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Aberdeen
Edinburgh
Glasgow
Belfast
Dublin Liverpool
IRELAND
ENGLAND
London
Southampton
O
Poldhu
Montreal
DOMINION
OF
CANADA
UNITED
STATES
New York
Baltimore
O
Boston
Wellfleet
Brooklyn
Philadelphia
Washington
LABRADOR
Halifax
Transmission No.1 Dec. 12 1901
66
64
2 March, 1902
"3 Dec. 22 1902
64 4 Jan. 19 1903
In 200 miles the curvature of Earth is ten thousand feet.
In 2,100 **
NEWFOUNDLAND
Table Head
St.Johns
64
64
64 ** 110 miles
Queensto
A 1,551 miles W. of Poldhu
*B
B 2,000 miles W. of Poldhu
ATLANTIC
OCEAN
Curvature of Earth
Lisbon
CAPE BRETON
Nova Scotia
110 Miles
αι
MID OCEAN
PORTUGAL
Paris
FRANCE
Madrid
SPAIN
Maiseilles
POLDHU
Cornwall
N FRONTISPIECE, the repetition in No. 1 of the group of three dots,
I'
S, illustrates the stream of signals that were sent out from Poldhu,
England, and which Marconi heard in the telephone at Cape Race, New-
foundland. Three short marks combined with a longer one, as shown
in No. 2, represent the code designation for the letter V, a favorite
experimenting signal with wireless-telegraph workers. The dots and
dashes in No. 3, from Table-Head, say in the alphabet of the European
telegraphs "first msg (message) shore to shore"; and in line No. 4 from
Wellfleet, Massachusetts, to Poldhu are Morse characters, such as are
used by American telegraphers, arranged to spell "Roosevelt to Edward."
WIRELESS TELEGRAPHY;
:
ITS ORIGINS, DEVELOPMENT, INVENTIONS,
AND APPARATUS
BY
CHARLES HENRY SEWALL
}
AUTHOR OF PATENTED TELEPHONY," THE FUTURE OF LONG-DISTANCE
COMMUNICATION"
WITH 85 DIAGRAMS AND ILLUSTRATIONS

}
NEW YORK
D. VAN NOSTRAND COMPANY
23 MURRAY AND 27 WARRen Sts.
1903
:
Transportation Library
TK
57-41
.852
COPYRIGHT, 1903, BY
D. VAN NOSTRAND COMPANY
Transpor
1.
PREFACE
4
THE aim of this book is to present a comprehensive
view of wireless telegraphy, its history, principles, systems,
and possibilities in theory and practice. In considering
inventions controversy has been avoided, although the
claims of individual inventors have been carefully defined.
Because of the complexity of the subject a certain amount
of allusion in one part, to matters dealt with in another,
has been inevitable; but it is hoped that such repetition
may prove helpful to the reader. The book itself is de-
signed to be of use both to the general public and to the
technical student.
The author begs to acknowledge to the publishers his
obligation for kind co-operation; to the Century Magazine
for extracts from the article by Mr. McGrath of St. Johns;
and to the Scientific American for extracts and diagrams
from an article by Mr. A. F. Collins.
A
NEW YORK, September, 1903.
CHARLES H. SEWALL.
PROPHECY
DISCOVERY
ACHIEVEMENT
EXPLANATORY
DESCRIPTIVE .
•
TABLE OF CONTENTS.
INVENTORS AND INVENTIONS.
PART I.
PAGE
I
PART II.
PART III.
THE COMPARATIVE MERITS OF Wireless TELEGRAPHY AND OF
TELEGRAPHY BY WIRES AND CABLES, AND
CABLES, AND THE COMMER-
CIAL OUTLOOK FOR EACH.
APPARATUS.
NOMENCLATURE
PART IV.
TRANSMITTERS
WAVE-RESPONSIVE-DEVICES
WAVE-GATES
Shields
CONDENSERS, INDUCTANCE COILS AND KEYS
APPENDIX
INDEX
4
II
24
38
91
•
125
1
143
145
152
168
!
•
179
182
190
226
+
WIRELESS TELEGRAPHY.
PART I.
PROPHECY.
"Canst thou send lightnings, that they may go, and say unto thee,
'Here we are?'”— JOB, 38th chapter, 35th verse.
IN 1632 Galileo wrote a dialogue of which a Latin trans-
lation appeared at Leyden in 1700: Mr. Robert Sabine, in
his work on the Electric Telegraph,¹ rendered into English
a paragraph from the Latin version, wherein Sagredus, one
of the colloquists, is made to say:
"You remind me of one who offered to sell me a secret art, by which
through the attraction of a certain magnet needle it would be possible to
converse across a space of two or three thousand miles. And I said to him
that I would willingly become the purchaser provided only that I might
first make a trial of the art, and that it would be sufficient for the purpose
if I were to place myself in one corner of the sofa and he in the other. He
replied that in so short a distance the action would be scarcely discernible :
so I dismissed the fellow, and said that it was not convenient for me just
then to travel into Egypt or Muscovy for the purpose of trying the experi-
ment, but that if he chose to go there himself I would remain in Venice
and attend to the rest."
In the sixties of the nineteenth century Mr. Sabine
supposed this expression to be a prescient description of
telegraphy with wires. In 1877 it could be better associ-
1 D. Van Nostrand, New York, 1869.
T
2
WIRELESS TELEGRAPHY.
1
}
ated with telephone transmission over a conductor. To-
day, however, we can readily see that Galileo wrote of
"Wireless Telephony," an art not quite arrived. It will
be observed that as translated the words are "to converse,"
not "to signal"; and the correctness in translation is cor-
roborated by the fact of the action at short distance being
undiscernible. Readers of this generation will understand
that between two persons sitting upon the same sofa, tele-
phonic action is not palpable; whereas nearness of sender
and receiver is no bar to the observation of signals.
It may be that Galileo had read the "Prolusiones
Academicae" of Strada, published in 1617, and which de-
scribed communication at a distance by means of two
needles that had been touched with lodestone. These
needles were mounted upon pivots. If either of them were
moved it caused its mate to turn and to point in the same
direction as itself. Possibly Galileo had an independent
vision of wireless communication, seeing farther than
Strada, and dared make of it but guarded mention. It is
only necessary to read Galileo's biography to realize how
disastrous in 1632 might have been the consequences of an
announcement in scientific discovery.
A work entitled "Voyage du Jeune Anacharsis" by the
Abbé Barthélemy, published in 1788, mentions alphabetic
dials, having hands or pointers which were electrically
magnetized; these hands on the clock faces being analo-
gous to Strada's description one hundred and seventy
years before.
James Bowman Lindsay in 1854 made calculations to
demonstrate that stations in England and Scotland could,
without wires, signal across the Atlantic to stations in
America.
3
·
¡
i
•
PROPHECY.
3
Sir William Crookes, 1892, reading a paper entitled
"Some Possibilities of Electricity," said: "Rays of light
will not pierce a wall, nor, as we know only too well, a
London fog; but electrical vibrations of a yard or more in
wave-length will easily pierce such media, which, to them,
will be transparent. Here is revealed the bewildering
possibility of telegraphy without wires, posts, cables, or any
of our present costly appliances." Again he said that
Hertzian rays could be received "on a properly constituted
instrument, and by concerted signals messages in the Morse
code can thus pass from one operator to another."
Tesla (1893) much in the manner outlined by his
patents,¹ predicted the transmission through space and with-
out conductors of electrical oscillations.
Professor Lodge testifies that during the year 1894 Dr.
Alexander Muirhead clearly foresaw the telegraphic im-
portance of the transmission of Hertzian waves.
Professor Ayrton, an English scientist, predicted, in
1897, that the time would come when the man with the
electromagnetic voice in one part of the world would call
to and be heard by the man with the electromagnetic ear
at any other part of the world; and just as housemates
call to one another in the same dwelling would be the
long-distance conversation; excepting that in the latter
communication only the selected ear might catch the
sound.
1 See page 38.
4
WIRELESS TELEGRAPHY.
DISCOVERY.
CONNECTED with electrical science are four great philos-
ophers, Davy, Faraday, Helmholtz, and Hertz, whose
discoveries all but span the nineteenth century; and in-
terwoven with the work of those four discoverers are the
important achievements of Joseph Henry, Lord Kelvin,
Feddersen, Maxwell, Lodge, Edison and Tesla.
Sir Humphry Davy was born in 1778, and consequently
commenced his scientific career with the century. Perhaps
his greatest gift to electrical progress was his pupil Michael
Faraday. The latter, in 1812, happening to be admitted
to one of Davy's lectures, became at first his pupil, then
his amanuensis and assistant, and finally in 1827 succeeded
Sir Humphry as Professor of Chemistry at the Royal
Institution of London. This happy combination in Eng-
land whereby a great teacher was enabled to bequeath to a
disciple equally talented the results of his researches was
subsequently duplicated in Germany when Heinrich Hertz
became assistant to Helmholtz. It was fortunate also
that the early labors of Helmholtz were so timed that he
could avail himself of the work already done by Davy and
Faraday. The death of Helmholtz at an advanced age
in 1894, and of Hertz in the same year as his gifted
master, terminated the work of that remarkable quartet of
scientists.
Chronologically the thread of discovery begins with
Huyghens, a Dutch philosopher (born 1629, died 1693),
i
1
•
DISCOVERY.
5
who was apparently the originator of the undulatory theory
which assumes that light is propagated by the vibrations of
an imponderable medium called ether; and although for
many years after Huyghens the favored idea remained that
enunciated by Sir Isaac Newton-that light consists of
material particles projected from luminous bodies - New-
ton's hypothesis has since been rejected,' and that of
wave-motion is universally recognized.
In 1807, when Sir Humphry Davy decomposed potash
by electric-battery power there was inaugurated that won-
derfully rapid development in electrical matters which
characterized the nineteenth century. To this develop-
ment Davy gave the initial impulse His was a genius so
versatile that Coleridge said, "If Sir Humphry had not
been the first chemist of his age, he probably would have
been its first poet." At the age of twenty-three Sir Hum-
phry's scientific knowledge and his eloquence were at-
tracting in London brilliant audiences. He delivered a
series of lectures on Agricultural Chemistry," which
made an epoch in that science; he discovered the exhila-
rating effect produced by the breathing of nitrous oxide
gas; his lecture on "Some Chemical Agencies of Elec-
tricity" obtained for him the prize of the French In-
stitute; and the invention of the miner's safety lamp
brought a baronetcy and world-wide fame. Six years sub-
sequent to his electrical decomposition of potash, Davy
used the galvanic battery of the Royal Institution, consist-
ing of two thousand pairs of zinc and copper plates, and
produced between two carbon electrodes a sparking dis-
1 The Newton hypothesis, sometimes called the "corpuscular theory of light," was suc-
cessfully controverted by Dr. Thomas Young in 1773, who re-established "the undulatory
theory."
6
WIRELESS TELEGRAPHY.
charge four inches long in the air, and seven inches long
in a vacuum. This constituted the first voltaic arc.
Faraday in 1831 discovered the existence of a current in
a hollow coil of wire whenever a permanent magnet or an
electromagnet was introduced into, or withdrawn from,
its interior. He discovered also the principles of inductive
influences between electric currents, and found that dif-
ferent insulating media had varying capacities to produce
inductive effects. Maxwell quotes Faraday as saying, "It
was allowable to admit that the propagation of electricity
might be effected by means of the ether, because it was
probable that if this ether existed it could fill another
office besides serving as a medium for the transmission of
light."
In 1842 Professor Joseph Henry of Princeton, United
States, drew attention to the fact that the phenomena
accompanying the discharge of a Leyden jar was oscillatory
in character, and Helmholtz in 1847 confirmed this. Lord
Kelvin in 1853 demonstrated mathematically the oscilla-
tory effect, and Feddersen in 1859 proved it by experiment.
Hermann Helmholtz was born at Potsdam, Prussia, in
1821, and was consequently beginning his life-work when
Faraday had reached middle age. Like Davy, Helmholtz
was a genius of great versatility. He was first a surgeon
in the army, and during his medical practice invented the
ophthalmascope, still an indispensable piece of apparatus for
the oculist. He was metaphysician, mathematician, physi-
ologist, and physicist. The most famous writing of Helm-
holtz was his essay on "Conservation of Energy," which
firmly established that law; for by reason of diversified
knowledge he was able to bring to its demonstration facts
from all departments of science.
In the same paper
¡
!
i
"
DISCOVERY.
7
Helmholtz proclaimed the oscillatory nature of a discharge
from the Leyden jar; and explained that the oscillations
would grow weaker and weaker until their entire energy
was damped out by opposing resistances. By analyzing
complex tones Helmholtz made science explain music, and
his investigations in the laws of sound did much toward
the establishment of modern wave theories. His paper on
the vortex motion in fluids was probably the basis for
Lord Kelvin's hypothesis that all matter is made up of
small vortices of fluid, each rotating about a hollow space.
It also helped to formulate Maxwell's proposition.
During the period from 1863 to 1873 there was developed
the philosophical demonstration by James Clerk Maxwell,
that the propagating medium of electromagnetic waves was
identical with that of light; and although he was not able
to prove it by experiment, Maxwell was the first who fully
understood what is now admitted to be the true nature
of electrical phenomena. Thus by 1873 it had been
established that light with a velocity of 186,000 miles per
second consisted of a wave motion produced in a medium
called "ether," which Maxwell defined as "a material sub-
stance of a more subtle kind than visible bodies, and
supposed to exist in those parts of space which are
apparently empty."
Recapitulating, Huyghens in the seventeenth century had
proclaimed the existence of ether and the undulatory mo-
tion of light, and this was confirmed by Dr. Thomas Young
in the eighteenth. In the nineteenth century, Henry,
Helmholtz, Kelvin, and Feddersen demonstrated that the
discharge of a Leyden jar was oscillatory. Maxwell con-
tended that if the velocity of propagation of electromag-
netic disturbance was the same as that of light, which had,
8
WIRELESS TELEGRAPHY.
he thought, been proved, then the media through which
either light or electricity was transmitted occupied the
same space and must be identical; and the difference be-
tween their resultant manifestations depended only upon
the lengths of their respective waves. Thus the matter
stood at the death of Maxwell in 1879.
As has been said, Heinrich Hertz was a pupil of Helm-
holtz. From 1883 to 1885 Hertz occupied at Kiel, Ger-
many, the chair of theoretical physics, and in the latter year
was appointed Professor of Physics in the Technical High
School at Carlsruhe. During the delivery of a lecture at
this institution, and while experimenting with a Leyden jar
and two flat coils of wire, Hertz observed that the discharge
of the jar through one of the coils would induce appreciable
current in the other coil (although the jar was a very small
one), provided that there was a spark gap in the inducing
coil. This accidental discovery came to a man who has
since proved to be perhaps the most brilliant experiment-
alist and the ablest physicist the world has seen. Hertz
demonstrated that the reasoning of Maxwell was correct;
the experiments proving conclusively that the medium which
is vibrated by light and the medium which is vibrated by
electromagnetism is one and the same; that each travels
with the same velocity; that waves of electromagnetic
disturbance (now called "Hertzian" waves) are reflected
from conducting surfaces and refracted by dielectric sub-
stances; and are plainly analogous to the reflection of light
from polished surfaces and its refraction through glass
prisms.
""
"This great discovery of Hertz," says Professor Lodge,
was by no means his only one. In addition to his well-
known essays on electric waves, which marked an epoch in

1.
DISCOVERY.
experimental physics, no less than eighteen papers, all
original, and all important, were, by him, contributed to
German periodicals."
After the experiments at Carlsruhe, Hertz in 1889 was
called to the chair of physics in the University at Bonn.
His health failed, however, and he died at Bonn in 1894.
He was the first understandingly to transmit electric waves
through ether; and is the most important figure in the
history of Wireless Telegraphy. From his discovery in
1886, that etheric vibrations would result from the passing
of sparks across an air-gap, began the development of
electric transmission without conductors.

