments With reless Te
Telephony ~
15
Counsel
During what years was this machine used?
Tesla
This certainly,
was It in 189. I used it 1905 or 1906.
When was it you reduced the number of poles?
Tesla
I reduced the number of es, I think, in 1901. But
then I reduced it for the purpose of
currents of
f had a
number of poles, could
not realize my
because these poles would come in
succession and
ce a rate of
to the
rate of change
is obtainable
denser owing to a sudden break of the electric.
to
say, a blow. It has to be a blow,
see. I had to
my
y far
f then run them at excessive
and generate
ly few impulses, but each of
those impulses are of such tremendous intensity that the
dynamo is
ical short-ci ted. That gave me a blow
which replaced the arc. And then, of course, there
to be perfected a scheme enabl me to
the energy of the
alternator in the most economical manner, in
harmonics.
That is not known, at least I have not seen
ing of that
kind in literature, and I bel
that if anybody would at-
it without the devices which I have invented, he could
not get much of the energy in
harmonics.
What was the
of that
in its
form?
Tesla
The
of the machine was about 8 kilowatts; but, ob-
serve, I did not [then] have the turbine [patented in 1913] .
If I had had the turbine, I could have run this mach
[at]
20,000 revolutions, and then I would have had a [s ficantly
h
]
[The machine] had a s
was of the finest steel, all
taken from stat
terminals.
which, after al
armature and no wire. It , and the current was
[It] is the have come to.
ÆTHERFORCE
16
Work With Alternating Currents
Counsel
How fast did you run that before you reduced the number of poles?
Tesla
Up to 12,000 [revolutions]. I used this machine in transmission of signals, particularly with the telephone, in a great many investigations, and I discovered a way, for instance, of measuring accurately capacities employing this machine. You know that, normally, the capacity of an antenna cannot be measured very closely. The ablest men [in the art] -- Prof. Zenneck and Prof. Stone -- know how it is. But, with the scheme I have developed, I could measure any capacity. With an antenna of 1,000 centimeters, I can very easily read half a centimeter. [*] There is no method known which would
Figure 7. Photograph of machine covered by U.S. Patent No. 447,921 of March 10, 1891. Application filed November 15, 1890.
* Editorial note: Capacitance values expressed in centimeters are in electrostatic units; to convert from centimeters to picofarads, mUltiply by 10/9. Thus, in the situation described, with an antenna of 0.0011 microfarad, Tesla could read an increment of 0.55 picofarad.
ÆTHERFORCE
Wi Wire ss
y
Telephony ~
17
enable an expert to read as closely as that. I used this
machine in
as these. It was a very fine
of
for all sorts of
s demonstrations.
In those years, of course, I was deve
c
s. I have shown that five
had to be
before wireless was an art, a real art that could be
ifically .
. 7] shows this machine as it actually was. You
here a wire [point
to the
]
a solid, thick
wire. In the form that you see the machine here, I used it
for developing harmonics, and in this case I had a condenser
soldered to the alternator so that I would
a system of no
resistance,
y. The resistance in my alternator was
1/40 of an ohm. I made a
-- that
seen
here -- the resistance of which was also
I com-
bined it
the condenser and tuned it so that I
a cur-
rent of tremendous volume in that circuit, and then I operated
it with the
. 8 shows] another machine. This is the third
machine which I built, a
one. This machine is de-
sc
by me in the U.S. Patent No. 447,921 of March 10,
1891. It was constructed early in 1891.
Then I made a
On my
from
[in
1892], I took it
in a little
ion in next
at 35 South Fifth
Avenue. In this
, I had the same kind of
what
we call a "stiff" field -- and in that I
a sc to
which was cut out in a proper way so as to give me a
I wanted to have a very 1
rotor, and
rotating,
the
in
[aJ plane
force, would be a very
one to
experiment with. The machine was of very much larger capa-
; it was built with 480
s, and I could get from it, at
ively low
30,000 cycles per
I could
, in fact, more. This machine was also de
Of these three machines which I have
second one was saved from my 1
[*J
* Editorial note:
Another machine, whi
Company,
a 1938
taken after the laboratory fire.
to
Westinghouse Electric &
laboratory fire. See Appendix I,
ÆTHERFORCE
18
Work With Alternating Currents
(No Model.)
N. TESLA.
~ Shp,ets-Sheet 2.
ALTERNATING ELECTRIC CURRENT GENERATOR.
No. 447,921.
Patented Mar. 10, 1891.
Figure 8. Diagrammatic drawing of the third and larger machine with 480 poles, taken from U.S. Patent No. 447,921.
ÆTHERFORCE
Experiments With Wireless Telegraphy and Telephony ~
19
Figure 9. Photographic view of alternator covered by U.S. Patent No. 447,921. Illustrated in Martin book, Fig. 98, p. 154.
[Fig. 9J is a photographic representation of the machine, but it is not so apparent that it was a machine of much larger capacity. I could get out if it readily 25 kilowatts.
Those are not the only machines I built. I constructed quite a number of other high frequency machines. Some of these were obviously small, and I built them chiefly for scientific investigations and for use in connection with receiving circuits.
One of my ideas was to generate at the receiving station oscillations of a certain frequency, and then combine them with an incoming oscillation to obtain beats. And later on, in 1898, I worked this idea into an invention which has been called a ~telautomaton,H and which has begun to be appreciated because Congress voted a certain expenditure of money, $750,000, for that machine which I vainly attempted to persuade them to accept. [*J I perfected the machine in 1898, and tried everything in my power to have it adopted; but, everybody was ridiculing my efforts. Everybody said it is impracticable, and after my patent expired only a few months ago, Congress appropriated this sum and I have now the pleasure of simply looking on when others are using my inventions, which I could not persuade people to adopt. This is usually so.
[Fig. 10J shows a type of small alternator, one of two forms which I will show you, that from the constructive point of view, is rather poor. I will admit that. But, it was
* Editorial note: For further remarks on attempts to persuade the U.S. Navy Department to fund the idea, see p. 158.
ÆTHERFORCE
20
Work With Alternating Currents
convenient for me to construct it that way. You see, the magnetic circuit is constituted by the laminated core here, [andJ there is an exciting coil. In this picture you will also note the field wires, and the rotor is indicated. With this machine I could get 200,000 cycles per second, [*J very readily, but the output was very small. It was used mostly for telephonic work and for scientific investigations.
Figure 10. Small alternator of very high frequency built for purposes of investigation, chiefly in conjunction with receivers. Drawing. Measurement purposes.
This [Fig. 11J, if you please, is another small machine which I built, and with it I also obtained a very high number of cycles. You see how that was made. Here [fieldJ I have 8 laminated magnets, and the circuit was formed through here, you see. On the rotating part I had 9 projections so that if,
0 '.· · 0
Figure 11. Another small high-frequency alternator of different construction intended for the same purposes. Drawing. Mercury interrupters, 1898.
* Editorial note: This was accomplished by having the number of field magnets differing from the number of armature projections by one. For the general case, the number of field magnets and armature projections must have an even-odd relation.
ÆTHERFORCE
nts th Wireless Telegraphy and Telephony -
21
for tance, this armature was rotated, say, in the clockwise
direction, then the
ts will come successively into
also in the lockwise direction. [*] But, as you will readily
note, I had a very small electromotive force, for the reason
that
the inductance of seven coils while one
was
the electromotive force. However, [the] induc-
tance I could overcome resonance, in properly ust
so
was no objection, and the machine was ex-
serviceable. This machine
s, by one
72
,
there are 8
sand 9
ections. That means 8 x 9 = 72. And, of course,
small, I
, and balanced, I could rotate it a very
and
a very h
Counsel
In what
was that shown?
Tesla
This
was
in my patents on mercury inter-
s which were
1898. You will find the same
my mercury
I used 7 streams of mercury,
ections. In fact, in one I have constructed, I used
ect
and 24 streams, and I could get a very
which is unobta
e with a very high frequency
I have described so far were all of
the
; that is, insofar as the mode of fie ex-
citation was concerned .
. 12] shows another type of machine which was
me before I had conceived the princ
of excit a
, not
rect current, but by current of fferent
a whirl magnetic field, and then rotat
in that field an armature and generating currents in the same.
This
has been taken up later by a very able German en-
neer, Mr. Gol
, and today it is known as the Gold-
s
machine. Of course,
mentions me at all, and
I suppose
is
in wireless as in love and war.
But, I gave the
of these machines, and I had several of
them with which I
continuously.
There is s to be
[about this type of
] .
When you rotate the armature in the direction of the rotat
s, but
a
velocity, then it is a
which
has
the field excited by a simple
current;
* Editorial note: For the case where the number of field magnets is 8 and the
number of armature projections is 7, resulting in 56 impulses
revolution,
and the armature is rotated in the clockwise direction, the
magnets will
come success
into play in the counter-clockwise direction.
ÆTHERFORCE
22
Work With Alternating Currents
(No Model.)
No. 390,721.
N. TESLA.
DYNAMO ELEOTRIC MACHINE.
Patented Oct. 9, 1888.
I I
I I
!
I I I I 1
-, I
(~,,.-- ---} ,iI" ,iI Q~~
, I I I
i '
, : I
I I
I,~--"~-I','1
, .1Jii~1
-
I'1'
. I , I I
WITNESSES:
~.~,--
RoM.¥: ~a.;~
1NVENTOO
~,~.
BY r-""'-T-'" -OUc.c Ca c ~. ~z:" A
% ATTORNEY~.
Figure 12. Diagrammatic illustration of another type of machine with rotating magnetic field excitation, as described in U.S. Patent No. 390,721 of October 9, 1888. Application filed April 28, 1888.