X
10
WIRELESS TELEGRAPHY.
From a photograph, by courtesy of the Century Company.
Fig. 2.-Signal Hill, St. John's, Newfoundland. X, Room in which the Message
from Cornwall was received.
ACHIEVEMENT.
II
ACHIEVEMENT.
THE record of operative electric telegraphs begins in
1774 with that of Lesarge at Geneva, Switzerland, and
prior to 1837 twelve had been constructed.
In July, 1837, Steinheil operated in England a telegraph
line twelve miles long, which, besides its two terminal
points, was provided with three intermediate, or way, sta-
tions. He used but one wire, employing the earth as a
return circuit. There were alarm-bells for "calling," and
the signals could be read either by sound, or by ink-marks
recorded upon paper.
In 1838 Professor Joseph Henry, of Princeton, making
with an electrical machine and Leyden jar a one-inch
spark in the top room of his residence, set up induced cur-
rents in the cellar of the same building.
During that year Steinheil endeavored, although without
success, to utilize the two rails of a steam tramway as a
telegraph circuit, but suggested the possibility of doing
away altogether with conducting wires.
Professor Morse, who had conceived his idea of the tele-
graph in 1832, did not succeed in operating it until 1838.
His plan was the most practical of any brought forward,
and proved the most successful; but he was by no means,
as is popularly supposed, the originator of the electric tel-
egraph with wires. There seems, however, to be no doubt
but that he was the very first to signal without wires; for
on December 16th, 1842, he sent a wireless telegram
12
WIRELESS TELEGRAPHY.
•
across a canal eighty feet wide; and in November, 1844,
Mr. L. D. Gale, acting under instructions from Professor
Morse, made wireless signals across the Susquehanna
River at Havre de Grâce, a distance of nearly one mile.
In the latter experiment Mr. Gale used, as a source of
energy, six pairs of plates in the form of a galvanic
battery. He found that the best results were obtained
when on each side of the river two plates were immersed
near its bank, and were connected by an insulated wire
stretched along each shore for a distance three times as
great as that which measured either path of the crossing
signals.
The few chroniclers of wireless telegraphy have all
spoken with respect and affection of Mr. James Bowman
Lindsay. Several years after Mr. Gale's experiments on
the Susquehanna River, Lindsay, having no knowledge of
what Morse had done in America, reached the same results
in Scotland. It is said that by gradually increasing his
distances, Lindsay succeeded at last in signaling across
the Tay where the river is two miles wide. In 1854
Lindsay took out an English patent, of which the follow-
ing brief is from the Abridgements by the British Com-
missioners of Patents:
"This invention consists of a method of completing the circuit of elec-
tric telegraphs through water without submarine cables or submerged
wires extending across such water, water being the connecting and con-
ducting medium for the electric fluid.
"The two wires respectively connected with the battery and signal
instrument on one side of the water are attached to metal balls, tubes, or
plates placed in the water or in moist ground adjacent to the water. The
same arrangement is placed on the other side of the water; and the for-
ward as well as the return current passes between the respective plates.
"It is preferred to place the plates on one side of the water at a greater
ACHIEVEMENT.
13
distance apart than the distance across the water; but in case this is not
practicable, the battery power must be augmented, and the size of the
immersed plates increased. It is also necessary to place the plates for the
forward current opposite to each other and the plates for the return cur-
rent opposite to each other."
Though a man of learning, Lindsay had little worldly
wisdom. He was one of the best linguists, and for many
years employed himself upon a dictionary of fifty lan-
guages in one book. He foresaw and accurately predicted.
the universal employment of electric light and electric
power. He thought that by his own plan of wireless
telegraphy it would be possible to span the Atlantic
Ocean. Lindsay was born in 1799, and died in 1862, re-
siding chiefly at Dundee, Scotland. He was a bachelor,
and his life was one of consistent and continuous self-sac-
rifice to science. It is said that during the year 1835 he
lived in one room, which was illumined, however, by an
electric lamp whose installation was the work of his own
hands. In 1859 he read a paper before the British Asso-
ciation on the subject of "Telegraphing without Wires,"
and among his hearers were Faraday and Sir William
Thompson, now Lord Kelvin.
While Lindsay was not an
original discoverer in wireless telegraphy, he was a notable
pioneer; and his unselfish devotion to learning has won
for him deserved distinction.
The invention of the telephone in 1876 and 1877 fur-
nished a detector of great delicacy, and immediately after
its discovery novel electrical phenomena were noted. The
author in 1877 was an observer of those remarkable induc-
tive effects upon neighboring circuits during the progress
of experiments made with Edison's "Singing Telephone
over a wire extending from New York to Saratoga Springs.
"}
•
14
WIRELESS TELEGRAPHY.
During that trial I had a Bell telephone receiver in cir-
cuit upon a telegraph wire in my residence on the east
side of the Hudson River at Albany. The wire to which
the Bell telephone was connected ran parallel in Albany
with the transmitting line for possibly three hundred feet;
but at no point were the respective circuits less than thirty
feet apart. That particular Edison apparatus transmitted
simply tones, no words. The receiving record of the Sing-
ing Telephone was a series of peculiarly harsh and scrap-
ing sounds, so that from the notes of a good soprano singer
at the transmitter there were audible at the singing re-
ceiver nothing but the different pitches of those tones, all
the refinements of sound being lost. Upon the unattached
circuits and with a Bell telephone receiver, however, the
harsh features were eliminated; and while no articulate
word could be distinguished, the musical flow was accurate,
smooth, and pleasing. Inductive effects from the same
Singing Telephone were also manifest at Providence, R.I.,
probably by reason of the proximity in New York City of
the wires leading to Providence, and those connected with
Saratoga.
At
In 1882 Mr. William H. Preece, Engineer-in-Chief of
Government Telegraphs in England, succeeded in signaling
across the Solent from England to the Isle of Wight.
two different points plates immersed in the sea near one
shore were put in line with similar plates near the opposite
shore; and upon each side two of the plates were electri-
cally connected by an over-land conductor. The arrange-
ments of the circuits was the same as that used by Morse
in 1842, and by Lindsay in 1854; but for apparatus Mr.
Preece had an advantage over his predecessors in that he
could use a receiving telephone to detect signals; and he
ACHIEVEMENT.
15
also improved upon former practice by employing as a
transmitter, and in place of a contact key, a rapidly vibrat-
ing reed called a "buzzer," signals appearing at the receiv-
ing end as long and short buzzing sounds. At other times
and localities in England Mr. Preece made transmissions
in a similar way.
The year 1882 was also that during which Professor
Dolbear in America filed his application for United States
Letters Patent 1 to protect devices for wireless signaling.
His patent is further discussed under "Inventors and In-
ventions." The distances over which he succeeded in
sending impulses are variously reported to have been from
half a mile to thirteen miles.
Mr. Edison (1885), using just such inductive effects as
were observed in 1877, when his Singing Telephone was
tried, signaled through space to a moving train from a
wire beside the railway.
The crowning achievement was that of Hertz in 1886.
Across the little gap in a ring of wire suspended in a room
(there being no electrical contact with the charging appara-
tus) Hertz made tiny sparks appear, as the result of the
passage across another and longer spark gap of the oscilla-
tory discharge from a Leyden jar.
Calzecchi Onesti about 1886 observed the coherency
among metal filings produced by the impulsive discharge
of a previously electrified wire or coil.
Second in importance only to Hertz is the connection
with Wireless Telegraphy of Dr. Oliver Joseph Lodge.
This eminent scientist, born in England in 1851, became
Professor of Physics at the new University of Liverpool in
1880, and during 1887 was elected a Fellow of the Royal
1 Printed in full in the Appendix. See also Edison Patent of 1885, p. 96.
16
WIRELESS TELEGRAPHY.
}
Society. At the date of Hertz's first etheric transmis-
sion, his English contemporary was conducting experiments
along the same lines, and Hertz said that in time Lodge
would undoubtedly have reached the same results as him-
self. Between the fil-
ings tube of Onesti,
1886, and that of Bran-
ly, 1891, there inter-
venes an experiment of
Dr. Lodge in 1889,
described by him to the
Institution of Electri-
cal Engineers of Lon-
don in 1890. He had
observed "that two
knobs sufficiently close
together, far too close
to stand any voltage
such as an electroscope
can show, would, when
a spark passes between
them, actually cohere,
conducting, if a single

S
Fig. 3.
B
voltaic cell was in circuit, an ordinary bell-ringing cur-
rent." With permission there is here presented from
Dr. Lodge's "Signalling through Space without Wires,"
the diagram shown as Fig. 3, and the following descrip-
tion :
“The experiment of the syntonic Leyden jars can be conveniently
shown with the double knob or 1889 coherer. The pair of knobs are
arranged to connect the coatings of the receiving jar (a large condenser
being interposed to prevent their completing a purely metallic circuit),
ACHIEVEMENT.
17
and in circuit with them is a battery and bell. Every time the receiving
jar responds syntonically to the electric vibration of the other jar, the
knobs cohere (if properly adjusted) and the bell rings. If the bell is
free in air it continues ringing until the knobs are gently tapped asunder;
but if the bell stands on the same table as the knobs, especially if it rests
one foot on the actual stand, then its first stroke taps them back instantly
and automatically, and so every discharge of the sending jar is signaled
by a single stroke of the bell. Here we have in essence a system of
very distinctly syntonic telegraphy, for the jars and their circuits must be
accurately tuned together if there is to be any response. A
A very little
error in tuning, easily made by altering the position of the slider (see s,
Fig. 3), will make them quite unresponsive unless the distance between
them is reduced."
Much of the history of wireless telegraphy after 1889
is set forth in detail in succeeding divisions of this work.
Briefly, Branly (1890-1891) made the filings coherer
that is sensitive to Hertzian waves. Dr. Lodge in 1893,
having learned of Branly's results, commenced a series of
experiments, one of which led to inclosing the filings in a
vacuum, and another to the making of a more positive de-
coherer than was obtained by merely mounting the electric
bell upon the base of the filings tube. In 1894 Lodge
delivered his famous lecture reviewing the work already
done with Hertz's oscillators, with Branly's coherer, and
by himself. In 1895 was accomplished the undertaking
of Count Popoff of Russia, described under "Inventors and
Inventions." In the same year Captain Jackson, by direc
tion of the British Board of Admiralty, passed electrical sig-
nals between ships. In 1896 Marconi came to England,
and signaled across a space of one hundred yards at the
British Post Office in London. Soon afterwards he made
a successful trial of two miles overland on Salisbury Plain.
In May, 1897, a distance of nine miles over water was
attained by Marconi, and from that time his signaling dis-
18
WIRELESS TELEGRAPHY.
tances were gradually increased until he spanned the
ocean.¹
Guglielmo Marconi was born at Bologna, Italy, on April
25th, 1874. His father is an Italian nobleman, and his
mother of Irish nationality. He studied at Leghorn under
Professor Rosa, and afterward under Righi at the Univer-
sity of Bologna, of which institution he is a graduate, and
has been interested in wireless telegraphy since his six-
teenth year.
He is of middle height, slim in figure, with
blue eyes and brown hair, and his bearing indicates rather
a nervous temperament. Upon November 25th, 1901, Mr.
Marconi sailed from England, his destination being an ex-
perimental station which had been established at Cape
Race, some eighty miles from St. Johns, Newfoundland.
When interviewed as to this journey by reporters, he said
to them that there was a possibility of signaling over three
hundred miles of sea, and felt quite sure that two hundred
miles would be reached. During that same November,
however, the author was privately assured by an official of
the Marconi Company in New York City, that within
thirty days there would be a record of transatlantic sig-
naling. This prediction was confirmed by the event.
There had been constructed at Poldhu, England, and at
Cape Cod, Massachusetts, stations with powerful machinery
1" Its progress has not been slow. Five years ago my system worked satisfactorily over
a distance of about two miles. Since then its range has been rapidly increased, until, a few
months ago, by means of improved and attuned apparatus, a distance of over two hundred
miles was successfully bridged, and wireless communication at this distance is now an
everyday occurence. A certain commercial application of my system has already been
achieved. In all, seventy ships carry permanent installations, and there are over twenty
land stations in Great Britain and on the continent of Europe, besides several in this coun-
try. To what further extent the system may be commercially applied is not easy to foretell.
My recent successful experiments between Poldhu and St. Johns, however, give great
hopes of a regular transatlantic wireless telegraph service in the not too distant future."
From Marconi's prefatory note in Century of March, 1902.
ACHIEVEMENT.
19
for generating electricity; and especial attention had been
paid to the vertical conductors or wave-gates by which
the ether waves were emitted and received. These struc-
tures consisted at either station of twenty poles, each two
hundred and ten feet high, by which a large number of
wires were supported. The poles and wires, both in Amer-
ica and England, had been damaged by storm, in the latter
country the structure at Poldhu being practically destroyed.
Neither had been fully replaced. The aerial distance
between Poldhu and Cape Cod was some six hundred
miles farther than that between Poldhu and Cape Race.
Before leaving England, Marconi had arranged with his
Engineer at Poldhu to send signals in a certain manner
after a date which would be fixed by cablegram, and upon
December 9th Poldhu station was instructed (by cable) to
begin sending signals every day at three o'clock in the
afternoon, and to continue until six o'clock evening, these
hours by Newfoundland time being respectively 11.30
A.M. and 2.30 P.M. The signals agreed upon were rep-
etitions of the letter S (by telegraphic code three short
marks - - -), to be repeated a certain number of times and
then discontinued, for intervals of three minutes' duration.
On Thursday, December 12th, 1901, at 12.30 P.M.
Marconi and an assistant, Mr. Kemp, received the first
transatlantic signals. During the appointed hours these
signals were detected a number of times, and upon the
following day, Friday, were again noticed. The public
announcement of this event caused great excitement.
Marconi was the recipient of congratulatory messages from
all over the world, and during the next few weeks he was
met everywhere with a series of ovations, the most nota-
ble, perhaps, being the dinner held in his honor at the
20
WIRELESS TELEGRAPHY.
Waldorf-Astoria Hotel in New York City by the American
Institute of Electrical Engineers.
On the first day of March, 1902, Marconi arrived in
New York City from England; and declared that he had
received on a moving vessel at a position fifteen hundred
and fifty-one miles from the sending point ¹an actual mes-
sage in words; also that he had witnesses to prove beyond
peradventure that he had done this through space without
wires or cables. Further, that at a distance two thousand
and ninety-nine miles¹ from the sending point he had
received signals more or less distinct but unmistakable.
The vessel conveying Marconi and his telegraphic devices
was the steamship Philadelphia. Upon the following
day, March 2d, arrived at New York the Umbria of the
Cunard line; and although the latter ship all the way
across the Atlantic had been in the same receiving zone as
the Philadelphia, and was actually nearer the Cornish
coast during the time the latter was receiving messages
from England, not a word or signal of those messages was
impressed upon the apparatus of the Cunard steamer;
although with the Campania and Etruria, whose instruments
were attuned with those upon the Umbria, perfect com-
munication was had. The inventor contended that two
sets of instruments of different electrical tone might work,
without interference, within five inches of each other; that
he had two hundred and fifty tunes which would prevent
"tapping the circuit"; that the secrecy of the message
was complete.2
¹ See frontispiece.
2 "It seems to be a matter of popular belief that any receiver within effective range of
the transmitter is capable of picking up the messages sent, or, in other words, that there can
be no secrecy of communication by my system. Were this so, a very important limitation
would be imposed upon the practical usefulness of the system; but by the introduction of
important and radical modifications in the original system, and by a systematic application
ACHIEVEMENT.
21
In the communication between Cornwall and the steam-
ship all the messages were one way, all from the station to
the vessel. Mr. Marconi explained that while the Phila-
delphia's equipment admitted the reception of signals, it
had not a sufficiently powerful transmitting apparatus to
reach to England; but that the Cornwall station could put
forth enough energy to overcome that distance.
So far as is generally known, there was from the time of
the messages to S. S. Philadelphia in March, 1902, no
further signaling across the Atlantic until October 31st of
the same year, when transoceanic messages were received
upon the Italian warship Carlo Alberto while that vessel lay
at anchor in the harbor of Sydney, Nova Scotia. The wire-
less telegrams were transmitted from Poldhu. The distance
covered is estimated at twenty-three hundred miles. The
Carlo Alberto had been placed by the King of Italy at Mar-
coni's disposal as an assistance to wireless experiments.
It was on Sunday, December 21st, 1902, one year and
nine days after the letter S from Poldhu was heard at
Cape Race, that Marconi announced the transmission of
three entire messages from Table Head station at Glace
Bay, Cape Breton, to Poldhu station in Cornwall, England,
viz. one from the Governor General of Canada to King
Edward of England; another from the Commander of the
Carlo Alberto to the King of Italy; a third to the Times,
in London, from its special correspondent. The latter was
in the nature of formal evidence, and read as follows:
Being present at its transmission in Signor Marconi's Canadian station,
I have the honor to send the Times the inventor's first wireless transatlantic
message of greeting to England and Italy."
of the principles of electrical resonance, this objection has, in very great measure, been
overcome.”—From Marconi's prefatory note in Century of March, 1902.
22
WIRELESS TELEGRAPHY.
Upon January 19th, 1903, the Marconi Station at
Wellfleet, Cape Cod, Massachusetts, transmitted the follow-
ing :
HIS MAJESTY, EDWARD VII.,
LONDON, ENGLAND.
In taking advantage of the wonderful triumph of scientific research and
ingenuity which has been achieved in perfecting a system of wireless tele-
graphy, I extend on behalf of the American people most cordial greetings
and good wishes to you and to all the people of the British Empire.
THEODORE Roosevelt.
Wellfleet, Mass., Jan. 19, 1903.
The reply which follows was returned by cable :
SANDRINGHAM, JAN. 19, 1903.
THE PRESIDENT,
WHITE HOUSE, WASHINGTON, AMERICA.
I thank you most sincerely for the kind message which I have just re-
ceived from you, through Marconi's transatlantic wireless telegraphy. I
sincerely reciprocate in the name of the people of the British Empire the
cordial greetings and friendly sentiment expressed by you on behalf of the
American Nation, and I heartily wish you and your country every possible
prosperity.
EDWARD R. AND I.
Mr. Marconi explained that his apparatus not being
quite ready for long-distance operation, the message from
President Roosevelt was directed to be relayed by Table
Head, Nova Scotia, station. It was found, however, that
the Poldhu station in England had been able to copy the
telegram while it was being sent to Table Head.
Upon January 21st, 1903, the Italian Government asked
for an appropriation of $150,000 to erect, under the direc
tion of Marconi, wireless telegraph stations with a capacity
of six thousand miles, for service between Italy and South
America.