ÆTHERFORCE
riments Wi
re ss Te
Telephony -
23
when you rotate it in the other di field really comes in, and you you rotate the field just as fast one rotated the other way, you have then,
on, then the rotat
frequency. If
as the armature s
example,
the
The objection to s machine I found to lie in the fact
that the current is not strictly s
You see, when
flux in the f
varies harmon
there are two
inductions; one is the induction due to the motion of the wire
across the field and the other is the induction
to
that taking place a static transformer. This latter is
ional to the sine, the other is
onal to the
square of the s ,and the result is that we get a little
storted curve. Nevertheless, the
is applicable,
and [it] has been
ied Golds
commercial
machine.
Now I am
to a very wonderful discovery which
made in connection with high frequency alternators, and I do
not believe that there is a man in the
cal profession
who dreams about it; not one. This scovery
to
me that, without further provision,
was impossible to
frequency alternator in wireless work that requi
kind of fineness; and I made this scovery in the fol
way. I was
with three
alternators in
my
at 35 South Fifth Avenue. I would run [any] one
o the machines, tune a circuit, then go around the ci and
the hum of the alternator in my tuned
circuit,
and
this note
the intens of
sound I could
j
the
of the devices that I was using. That was a
very convenient way; I did it cont
I
most
between the 1
on South
the Hotel
Gerlach on 27th Street, near Sixth Avenue, where I was s
p
While I was ca
on this work I was perfect
ods and
for attunement, and I noticed that
lly
could not get as
results as
before. I could not
understand this. But after a few
of invest
,one
happened that I was
a note on the
of
the Gerlach
could not get
hum of the alternator. I
was giving it up, when all of a sudden out it rang very
and clear, and was off
, as though a wire had
been broken. I s
to myself, a
has been broken some-
where in the ci t and went down to the laboratory where I
examined all care lly. But eve
was in order. Then
the idea flashed upon me that my
circuit was
y
and the alternator was
not one but many
ies; the alternator was all
changing
, like
every alternator does. It does not
one
, it
s many
ies.
ÆTHERFORCE
24
Work With Alternating Currents
Now, I solved that problem in 1898, and I will tell you how I solved it. I said to myself, here is a generator that gives a dozen different frequencies, but very closely related. They follow one another in succession. How am I going to get selectivity, and at the same time have a perfect response? I solved this through what I term the principle of individualization. An ordinary circuit has one characteristic; it responds to a certain note. An individual has more than one characteristic; [he] comprises many in combination. Similarly, I combine several circuits and depend on the cooperation of these circuits to operate my device.
My first step was to tune several circuits very closely together, so closely that they would pick up [any] of the frequencies within the range of the change of the alternator [speed], and I operated with all these circuits on my receiver. The moment I used that kind of a circuit, I found that I got very clearly the note of the alternator because my receiver was responding to any of the frequencies which were produced. On the other hand, when foreign frequencies would come in to disturb, I would only get a partial effect, as my normal effect was due to all the frequencies combined, whereas the outside effect was due to just the one frequency. I presented the same principle in a lecture before the New York Academy of Sciences on April 6, 1897, but which was not published.
There were certain steps to be accomplished, [however,] before the wireless could be on a really practical and scientific basis. The next step to accomplish, after all had been done, was to design an apparatus which will exactly suit the earth; that is, which will give the proper wavelengths suitable for it, and will also be in all other respects adapted to the physical conditions of the globe on which we live, and to the place on which the plant is erected. The earth is not a sphere; it is an oblate spheroid, owing to the effect of centrifugal force. Now, it makes all the difference whether a scientifically correct apparatus is placed in a northern region, near the pole, or near the equator, because the length of the conductor is not the same.
In the account of the experiments and machines which I [have earlier shown], I hope I have proved that those machines represented the farthest advancement in the art, not only of that time but of the present day. Not that I would say I was a better designer -- nothing would be further from my mind. I simply mean that my followers did not require the limitations of frequency, and I have stuck to those designs which were most efficient. Alexanderson said,
"We are compelled to go to the very frequencies that you [i.e., Tesla] used in your earlier demonstrations."
There were reasons why I made machines of low frequency
ÆTHERFORCE
Experiments With Wireless Telegraphy and Telephony ~
25
in my experimental work, why I stuck to these frequencies which I have used in my early lectures and public demonstrations. Firstly, because such a machine can be efficiently built for high output, which a machine for 200,000 cannot. Secondly, the waves which are generated were less absorbed because they are of lower frequency. They went to greater distance; the effects were greater. But there was still a third reason: Whenever I received the effects of a transmitter, one of the most convenient and simplest ways [to detect them] was to apply a magnetic field to currents generated in a conductor, and when I did so, the low frequency gave audible notes.
Figure 13. Instrument to receive radio waves of 1896-1899 structure.
One of the simplest devices I used in my experiments between my laboratory on South Fifth Avenue and [at] the Gerlach Hotel, and other places in and outside the city, was an instrument constructed in 1896 with a magnet which sometimes was so designed as to give me a very intense magnetic field up to 20,000 lines per square centimeter. In this [field] I placed a conductor, a wire or a coil, and then I would get a note which I amplified and intensified in many ways. From the characteristics of the audible note, I would immediately judge the quality of my apparatus.
When I speak of an audible note, I mean a note audible in a telephone as produced by the diaphragm of a telephone, or by a vibrating wire within the range of audibility.
[Fig. 13] shows the general arrangement of [the receiving] apparatus. [*] Two condensers are the boxes at each end,
* Editorial note: Also see discussion in association with Fig. 94, p. 162.
ÆTHERFORCE
26
Work With Alternating Currents
and in the center a coil, or two coils, according to necessity, with which I produced a strong magnetic field and [placed] in it a wire. These condensers and the wire form a circuit which I tune. The condensers are of comparatively large capacity because my conductor is so short. I usually would transform the current in the receiving circuit and make as close a connection as possible and then tune the circuit to the vibrations. I would also mechanically tune the wire, according to the frequency, to the same note or to a fundamental.
This machine was suitable for transportation. I could put it under my arm with a couple of batteries. I had relays, which were very big, in which I produced (for stationary work) a very intense magnetic field so as to affect the conductor by the feeblest current. Furthermore, I used these relays particularly in connection with beats. When the frequencies were very high, I combined two frequencies very nearly alike. That gave me a low beat. One of the frequencies I sometimes produced at the receiving station, and at other times at both the receiving and transmitti n g stations. This always gave me the means of producing an audible note. I used machines of this character from 1892, but this specific instrument in my laboratory on Houston Street.
This instrument comprising a magnet and chord or coil in the magnetic field -- I mean a wire or coil in the magnetic field -- is an old academic device, used in all sorts of demonstrations at the schools and the university where I was studying. My professor of physics has had similar instruments with an adjustable spring and magnet, and I have employed them in assisting him. There is nothing novel in the idea. The only novelty was that I kept my alternation low and I made this arrangement with conductors to tune.
It was very convenient for producing audible effects because, if I used other forms of a receiver, I had a reading which was not at once translatable. If I listened to a note, I could immediately tell the quality of the transmission. For instance, I would tune a circuit in my laboratory, take it out to another building, and I would receive the signals; and from the quality of the signals I would see how I was progressing.
Counsel
In the experiments that you have spoken of with the instrument of which the picture is shown [as Fig. 13], what were the distances between the transmitting and receiving stations?
Tesla
The distance at that time, and I think the greatest distance at which I ever received signals from the Houston Street
ÆTHERFORCE
With re 55 Telegraphy
Te
27
, was from
Houston
I think, a stance of about
1897 when Lord Kelvin came to my
made certain demon
before the
the Patent Office, Mr. See
and it was
lity of
to me.
At that experiment were you at the Houston Street end or at the West Point end?
Tesla
In that
I
continuous
of oscil-
lations and went with the instrument to West Point. I did
s two or three
s. There were no s
s actually
en. I s
the note,
that was for me just the same.
Counsel
That is to say, you
not make and break the circuit?
Tesla
No, and I did not receive the audible notes in
but I did receive
Counsel
At West Point?
Tesla
Yes, in or about the year 1897.
Counsel
And did the cont from Houston Street?
s tran ssion thus
start
Tesla
Yes.
Counsel
Was one of your emp
there?
Tesla
Yes, the employees knew that I was
the
ÆTHERFORCE
28
Alternating
s
On
occas s, I would
a
to make and break the
found it was much s
er to just let the ap-
run and
the notes.
Counsel
What was the distance between
ssion and reception?
Tesla
That was the distance from my Street to the Gerlach Hotel.
on Houston
Counsel
Is this
[Fig. 13]
is colI
ly known as a string
type which
Tes
No, it is not. Such a sc the schools, for instance, in
c strument is used in of demonst
Counsel
In
13], is that [wire) shown on the apparatus in
series in the
f and is it in
of the
?
Tesla
Yes. I had a it made no f the f Id that
, or a s
wire, in the field --
It was the react of the currents on
the
note.
Counsel
What is the furthest distance from your source of transmission that you u the apparatus of this character?
I think
I used this once at the Western Union Build-
ing -- on the roof -- in company with Mr. Alfred K. Brown.
That would be a stance of
2 miles.
Counsel
What was
character of the re
on?
Tesla
Just the alternator was run and you could hear the note
of the same when
rcuit and
st
was tuned to
ÆTHERFORCE
s Wi
re ss
Te
29
the same
Counsel
Did you hear it?
Tesla
You could hear it allover the
Coun 1
You mean you did not have to have your ear in the
te
to hear it?
Te la
No, not at all; I could hear it from a distance. The vibrations were very
Counsel
About when was that?
Tesla
That must have been
late 1896 or
in 1897.
Counsel
What was the us ?
of alternation that you were
Tesla
The
might have been
say - in the neighborhood of 5,000.
like
I should
Was there
hidden about these uses, or were
open so that anyone could use them?
Tesla
There were thousands of
e,
shed men of all
kinds, from
and
artists and scientists in the
down to some old
of mine mechanics, to whom my
laboratory was always open. I showed it to
; I
talked
about it.
ÆTHERFORCE
30
Work With Alternating Currents
~li a Model.)
No. 464,667.
N. TESLA.
ELECTRICAL CONDENSER.
Patented Deo. 8, 1891.
Jt)'!J. 1
-!f!I. 2
bwt'niol'
1U1~Y~
e&!a:u.v v-P~ .;yj!lorll~~
Figure 14. Construction described in U.S. Patent No. 464,667 of December 8, 1891. Application filed August 1, 1891.
ÆTHERFORCE
Experiments With Wireless Telegraphy and Telephony ~
31
. (If 0 Model. )
No. 567,818 .
N. TESLA.
ELECTRICAL CONDENSER.
Patented Sept. 15. 1896 .
WITNESSES
Figure 15. Forms described in U.S. Patent No. 567,818 of September 15, 1896. Application filed June 17, 1896.
ÆTHERFORCE
32
Work With Alternating Currents
Counsel
When you said, "5,000," did you mean cycles or alternations?
Tesla
I mean cycles. On another occasion I have also operated going a little further into showing the reactions of high frequency currents upon magnetic fields -- I have operated motors, and at that time I have stated what frequencies had to be used in order to produce these rotations, which are, of course, due to reactions of the currents on the field. I have pointed out, in the Martin book, that they should be from 5,000 to 10,000.
I would like to proceed, without going into details making this too hard to follow. I would like to have this simply a clean story with only the salient facts pointed out, and not a maze of little details which would complicate it and spoil the harmony. Proceeding, then,
[Fig. 14] shows a form of condenser in which I have boiled out all the air bubbles, and the next drawing [Fig. 15] shows another form.
I have made a notable advance in this condenser, with which I have operated in my laboratory on Houston Street and in experiments at my wireless station in Colorado. This is the most efficient form of condenser known, showing practically no loss whatever. And it is only with this condenser that really very fine results are obtainable because, even if we employ mica condensers immersed in oil, or glass of the best kind coated with tinfoil, we do not get the results which we get with this condenser, and they are obtained by substituting electrolyte for the metallic coatings as before. I used electrolytes which were especially adapted for that, and cheap -- for instance, like a solution of ordinary salt. It is cheap and readily obtainable.
[Fig. 16] shows a type of this kind of condenser in finished form as I used them in my laboratories. There were many of these adapted to be secured on the bottom. They were readily transportable. Occasionally, I took some of these condensers with me when I experimented.
[Fig. 17] shows another improved form of condenser. I do not have a photograph of a finished apparatus and this is a sketch that was made in 1896 shortly before a condenser of this kind was constructed. That was a condenser intended for high electric pressure and the insulation was obtained through the air. It was built for 500 atmospheres air pressure safely. There is a reference in my writings where I point out
ÆTHERFORCE
Experiments With Wireless Telegraphy and Telephony -
33
the use of compressed air, and therefore there was no creative effort involved in any patent in that direction by Fessenden and others.
Figure 16. Improved form of electrolyte condenser as used in laboratories on
35 s. Fifth Avenue and 46 E. Houston Street.
Figure 17. Form of condenser with air under great pressure as dielectric used at the same period, subsequently patented by others.
The apparatus shown by the drawing [Fig. 18] which I designed and installed was for years employed to practice this process of manufacture. This process is [now] universally adopted; everybody uses it. There are millions and millions involved in it. If I could only get one cent for every apparatus that is manufactured in accordance with my invention, I could erect a building like the Woolworth and not feel the expense. [*] Everybody uses it, but nobody says thanks. That was arranged for what was called a vacuum pressure process.
* Editorial note: At the time of this interview, Tesla had shortly before removed his offices from the Woolworth Building where they had been established for one year.
ÆTHERFORCE
34
Work With Alternating Currents
(No ModeL)
N. TESLA.
MANUFAOTURE OF ELEOTRIOAL CONDENSERS, COILS, &0.
No. 677,671.
Patented Feb. 23, 1897.
/~.~~ i TTORIiEfa.
Figure 18. Apparatus for manufacture of condensers and coils to exclude air as described in U.S. Patent No. 577,671 of February 23, 1897. Application filed November 5, 1896. The whole manufacture is now dependent on this or similar processes, and many patents have been secured by others.
ÆTHERFORCE
riments
Wireless Tel
and Te
35
Steinmetz says,
"No, I have found a better way. I just
"
the thing in
It is thin and s a
s in the
and, of course, he
I am [next] coming to a
in my life which was very
fruitful. I was absorbed in the development of a new type of
generator. The solution, which enables me to use the high
alternator
ical, was not yet found at that
time. I saw that the high
was not usable
for any finer work. We were
toward perfection and
that if we attained it, the alternator would be s y thrown
away as an absolute useless
rument. That was my convic-
tion, and I
to
results
I subse-
ly reached with the alternator in another way. To this
end I built a
many machines of a novel
, which I
called oscillators -- mechani
electri oscillators
it is with these that my best results in the investiga-
tions of these
le to wireless in many of
ÆTHERFORCE
III. Mechanical and Electrical Oscillators Tesla
The photograph [Fig. 19J shows my earliest experimental oscillator which I used to generate electrical vibrations.
Figure 19. Simple mechanical oscillator used in first experiments.
My first efforts were to produce this vibratory mechanical motion, then attach to this system an electrical generator; that is, I would attach a conductor to it and vibrate it in a magnetic field. That was the first step in the evolution of the idea. The machine is shown here without any attachment.
The drawing [Fig. 20J illustrates the next advance in the evolution of the idea. I have produced isochronous oscillation, and now I am applying considerable power to the piston to develop energy in this electric system. It is the energy of the mechanical system which produces the electrical energy in the circuit, but the vibration is controlled by the tremendous force of the air spring against which the small impressed force is nothing. In this manner, then, I first obtained isochronous electrical oscillations, which no transmitter made today furnishes except my own.
The drawing [Fig. 21J illustrates the next improvement. I conceived the idea, instead of using a mechanical air spring
ÆTHERFORCE
Mechanical and Electrical Oscillators ~
37
(lfo ModeL)
No. 611,916.
N. TESLA.
ELECTRIC GENERATOR.
2 Sheets-Sheet 1.
Patented Jan. 2, 1894.
Figure 20 . Mechanical oscillator with air spring combined with electric generator as shown in U.S. Patent No. 511,916 of January 2, 1894. Application filed August 19, 1893.
ÆTHERFORCE
38
Work With Alternating Currents
(No ModeL)
No. 611,916.
N. TESLA .
ELECTRIO GENERATOR.
2 Sheeta-Sheet 2.
Patented Jan. 2, 1894.
Figure 21. Another mechanical oscillator with controlling electromagnetic system described in U.S. Patent No. 511,916 of January 2, 1894. Application filed August 19, 1893.
ÆTHERFORCE
Mechanical and Electrical Oscillators -
39
for exercising the controlling force, to obtain it electrically. Boiling water was employed to keep the temperature of the air spring perfectly constant and the oscillations isochronous. I constructed an electromagnetic field so that it could be used for isochronous control. This invention I also exhibited at the Chicago World's Fair where scientific men, Helmholtz and others, saw it. The magnetic field [of the] core generates currents in the coils. Two coils are used for excitation and two for induction. I connect a condenser to the latter and adjust the period of the electromagnetic system, comprising the condenser and the self-inductance, so that it is just suitable for the conditions under which I wish to operate. Then the magnetic system, having a constant period of vibration, controls the admission of the fluid to the piston, and when I use the currents I find them perfectly isochronous. I can run a clock with them and it will show correct time. The vibrations obtained in this way would not vary onemillionth of a second in a thousand years.
The photograph [Fig. 22] shows another form which I also exhibited at the Chicago World's Fair. There is a round coil, you see, in the field; on the other side is another such coil. I performed very curious experiments with this machine. For instance, among other things, I produced direct currents without commutation.
Figure 22. Another type of small mechanical electromagnetically controlled mechanical oscillator.
ÆTHERFORCE
40
Work With Alternating Currents
Figure 23. Large electromagnetically controlled mechanical oscillator for generating isochronous oscillations, used in demonstration before the Electrical Congress at the Chicago World's Fair, August 25, 1893. Illustrated in Martin book, Fig. 312, p. 490.
o
M
o
o
M
o
FIG. 31S.
Figure 24. Diagrammatic representation of electro-magnetically controlled mechanical oscillator for generating isochronous oscillations. Shown in Martin book, Fig. 313, p. 491.
ÆTHERFORCE
Mechanical and Electrical Oscillators -
41
Here [Fig. 23] is, I might say, the first commercial oscillator which I designed and constructed and which was exhibited at the Chicago World's Fair. With this, I also performed many experiments. As you will observe, I have a powerful magnet in two parts for producing a strong field on both sides, and in it are conductors which are vibrated by an engine in the center.
That [Fig. 24], as you see, diagramatically represents the arrangement. Here [at the center] is my little engine, and here [at Hand M] are the conductors and the magnets producing a very strong field. I observed very curious phenomena with this machine, which I subsequently turned to great advantage.
We are now coming to a form of machine which was on an industrial scale.