ACHIEVEMENT.
23
Fig. 4. Outside the Cabot Tower on Signal Hill, St. Johns, Newfoundland.
1. Mr. Kemp. 2. Mr. Marconi. 3. Mr. Paget. 4. The keeper of the station.
From a photograph. Copyright by James Vey. By Courtesy of the Century Company.
24
WIRELESS TELEGRAPHY.
EXPLANATORY.
WHAT were the devices and methods employed to ac-
complish the transmissions? How were they used? Why
did they produce the results desired?
Coherer. The prime factor is the coherer, which in
Fig. 5 to show clearly the position of the grains g, that
constitute the kernel of the whole matter, is drawn some-
what out of proportion. Those metallic grains are inclosed
in a glass tube, G G G G, between two silver plugs, P and
P'; to which plugs are connected platinum wires, W and
W'. When proper action is taken at a transmitting station

g
G
G
G
Fig. 5.
the grains g at a receiving point cohere. If, after cohesion
is established, the glass tube be gently tapped, the grains
will separate, i.e., will decohere. When these minute par-
ticles are together they close an electric circuit, producing
an effect which, on account of the delicacy of the instru-
ment, is rather weak, but which may be made through a
relay to close another electric circuit sufficiently powerful
to produce either an audible signal, as when a telephone or
sounder is used, or to exhibit a visual one, as when ink
EXPLANATORY.
25
marks are made upon paper tape. It is also possible, by
means of this second and stronger electric circuit, auto-
matically to set in motion, immediately after the mark has
been made, a vibrating hammer such as is used in electric
door-bells, and which the English call a "trembler." By
directing the vibrating hammer against the coherer, or
against anything to which the coherer is secured, the grains
g may be separated, and the electric devices will then be in
position to make another mark.¹
Signals. — In telegraphy marks, or "signals," are made
of two decidedly differing lengths, designated "the long
and the short." Combinations of long and short marks.
are used for letters.
Upon the paper ribbon of the wireless
telegraph recorder the name of the genius who signaled
from Poldhu to Cape Race would appear thus:
M
A
R
C
N I
Circuits. Fig. 6 is a diagram devoid of many details.
which will be supplied hereafter in other drawings. Upon
the receiving side letters H, B', and R represent respect-
ively a coherer and the battery and relay of the weak
electric circuit before noted. On the transmitting side B is
a battery, and K a key for closing the primary circuit of a
sparking appliance of which P is the primary winding and
L the secondary part of a "step-up
step-up" induction coil. SG
stands for the spark-gap. Upon each closure of the key K,
there is produced sufficient strain to cause sparks to fly
between terminating electrodes T T of the secondary coil
1 See Fig. 3, Part I., p. 16, and Fig. 31, Part II., p. 98, and accompanying descriptions.
26
WIRELESS TELEGRAPHY.
L. A A' are vertical wires which in the first transatlantic
transmission were respectively maintained in position by
masts at Cornwall and by a kite in Newfoundland. They
are sometimes called "antennae." It will be seen that at
Transmitter" one of the electrodes T is in connection
with the high wire A, while the other is put to earth at E.
When key K is brought onto the anvil V, an electric cir-
cuit is made, and the current in it by inductive influence is
CC


Transmitter
B
→ K
V
A
T
Receiver
So
leeeeeee
еее
a
G
T
о
H
B
R
E
Fig. 6.
E'
communicated to the secondary coil and raised in pressure.
The sparking across S G becomes the center of a disturb-
ance from which waves spread in all directions. These
are picked up by any vertical wire as A' and pass through
P' to earth at E'. In the receiving apparatus, the sparking
(exceedingly weak by reason of dissipation of the energy
on the long journey), being "stepped up" from P' to L'
is now through the filings at H, causing them to cohere,
the relay R is energized through coherer, and by a local
circuit (not shown in Fig. 6) a mark is made.
EXPLANATORY.
27
In a general way the action just described is what took
place at Newfoundland when the Poldhu station sent the
letter s, three short marks. It was also the method
employed to send from Poldhu to the S. S. Philadelphia at
sea. In the trial to Newfoundland the receiving station
used an ordinary hand (listening) telephone in place of the
relay R shown in Fig. 6, a telephone receiver being much
more sensitive than a relay. Upon the Philadelphia, how-
ever, ink-marks were recorded upon paper tape.
TUNING.
It will be remembered that immediately after the Corn-
wall-Newfoundland demonstration, Marconi, upon being
asked if it were not probable that he received the sig-
nals from some ship or station other than the Cornwall
plant, replied, "It is impossible; I was tuned only for
Poldhu."
Theory of Electrical Resonance. To understand the
devices used for electrical tuning it will be necessary to
consider first the theory by which "electrical resonance" is
explained, and then the analogies that are used to demon-
strate that theory.
It is supposed that all matter, solid, liquid, or gaseous,
is made up of molecules; and that these molecules are
combinations of atoms of different chemical elements, atoms
being quantitatively the smallest divisions of matter, and
an element an individual substance, as distinguished from
those substances which are a combination of two or more
elementary kinds of matter. The density, and to an extent
the weight, of any substance depends upon the nearness of
the molecules to one another. In air, or other gases, they
28
WIRELESS TELEGRAPHY.
are widely separated. In metals they are very close to one
another. In either substance there is between them space,
and that space is said to be permeated by "ether." Scien-
tists have not yet added a fourth dimension to length,
breadth, and thickness; but the three divisions of matter
are now supplemented by a fourth, and they speak of the
solid, the liquid, the gas, and the ether.
Analogy of Jelly. - An analogy to ether and matter is
furnished by the contents of a vessel containing a mixture
of lead bullets and jelly. Imagine the jelly to be so tremu-
lous as to be capable of vibrating from a disturbance by
which the bullets, being much more inert, move so little as
to be practically still. Further imagine that the jelly be
made to oscillate, being first pushed forward and then
pulled backward, very rapidly. It will readily be under-
stood that before the forward motion of the jelly has over-
come the inertia of the bullets, the backward one will have
reversed and neutralized that motion.
Analogy of a Pool of Water. If a person standing upon
one side of a pool of water strikes into the water with a
paddle each time in the same direction and at regular
intervals, so that he maintains a rhythmical beat, it will be
found that after each stroke and up to a certain maximum
the waves caused by the paddle will augment in size; but
that if strokes be afterward made at irregular intervals the
waves will decrease in volume. Discord will tend to undo
the work that has been done by rhythm.
Analogy of Spring and Timber. Suppose, as in Fig. 7,
a stick of timber L is suspended from a rigid support E by
EXPLANATORY.
29
E
www
a spiral steel spring C, and that the timber be given a push
upward, or a push downward, then it will vibrate a certain
number of times per minute. If it be pushed gently it will
move slowly through a small space,
if pushed forcibly it will move
more quickly through a greater
space; but the oscillations in a
unit of time will always be the
same. This rate of vibration is
governed by the resiliency of the
spring C and the weight of the load
L. If the resiliency of the spring
be increased, or the weight of the
timber be decreased, the rate of
vibration will be quickened. If C
be made less springy, or L be
máde heavier, the rate will be
slower. To change the rate by altering either or both of
the conditions has been called by clockmakers "regu-
lating"; Scientists of to-day call it “tuning.”

Fig. 7.
Advantages of Harmonious Action. The pushing if
continued should, in order to get the best results, be in
accord with the rate of the apparatus; that is to say, the
strokes must be exactly as many per minute, or exactly
one-half as many, or twice as many, or some even division
or multiple of the rate. Irregular strokes will tend to stop
the motion just as in the case of the paddle and waves.
Now set the timber L upon the surface of the water on
one side of a pool of considerable width, and so that the
crest of a small wave will just uplift it. By moving the
timber and timing its oscillations the rate may be ascer-
30
WIRELESS TELEGRAPHY.
A- String
E- String)
tained. If the water upon the far side of the pool be struck
with the paddle time after time at the timber's rate, waves
will spread from the paddle; and although only a few faint
ripples may reach the timber-and-spring-device they will
be attuned to it, and, if the strokes be regularly continued,
each wave will tend to increase the length of the oscillation
of the spring.
At Poldhu a powerful source of vibration was sending
waves into the ether, and the little ripples were caught at
Newfoundland by a delicate receiving apparatus which had
been adjusted to vibrate at the same rate as the Cornwall
transmitter.
Fig. 8 represents a guitar, which instrument may be
used to demonstrate the fact that air waves when set in