Figure 25. Double compound mechanical and electrical oscillator for generating current of perfect, constant, dynamo frequency of 10 horsepower. (Article by Martin ["Tesla's Oscillator and Other Inventions"], Century Magazine, April 1895, Fig. 2, p. 921.) (Built in 1893 . )
ÆTHERFORCE
42
Work With Alternating Currents
With this one [shown in Fig. 25], I operated normally in my laboratory at 35 South Fifth Avenue. It was primarily installed there. The Babcock and Wilcox people had the kindness of specially constructing a boiler for me which could stand a pressure of 1,000 pounds. This machine was capable of developing up to 10 horsepower. It was, as you see, composed of two magnets or magnetic fields and a compound engine for imparting vibration to the conductors in the fields. It was controlled by an isochronous oscillator and, in addition, I tuned the electromagnetic system when I operated.
Counsel
What frequencies were developed?
Tesla
Those were low frequencies, but I will tell you how I solved the problem of high frequencies.
Figure 26. Diagrammatic representation of double compound mechanical and electrical oscillator for generating currents of perfectly constant dynamo frequency. Shows mechanical and electrical parts.
ÆTHERFORCE
Mechanical and Electrical Oscillators ~
43
Counsel
When was that machine developed, Mr. Tesla?
Tesla
This machine was built in 1893 and was operated until May 1895, when a fire destroyed my laboratory. You will appreciate better this photograph [Fig. 25] if I show this drawing [Fig. 26] that was made for the patent specification at that period.
I come now to a large machine which was built in my laboratory on Houston Street. Immediately after the destruction of my laboratory by fire, the first thing I did was to design this oscillator [shown in Fig. 27]. I was still recognizing
Figure 27. Large mechanical and electrical oscillator with four vibrating parts installed in the laboratory at 46 E. Houston Street, for furnishing isochronous currents of desired wave frequencies, phases, and beats.
ÆTHERFORCE
44
Work With Alternating Currents
the absolute necessity of producing isochronous oscillations, and I could not get it with the alternator, so I constructed this machine. That was all a very expensive piece of work. It comprised four engines. Those four engines were put in pairs and there was an isochronous controller in the center, and furthermore, that controller was so arranged that I could set two pairs of engines to any phase or produce any beat I desired. Usually I operated quarter phase; that is, I generated currents of 90° displacement.
By the way, now, for the first time you see my apparatus on Houston Street, which I used for obtaining oscillations, damped and undamped as well. But, it is necessary to state that while others, who had been using my apparatus, but without my experience, have produced with it damped oscillations, my oscillations were almost invariably continuous, or undamped, because my circuits were so designed that they had a very small damping factor. Even if I operated with very low frequencies, I always obtained continuous, or undamped, waves for the reason that I designed my circuits as nonradiative circuits. I will explain that later.
Figure 28. Diagram showing length of section of large mechanical and electrical oscillator.
ÆTHERFORCE
Mechanical and Electrical Oscillators ~
45
In this diagram [Fig. 28] I show the general arrangement of these engines installed in the laboratory at 46 East Houston Street. There were four, with four vibrating parts installed for furnishing isochronous currents of desired wave frequencies, phases, and beats.
Figure 29. Small high frequency mechanical and electrical oscillator used in many investigations.
That oscillator [Fig. 29] was one of high frequency for isochronous work, and I used it in many ways. The machine, you see, comprised a magnetic frame. The energizing coil, which is removed, produced a strong magnetic field in this region. I calculated the dimensions of the field to make it as intense as possible. There was a powerful tongue of steel which carried a conductor at the extreme end. When it was vibrated, it generated oscillations in the wire. The tongue was so rigid that a special arrangement was provided for giving it a blow; then it would start, and the air pressure would keep it going. The vibrating mechanical system would fall into synchronism with the electrical, and I would get isochronous currents from it. That was a machine of high frequency that emitted a note about like a mosquito. It was something like 4,000 or 5,000. It gave a pitch nearly that of my alternator of the [first] type which I have described.
Of course this device was not intended for a big output, but simply to give me, when operating in connection with receiving circuits, isochronous currents. The excursions of the tongue were so small that one could not see it oscillate, but when the finger was pressed against it the vibration was felt.
ÆTHERFORCE
46
Work With Alternating Currents
This drawing [Fig. 30] shows the construction in detail. Here is the field coil, here are the conductors in the intense field, the valves for air supply, and the stops for limiting vibration. The stronger the field was excited, the [stronger] the vibrations became, but just the same, while the amplitude changed, the isochronism was not disturbed.
Figure 30. Diagrammatic representation of small high frequency mechanical and electrical oscillator used in many investigations.
I want to say now why these machines were the means of obtaining the best results in my wireless work. The machine at the Houston Street laboratory with which I could obtain any difference of phase, as well as that machine at 35 South Fifth Avenue, were the means of running a motor in perfect isochronism. That is, if I connected a synchronous motor to these machines and drove it with currents of different phase, I obtained an absolutely uniform rotation -- constant in time -and when I coupled this motor directly to an alternator, I obtained from the latter currents of absolutely constant frequency, all the more readily as I tuned the circuit of the alternator to the same frequency.
These machines I have described in a general way only. The work has covered years, and it would take a long time to explain all about them. They enabled me to operate in whatever I did with currents of constant frequency, and the small
ÆTHERFORCE
cal
Oscillators -
47
alternators in my
were dr
While
work was go on, I was perfect
other ways of
e
llations of absolutely constant fre-
quency which were then not
in the art.
ÆTHERFORCE
IV. Apparatus for Transformation by Condenser Discharges; Damped Waves
This work [ . 31] was begun already in 1889. This
of
is identified with my name as certain as the law
of gravitation is with that of Newton. I know that some have
that Professor [Elihu] Thomson also invented the so-
called Tesla coil, but those feeble chirps ne'er went beyond
t. Professor Thomson is an odd sort of man; very
, but he never was a wireless
; he never could
be. Moreover,
to realize that this
le
is
The
ence have told me that this was my best
and, in
connection with this
[
to schematics of
. 31], I may say that a lot of liberties have been taken.
For instance, a man fills this space [break D] with hydrogen;
he
all my instrumentalities,
that is neces-
sary, but calls it a new wireless
the Poulsen arc.
I cannot
Another man
in here [
to
space between self-inductive lines L L] a kind of gap -- he
a Nobel
My name is not
Still another man
s here [conductor B] a mercury[-arc]
rectifier. That is my friend [Peter}
Hewitt. But,
as a matter of fact, those devices have nothing to do with
the
If these men knew what I do,
would not touch my
;
would leave my
as it is.
in here [break D] two wheels.
one wheel;
he shows two. And he says, "See what
s when the wheels
are
a wonderful
s!" What is the wonder-
ful
Why, when the teeth of the wheels pass one an-
other, the currents are broken and
That is the
ful thing that
? The
f could not
make anything else happen unless he broke his own laws. So,
in this way, invention
debased, prosti-
tuted, more in connection with my
s than in
else. Not a ves
of invention as a creative effort is in
the thousands of
s that you see under the name of
other
a ves
of invent
It is exactly
like in car
which 6,000
have been taken
out; but all
are constructed and
ex-
actly the same way. The inventive effort involved is about
the same as that of which a 30
mule is
This
is a fact.
is one of most beautiful
ever
in the
I take a
of any kind. With the
a condenser. Then I di
the conden-
ser under conditions which result in the
of vibra-
tions.
it was known since Lord Kelvin that the condenser
ÆTHERFORCE
r Discharges:
Waves -
49
Ufo Model.)
N. TESLA.
METHOD OF AND APPARATUS FOR ELECTRICAL CONVERSION AND
DISTRIBUTION.
No. 462,41
Patented Nov. 31 1891.
31.
Method of transformation of electrical
oscillatory condenser
descr~ed in U.S. Patent No.
of November 3,
1891. Application filed February 4, 1891. Announcement of this
invention was made in Tes1a's lecture before the American Institute of
Electrical Engineers at Columbia College,
20, 1891, where it was
that this
afforded vast
and would
an important
in the future. Illustrated and descr~ed in
Martin book, Figs.
and 121, pp. 191-194.
ÆTHERFORCE
50
Work With Alternating Currents
discharge would give this vibration, but I perfected my apparatus to such a degree that it became an instrument utilizable in the arts, in a much broader way than Lord Kelvin had contemplated as possible. In fact, years afterwards when Lord Kelvin honored me by presenting to the British Association one of my oscillators of a perfected form, he said that it was "a wonderful development and destined to be of great importance."
[Returning to a discussion of Fig. 31], [E] is supposed to be a condenser. That [A] is the generator. Now then, supposing that this is a generator of steady pressure. I can obtain oscillations of any frequency I desire. I can make them damped or undamped. I can make them of one direction or alternating in direction as I choose. At G are devices which operate -- lamps, or anything else. Some experimenters who have gone after me have found a difficulty. They said,
"No, we cannot produce a constant train of oscillations."
c
--.. ..--4...---- .... -.:::....---__ R ~I t '::::~
,
.
.
.
.
.
.~'::a.-_
-
:
!
:
".'
--
-
-
-
-
-
~"'...
-_
:......
_
.
"
_.:::::':._--..g-
-
-
.
-..
..
-
I
I
I
I
e
e
e
Figure 32. Quenched spark gap. (Tesla at that t~e pointed out the future of quenching and showed that oscillations can be maintained without a spark being visible to the naked eye between the knobs.) Illustrated in Martin book, Figs. 135 and 136, p. 211.
ÆTHERFORCE
Condenser Discharges; Damped Waves -
51
Well, it is not my fault. I never have had the slightest difficulty. I produced constant oscillations and I have described how I produced them. Anyone who has no more than my own skill can do it.
This [Fig. 32J is another improvement in that particular device, which was the weakness of the invention and which I tried to eliminate. This device incorporated many spark gaps in series. It had a peculiar feature; namely, through the great number of gaps, I was able, as I have pointed out in my writings, to produce oscillations without even a spark being visible between the knobs. This device is now known in the art as the "quenched spark gap." Professor Wein has formulated a beautiful theory about it, which I understand has netted him the Nobel prize. Wein's theories are admirable. The only trouble is that he has overlooked one very important fact. It is this: If the apparatus is properly designed and operated, there is no use for the quenched gap, for the oscillations are continuous anyway. The radio men who came after me had the problem before them of making a bell sound, and they immersed it in mercury. Now, you know mercury is heavy. When they struck their bell, the mercury did not permit it to vibrate long because it took away all the energy. I put my bell in a vacuum and make it vibrate for hours. I have designed circuits in connection with an enterprise in 1898 for transmission of energy which, once started, would vibrate three years, and even after that the oscillations could still be detected. Professor Wein's theory is very beautiful, but it really has no practical meaning. It will become useless as soon as the inefficient apparatus of the day, with antennae that radiate energy rapidly, [areJ replaced by a scientifically designed oscillator which does not give out energy except when it gets up to a tremendous electromagnetic momentum.
c
Figure 33. The discharger working in an atmosphere, chiefly consisting of hydrogen, still further weakened by heat. The use of hydrogen in this connection has been claimed as a discovery and patented. Presented in Tesla's lectures before the Franklin Institute and the National Electric Light Association. Martin book, Fig. 167, pp. 307-308.
FlO . 107.
ÆTHERFORCE
52
Work th ternat
Currents
In this form of break [
the atmo
in which the arc was
ing.
was mostly
hydrogen, and with this device I
experiments
before the Franklin Institute
and the National
As
ion in St. Louis.
has been used
by Poulsen and
is now called
"Poulsen arc" and "Poulsen
" But, of course, there is no
ion in
I am
on record with prior publ
, and besides, the
does not have any other effect
that it lowers the ten-
sion under which the device can operate. It has the disadvan-
of
rical or dis
waves, and the im-
s
not best suited for
ng.
s [
34 is the
position of 1893, at which
to Professor Helmholtz my
for
I had shown Professor Helmholtz
certain
, he asked me,
the
cago Ex-
the first time
energy. After
ific men there
"Now, what is all this
for?"
I told him I was energy without
purposes. When I idea, I said,
to develop an
for transmit-
for
telephony, and other
ained to Professor
Itz the whole
"Excel
do you think that my plan is realizable?"
He
ied,
"Why, s."
Y it is, but first you must
the ap-
I started then and there to
the
s .
Was that conver
at the Chicago
ion?
la
Yes.
a
ion which was built espe-
cially for
my inventions and discoveries. I be-
l
Professor Wedding was there and some other s
ists
whom I cannot remember now. I showed Professor Helmholtz my
vacuum tubes and performed many other
Will you describe this apparatus in a
Ie more detail?
ÆTHERFORCE
r s
s; Damped Waves ~
53
rN() ModeL)
N. TESLA.
MEANS FOR GENERATING ELECTRIO OORRENTS.
No. 614,168.
Patented Feb. 6, 1894.
apparatus with interrupter in oil. Exhibited in the Exposition of 1893 before Helmholtz. Described in U.S. Patent ,168 of February 6, 1894. Application filed August 2, 1893.
ÆTHERFORCE
54
Work With Alternating Currents
Tesla
The apparatus [Fig. 34], as you see, comprised primary and secondary coils immersed in a large tank of oil. The break was automatically effected by means of a turbine. The oil was circulated by a pump, and the current [i.e., stream flow] of oil drove the turbine which effected the make and break. Owing to the fact that the oil used was a very good insulator, rapidly flowing and of great dielectric strength, these make-and-break points were very close together, and the arcs extremely short. The effects were accordingly more intense. Here [T in Diag. 1 of Fig. 34J is a cooler through which the oil was circulated. The oil was forced through the gaps at great speed, and as it flowed out it was supplied again to the tank and the current driving the turbine.
Counsel
That device [Diag. 2 of Fig. 34] you call a turbine?
Tesla
Yes. It had vanes like those of a propeller and constituted a rotary break in the circuit.
Counsel
What was your prime source [of powerJ?
Tesla
The primary source was an alternator with a frequency of 133 cycles and, if I recollect rightly, the pressure [at the secondaryJ was about 20,000 volts. I may have had 10,000 volts. I am not sure what it was, but it must have been certainly from 10,000 to 20,000 volts -- within that range.
Counsel
I notice you have two sets of transformers in there marked Sand S', have you not?
Tesla
This [S'J is my oscillatory circuit. That [SJ is the transformer from which the condenser was charged. Here [at S] we had 20,000 volts, or whatever it was, from the commercial transformer and here [at S'] is my secondary which generated the high frequency currents. The rotary gap is shown in detail [Diag. 2 of Fig. 34J.
I had a special reason for showing this. To meet that great man Helmholtz and other scientific men, and to bring
ÆTHERFORCE
Condenser Discharges; Damped Waves -
55
before them for the first time the results of years of previous labor, was an important moment in my life -- particularly because Professor Helmholtz gave me the assurance himself that what I explained to him was realizable, provided that I could produce the apparatus. I was very much encouraged.
-- - ...... [
Figure 35. Apparatus with mechanical break as installed on a large scale in the laboratory at 35 So. Fifth Avenue and subsequently at 46 E. Houston Street. Described in U.S. Patent No. 645,576 of March 20, 1900. Application filed September 2, 1897.
I
h
.
-
,
.)
)
.J
>
This [Fig. 35J is the apparatus I had at 35 South Fifth Avenue and also Houston Street. It shows the whole arrangement as I had it for the demonstration of effects which I investigated. [*J This cable you see [square loop in top half of Fig. 35J is stretched around the hall. These are my condensers. There is the mechanically operated break, and that is a transformer charged from the generator. That is the way I had it for the production of current effects which were rather of damped character because, at that period, I used circuits of great activity which radiated rapidly. In the Houston Street laboratory, I could take in my hands a coil
* Editorial note: This diagram is not provided in the referenced patent.
ÆTHERFORCE
56
Work
rnating Currents
tuned to my body and collect 3/4
re in the
room without
connection, and I have often disillu-
sioned my vis
to such
effects. Some-
times, I would
flames shooting out from my head and
run a motor in my hands, or light six or e
could not understand
festations of energy and
that it was a
transmiss of power. I told
them that these
were wonderful, but that a system of
transmission, based on the same principle, was absolutely
worthless. It was a transmission by e
ic waves.
The solution
in a different direction. I am showing you
s [diagram] s
y as a typical form of
of that
pe
and if you go over the 1
of the present
you will find that the newest arrangements have nothing better
to show.
Counsel
What was the rna and break that apparatus?
you got from
Tes
It was 5,000, 6,000 -- sometimes
r still. I had two
oppositely rotating discs which I will show
and with
I could have
y, 15,000 or 18,000.
Counsel
What wave
s did you
?
Tesla
I could
from a few thousand up to a million per
second, if I wanted.
Counsel
What did you actually use?
Tesla
In these demonstrat , which I
these effects,
these most powerful e fects that were
s
of New
York at that time, I
with
ies from 30,000 to
80,000. At that
ck up a re,
1 it up, and
tell what the vibrat would be, without any test, because I
was experimenting
and
This [Fig. 36] is a form of break which I
in
working with alternators. I recognized that it was of tremen-
dous advantage to break at the peak of the wave. If I used
just an ordinary
, it would make and bre the current at
ÆTHERFORCE
Condenser Discharges; Damped Waves ~
57
(No Model.)
N. TESLA.
:.! Sheets-Sheet 2.
APPARATUS rOR PRODUCING ELECTRICAL CURRENTS or
HIGH FREQUENCY.
No: 668,180.
Patented Sept. 22, 1896.
INVENTOR
8'
AT TORNE'3
Figure 36. Isochronous mechanical break used in the laboratory at 35 South Fifth Avenue. Described in U.S. Patent Nos. 568,179 and 568,180 of September 22, 1896. Applications filed July 6 and 9, 1896. (Diagram taken from Patent No. 568,180.)
ÆTHERFORCE
58
Work With Alternating Currents
low as well as high points of the wave. Of this apparatus I had two forms; one in which I drove the break right from the shaft of the dynamo and the other in which I drove it with an isochronous motor. Then, by a movement of these knobs (K K), I would make the adjustments so that the makes would occur exactly at the top of the wave. That is a form of break which is embodied in hundreds of patents and used now extensively.
< I ,t .::--.9 '~"",..-_ _ 1
. I i}· , " --.-~,I " .
: -.."..-=__.~J ~.
;
'- -
Figure 37. Mechanical break with two oppositely rotating discs used for the purpose of increasing the number of breaks and alternating the oscillations practically undamped. (Subsequently patented by others.)
Here [Fig. 37] I show an apparatus that was installed in the Houston Street laboratory prior to the other break because I wanted to get as high a number of impulses as possible. The drawing dates from the spring of 1896. It is a break with which I could reach from 15,000 to 18,000 interruptions per second. I used it very much until later I found it was not necessary. That is the innocent device which Marconi thought a great invention.
Counsel
This is also a rotary gap?
ÆTHERFORCE
r Dis
Waves -
59
Tesla
Yes, and it consists of two scs of a
with teeth
of
side.
were rotated by two motors in
opposite
y rotated they alternately
closed and
t. In some tances I used an
uneven number of teeth on one
and even number on the other
so that I
as many breaks as I desired. I will
show you later an
more perfect than s one, and of
a different kind, in which I have 24
contacts, and
25 rotat elements that established the contact and broke
one
I
24
25, or 600
[per revolution].
el
Whenever you say "the break", you mean "a
gap"?
la
Yes: prefe
I use the term "circuit controller,"
This [Fig. 38] illustrates another deve
in a dif-
ferent direct
In order to increase
number of breaks,
currents of different
I had in my labora-
,
ly, a
and could
between; that is, from
apart, I could
four
s, 45
Here is an
shown as I had
it,
with three
[60
I and could obtain six
, 30
], and later on I had one with four
s
[45 apart, and could obtain e
phases 22 1/2
You
see, as I mult ied the number of the
Sf I
the
number of the fundamental scharges.