Frets 1 2 3 4 5 6 7 8
Fig. 8.
motion by one string of a certain note will cause to vibrate
another string tuned to the same note. In trying this
experiment, to avoid troublesome stretching of strings, it
will be advisable to keep about a half-tone below "concert
pitch." When the A string is brought to such tension as
to be in its proper relative tune with the E string, it will
sound in unison with the latter, whenever the E is stopped
by the finger pressing the E firmly against fret 5.
EXPLANATORY.
31
Mechanical Tuning. To ascertain if the two notes are
in unison, cut a piece of medium writing-paper to a size
about five-eighths of an inch square, fold it one way in the
middle and set it astride of the open A string. When the
two strings are properly tuned, and the E string is struck
below the stopped point at fret 5, the paper on A will vi-
brate so strongly as to be perceptible both to the eye and
also by a buzzing noise to the ear. If now the E string be
stopped either on the 4th or the 6th fret, or if the tension
on the A string be increased or decreased in the slightest
degree, the paper will remain motionless, no matter how
violently the E string may be set in motion.
Such an
operation is sometimes called "mechanical tuning," and
more accurate results may be obtained than by the usual
method of listening.
Referring back to the spring and timber demonstration
in a pool of water (Fig. 7), the weight of the A string is
analogous to that of the timber, the tension upon it to the
elasticity of the spring. The stopped E sets up waves of
exactly the same rate as those to which A is attuned.
In the pool the waves are of water moving a few feet
per second. In the guitar demonstration the waves are of
air moving at the rate of 1400 or 1500 feet per second.
In the transatlantic transmission of Marconi the waves
were of ether, traveling 186,000 miles per second.
Electrical Resonance in Practice. It is hoped that the
foregoing illustrations will make clear the principles of
electrical resonance. The practice is illustrated in Fig. 9.
Transmitting Side. B is a battery or other source of
energy. P is the primary winding of an induction coil,
32
WIRELESS TELEGRAPHY.
:
and K the key of transmission. L is a secondary wind-
ing complementary to the primary P. T T are electrodes
of S G the spark-gap. C is a condenser. P2 and L2 are
respectively the primary and secondary of another induc-
tion coil in the transmitting apparatus which may, by way
of distinction, be called a transformer, its function being
to convert the waves that oscillate in the spark-gap to a
still higher intensity. D is a variable inductive resistance
B
Transmitter
a
ZK
еееее
T
T
S
G
A
A'
100000


d
eeeee
No
E
0000
C
Receiver
H
о
TB'
E'
R
Fig. 9.
placed in the circuit between the vertical wire or wave-gate
A and the earth at E. At the transmitter the condenser
C is analogous to the resiliency of the stopped E string of
Fig. 8, and L 2 and D represent the inertia of the spring,
or the load. By moving the pointer d the load may be
changed, and by giving the condenser more or less surface
the force of oscillation may be intensified or diminished.
EXPLANATORY.
33
Receiving Side. - Looking now at the receiver in Fig. 9
A' is the vertical wire. The changeable inductive resis-
tance D' and primary coil P 3 of a transformer is placed
in that part of the wave circuit which reaches from A' to
the earth at E'. D' with P3 constitute the load, being
analogous to the timber in Fig. 7. Inductive transference
of the waves from P3, to L3 and L4, increase the intensity
of the faint ripples which come through space from the
vertical wire A of transmitter. C' is a condenser placed
in a bight of the long wire which forms the secondary
winding of L3, L4. This condenser (C') represents the
steel spring C of Fig. 7. In tuning the receiver, either
the load D' P3, or the spring C' may be changed to in-
crease or decrease the rate of the receiver. Infinitesimal
waves passing through the gaps in metallic powder of H
will cause those grains to cohere, and so close the electric
circuit H B' R. Relay R translates the signal into a more
powerful local circuit, which actuates an ink-marking regis-
ter, and, at the same time, causes a "tapper"¹ (not shown
in Fig. 9) to strike the glass tube H and "decohere" the
powder. The apparatus is then ready for another signal.
LOCALIZATION.
The following extract of a letter from Dr. A. Fleming,
which was published in the London Times, October 4,
1900, will serve to define and illustrate the term used as
a heading for this division:
Two operators at St. Catherine's, Isle of Wight, were instructed to send
simultaneously two different wireless messages to Poole, Dorset, and with-
out delay or mistake the two were correctly recorded and printed down at
¹ Similar to the device shown in Fig. 31, Part II.
34
WIRELESS TELEGRAPHY.
the same time in Morse signals on the tapes of the two corresponding
receivers at Poole.
In this first demonstration each receiver was connected to its own
independent aerial wire, hung from the same mast. But greater wonders
followed. Mr. Marconi placed the receivers at Poole one on the top of the
other, and connected them both to one and the same wire, about forty feet
in length, attached to the mast. I then asked to have two messages sent
at the same moment by the operator at St. Catherine's, one in English and
the other in French. Without failure, each receiver at Poole rolled out its
paper tape, the message in English perfect on one, and that in French on
the other. When it is realized that these visible dots and dashes are the
result of trains of intermingled electric waves rushing with the speed of
light across the intervening thirty miles, caught on one and the same short
aerial wire and disentangled and sorted out automatically by the two ma-
chines into intelligible messages in different languages, the wonder of it all
cannot but strike the mind.
Your space is too valuable to be encroached upon by further details, or
else I might mention some marvelous results exhibited by Mr. Marconi
during the same demonstrations, of messages received from a transmitter
thirty miles away, and recorded by an instrument in a closed room merely
by the aid of a zinc cylinder, four feet high, placed on a chair.¹ More
surprising is it to learn that, while these experiments have been proceeding
between Poole and St. Catherine's, others have been taking place for the
admiralty between Portsmouth and Portland, these lines of communication
intersecting each other; yet so perfect is the independence that nothing
done on one circuit now affects the other, unless desired.
Mr. Marconi has insisted that his transmitted signals
are perfectly localized. He has even challenged Professor
Lodge and Mr. Preece either to interrupt or to intercept
them, offering the use of his company's stations should
those eminent scientists desire to experiment. If, however,
they try, and fail to catch the signals, it does not follow
that human ingenuity will never succeed in doing so. Un-
less, indeed, Marconi has means other than those generally
known to the electrical profession, it is believed that "syn-
tony," as it is called, is a combination not difficult to unlock.
1 See Fig. 37, Part II.
1
EXPLANATORY.
35
.
The company's experts claim first, that their spark-gap
will not be known to unauthorized persons; again, that
their coherer may be made so insensitive that it will an-
swer only to a considerable force at the sending station,
and that all energies less than theirs will not affect it;
again, that in addition to a knowledge of the force
required it will be necessary for the intercepter to know
the self-induction (the load) and the condenser effect
(the resiliency). It would seem, however, that it is not
necessary to ascertain each of these facts, but merely
to find the rate of beat to which the coherer will respond,
and that may be any combination of load and spring
which will produce the right wave-motion. If, then, a
would-be tapper-in exposes a number of coherers differ-
ently sensitized, and with each coherer connected with a
maximum or a minimum condenser effect, he will need
only to vary the load upon each coherer, which may be
very rapidly done. Having found the "rate," he may
"interrupt” as well as
as well as "intercept."
QUANTITATIVE DATA.
Power. In quantitative terms authorized statements
in the March Century, 1902, give the energy used in the
Cornwall-Newfoundland transmission as being supplied by
a 40 h. p. alternating current dynamo, having an initial
pressure of two thousand volts which was "stepped up"
to fifty thousand volts. There were at Poldhu twenty¹
masts, each two hundred and ten feet high, the conductors
upon each mast being in electrical connection with all the
others. The metal spheres forming high-tension terminals
¹ See Fig. 66, Part IV.
36
WIRELESS TELEGRAPHY.
of the transformers were separated by a distance which
varied from about inch to about inch. At the
4
10
8
10
Newfoundland station the aerial wire was elevated by a
kite to an altitude of about four hundred feet; its swaying
varied the altitude, which variation was a serious obstacle
to the uniform reception of signals. The coherer used
was a small glass tube one and one-half inches long and
one-tenth inch internal diameter. Within the tube were
tightly fitted two silver plugs separated inch. This lit-
tle space was partly filled with a mixture of nickel and sil-
ver filings to which a trace of mercury had been added.¹
30
Comparative Speed of Signal Propagation by Wireless
Telegraph and by Cables. - Marconi has said to his Eng-
lish stockholders that whereas the speed of the submarine
cable is directly affected by length of transmission, the
wireless system is not in the least affected by distance.
That "it is just as easy to work at high speed across the
Atlantic or Pacific as to work across the English Channel."
He is confident of establishing direct communication be-
tween England and New Zealand.2 He says that the curv-
ature of the earth does not affect the signals, and that
ultimately he will be able to send them all around the
world.
Marconi's Conclusions. From that excellent article in
the Century Magazine of March, 1902, already mentioned,
there is a summing up of Marconi's conclusions at that
date.
Wireless telegraphy is most effective over marine areas.
Over low lying country two-thirds of marine distance may
1 See description of “silver coherer" in Part IV.
2 See chart, Fig. 39.
1...
ง
EXPLANATORY.
37
be reached, but over ordinary diversified country the po-
tency of vibrations is reduced to one-half what it is at sea.
High hills do not constitute an obstacle, but the ground
itself retards the signals. The vibrations seem to reach
slightly farther in fog than in fine weather. Atmospheric
conditions do not seriously affect the signals. Electrical
disturbances are their only foe. Indications are that a
pole two hundred feet high gives the best results. With a
a balloon or kite elevated to four hundred feet, the wire
must necessarily be very slight, and the ceaseless swaying
of the upholder also interferes. A horizontal wire (as an
antenna) gives no energy. No advantage in marine signal-
ing is gained by setting a pole on a high hill. Proximity
to the sea is desirable and a low-lying spit of land the best.
Some geological formations are perverse, others are respon-
sive.
V
38
WIRELESS TELEGRAPHY.
TESLA 1
DESCRIPTIVE.
IN WIRELESS TRANSMISSION.
Tesla's Proposed Plan of 1893. Nikola Tesla devoted
himself early to the problem of transmitting electrical
energy without wires, not only for telegraphic, but also for
industrial purposes. In February and March, 1893, he
delivered lectures before the Franklin Institute in Phila-
delphia and the National Electric Light Association in St.
Louis, in which he advanced a plan of wireless transmis-
sion, and expressed his conviction that "it certainly is
possible to produce some electrical disturbance sufficiently
powerful to be perceptible by suitable instruments at any
point of the earth's surface."
In describing his plan in detail he says:
"Assume that a source of alternating currents, s, be connected, as in Fig.
10, with one of its terminals to earth (convenient to the water mains), and

P
cbs
E
Տ
E
Fig. 10.
with the other to a body of large surface, P.
When the electric oscillation
is set up, there will be a movement of electricity in and out of P, and
1 TESLA, NIKOLA, born at Smiljan, Lika, Austria-Hungary, in 1857. A noted physicist
and electrician. He came to the United States in 1884 with a view of developing motors
based on his discovery of the rotating magnetic field; this he completed in 1888. He has in-
vented a number of methods and appliances in the line of electrical vibrations aiming at the
production of efficient light with lamps without filaments, and the production and transmis-
sion of power and intelligence without wires. On his discovery of the action of air or gase-
ous matter when subjected to rapidly alternating electrostatic stresses is based the modern
art of insulating currents of very high tension. He has also constructed steam-engines and
electrical generators (oscillators) with which otherwise unattainable results are obtained. —
Century Dictionary and Cyclopedia, 1895.
WIRELESS TELEGRAPHY.
39
alternating currents will pass through the earth, converging to or diverging
from the point C, where the ground connection is made. In this manner
neighboring points on the earth's surface within a certain radius will be
disturbed. But the disturbance will diminish with the distance, and the
distance at which the effect will still be perceptible will depend on the
quantity of electricity set in motion. Since the body P is insulated, in
order to displace a considerable quantity the potential of the source must
be excessive, since there would be limitations as to the surface of P. The
conditions might be adjusted so that the generator, or source, s, will set up
the same electrical movement as though its circuit were closed. Thus it
is certainly practicable by means of proper machinery to impress an
electric vibration, at least of a certain low period, upon the earth. Theo-
retically it should not require a great amount of energy to produce a dis-
turbance perceptible at great distance, or even all over the surface of
the globe. Now, it is quite certain that at any point within a certain
radius of the source, s, a properly adjusted self-induction and capacity
device can be set in action by resonance. Not only can this be done,
but another source, s,¹ Fig. 10, similar to s or any number of such sources,
may be set to work in synchronism with the latter, and the vibration thus
intensified and spread over a large area; or a flow of electricity produced
to or from the source s,¹ if the same be of opposite phase to the source, s.
Proper apparatus must first be produced, by means of which the problem
can be attacked, and I have devoted much thought to this subject."
In the same lectures he showed a number of novel ex-
periments, among which was the operation of a variety of
devices by using one wire, instead of two as is usual in elec-
trical connections. He continued investigations along these
lines, and in 1898 had already developed apparatus of great
power, giving a pressure of four million volts and dis-
charges extending through sixteen feet, which at that time
were considered remarkable.¹
Tesla's First Two Patents on Methods and Apparatus
for the Wireless Transmission of Energy. - The patents
are numbered 645,576 and 649,621, and were issued
1 See Electrical Review, New York, October 26, 1898.
E
40
DESCRIPTIVE.


:
D
B
M
D¹
B¹
O
Fig. 11.
Diagram of wireless transmission accompanying Tesla's U. S. patents No. 645,576 and
No. 649,621. The transmitter comprises a generator of electric oscillations G, a primary
conductor C, and a secondary coil A B, which is connected to ground and to an elevated
terminal D, and tuned to the oscillations of the generator. The receiving apparatus has a
similarly arranged coil A' D' tuned to the transmitted oscillations, and associated with a
secondary circuit containing the receiving devices. The terminals D and D' are maintained
above the surrounding objects, the height being determined by the amount and quality of
the work to be performed. The length of the grounded conductors A D and A' D' is
preferably made equal to one quarter of the wave length of the oscillations. The trans-
mitter and receiver may be thousands of miles apart.
DESCRIPTIVE.
4I
respectively March 20th, and May 15th, 1900. The origi-
nal application covering both inventions was filed September
2nd, 1897. The system, as described by the inventor in
these patents, is radically different from the Hertzian, both
in the methods and apparatus employed. In the Hertzian
system, the energy is transmitted to the receiver by elec-
tro-magnetic waves which pass out laterally from the
transmitting wire into space. In Tesla's system the energy
radiated is not used, but a current is led to earth and to
an elevated terminal, and the energy is transmitted by a
process of conduction. Quoting from one of his patents:
"It is to be noted that the phenomenon here involved in the trans-
mission of electrical energy is one of true conduction, and is not to be
confounded with the phenomena of electrical radiation which have here-
tofore been observed, and which, from the very nature and mcde of propa-
gation, would render practically impossible the transmission of any appreci-
able amount of energy to such distances as are of practical importance."
The arrangement of his transmitting and receiving
circuits is illustrated in Fig. 11, and will be understood
with reference to the explanatory note.
As characteristic of these inventions the following two
claims may be quoted:
"The method hereinbefore described of transmitting electrical energy
through the natural media, which consists in producing at a generating
station a very high electrical pressure, causing thereby a propagation or
flow of electrical energy, by conduction, through the earth and the air
strata, and collecting or receiving at a distant point the electrical energy so
propagated or caused to flow.
The combination with a transmitting coil or conductor connected to
ground and to an elevated terminal respectively, and means for producing
electrical currents or oscillations in the same, of a receiving coil or conduc-
tor similarly connected to ground and to an elevated terminal, the said coil
or coils having a length equal to one-quarter of the wave length of the
disturbance propagated, as set forth.”
42
WIRELESS TELEGRAPHY.
Description of Transmitter Giving Four Million Volts.—
In describing a special apparatus Tesla says:
"The transmitting apparatus was in this case one of my electrical
oscillators, which are transformers of a special type, now well known and
characterized by the passage of oscillatory discharges of a condenser
through the primary. The source G, forming one of the elements of the
transmitter, was a condenser of a capacity of about four one-hundredths of
a microfarad, and was charged from a generator of alternating currents of
fifty thousand volts pressure, and discharged by means of a mechanically
operated break five thousand times per second through the primary C.
The latter consisted of a single turn of stout, stranded cable of inappreciable
resistance and of an inductance of about eight thousand centimeters, the
diameter of the loop being very nearly two hundred and forty-four centime-
ters. The total inductance of the primary circuit was approximately ten
thousand centimeters, so that the primary circuit vibrated generally accord-
ing to adjustment, from two hundred and thirty thousand to two hundred
and fifty thousand times per second. The high-tension coil A in the form
of a flat spiral was composed of fifty turns of heavily insulated cable No. 8
wound in one single layer, the turns beginning close to the primary loop
and ending near its center. The outer end of the secondary or high-tension
coil A was connected to the ground.
The primary and secondary circuits in the transmitting apparatus being
carefully synchronized, an electromotive force from two to four million volts
and more was obtainable at the terminals of the secondary coil A.”
Curious Phenomena Produced.— Tesla's apparatus seems
to be capable of peculiar actions. He says:
"For example, a conductor or terminal, to which impulses such as those
here considered are supplied, but which is otherwise insulated in space and
is remote from any conducting-bodies, is surrounded by a luminous flame-like
brush or discharge often covering many hundreds or even as much as
several thousands of square feet of surface, this striking phenomenon clearly
attesting the high degree of conductivity which the atmosphere attains
under the influence of the immense electrical stresses to which it is
subjected. This influence is, however, not confined to that portion of the
atmosphere which is discernible by the eye as luminous, and which, as has
been the case in some instances actually observed, may fill the space within
a spherical or cylindrical envelope of a diameter of sixty feet or more, but
reaches out to far remote regions, the insulating qualities of the air being,
1