What is the date of this
?
Tesla
I
in the 35 South Fifth Avenue
labo
remember that
several sc ific soc
s and it was
know on one occasion there was the Society 0
another, the Electrotherapeutic Soc
and then I
tingu
men like Mark Twain and Joseph Jefferson I gave
them a demonstration which was published in Martin's article
in the
of il 1895,
I know
on
Later on I
made it four
therefore,
to the destruction of my laboratory
ÆTHERFORCE
60
Work With Alternating Currents
)
- ~" ,
Figure 38. Use of multi-phase generator with mechanical break. Experiments in the laboratory at 35 So. Fifth Avenue and subsequently.
Counsel
Do you recall any publication in which this diagram was illustrated?
Tesla
I made no publication, and I vividly remember that when I installed my apparatus on Long Island I had an arrangement with four transformers and four phases 45 apart. After I had been using this apparatus there, several years afterwards, I ran across a patent, I believe held by the General Electric Company, describing precisely the same arrangement. [*] It was a similar experience as with that patent of Fessenden on the compressed air condenser. Any time I want to use these improvements all I need to do is to produce my records and that will settle the patents.
Counsel
When was that drawing [Fig. 38]?
* Editorial note: Tesla refers to U.S. Patent No. 996,580 dated June 27, 1911, of Charles Green with assignment to G.E.; application filed September 30, 1907.
ÆTHERFORCE
ser Dis
Si
Waves ~
61
la
This is from an old Netter.
Counsel
But that
not go to
which was made by Mr. ?
No. I have hundreds of inventions that were to be
but
The expense was too
and I could
not do it. This form of
with two and
phases
was used prior to the destruction of my labo
in 1895,
and it was instal
on a
scale with four
in my
plant on
Island with which I was to tel
around the
world, but that is a long story.
I
In that use you made of it at your
, was that
connected up as shown there [ . 38], to an antenna?
la
I used the
s, yes, in
with the antenna
too, but this is from a
drawing in ch an antenna is
shown; I mean, I used in every connection. [Fig. 38] il-
lustrates an antenna with my tran
circuit, but the ap-
was used in all my work, in all my invest
And when this was connected and used in an antenna, did you use it as in other instances -- go off and listen to the notes which you rece
Tesla
Oh, certai
But I remember that, bes
fferent nds
Then I had a sensibly
wave because at
I still was laboring under the same
ff It s as some do this day -- I had not learned how to
a circuit which would give me, with very few
cont
s wave. That carne with the
ces. When I carne to my
in
Colorado, I could take my
like that and get a con-
tinuous
undamped wave, almost without except I between
s
s.
ÆTHERFORCE
62
Work With Alternating Currents
Counsel
Speaking of your not having perfectly undamped waves at that time, you were referring to that character of circuit?
Tesla
Yes, but with another kind of circuit I could, of course. The advantage of this apparatus was the delivering of energy at short intervals whereby one could increase activity, and with this scheme I was able to perform all of those wonderful experiments which have been reprinted from time to time in the technical papers. I would take energy out of a circuit at rates of hundreds or thousands of horsepower. In Colorado, I reached 18 million horsepower activities, but that was always by this device: Energy stored in the condenser and discharged in an inconceivably small interval of time. You could not produce that activity with an undamped wave. The damped wave is of advantage because it gives you, with a generator of 1 kilowatt, an activity of 2,000, 3,000, 4,000, or 5,000 kilowatts; whereas, if you have a continuous or undamped wave, 1 kilowatt gives you only wave energy at the rate of 1 kilowatt and nothing more. That is the reason why the system with a quenched gap has become popular.
I have refined this so that I have been able to take energy out of engines by drawing on their momentum. For instance, if the engine is of 200 horsepower, I take the energy out for a minute interval of time, at a rate of 5,000 or 6,000 horsepower, then I store [it] in a condenser and discharge the same at the rate of several millions of horsepower. That is how these wonderful effects are produced. The condenser is the most wonderful instrument, as I have stated in my writings, because it enables us to attain greater activities than are practical with explosives. There is no limit to the energy which you can develop with a condenser. There is a limit to the energy which you can develop with an explosive.
A common experiment, for instance, in my laboratory on Houston Street, was to pass through a coil energy at a rate of several thousand horsepower, put a piece of thick tinfoil on a stick, and approach it to that coil. The tinfoil would melt, and would not only melt, but while it was still in that form, it would be evaporated and the whole process took place in so small an interval of time that it was like a cannon shot. Instantly I put it there, there was an explosion. That was a striking experiment. It simply showed the power of the condenser, and at that time I was so reckless that in order to demonstrate to my visitors that my theories were correct, I would stick my head into that coil and I was not hurt; but, I would not do it now.
ÆTHERFORCE
Condenser Discharges; Damped Waves ~
63
[Fig. 39) shows a four-phase machine which was furnished me by the Westinghouse Electric Company at the close of 1895. My laboratory burned out in May, and I urged my friend, Mr. Albert Schmidt, who was the Superintendent, to give me this alternator as soon as possible. He worked day and night until he got it out, and he certainly did notable work because while the machine was rated at 30 horsepower, I have run it at 150 horsepower.
Figure 39. Apparatus furnishing direct currents of high tension, producing undamped electrical oscillations of high frequency. (This is also shown in [Fig. 27]). Apparatus built in 1895.
By the way, and this is a painful reflection, it was Schmidt and I who developed this type of frame and this general arrangement which is universally adopted now -- a base, with the magnets cast below, split at the center line, and a corresponding upper part. That is now used everywhere. I remember years ago, some of my friends, Messrs. Crocker and Wheeler, started with those long magnets and I told them, "The sooner you throw these away and adopt this construction, the better it will be for you." They have got it now; it is all right.
Counsel
How is this machine [Fig. 39) shown in connection with that?
ÆTHERFORCE
64
Work With Alternating Currents
Tesla
This dynamo [Fig. 39], you see, is a two-phase machine; that is, I develop from it currents of two-phase. Now, there are four transformers, you see them down here [lower left of Fig. 39], that furnish the primary energy. From these two phases I develop four phases. [However,] this involves something else which I have referred to before; namely, an arrangement which enables me to produce from these alternating currents direct currents and undamped -- absolutely undamped isochronous oscillations of any period I like.
This is accomplished in the following manner: The secondaries of the four transformers could each develop 44,000 volts. They were specially built for me by the Westinghouse Company. They could, however, be connected in such a way that each would give 11,000 volts, and then I would take these 11,000 volts and these four phases and commutate them by a commutator consisting of aluminum plates, or aluminum segments, which were rotated in synchronism with the alternator. Then I obtained a continuous pressure; that is, direct current of a tension of 44,000 volts, and with these 44,000 volts I charged my condensers. Then by discharging the condensers, either through a stationary gap or through a gap with a mechanical interrupter, I obtained any frequency I desired, and perfectly undamped waves. This arrangement was installed in 1901 in my wireless plant at Long Island, with which I was to telephone around the world.
Counsel
Who built that machine?
Tesla
The Westinghouse Company, [under direction of] Mr. Albert Schmidt, Superintendent. It was especially built for me and furnished to my laboratory on Houston Street.
While I was with the Westinghouse Company, I did two things in addition to bringing my motors to them. I had discovered that Bessemer steel was a much better material for transformers and motors than the soft iron which was previously used. When I came to Pittsburgh, my motors gave results which their motors could not at first produce, and I told them that I had used Bessemer steel. I discovered, in following up the analysis of the steels which were used, that the Bessemer was not steel but really soft iron. The Westinghouse people then adopted my suggestion. At first, Mr. Shallenberger and other electricians there objected very much, but I persuaded them and when the transformers were built we found that we could get 2 1/2 times the output we got before.
ÆTHERFORCE
ser s
Si Damped Waves ~
65
The Westinghouse people kept a secret for a
time
and no one understood how they could make
trans for-
but all
was to use the Bessemer steel, on my
on, instead of the soft iron the General Electric and
people used. Mr. Westinghouse e
ally requested me
efforts with Mr. Schmidt and
the des of his
and we did so. We evolved this design, introduced
the
which are pressed on the armature, and
of
s out with Mr.
, and
it. I nk
like that, for my
You have
of the use of that
Street. In what way was it used?
ne at Houston
Tesla
I used s machine, as I said, either to
alter-
nat currents and then interrupt them with a
cal
break at
high peaks of the wave; or, I used alternat
currents and interrupted them with an i
ng
break
ng a
number of teeth. Or, I generated con-
tinuous currents commutating the
tension ternating
currents of
transformer. At that time I had two trans-
formers from which I obtained a constant
sure,
the
condenser, and produced undamped waves of any
wanted. As to the machine here [ . 39J, that is the way it
It was for the generat of cont
elec
force and production of
waves from 1895
and on.
purpose
s was it connected up to for the
Tesla
I was
same as shown here [ . 38]. It was con-
nected to the condensers, and these condensers were discharged
a primary which excited the
; the antenna was
i
in the secondary. At other
s we scha
the
condensers rectly so that I could use
antenna without
the
Counsel
In the same way did you note the waves?
ion of these
ÆTHERFORCE
66
Work With Alternating Currents
Tesla
We did, of course, only in most cases the instrument of
was different. When I
with these con-
or undamped, waves,
in this way, I usually
went
frequencies. I
[at] a very few
thou
but that gave me a smaller
Such a machine
you have to operate at high f
power.
Counsel
What do you mean
s?
Te
I mean frequencies of 30,000, 40,000, 50,000, or someth 1 that.
189S?
by means of that
, you
undamped waves of
about 50,000 into that antenna at Houston Street in
not in 1895. Late in 1895 the machine was furnished
to operate in early 1896. That when I
to
Then you did this, that I
of,
1896?
Tesla
Yes, from 1896 to 1899,
Counsel
When you used
s like that in your antenna, was
your antenna tuned or untuned?
Te 1
I could not use it untuned. That would be absurd.
1
What form of device did you use, and where did you use
it, for
the
of these oscillations or waves
in the antenna?
ÆTHERFORCE
Condenser Discharges; Damped Waves -
67
Tesla
I suppose I had hundreds of devices, but the first device that I used, and it was very successful, was an improvement on the bolometer. I met Professor Langley in 1892 at the Royal Institution. He said to me, after I had delivered a lecture, that they were all proud of me. I spoke to him of the bolometer, and remarked that it was a beautiful instrument. I then said,
"Professor Langley, I have a suggestion for making an improvement in the bolometer, if you will embody it in the principle."
I explained to him how the bolometer could be improved. Professor Langley was very much interested and wrote in his notebook what I suggested. I used what I have termed a small-mass resistance, but of much smaller mass than in the bolometer of Langley, and of much smaller mass than that of any of the devices which have been recorded in patents issued since. Those are clumsy things. I used masses that were not a millionth of the smallest mass described in any of the patents, or in the publications. With such an instrument, I operated, for instance, in West Point -- I received signals from my laboratory on Houston Street in West Point.
Counsel
This was then the machine that you used when working with West Point?
Tesla
I operated once or twice with it at that distance, but usually as I was investigating in the city. My work at that time was to prepare for the development of a commercial plant, and with me the question was not to transmit signals, but to see what intensity I could get to put me in position to calculate out my apparatus, the dimensions and the forms, before I began the undertaking. It was nothing but preparatory work for the construction of a commercial plant, and I demonstrated its practicability through my experiments, a plant which was to accomplish much more than all others.
Counsel
What was the horsepower activity in the oscillating circuits when you used this machine?
Tesla
Usually something like 50 horsepower, and I would get, I should say, approximately 30 horsepower in the antenna; that
ÆTHERFORCE
68
Work With Alternat
Currents
is, I would get 30
in the oscil
rcui t.
1
I understood a little while ago when you made the state-
ment of using several thousand horsepower put
a conden-
ser, you could take out of the condenser a mill horsepower.
I
if you
the same condition with s machine.
Yes; I charged
with 40,000
When it
full, I
suddenly,
a short
which gave me a very
rate of oscillation. Let
us suppose that I had
in the condenser 10 watts. Then,
for such a wave there is a flux of energy of (4 x 04)2, and
s is multiplied by the
of 100,000. You see, it
may go into thousands
s of horsepower.
What I wanted to suddenness of the dis
was, did that
upon the
Yes. It is merely the electrical
Ie
or a hammer. You accumulate energy
a long dis-
tance and then you del
th a tremendous suddenness.
The distance
ch the mass moves is small -- the
pressure immense.
Counsel
Did you find that that was the best condition for transtt energy without the use of wire?
Tesla
No, I did not use that method when I was
energy. I used on in the production of those freaks for
I have been called a magician. If I had used merely un-
would have been an ordinary e
ian like
Counsel
You have Did you static?
some delicate
struments.
those burning out on account of
ÆTHERFORCE
Condenser Discharges; Damped Waves ~
69
Tesla
My dear sir, I burned out so many instruments before I discovered what was the matter with them! They burned out instantly until I learned how to make them so that they could not burn out. Yes, that was a great trouble in the beginning.
Counsel
Did you succeed in getting them so they would not burn out?
Tesla
Yes. If lightning struck close by, it would not burn out my instrument that has a millionth of the smallest mass used in the instruments of others.
.D
.1\J.iV
FIG. 165.
rOOOOOOO) 'Sf
Figure 40. Apparatus and method of conversion by condenser discharges applicable to both alternating and direct currents. Described in lectures before the Franklin Institute and the National Electric Light Association early in 1893. Illustrated in Martin book, Fig. 165, pp. 302-317.
This [Fig. 40] is a systematic representation of the various ways which I gave in my lecture before the Franklin
ÆTHERFORCE
70
Work With Alternating Currents
Institute and the National Electric Light Association, embodying the general arrangements for the obtainment of continuous waves, undamped or damped waves, from direct and alternating current supply. On the one side [right] you have direct, on the other side alternating current supply. Some electricians have had difficulties in operating some of this apparatus. I had none. I can take an ordinary circuit of 50 volts and produce from it absolutely undamped oscillations and never have the slightest difficulty about it.
Figure 41. Illustrating one of the early experiments with a tuned transformer in the laboratory at 35 So. Fifth Avenue.
Figure 42. Another experiment illustrating one of the early experiments with a tuned transformer in the laboratory at 35 So. Fifth Avenue. (Article by Martin ["Tesla's Oscillator and Other Inventions"'], Century Magazine, April 1895, Fig. 9, p. 926.)
ÆTHERFORCE
er s
s; Damped Waves ~
71
Now I come to a few pieces of apparatus which I used
the Houston Street
and the South Fifth Avenue labo-
I have here
41J what you might call a
I emp
usually another secondary and had my con-
densers on the table. You see one of the coils in action.
This is a tuned
which responds to e
c
waves which are
the room.
Counsel
This is be used as a receiver of waves?
Te
Yes.
Th s
t shown in Fig. 42] was used in the labo-
on
Fifth Avenue. Here [large rcular sc pos
on
coil] is the tuning table with the condensers,
a thick
, and another secondary wire. Somet s I
operate with two
and I would tune the first ci
to one and the
to the other. Here [re
to
nets in back of room] you see some of my historical
Professor Fairf Id Osborn[*] came once to my
said to me, "Why on earth do you keep in s
I had all of this apparatus, 400 pieces, absolutely
and offered to take it over to the Museum. But I
heed s advice, and it is gone.
* Editorial note:
Fairfield Osborn, Dean,
of Pure Science,
Columbia College in Seth Low
of New York. Osborn wrote
in part, ar have
lege President upon my mind two
matters which
to
very
rst is connected
with Mr. Hill
with Mr.
New York.
have
is considered the
mathematician in this
country, and
seems to be little doubt that Mr.
is
elec-
trician. They both are in a measure connected with Columbia through
lectures here, and
the fact that Mr. Tesla at Professor
fessor Crocker's invitat
his first electrical lecture in
that we have already establ
a sympathetic relation with these
men. r
an afternoon recently with Tesla, and regard him as one of
most dis
men I have ever met. r happened to meet Professor Crocker shortly
afterwards, and learned from him that he had spoken to you in regard giving
Tesla an Honorary
I would like to support this in the most earnest
manner. Poulton [
. of
at Oxford] tells me that Tesla was covered
with honors while in England
France. We certainly must not allow
other
University to anticipate us in honoring a man who lives under our
In response to this, President Low recommended, in a letter dated
5,
1894, to the Trustees, that the honorary degree of LL.D. should be conferred on
Tesla. The degree was awarded in June, 1894.
Source: Columbia
Archives
ÆTHERFORCE
72
Work With Alternating Currents
Counsel
Where were the waves sent from?
Tesla
The whole room was energized by electromagnetic waves and the receiver responded at any place in the hall. The hall was bigger than this room [shown in Fig. 42], twice as long, and anywhere the intensity of action was the same. These discs [vertical, on top of tuning table] were, I think, about 14 or 15 inches in diameter, and you could see the streamers [shown as white between the discs] anywhere in the room. In a hall twice as long as this, wherever I placed the instrument, it would respond to the electromagnetic waves.
Counsel
In this particular instance you are speaking of, the waves were generated right there at 35 South Fifth Avenue?
Tesla
Yes.
Counsel
Was that the apparatus in which you had the primaries running entirely around the room?
Tesla
Yes. This was shown to many people and societies.
This [Fig. 43] shows the first single step I made toward the evolution of an apparatus which, given primary oscillations, will transform them into oscillations capable of penetrating the medium. That experiment, which was marvelous at the time it was performed, was shown for the first time in 1894. I remember the incident perfectly. I called Mr. Edward Adams, the banker, to come and see it, and he was the first man to observe it and to hear my explanation of what it meant.
This coil, which I have subsequently shown in my patents Nos. 645,576 and 649,621, in the form of a spiral, was, as you see, [earlier] in the form of a cone. The idea was to put the coil, with reference to the primary, in an inductive connection which was not close -- we call it now a loose coupling -but free to permit a great resonant rise. That was the first single step, as I say, toward the evolution of an invention which I have called my "magnifying transmitter." That means, a circuit connected to ground and to the antenna, of a tremendous electromagnetic momentum and small damping factor, with
ÆTHERFORCE
Condenser Discharges; Damped Waves -
73
all the conditions so determined that an immense accumulation of electrical energy can take place.
Figure 43. Apparatus in action illustrating the first step in the evolution of the magnifying transmitter in the laboratory at 35 So. Fifth Avenue. (Article by Martin ["Tesla's Oscillator and Other Inventions"], Century Magazine, April 1895, Fig. 15, p. 932.)
It was along this line that I finally arrived at the results described in my article in the Century Magazine of June 1900. [Fig. 43] shows an alternator; not the alternator that was furnished for my laboratory on Houston Street -- that was another one, [but] at 35 South Fifth Avenue [and] operated on the same principle. Here [lower left] are the condensers,
ÆTHERFORCE
74
Work With Alternating Currents
primary, and all the rest. The discharge there was 5 or 6 feet, comparatively small to what I subsequently obtained. I have produced discharges of 100 feet, and could produce some of 1,000 feet if necessary, with the greatest facility.