1-

NIKOLA TESLA.
DESCRIPTIVE.
43
་
as I have ascertained, still sensibly impaired at a distance many hundred
times that through which the luminous discharge projects from the terminal
and in all probability much farther."
The conductivity imparted to the air by these currents
Tesla proposes to utilize in the wireless transmission of
power on an industrial scale.
Transmission of Enormous Energy Over Vast Dis-
tances. From my experiments and observations I con-
clude that with electromotive impulses not greatly exceeding
fifteen or twenty million volts the energy of many thousands
of horse-power may be transmitted over vast distances,
measured by many hundreds and even thousands of miles,
with terminals not more than thirty to thirty-five thousand
feet above the level of the sea; and even this comparatively
small elevation will be required chiefly for reasons of econ-
omy, and if desired it may be considerably reduced, since,
by such means as have been described, practically any
potential that is desired may be obtained and the currents
through the air strata may be rendered very small, whereby
the loss in the transmission may be reduced. It will be
understood that the transmitting as well as the receiving
coils, transformers, or other apparatus may be in some
cases movable - as, for example, when they are carried by
vessels floating in the air, or by ships at sea.'
To express this idea in other language, if one captive
balloon were put at seven miles' elevation over Niagara Falls,
and another balloon at the same height in France, energy
from a dynamo at the former station might without undue
loss in transmission be made to set in motion upon French
territory electric motors, or to supply the power to illumine
electric lamps.
44
WIRELESS TELEGRAPHY.
Tesla's “Telautomata.”
On July 1, 1898, Mr. Tesla
filed an application for another American Patent, No.
613,809. Its first claim is an excellent brief. It reads:
"The improvement in the art of controlling the movements and opera-
tion of a vessel or vehicle herein described, which consists in producing
waves or disturbances which are conveyed to the vessel by the natural
media, actuating thereby suitable apparatus on the vessel and effecting the
control of the propelling engine, the steering and other mechanism by the
operation of the said mechanism as set forth."
Methods Described. The inventor describes a number
of methods for producing waves. The preferred one
seems to be the "passing through the conducting path
currents of a specially designed high frequency alternator,
or, better still, those of a strongly charged condenser," and
then "adjusting the circuit on the moving body so as to be
in exact electromagnetic synchronism with the primary dis-
turbances ;" and he says that in such a way "this in-
fluence may be utilized at great distances."
Application to Warfare. In summing up the many use-
ful purposes to which this invention may be applied, the
pantentee thinks its "greatest value will result from its
effect upon warfare and armaments, for by reason of its
certain and unlimited destructiveness it will tend to bring
about and maintain perfect peace among nations." It may
be inferred that this refers more especially to the moving
and direction of torpedoes.
In the Tesla system methods of electrical conversion by
means of condenser discharges and the so-called "Tesla
coil" play an important part. The earliest records of these
inventions in the U. S. Patent Office date from 1891.
DESCRIPTIVE.
45
Method of Electrical Conversion by Condenser Dis-
charges. This method is described in Patent Number
462,418 of November 3, 1891 (application filed February
4, 1891).
Quoting in the language of the inventor:
"I employ a generator, preferably of very high tension, and capable of
yielding either direct or alternating currents. This generator I connect up
with a condenser or conductor of some capacity, and discharge the accumu-
lated electrical energy disruptively through an air-space or otherwise into
a working circuit containing translating devices and, when required, conden-
sers. These discharges may be of the same direction or alternating and
intermittent, succeeding each other more or less rapidly or oscillating to
and fro with extreme rapidity. In the working circuit, by reason of the
condenser action, the current impulses or discharges of high tension and
small volume are converted into currents of lower tension and greater vol-
ume. The production and application of a current of such rapid oscillations
or alternations (the number may be many millions per second) secures,
B
B
Fig. 12.
D

C
C
G
among others, the following exceptional advantages: First, the capacity
of the condensers for a given output is much diminished; second, the
efficiency of the condensers is increased and the tendency to become heated
reduced; and, third, the range of conversion is enlarged. I have thus suc-
ceeded in producing a system or method of conversion radically different
from what has been done heretofore — first, with respect to the number of
impulses, alternations, or oscillations of current per unit of time, and, second,
with respect to the manner in which the impulses are obtained. To express
this result, I define the working current as one of an excessively small
period or of an excessively large number of impulses or alternations or oscil-
lations per unit of time, by which I mean not a thousand or even twenty or
thirty thousand per second, but many times that number, and one which is
made intermittent, alternating, or oscillating of itself without the employ-
ment of mechanical devices."
46
WIRELESS TELEGRAPHY.
Referring to the diagram in Fig. 12:
“A represents a generator of high tension; B B, the conductors which
lead out from the same. To these conductors are connected the conduc-
tors C of a working circuit containing translating devices, such as incandes-
cent lamps or motors G. In one or both conductors B is a break D, the
two ends being separated by an air-space or a film of insulation, through
which a disruptive discharge takes place. F is a condenser, the plates of
which are connected to the generating-circuit.
The discharges will follow each other the more rapidly the more nearly
the rate of supply from the generator equals the rate at which the circuit
including the generator is capable of taking up and getting rid of the
energy. Since the resistance and self-induction of the working circuit C
and the rapidity of the successive discharges may be varied at will, the cur-
rent strengths in the working and in the generating circuit may bear to one
another any desired relȧtion.
Tesla Coil. This invention is first described in Patent
No. 454,622 of June 23, 1891 (application filed April 5th,
1891). In the description the inventor says:
"To produce a current of very high frequency and very high potential,
certain well-known devices may be employed. For instance, as the primary
source of current or electrical energy, a continuous-current generator may
be used, the circuit of which may be interrupted with extreme rapidity by
mechanical devices, or a magneto-electric machine specially constructed to
yield alternating currents of very small period may be used, and in either
case, should the potential be too low, an induction-coil may be employed to
raise it; or, finally, in order to overcome the mechanical difficulties, which
in such cases become practically insuperable before the best results are
reached, the principle of the disruptive discharge may be utilized. By
means of this latter plan I produce a much greater rate of change in the
current than by the other means suggested, and in illustration of my
invention I shall confine the description of the means or apparatus for pro-
ducing the current to this plan, although I would not be understood as
limiting myself to its use. The current of high frequency, therefore, that is
necessary to the successful working of my invention, I produce by the dis-
ruptive discharge of the accumulated energy of a condenser maintained by
charging said condenser from a suitable source and discharging it into or
through a circuit under proper relations of self-induction, capacity, resist-
DESCRIPTIVE.
47
ance, and period in well-understood ways. Such a discharge is known to be,
under proper conditions, intermittent or oscillating in character, and in this
way a current varying in strength at an enormously rapid rate may be pro-
duced. Having produced in the above manner a current of excessive fre-
quency, I obtain from it by means of an induction-coil enormously high
potentials that is to say, in the circuit through which or into which the
disruptive discharge of the condenser takes place I include the primary of
a suitable induction-coil, and by a secondary coil of much longer and finer
wire I convert to currents of extremely high potential."
With reference to the diagram Fig. 13.
"G is the primary source of current or electrical energy. I have explained
above how various forms of generator might be used for this purpose; but
in the present illustration I assume that G is an alternating-current generator
of comparatively low electromotive force. Under such circumstances
I raise the potential of the current
by means of an induction-coil hav-
ing a primary P and a secondary S.
Then by the current developed in
this secondary I charge a condenser
C, and this condenser I discharge
through or into a circuit A, having
an air-gap a, or, in general, means
for maintaining a disruptive dis-
charge. By the means above de-
scribed a current of enormous fre-
quency is produced. My object is
next to convert this into a working-
circuit of very high potential, for

W
M
CPA
S'
W
Fig. 13.
which purpose I connect up in the circuit A the primary P'of an induction-
coil having a long fine wire secondary S'. The current in the primary P
develops in the secondary S'a current or electrical effect of corresponding
frequency, but of enormous difference of potential.”
Tesla has invented and patented numerous modifications
of apparatus embodying these principles. One of the fea-
tures in his later patents, for which great advantages are
claimed, is a series of tuned circuits of high frequency
exciting one another.
48
WIRELESS TELEGRAPHY.
System of Concatenated Tuned Circuits. In his patent
No. 568,178 of September 22, 1896 (application filed June
20, 1896), the inventor says in setting forth the invention:
"It is well known that every electric circuit, provided its ohmic resistance
does not exceed certain definite limits, has a period of vibration of its own
analogous to the period of vibration of a weighted spring. In order to
alternately charge a given circuit of this character by periodic impulses
impressed upon it, and to discharge it most effectively, the frequency of the
impressed impulses should bear a definite relation to the frequency of vibra-
tion possessed by the circuit itself. Moreover, for like reasons, the period
or vibration of the discharge-circuit should bear a similar relation to the
impressed impulses or the period of the charging-circuit. When the con-
ditions are such that the general law of harmonic vibrations is followed, the
circuits are said to be in resonance or in electromagnetic synchronism, and
this condition I have found in my system to be highly advantageous.
Hence, in practice, I adjust the electrical constants of the circuits so that in
normal operation, this condition of resonance is approximately attained.
Any departure from this condition will result in a decreased output, and
this fact I take advantage of in regulating such output by varying the fre-
quencies of the impulses or vibrations in the several circuits.
Inasmuch as the period of any given circuit depends upon the relations
of its resistance, self induction, and capacity, a variation of any one or more
of these may result in a variation in its period. There are, therefore, vari-
ous ways in which the frequences of vibration of the several circuits in the
system referred to may be varied, but the most practicable and efficient
ways of accomplishing the desired result, are the following: (a) varying the
rate of the impressed impulses of current, or those which are directed from
the source of supply into the charging-circuit, as by varying the speed of the
commutator or other circuit-controller; (b) varying the self-induction of
the charging-circuit; (c) varying the self-induction or capacity of the dis-
charge circuit.
Intensifying Electric Oscillations by Means of Refriger-
ant. Another suggestion from Mr. Tesla is to employ as
a means of increasing the intensity of electric oscillations a
refrigerant, He says that "when a circuit adapted to
vibrate freely is maintained at a low temperature, the
:
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:
ป
F
!
རྩྭ་