Counsel
Mr. Tesla, at that point, what did you mean by electromagnetic momentum?
Tesla
I mean that you have to have in the circuit, inertia. You have to have a large self-inductance in order that you may accomplish two things: First, a comparatively low frequency, which will reduce the radiation of the electromagnetic waves to a comparatively small value, and second, a great resonant effect. That is not possible in an antenna, for instance, of large capacity and small self-inductance. A large capacity and small self-inductance is the poorest kind of circuit which can be constructed; it gives a very small resonant effect. That was the reason why in my experiments in Colorado the energies were 1,000 times greater than in the present antennae.
Counsel
You say the energy was 1,000 times greater. Do you mean that the voltage was increased, or the current, or both?
Tesla
Yes [both]. To be more explicit, I take a very large self-inductance and a comparatively small capacity, which I have constructed in a certain way so that the electricity cannot leak out. I thus obtain a low frequency; but, as you know, the electromagnetic radiation is proportionate to the square root of the capacity divided by the self-induction. I do not permit the energy to go out; I accumulate in that circuit a tremendous energy. When the high potential is attained, if I want to give off electromagnetic waves, I do so, but I prefer to reduce those waves in quantity and pass a current into the earth, because electromagnetic wave energy is not recoverable while that [earth] current is entirely recoverable, being the energy stored in an elastic system.
Counsel
What elastic system do you refer to?
Tesla
I mean this: If you pass a current into a circuit with
ÆTHERFORCE
Condenser Discharges; Damped Waves -
75
large self-induction, and no radiation takes place, and you have a low resistance, there is no possibility of this energy getting out into space; therefore, the impressed impulses accumulate.
Counsel
Let's see if I understand this correctly. If you have radiation or electromagnetic waves going from your system, the energy is wasted?
Tesla
Absolutely wasted. From my circuit you can get either electromagnetic waves, 90 percent of electromagnetic waves if you like, and 10 percent in the current energy that passes through the earth. Or, you can reverse the process and get 10 percent of the energy in electromagnetic waves and 90 percent in energy of the current that passes through the earth.
It is just like this: I have invented a knife. The knife can cut with the sharp edge. I tell the man who applies my invention, you must cut with the sharp edge. I know perfectly well you can cut butter with the blunt edge, but my knife is not intended for this. You must not make the antenna give off 90 percent in electromagnetic and 10 percent in current waves, because the electromagnetic waves are lost by the time you are a few arcs around the planet, while the current travels to the uttermost distance of the globe and can be recovered.
This view, by the way, is now confirmed. Note, for instance, the mathematical treatise of Sommerfeld, [*] who shows that my theory is correct, that I was right in my explanations of the phenomena, and that the profession was completely misled. This is the reason why these followers of mine in high frequency currents have made a mistake. They wanted to make high frequency alternators of 200,000 cycles with the idea that they would produce electromagnetic waves, 90 percent in electromagnetic waves and the rest in current energy. I only used low alternations, and I produced 90 percent in current energy and only 10 percent in electromagnetic waves, which are wasted, and that is why I got my results.
* Editorial note: Sommerfeld, Arnold N., ·Uber die Ausbreitung der Wellen
in der drahtlosen Telegraphie," Annalen der Physik, March 16, 1909 (Vol. 28, No.4), pp. 665-736.
ÆTHERFORCE
v. Apparatus for Transformation by Condenser Discharges; Continuous Waves
Figure 44. One of the many forms of mercury circuit controllers described in various U.S. Patents.
Figure 45. Hermetically enclosed mercury circuit controller with compact oscillatory transformer. Described in U.S. Patent No. 609,245 of August 16, 1898.
ÆTHERFORCE
Discha Si Continuous Waves ~
77
44 (verso).
One of the many forms of mercury circuit controllers. Described
in u.s. Patent Nos.:
609,245 of August
609,246
609,247
609,248
609,249
"
609,251
16, 1898, application filed December 2, 1897
" ,
28, 1898
" ,
" March
12,
" ,
"
"
", "
"
" ,
June
3, 1897
611,719 " October 4,
December 10, 1897
613,735 " November 8, "
19, 1898.
Tesla
This [Fig. 44] shows a further
in the direc-
tion of perfect
a way of making and bre
the current,
and illustrates one
the simplest forms of my apparatus,
which was special built with a mercury interrupter i
of cons
That was
from an
circuit
y and could stand a current of 20 or
25 amperes. It was a very compact instrument. I had dozens
these instruments,
obtained ei
on the same;
were all is
in 1898.
The next hermetically [ a motor, e
I
was to enclose the mercury break
45] • You see, here [
46, overleaf] is
de
this
ley.
In this
[referring to the cross
is
a jet of mercury, and there are
around which make and break the current. The whole is encased
hermetically. Here I have a German-silver cup that is ckel
on the ins , and there is a
d magnet outs
which holds the mercury jet stat
while the pulley
tates. I could
this instrument about 2,000
very nicely, and was a machine that would
an
of
about 1 ki
It was a fairly effi
instrument, per-
80 percent of the energy of the
was obtained in
the secondary_
47] come to another
That was
another
of the
of
currents of very
An
rnator was difficult to construct; if
one went into too h
I
became inefficient and
worthless. But, in this way, I was able to
any
up to 200,000 per second, or more, in a perfectly reliable
manner, and I could
a couple of kilowatts output very
easily. [*] That was especially built for telegraphy,
te
, and similar experiments.
* Editorial note: In the article, "Dr. Nikola Tesla and His Achievements"
Samuel Cohen,
the Electrical
magazine, February 19
(pp. 712, 713,
),
4 shows an
having a similar external
appearance and it is described as handling
(37 kilowatts).
ÆTHERFORCE
78
Work With Alternating Currents
No. 609,245.
(110 Model.)
A
It .TESLA.
Patented Aug. 16, 1898.
ELECTRICAL~IRC.lUT CONTROLLER.
» - (.&ppli<a&iaa &Iod
11, 11IW7.)
A
fiKola U.rta, ./IHII1nhJ
6~ ~. ~ yt?~.J~
Figure 46. Diagrammatic illustrations of hermetically enclosed mercury break described in U.S. Patent No. 609,245 of August 16, 1898.
ÆTHERFORCE
Condenser Discharges; Continuous Waves -
79
Figure 47. Large mercury circuit controller of high frequency (telegraphic and telephonic experiments) .
The arrangement was simply this. I had a number of studs with cups which were insulated, 24 if I recollect rightly. In the interior was a mechanism that lifted the mercury, threw it into these cups, and from these studs there were thus 24 little streamlets of mercury going out. [*] In the meantime, the same motor drove a system with 25 contact points, so that for each revolution I got a product of 24 times 25 impulses, and when I passed these impulses through a primary, and excited with it a secondary, I got in the latter complete waves of that frequency.
Counsel
What frequency, then, did you get in your secondary?
Tesla
Oh, I could get in this, 600 per revolution.
Counsel
You mean 600 trains?
Tesla
No, 600 waves. Assume then, 600 impulses per revolution and suppose that I rotated it 100 times per second [6,000 RPM]; then I would get 600 times 100, or 60,000 primary
* Editorial note: This controller mechanism is described in Tesla u.s. Patent
No. 611,719.
ÆTHERFORCE
80
Work With Alternating Currents
impulses [per secondJ, and in the secondary a frequency of 60,000 complete cycles. The primary impulses were unidirectional. They came from the direct current source, but in the secondary they were alternating -- full waves.
Counsel
How persistent were those waves?
Tesla
They were entirely persistent. I had 60,000 per second absolutely undamped waves; they could not be damped.
Figure 48. Drawing Interior arrangement of large mercury circuit controller of very high frequency. (1899)
I want to show you [Fig. 48J the general arrangement in such an instrument, except that this does not exactly illustrate the interior of the other one [Fig. 47J. But, you can readily see a pump that takes the mercury up, and then the mercury flows out against this stud, and as these arms rotate they break the mercury stream and interrupt the current.
ÆTHERFORCE
Condenser Discharges; Continuous Waves -
81
That [Fig. 48] was another type. I had probably 50 or 60 different instruments; in fact, I spent a little fortune on these devices, but some of them have been very valuable, and I do not know but that they will take an important place in the art. They are used very extensively.
The other day, some time ago, a German concern, in recognition of my inventions, made me a present of a very nicely developed interrupter which they had been manufacturing along the lines of my patents. My patents expired; they used the inventions and built up a business, and felt that at least they ought to give me one instrument, and they did. It was very nice.
Counsel
This then, as operated by you, produced undamped waves. Will you tell us just what use you made of it?
Tesla
Oh, I used it just exactly as I used the high frequency alternators. I would energize the primary circuit, and then in the secondary connect the antenna. You see, with an apparatus about 18 inches in diameter, I could get 2 kilowatts in undamped waves.
Counsel
When was this?
Tesla
These instruments all were made, practically all -- I had perhaps 40 or 50 of them -- prior to 1899. When I came to my plant on Long Island, I d i d some further work on them, but I used the old casings and simply changed the interior construction.
There was one construction I had, a very fine thing in which I did not produce any streams. It was so devised that the mercury filled these pockets, and I had 24 little droplets coming out of these places. Then, on the other hand, I had curved arms running around and forcing mercury out under small pressure due to a difference in the length of two columns in the curved arm. I had just the drops meeting, and there was no mercury flowing out in reality. There was simply mercury touching mercury, the contacts being at a distance of about 1/64 inch. These devices worked very well indeed. I have this little instrument from Germany -- of course the Germans do everything so thoroughly -- it is very reliable. I can pass through it regularly 20 amperes, and it works well -- no trouble at all. This [Fig. 48] is a little bit different in
ÆTHERFORCE
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