THE TESLA WIRELESS PLANT ON LONG ISLAND.
DESCRIPTIVE.
49
oscillations excited in the same are to an extraordinary
degree magnified and prolonged, and that he is thus enabled
to produce many valuable results which have heretofore
been wholly impracticable" The cooling agent may be
any freezing mixture. Liquid air is instanced. In the
transmission of etheric waves, he would apply this refriger-
ant to coils - both at the transmitting and at the receiving
ends. He says that the circuits at either end of the trans-
mission should have the greatest possible self-induction and
the smallest possible resistance. The invention is fully
described in Patent No. 685,012 of October 22, 1901.
(Application filed March 21, 1900.)
Methods of Storing the Energy Transmitted, and Strength-
ening Feeble Impulses. — In another series of patents, bear-
ing the numbers 685,953, 685,954, 686,955, and 685,956,
all granted in 1901, Tesla advances other improvements in
the transmission and utilization of electrical energy. The
fundamental idea underlying these inventions is to store the
energy transmitted in a condenser during any desired time
interval, and to utilize the stored energy, either directly to
operate a receiving device, or to control another circuit
including the same. In a modification of the apparatus
the latter circuit charges a condenser, and the impulses
transmitted are used to control the charge of the con-
denser. In order to effect a charging by the impulses
conveyed from distance, they are commutated either by a
mechanical device or by means of an electric valve with
stationary electrodes. In a special arrangement shown, the
energy accumulated in the condenser is discharged through
the primary of an induction coil, the secondary of which is
used for the purpose of controlling the operation of a
50
WIRELESS TELEGRAPHY.
delicate receiver. In this way almost any degree of sensi-
tiveness which may be desired can be attained. On this
point the inventor says:
"It will be seen that by the use of my invention results hitherto
unattainable in utilizing disturbances or effects transmitted through natural
media may be readily attained, since, however great the distance of such
transmission, and however feeble or attenuated the impulses received,
enough energy may be accumulated from them by storing up the
energy of succeeding impulses for a sufficient interval of time to render
the sudden liberation of it highly effective in operating a receiver.”
Improved Mercury Interrupters. In order to avoid
waste of energy and deterioration of the electrodes, Tesla
has designed a great variety of mercury interrupters, on
which he has obtained a number of patents dated 1897
and 1898. In these devices the circuit is made and broken
in an hermetically inclosed space and the wear of the elec-
trodes entirely prevented, the contact surfaces being con-
stituted of mercury. In some forms an inert gas under
great pressure is employed to improve the action, the
inventor claiming that he has discovered that “a gas under
great compression nearly fulfills the ideal requirements.'
New Methods of Individualization. Instead of relying on
simple tuning, Tesla has developed a new principle, which is
set forth in his last two patents bearing the numbers 723,-
188 and 725,605 (original application filed July 16, 1900).
In this invention the transmitter is made to give two, or
a greater number, of different vibrations, simultaneously or
in a certain order of succession. The receiver again has
a number of tuned circuits, each of which responds to
one of the vibrations of the transmitter, and the arrange-
ment is such that only when all the receiving circuits are
DESCRIPTIVE.
51
affected the indicating instrument is made to operate.
By the use of this principle "a degree of safety against
mutual and extraneous interference is attained, such as is
comparable to that of a combination lock." On the other
hand, any desired number of instruments can be simultane-
ously operated through the earth or other conducting
channel. The improvement is not limited to wireless
telegraphy. "It will be seen," says the inventor, "from a
consideration of the nature of the method, that the inven-
tion is applicable not only in the special manner described,
in which the transmission of the impulses is effected
through the natural media, but for the transmission of
energy for any purpose and whatever the medium through
which the impulses are conveyed.”
-
Marvelous Effects Produced by Oscillators of Great
Power. Early in 1889 Tesla went to Colorado to develop
his methods and apparatus for the transmission of wireless
energy, and to ascertain the laws of propagation of electri-
cal waves through the earth. Upon his return he published
an article which appeared in the "Century" of June, 1900,
in which photographic views of some experiments with one
of his oscillators were shown. It appears that with these
machines there is no limit to the intensity of the effects
and magnitude of the forces produced. According to Tesla
even interplanetary space may be bridged by the terrific
commotions of such an oscillator.
He says:
"However extraordinary the results shown may appear, they are but
trifling compared with those which are attainable by apparatus designed on
these same principles. I have produced electrical discharges, the actual
path of which, from end to end, was probably more than one hundred feet
long; but it would not be difficult to reach lengths one hundred times as
52
WIRELESS TELEGRAPHY.
great. I have produced electrical movements occurring at the rate of ap-
proximately one hundred thousand horse-power, but rates of one, five, or
ten million horse-power are easily practicable. In these experiments effects
were developed incomparably greater than any ever produced by human
agencies, and yet these results are but an embryo of what is to be.
That communication without wires to any point of the globe is practi-
cable with such apparatus would need no demonstration, but through a dis-
covery which I made I obtained absolute certitude. Popularly explained,
it is exactly this: When we raise the voice and hear an echo in reply, we
know that the sound of the voice must have reached a distant wall or
boundary, and must have been reflected from the same. Exactly as the
sound, so an electrical wave is reflected; and the same evidence which is
afforded by an echo is offered by an electrical phenomenon known as a
“stationary” wave that is, a wave with fixed nodal and ventral regions.
Instead of sending sound-vibrations toward a distant wall, I have sent elec-
trical vibrations toward the remote boundaries of the earth, and instead of
the wall the earth has replied. In place of an echo I have obtained a sta-
tionary electrical wave, a wave reflected from afar.
Stationary waves in the earth mean something more than mere tele-
graphy without wires to any distance. They will enable us to attain many
important specific results impossible otherwise. For instance, by their use
we may produce at will, from a sending-station, an electrical effect in any
particular region of the globe; we may determine the relative position or
course of a moving object, such as a vessel at sea, the distance traversed
by the same, or its speed; or we may send over the earth a wave of elec-
tricity traveling at any rate we desire, from the pace of a turtle up to
lightning speed."
One of the experiments produced with a comparatively
small machine of this kind is illustrated in Fig. 14. As
no person could be anywhere in the vicinity when the dis-
play is going on, the picture was obtained by two succes-
sive processes, the image of Mr. Tesla's assistant being
taken at one exposure and the electrical discharges photo-
graphed at another. Combined upon one plate they show
relative sizes of the streams of light as compared with a
human being. An idea of the force and volume of the
sparks may be gained when it is stated that the thick-
!

A TESLA EXPERIMENT IN ELECTRICAL DISCHARGES.
800 AMPERES, SPARKS 23 FEET LONG.
A ROAR LIKE NIAGARA.
DESCRIPTIVE.
53
་
est of them are about 23 feet long, and that a current of
approximately 800 amperes is passing through the air.
The roar of such a discharge can be heard several miles.
Since his return from Colorado in 1901 Tesla has begun
the erection of commercial plants; but since two years
nothing has been published about his work. It is under-
stood that his wireless plant on Long Island is nearing
completion. A photographic view of the same is shown in
the illustration on opposite page. The structure presents
a curious appearance. As to the purpose for which the
plant is designed, nothing has, as yet, been announced by
Tesla. Recently, however, the "New York Sun" in an
editorial authorized by him, stated that "the Tesla oscillator
will deliver to the earth the shock that will be felt and
recorded on its uttermost confines."
Tesla's Sun-Motors. —Fig. 15 and 16 illustrate other
devices by the same inventor. These are called " 'appara-
tus for the utilization of radiant energy."
In Fig. 15, P is a plate exposed to rays, and P'a plate
buried in the ground. C is a condenser, the plates of
which should present as large a surface as possible, the
inventor having ascertained the amount of energy con-
veyed to it per unit of time to be, under otherwise identi-
cal conditions, proportioned to the area exposed or nearly
SO. T and T' are terminals of condenser C. M a relay
magnet or any other device capable of being actuated by
an electric current. d may be composed of two very thin
conducting plates placed in close proximity, and, either by
reason of extreme flexibility, or from the character of
their support, very mobile.
It will be seen that the magnet M, if energized and
54
WIRELESS TELEGRAPHY.
de-energized, will actuate armature a, and, with a pawl and
ratchet movement, turn, one step at a time, the wheel W.
When the condenser C is charged to a certain potential
the dielectric between the strips will break down, and the
condenser discharge its accumulated energy through mag-
net M. When the strain on the dielectric has been re-
lieved the strips t t will resume their normal position.
The originator of this device says that "many useful
applications of utilizing the radiations emanating from the
sun, and many ways of carrying out the same, will at once.
suggest themselves."

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Fig. 15.
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M
R
Application of Preceding to Telegraphy. The applica-
tion of this invention to telegraphy is suggested in Fig. 16,
in which the source S of rays is a "Roentgen tube having
but one terminal k, generally of aluminum, in the form of
half a sphere with a plane polished surface on the front
side from which the rays are thrown off." Interruption
of the generation of the rays at differing intervals may
DESCRIPTIVE.
55
,
serve to produce long or short signals on the relay R.
The tt' of Fig. 15 takes, in Fig. 16, the form of a brush

k
S
T
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S
R
Inventor
Fig. 16.
and segmented wheel. The condenser discharges are
stepped to higher intensities through induction coil, p s.
:
1
56
WIRELESS TELEGRAPHY.
METHODS OF DR. SLABY.
In Mr. Kerr's work on Wireless Telegraphy is a foot-
note to the effect that Dr. Slaby of Charlottenburg, Ger-
many, was present with Mr. Preece in the latter's Bristol
Channel experiments, and had repeated them before the
Emperor of Germany at Berlin. Presumably this refers
to the tests of 1892. Mr. Fahie has recorded that Dr.
Slaby was also present at a Bristol Channel experiment
made by Marconi on May 13th, 1899; and it seems to be
the opinion of the English writers that Dr. Slaby's suc-
cessful trials in etheric transmission were all subsequent
to this latter visit to England.
Controversy Between Slaby and Marconi. — In a lecture
before the English Society of Arts delivered May 15th,
1901, Marconi quotes from a paper read by Slaby in
December, 1900, in which the latter, referring to the Mar-
coni system, said: "The receiving wire was suspended,
insulated, and attached at the end of the coherer, the
other pole of which was connected to earth." Marconi, in
controverting this point, contended that in one of his
British patents, application for which was made on June 1,
1898, or two and one-half years previous to Slaby's state-
ment, he (Marconi) said of his own device, "according
to this invention the conductor (aerial) is no longer
insulated, but is connected to earth through the pri-
mary of an induction coil, while the ends of the imper-
fect contact, or coherer, are connected to the ends of
the secondary of the connections passing through the
coherer."
DESCRIPTIVE.
57
Slaby's Multiplier. — Slaby has applied to his apparatus
a coil of wire, designated a multiplier, which he claims
acts as a resonator, being analogous to a hollow box placed
under a tuning-fork. The Slaby adherents are careful to
state that this device should not be confounded with an
induction coil. Marconi, however, in the same paper
before the Society of Arts, previously quoted, points out
that it is no new thing to use a single coil of wire to
produce self-induction.
sea.
Slaby's Achievements.— Immediately upon his return
from England in May, 1899, after his attendance at the
tests of the young Italian inventor, Dr. Slaby succeeded
with his own apparatus in transmitting signals a distance
of about thirteen miles; and it has been claimed for him,
although doubted by the friends of Marconi, that he has
covered ninety miles from the shore to a moving vessel at
The German electrical papers say that in competi-
tive tests the superiority of the German system has been
to them satisfactorily proved; but the Marconi adherents,
properly enough, contend that a more convincing test of
comparative merit might be had if each side were allowed
to handle its own apparatus. In a newspaper interview in
October, 1902, Marconi is reported as saying of Slaby,
"He has adopted the main features of my system, the
vertical wire, for instance. He introduces other variations
which I consider detrimental. He has established a so-
called system by which he has covered one-twentieth of
the distance I have covered."
No United States Patents to Slaby. Up to this writing
it has not been possible to find any American patent of
58
WIRELESS TELEGRAPHY.
the German scientist, but it is rumored that he has as-
signed American rights under his inventions to the Gen-
eral Electric Company of Germany.
The Slaby Theory. - Dr. Slaby has built his system on
the theory that if by means of a spark producer at its
lower end electrical oscillations are set up in a vertical
wire, the maximum amplitude of each oscillation will be at
the top point of the high wire.
Fig. 17 is a diagrammatic representation of one com-
plete wave A E. At B is its greatest rise, or its "crest.”

A
B
D
E
Fig. 17.
At D its point of extreme depression. A, C, and E are
neutral points called nodes. It follows, according to Dr.
Slaby, that a full wave from a transmitting station will be
just four times the length of the vertical wire which is set
in oscillation by the spark; and also that if the antenna
of the receiver be put to earth its vibration will produce a
crest at its top corresponding to B, Fig. 17; and that in
consequence at the point of connection with the earth will
be nodes such as are indicated in Fig. 17, at A and C
and E.
Now, if a wire be carried, as in Fig. 18, from the node
A, the wave motion, of which B is the crest, will be prop-
DESCRIPTIVE.
59
agated along the wire A F, and provided the wire A F is
of exactly the same length as the wire A G, the crest B'
of the new wave will be formed at F, the point at which
Dr. Slaby attaches his coherer. He claims by this scheme
of connections that transmitted waves always affect the
coherer when at their maximums of potential. It is said
that those waves for which the earthed point A is not a
node will fail to be propagated along the wire A F, but

G
B
A
Earth
B.
F
Im
Fig. 18.
will be conducted directly into the ground, with the result
that only waves of a predetermined period will affect the
coherer, thus guarding against interception or interference;
or, again, that a number of differently constituted receiving
conductors, each adapted to receive an especial kind of
wave, may be branched from one receiving antenna, thus
making a wireless multiplex. There are, however, so far
60
WIRELESS TELEGRAPHY.
as is known, no published results as to the number of cir-
cuits that may thus be operated, or the distance over which
signals in groups may be transmitted.
Application of Multiplier.
While the author has not
seen the application of the "multiplier" clearly shown, it
may be assumed that the lower part of the antenna itself
is in the form of a coil; that the path to the coherer, which
must equal in length the antenna, is also in the form of a
coil, but that these two coils are separate, and that there is
between them no inductive action.
Slaby Coherer. As a receiving device, Dr. Slaby uses
steel balls lying loosely between aluminum plates. It is
claimed, on the one hand, that this instrument is much
more sensitive than the ordinary forms of what are called
"permanent" coherers, such as tubes of carbon dust, but
admitted on the other that it is not so sensitive as a deli-
cately adjusted silver coherer; not, therefore, so well suited
to extreme long distance transmission; and that it is not
sufficiently diverse in its resistances to allow of working a
relay; and consequently that a recording instrument which
requires for its operation the local circuit of a relay cannot
be used. To restate the advantages of the steel and alu-
minum coherer, it is the most sensitive form of "self-right-
ing "coherer; and such being the case is best adapted of
any to work at moderate distances where the signaling
does not require a permanent record. The operator need
have no difficulty in reading by sound from a telephone
receiver, and can work faster than with an ink-marker;
and any system which eliminates the tapper does away
with a complicated and troublesome mechanism. The
DESCRIPTIVE.
61
4
Slaby receiver is apparently much easier of adjustment
than can be any non-restoring coherer.
Dr. Slaby's circuits have inductances and capacities both
at the transmitting and receiving ends.
transatlantic signaling he
will probably use a silver
coherer. Then he may
tune by getting the same
product value in the com-
bination of capacity and
induction at each end of
the transmission. Mar-
coni does the same.
Slaby's connections are
somewhat different from
those of his principal rival,
but whether his net re-
sults will be greater re-
mains for actual tests to
determine.
Mr. Collins's Descrip-
tion of Slaby System.
In the Scientific Ameri-
can of December 28th,
1901, is an article by Mr.
A. F. Collins which gives
D
H
When he essays

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B'
L'
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n
m
F
E
E
Fig. 19.
A
a number of diagrams of Dr. Slaby's plans of connections,
two of which, with a brief description, are by permission
reproduced.
Referring to Figs. 19 and 20, D is the coherer (consist-
ing of steel balls between aluminum plates).
In Fig. 19
62
WIRELESS TELEGRAPHY.
4
the path to ground from antenna A by way of coil L" is
in shunt with the coil L", and both are in shunt with the
key K', which while the operator is transmitting is kept
closed to protect the coherer from strong waves. Induct-
ance coil L, Fig. 19, is in tune with antenna A, and also
in accord with waves from the distant station (see Fig. 20).

Ο
D
2
ΟΟΟΣ
2
d
a
M
A
B
K
Kite
C
G
a
ய
E
Fig. 20.
E
It is regulated by the adjustments of induction L"' and
capacity C'. The method of changing the value of C' is
shown by the position of switch-arm F and connections at
m, n and o. Battery B' may be one dry cell; L" acts as
a choking coil. Fig. 20 represents the transmitting appa-
ratus of Dr. Slaby, in which M is a multiplier and A with
its terminating kite the wave-gate.
DESCRIPTIVE.
63
THE LODGE SYSTEM.
Fig. 21 is arranged as a typical diagram of Professor
Lodge's ethereal transmitter. In the Lodge nomenclature
it is called a "radiator." Three spark-gaps are in the series,
viz.: the "starting," the "supply," and the "discharge."
It is the assertion of the designer that by this multiplicity
of gaps the oscillations are made more "persistent," i.e.,
not so soon "damped." He says that charges so com-
municated are left to oscillate free from any disturbance
due to maintained connection with the source of electricity;
and therefore "oscillate longer and more freely than when
supplied by wires in the usual way." Another advantage
is that the same emitter, inductance coils, and earth con-
nection may conveniently be used as a part of the receiving
apparatus. It will be seen that at the supply knobs the
Ruhmkorff coil is always in absolute disconnection from
the final discharge circuit. If now the receiving circuit
shown in Figs. 22 or 23 be attached, as indicated by the
dotted lines X X in Fig. 21 and the solid lines rx in Figs.
22 and 23, and at the same time the discharge break be
bridged out of circuit by a good conductor across it, the
apparatus is ready for use as a receiver. The connections
may be so arranged that one movement of a knife switch
will change the device from transmitter to receiver, or, as
the inventor would say, from "radiator to resonator."
Inductance Coils. — Fig. 24 shows the inductance coil
of the receiver surrounded by a secondary winding, the
two coils forming a step-up transformer to raise the poten-
tial of waves from a distant source.
64
WIRELESS TELEGRAPHY,

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FOOF
CAPACITY AREA,
DISCHARGE
O
RECEIVING KNOB
●RECEIVING KNOB
SUPPLY GAP-
SUPPLY GAP
GAP
SUPPLY KNOB
SUPPLY KNOB
INDUCTANCE COIL
INDUCTANCE COIL
STARTING
GAP
RUHMKORFF
I
LEYDEN JAR
LEYDEN JAR
KEY
BATTERY
THIN WIRE INDUCTANCE Coll.
Fig. 21.
CAPACITY AREA EARTH

h

T
Fig. 22.
n'
h
8
h
U
h
e
Fig. 24.
Fig. 23.
2
æ
113
118

DESCRIPTIVE.
65
Capacity Areas. Fig. 25 represents the form preferred
by Professor Lodge for "capacity areas," "diverging cones
with vertices adjoining and their larger areas spreading
out into space." He

says that this form com-
bines low resistance with
h
great
electrostatic
ca-
h?
pacity.¹
ha
no
Supply Gap. The
action of the "supply
gap" is to cause to be
stored upon the " 'supply
Fig. 25.
knob" a charge of elec-
tricity that is sufficiently powerful to cross the air space.
A condenser is a similar storage of power, and supposedly
much easier of exact adjustment.
In Professor Lodge's device there is in the local cir-
cuit as here shown no condenser, such as is found in the
Marconi or Tesla systems, to build up the feeble waves ar-
riving at the receiving end of a long distance transmission;
nor are there any choking coils to prevent the dissipation
over the relay circuit of the charge that affects the
coherer.¹
1 See Fig. 68, p. 177, Part IV.
66
WIRELESS TELEGRAPHY.
WORK OF UNITED STATES WEATHER BUREAU.
Engagement of Specialist.-The United States Weather
Bureau began, early in 1900, a systematic course of experi-
mentation in Wireless Telegraphy, employing Professor
Reginald A. Fessenden as a specialist. In a paper written
by him in 1902, it was asserted that important advances had
been made, one of which was overcoming largely the loss
of energy experienced in other systems. He also declared
that syntony was not safely selecting, but that he had
discovered several methods which were. The following
extract from the Fifth Annual Report of the Secretary
of Agriculture is a generalization of the Government
work up to the year 1901:
"While there is much experimental work yet to be done before the
present system is reliable for intership communication, or before any two
systems can work within the same field without each rendering the other
useless, such progress has been made by the government experimenters
that, with no interference by private systems, stations can be successfully
operated over at least one hundred and fifty miles of coast line; and they
are now in operation on the North Carolina and Virginia coasts, and soon
will be instituted between the Farallone Islands and the mainland, and
Tatoosh Island and the mainland, on the Pacific coast."
Experimental Stations of U. S. Government. Early in
1901 the Weather Bureau official installed Mr. Fessenden
at Wier's Point, Roanoke Island, North Carolina; and he
has since made experimental transmissions across water to
a station located about five miles west of Cape Hatteras,
the distance between the two stations being almost exactly
fifty miles. The following letters from the Weather
Bureau staff have been given to the public:
DESCRIPTIVE.
67
MANTEO, ROANOKE ISLAND, N.C.,
April 4, 1902.
CHIEF United States WEATHER Bureau,
Washington, D.C.:
After working with Professor Fessenden's new receiver, between
Hatteras and Roanoke, I would report as follows:
The receiver is positive in its action, and entirely and absolutely reliable.
It is entirely different in nature and action from the coherer, and gives no
false signals like the latter does.
I could get every single dot and dash made at Hatteras with the utmost
clearness, and can receive with it at the same rate of speed as over an
ordinary telegraph line. It is possible for any expert telegrapher to receive
by it as fast as the key can be handled.
I have had no trouble in using the receiver except that due to bad
sending at the other end, and even then could make out every single dot
and dash, but could not read them.
The signals and messages were taken perfectly on the new receiver
when, under the same conditions and connections, the coherer was tried
and would not give a single dot.
Yours respectfully,
LOUIS DORMAN,
Observer, Weather Bureau..
MANTEO, ROANOKE ISLAND, N.C.,
April 8, 1902.
Professor REGINALD A. FESSENDEN:
I would report that in the test made by Mr. Dorman, the following is a
comparison of the amount of energy necessary to work the standard co-
herer and the receiver used by Mr. Dorman in the test referred to in his
report:
Taken as our standard coherer one working well-i.e., giving good
clear transmission of messages when attached to a single No. 18 wire five
feet long, the sending wire being similar and of the same length, the spark-
gap being one-eighth inch between slightly rounded points, and obtained
from a coil capable of giving three-sixteenths inch spark between points
when the distance between sending and receiving wires is forty-five feet, and
both coherer and coil are resting on the surface of the ground then the
third message received by Mr. Dorman in the tests referred to in his report
was received with one five-hundred-and-seventy-sixth of the least amount
of energy required to work the standard coherer over the same distance,
and with the same vertical and receiving wires used in each case, and with
the coherer worked with a transformer with maximum efficiency ratio of
transformation and circuit accurately tuned.
A. H. THIESSEN. Assistant.
68
WIRELESS TELEGRAPHY.
Upon April 27, 1902, a series of tests were made from
the Roanoke station before various Government officials,
resulting in good transmission over fifty miles of a surface
partly sea water and partly fresh water.
U. S. Government Opens Proposals For Wireless Tele-
graph in Alaska. Upon May 6th, 1902, the Chief Signal
Officer of the Weather Bureau opened proposals for estab-
lishing wireless telegraph systems in Alaska, over four
different routes, as follows:
A. Between Fort Davis and some point on Strait
Island, a distance of ninety nautical miles.
B. Between Fort Davis and Fort St. Michael's, a
distance of one hundred and eight miles.
C. From Rampart City to Winter Hours, a distance
of one hundred and thirty-six miles.
D. From Fort Gibbon to a point near Bates Rapids in
the Tanana River, an air-line distance of one hundred and
sixty-five miles.
The bidders were, Queen and Company of Philadelphia
representing the Fessenden Apparatus; The Marconi
Company of England; the owners of the Arco-Slaby
system in Germany; the American Wireless Telephone
and Telegraph Co. of Philadelphia; Foote, Pierson & Co.;
the DeForest Wireless Telegraph Company.
The proposals of the last four bidders were not con-
sidered, for the reason that they would not agree to
install and work their systems for ten days prior to accept-
ance by the Government. Contracts were finally made
with Queen and Company for the B route, one hundred
and eight miles, with a rate of transmission guaranteed to
be not less than twenty-five words per minute; with the
*
DESCRIPTIVE.
69
Marconi Company for the D route, one hundred and sixty-
five miles, with a guaranteed speed of twelve words per
minute.
The Marconi Company departed from the specifications
to the extent of demanding a royalty after the first year of
$250 per annum upon each set of instruments; and also
demanding one-half of any receipts for commercial tele-
graphy which might be received by the Government.
In accepting the contracts, both companies have agreed
that unless their systems shall work every day without
interruption the Government shall be exempt from pay-
ment. It was thought that both installations would be in
working order by October, 1902.
In an interview with
Interview with Mr. Fessenden.
a New York Journal correspondent, Mr. Fessenden said
of his apparatus that he did not use any air transformer
at the sending end; nor concentric cylinder for emitters
and antennae, such as were employed by the Marconi
Company; that he used capacity, but that it was arranged
in a manner entirely different from that in other systems;
that he did not employ a coherer or any form of imperfect
contact; that his apparatus was of solid metal, and acted
under a physical law entirely different from that which
governs the receiving devices of Marconi. While the
telephone was used as a recorder of signals, he said he
could also get good service from a siphon recorder. He
asserted that he had paid particular attention to selective.
and multiplex systems, and was well satisfied with the
results in that direction. He believed that when a system
of machine receiving was perfected it would be possible to
transmit five hundred words per minute.
70
WIRELESS TELEGRAPHY.
".
Lieutenant Beecher's Paper Before American Institute.
On May 28th, Lieutenant Beecher of the United States
Navy, who had been investigating the Fessenden system,
read a paper before the American Institute of Electrical
Engineers, in which he said that in some respects the Fes-
senden apparatus was more reliable than that devised by
other inventors. He emphasized the fact that one defect
of a telephonic receiving apparatus is the need of an
efficient calling-up signal; and suggested that a coherer
might be used to receive the calling signal, and be after-
ward switched out and replaced by a telephone receiver.
:
DESCRIPTIVE.
71
PATENTS ISSUED TO PROFESSOR FESSENDEN.
On August 12th, 1902, there were issued to Mr. Fes-
senden thirteen patents on various methods, devices, and
systems for signaling without wires.¹
The First Two Patents. In the first two patents of
the series it is indicated that it was Mr. Fessenden's inten-
tion to devise a signaling system which would be more
positive in its action at moderate distances than was the
only receiving instrument known at that time, the coherer.
He designated the transmitted vibrations which affect a
coherer as "voltages," meaning electric currents of high
potential in contradistinction to the "currents" of compar-
atively low potential which he employed.
His receiving organization is a tuned circuit which is
always closed, and is thus differentiated from a coherer
which may be called a normally open circuit. Hence his
receiver is always receptive, always capable of being affected
by waves; whereas for a portion of the time during which
signals are being sent, the coherer is incapable of response.
Another distinctive feature is the fact that the indications
produced by the Fessenden receiving mechanism are de-
pendent upon the total amount of energy emitted to form
a signal, and not, as in the case of a coherer, dependent
upon the maximum of the voltage.
In the description of that first invention it is explained
that a single electromagnetic wave of the type used by the
inventor "will have produced its impulses before the re-
ceiver employed will have made an appreciable motion";
1 Many of these devices are described as Apparatus" in Part IV., and a full list of
them is a portion of Part II., under " Inventors and Inventions.”
72
WIRELESS TELEGRAPHY.
but by using a source of sustained radiation at the sending
end the effect of the waves is cumulative; and since the
receiver is constantly receptive, the effects added together
from a number of waves serve to produce appreciable in-
dications. Repeating the foregoing statements in other
words, the appliances are adapted to produce at the send-
ing station electromagnetic waves of comparatively low
frequency and low potential, but to sustain as much as pos-
sible the oscillations from each impulse, and at the receiv-
ing station to use a wave-responsive-device upon a closed
circuit tuned to the same frequency as the sending organi-
zation, which would be sufficiently affected by the cumula-
tive effect of a number of waves as to produce observable
mechanical movements.
After the declarations of principles, which constitute
considerable portions of his first two patents, there ap-
peared in successive inventions two different forms of radi-
ating wave-gates.¹
Third Patent for a ""
System.'
""
Next in order is a
"system." Its objects are to provide suitable means for

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5
8
11
9
10
raising the voltage
at the receiving
station by a trans-
former; to increase
the number of os-
6
cillations in the
sending conductor
Fig. 26.
during its discharg-
ing period; and to improve localization by so tuning the
receiving apparatus that it will respond solely to waves
¹ See detailed description in Part IV.
DESCRIPTIVE.
73
of one periodicity.
Referring to Fig. 26, the inventor
says that a feature (indicated at 6) is the addition of a
capacity to the sending conductor in connection with
a transformer at the receiving station for raising the volt-
age in the secondary circuit; that another feature is the
capacity (8) placed in shunt with the coherer (9); still
another, an opposing source of voltage (12-11) bridged
across the secondary circuit and presenting a counter elec-
tromotive force to the local battery while the coherer is in
operation. The PRINCIPAL ADVANTAGE claimed seems to
be the improvement in selection, due to the use of a plu-
rality of TUNED CIRCUITS.
Quoting the inventor's own words:
Waves of One Periodicity Subject to Interference.
On account of the fact that it is preferable to use sending
conductors having large capacity, or large capacity and
self-induction, and that in these cases the curve of reso-
nance is broadened, it has heretofore been impossible to
make the receivers respond solely to waves of one periodi-
city, as other periodicities, if above a certain power, will
affect the receivers.
tors.
Perfect Resonance Attained by Plurality of Conduc-
By constructing the sending conductor so the oscil-
lations for each total discharge are increased, and by
employing at the receiving station two or more tuned cir-
cuits, a very perfect resonance or tuning between the
stations can be attained.
Effects from One-Tuned Circuit and Two-Tuned Cir-
cuits. With a one-tuned circuit at the receiving station
and with sending conductors permitting a rapid radiation.
74
WIRELESS TELEGRAPHY.
By
at the sending station, electrostatic and hysteresis effects
become very prominent, and the great self-inductance
desirable for sharp resonance cannot be attained.
employing at the receiving end two tuned circuits, the first
consisting of the receiving conductor and the other second-
ary to the first, the relative inductance may be greater in
the secondary than in the primary circuit of the receiv-
ing conductor or the sending conductor, in which latter,
as before explained, the capacity

11
6
5
-18
-19
is preferably a dominant factor of
8 tuning, and the electrical effect in
the secondary will occur only when
the periods are very closely the
same.
An Invention in Wireless Teleph-
ony. — In an application for a patent
filed September 28th, 1901, part of
the subject matter had reference to
telephoning without wires. The
method is illustrated in Fig. 27, in
which 9 is a transmitting telephone modifying by means
of battery 8, coil 7 and core 3, the impulses imparted to
wave-gate I.
Fig. 27.
a
An arrange-
Invention for Localization of Signals.
ment for the more distinct localization of signals than can
be obtained from one set of tuned apparatus is shown in
Fig. 28, in which 1ª and 2ª are emitting wave-gates tuned
to different periodicities, and 6ª and 7ª are receiving anten-
nae respectively corresponding in frequency to 1a and
2ª, and consequently the armature 16 which represents the
DESCRIPTIVE.
75
means for mechanical movement at the receiving station
responds "only to the combined action of waves or im-
pulses corresponding in period and in other characteristics
to those generated" by the combined action of 1ª and 2ª.


1a-
-2a
6ã
7a
14
14a
/13 13a
15
+416
Fig. 28.
Reference is made to Part IV., wherein are described
inventions by Mr. Fessenden of,
1. Means "to provide for the MAINTENANCE of a CERTAIN
DEFINITE RELATION BETWEEN the RESISTANCE and CAPA-
CITY of the sending mechanism, regardless of the POTEN-
TIAL employed.
2. A wave-RESPONSIVE-DEVICE, consisting of a conductor
having small heat capacity and low resistance.
3. An appliance adapted to make a highly cONDUCTIVE
WAVE PATH OVER THE EARTH for some distance, from the
sending end and receiving wave-gates respectively.
is denominated by the inventor a "wave-chute."
This
4. An arrangement for PRODUCING VISIBLE INTERPRET-
ABLE CHARACTERS on a strip or film by a PHOTOGRAPHIC
process, and for developing and fixing the same.
Fessenden's Selective System. - Another invention is a
system of selection whereby each of a number of stations
76
WIRELESS TELEGRAPHY.
་་
}
has a tune or period of resonance proper to itself, as each
Western Union Telegraph station has, where several
stations work upon one wire, its particular letter or com-
bination of letters for a "call." In this system, part of
the sending mechanism is a key,¹ constructed with a num-
ber of different contacts which are the terminals of differ-
ently tuned circuits. The connections are normally made
so that their period of resonance is that allotted to each
station; but any station may call and exchange signals
with any other station by first putting itself in resonance
with the one with which it desired to communicate.
Fessenden Signaling System of July, 1902 (Fig. 29).
For the Fessenden patent No. 706,745, application was
made July 1, 1902. It is for a "system," apparently the
final result of the researches and experiments made by the
inventor for the Government. The drawings of the patent
comprise five illustrations, the second, third, fourth, and
fifth figures being forms of apparatus at the receiving sta-
tion which are modifications of that shown in the first fig-
As it is presumable that the initial illustration is the
preferred one, it has been selected for description, and re-
produced here as Fig. 29.
ure.
Transmitter. Quoting from the patent specification,
"The form of apparatus shown in Fig. 29 consists at the
sending station of a radiating conductor (1) connected to
one terminal of the spark-gap, the opposite terminal being
grounded; a generator (A) and a local tuned circuit con-
¹ See Figs. 74, 75, and 76 in Part IV., p. 187.
DESCRIPTIVE.
77
taining a capacity (12) in parallel with the sending con-
ductor for the purpose of prolonging the radiation.

44
4 2
43
45
<46
424
37
411
47
43
40
3939
48
40a
5 3
6-

A
12
Fig. 29.
Receiver. — At the receiving end is employed a current-
operated wave-responsive-device¹ in a closed tuned circuit
(2, 3, 4, 5) energized by the receiving conductor (6) con-
taining the primary of a transformer.
Circuit. The circuit 2, 3, 4, 5, which is a secondary
circuit, is tuned to the frequency of the electromagnetic
waves, is preferably of low resistance, and has a larger
ratio of inductance to capacity than that of the receiving
conductor. This is for the purpose of protecting the
receiver from foreign electrical disturbances.
Indicating Mechanism. "Any suitable form of indicat-
ing mechanism, such as a telephone or galvanometer, may
be employed. A differentially-wound indicating mechan-
1 See Fig. 59, p. 167, Part IV.
78
WIRELESS TELEGRAPHY.
ism, such as the differentially-wound telephone 41, is desir-
able for many purposes, and has one circuit connected
across the receiver 14. A resistance 42, preferably formed
by a loop similar to the receiver 14, is arranged in one of
the circuits of the differential instrument, the receiver 14
being in the other circuit, so that the circuits are balanced.
Coils 43 and 44 are oppositely wound, and the two circuits
being balanced there is normally no appreciable effect on
the diaphragm 45. The source of voltage, 46, and tuning-
fork, 47, are used to produce intermittent currents in the
differential circuits, and, as mentioned above, there is nor-
mally no effect. When an electromagnetic wave causes a
current to pass through the loop 14, thereby raising its re-
sistance, the current in circuits containing the coils 44 of
the differential instrument is weakened, and the circuits
being out of balance an indication is produced by the
instrument.
Generation may be Made Continuous Instead of Intermit-
tent. "When it is not desired to use an intermittent cur-
rent, — as, for example, when the receiving mechanism is
tuned mechanically to a given note for selective purposes,
-the circuit including the generator is made continuous,
as by wedging the prongs of the tuning-fork, or in any
other suitable manner.
Operation.
"When a train of waves is radiated from
the sending station and received by the receiving conductor,
it causes currents to flow through the receiver, 14,¹ heat-
ing it up, thereby changing its resistance. The resistance
of the differential circuit containing the receiver is there-
fore increased, the current therein reduced, and sound pro-
duced by the telephone.
¹ See Fig. 59, p. 167, Part IV.
DESCRIPTIVE.
79
Transformer. "The transformer is here shown as a
step-down transformer, as this form has advantages when
used in connection with current-operated receivers of very
low resistance; but step-up transformers may be used."
"As a means of
Means of Amplifying Indications. "As a
amplifying the indications, I prefer to use a local micro-
phonic circuit, as shown in Fig. 29, where a small carbon
block, 36, is attached to the diaphragm of the differential
telephone, 41, and a carbon point, 37, bears lightly thereon.
A local battery generates a current which passes continu-
ously through the microphonic contact and a bridge con-
sisting of the arms, 39 39 and 40 40ª, and a siphon
recorder, 48. The arms of the bridge are balanced as
regards ohmic resistance. Hence for all steady or slowly
varying currents no portion of the current passes through
the siphon recorder. The arms 39 39ª have, however, very
high self-induction, and the arms 40 40ª very low self-induc-
tion, and both are of low resistance. On any sudden
change of current, such as will be produced by the motion
of the diaphragm on the receipt of a signal, the suddenly
varying current cannot flow through the arms 39 39ª, but
will flow through the arms 40 40ª and the siphon recorder,
48, thereby producing an amplified indication.
"The
Definitions and Uses of Closed and Open Circuits.
local circuit thus formed is a closed circuit, and is to be
differentiated from the open local circuits employed in con-
nection with the coherer. An alternating-current circuit
may be closed through a resistance, an inductance, or a
capacity; and since even the insulated ends of a circuit
80
WIRELESS TELEGRAPHY.
will always have some capacity relative to each other, it
follows that all alternating-current circuits are theoretically
closed. What is meant, therefore, by a 'closed alternating-
current circuit,' is a circuit in which the current is rela-
tively large for a small impressed voltage in the circuit,
i.e., the circuit is one of low virtual resistance as compared
with a coherer. By an 'unclosed' or
By an unclosed' or 'open' circuit is
meant one in which the current is relatively small or neg-
ligible for a small impressed voltage, -i.e., one whose
virtual resistance is high. Where a current-actuated wave-
responsive-device is employed, a closed circuit should also
be employed to obtain a large effective current to actuate
said-device. Where a voltage-actuated device, such as a
coherer, is employed and a large effective difference of
potential is required, an open circuit, as defined above,
should be used. This is especially important, because
while a resonant rise of voltage may be obtained in an open
circuit, a large resonant rise of current is possible only in
a closed circuit of low ohmic resistance used in connection
with a source of maintained radiation. It will be evident
that according to this definition of closed and unclosed
tuned circuits, in many cases the sending or receiving con-
ductor would come under the head of a 'closed tuned
circuit,' especially when having large capacity and low in-
ductance; but where reference is made herein to a closed
tuned circuit' a sending or receiving conductor is not
meant. It is characteristic of these closed tuned circuits
that they have a peculiar advantage when used in connec-
tion with the form of receiver in that such circuits act to
prevent the burning out of the receivers by electrical dis-
turbances produced by lightning discharges. They also
permit of the employment of more sensitive current-actu-
DESCRIPTIVE.
81
ated wave-responsive-devices. They also permit of step-
down transformers being used, instead of step-up, thus
enabling practically all of the energy of the waves to be
utilized, and giving sufficient inductance with small length
of wire."
Small Voltages Characteristic of Fessenden Circuits.
"It is especially characteristic of my invention — i.e., the
use of closed tuned circuits in connection with current-
actuated wave-responsive-devices as distinguished from
open tuned circuits and voltage-actuated wave-responsive-
devices that in my construction the voltages in the
receiving circuit are kept small, and hence practically all
the energy received from the electromagnetic waves is
employed affecting the receiver, and hence indications can
be produced by an amount of energy which is an extremely
small fraction of that necessary when open tuned circuits
and voltage-actuated wave-responsive-devices are employed.
Practical Test of Transmission. "Thus since the ca-
pacity of a coherer is small, a small amount of energy is
sufficient to raise it by itself to a breakdown voltage; but
in operation it is connected to a circuit having several
hundred times the capacity; and as this circuit must be
raised to practically the same potential as the coherer, the
efficiency of working is low- as, for example, with closed
tuned circuits and a receiver, messages at the rate of thirty
words per minute were sent and received over a distance
of fifty miles, (i.e., from Cape Hatteras to Roanoke Island,)
using a spark one thirty-second (2) of an inch long at the
sending end. When a coherer and an open tuned circuit
were used under the same circumstances, the spark length
82
WIRELESS TELEGRAPHY.
had to be increased to five and one-half inches before any
messages could be received. The energies in the two cases
were approximately in the ratio of one to forty thousand.
Definition of Current-Operated Wave-Responsive-Device.
-"By the term 'current-operated wave-responsive-de-
vices' as used herein and by me generally is meant wave-
responsive-devices having all their contacts good contacts,
and operated by currents produced by electromagnetic
They are hence to be distinguished from wave-
responsive-devices depending for operation upon varying
waves.
contact resistance."
DESCRIPTIVE.
83
EHRET'S DEVICE.
4
Fig. 30.— From the multitude of inventions contribut-
ing to wireless telegraphy not familiar to the public, one
is selected here as representative of recent advances in
this art, although the author has not had opportunity from
the data of results or from knowledge of experimental
demonstrations, to judge of its relative importance. The
invention is described in United States Letters Patent
No. 699,158, dated May 6, 1902, and issued to Cornelius
D. Ehret of Washington, D.C. One of the striking feat-
ures of this patent is its comprehensive brevity. All of
the drawings are shown as Fig. 30. The figure I extend-
ing across the top of the page gives a detailed representa-
tion, and the other six drawings illustrate modifications of
the first organization. While the space is well filled, it
will be noted that there is neither confusion of line nor
the omission of any necessary detail. The description of
the invention is equally brief, about one thousand words
sufficing to explain seven different schemes of connections.
Recording Mechanism. In the figure at the top of the
page, S may represent a register which records dots and
dashes in ink upon paper tape, and is operated whenever
battery B" is put on a closed circuit by reason of retractile
spring 7 pulling lever 4 against contact 5. When the
apparatus is at rest, lever 4 is held against stop 6.
Differential Relay (R). It will be noted that relay R
has wound differentially about its core 3 two coils ƒ and g;
and consequently if electric currents of the same strength
84
WIRELESS TELEGRAPHY.
t

b
B
a-
e
C
3
R
FIG. I
IBRA
f
7
6
5
B"
S
FIG. II
FIG. V
B'
B
h
R
R
ƒ
g
4
f
g
b
B
e
Ъ
af
FIG. III
ad
b
B
h
B
C
C
a-
FIG. IV
b
B
C
C
Fig. 30.
FIG. VI
B'
C
f
e
B
R'
FIG. VII
B
b
DESCRIPTIVE.
85
and direction be sent through them simultaneously the
effect on core 3 is nil.
Core (3).
Core 3 in itself, without the aid of current
effect, is slightly magnetic; and battery B and coil g are
so arranged that their influence upon core 3 is to induce in
it a magnetism of the same polarity as that already existing,
and so to increase the magnetic effect.
Coherer (c). — On the other hand, battery B' and the
winding of coil ƒ are arranged to work in opposition to coil g
and battery B. c is the usual filings coherer which, under
the influence of Hertzian waves, decreases in resistance.
It is a part of the same circuit which includes battery B'
and coil f.
Anti-Coherer (2). — 2 is a device called an anti-coherer,
and may consist of tin-foil glued to a glass plate, as in a
mirror, and with slits cut across the metal as indicated in
the drawing. The effect of etheric impulses upon an
anti-coherer is to increase its resistance. The anti-coherer
2 is a part of the same circuit which includes battery B
and coil g.¹
1
Operation. When, therefore, waves from a distant
source impinge upon antenna a circuit 2 B g which tends
to hold lever 4 against stop 6 is greatly weakened; and
circuit c B'f which tends to repel the armature of lever 4
is made much stronger. Consequently the magnetic effect
in core 3 is neutralized, and spring 7 draws lever 4 against
contact 5, thus actuating S. Tapping the coherer c during
1 See p. 154, Part IV., in connection with "anti-coherers."
86
WIRELESS TELEGRAPHY.
the absence of wave effect opens circuit c B'f, and at the
same instant anti-coherer 2 regains its normal conductivity
and the armature 4 is again attracted to core 3.
Advantages.
Presumably the advantages attained by
this plan of connection are, first, greater certainty of ac-
tion; second, a closer adjustment; third, less self-inductive
influence in the receiving relay, and consequently its
quicker action.
$
L
DESCRIPTIVE.
87
THE DEFOREST SYSTEM.
Officials connected with the DeForest system claim the
best record for accurate service during the naval maneu-
vers which took place off the New England coast in the
summer of 1902. The principal feature of their system is
the wave-responsive-device, which is designated by its in-
ventors a "responder." This instrument is described as
an anti-coherer in Part IV., and is illustrated by Fig. 49.
In connection with transmitters the DeForest system is
further described in the same division.
WIRELESS TRANSMISSION OVERLAND.
There have been no records available of successful ex-
periments in this country with wireless telegraphy over-
land, but in the Marconi article in the Century Magazine,
March, 1902, the inventor expressed the belief that the
possibilities for inland wireless telegraphy are limited to
one thousand miles. The Federal Wireless Telephone
Company of New York has frequently advertised that it
was about to open communication between Baltimore and
Washington, a distance of forty miles, but there is no
record of a test for even so far. In newspaper interviews
Mr. Fessenden is reported as saying that his apparatus was
about to be tested between Annapolis and Washington,
after which he should try a circuit from Chicago to New
York; but directly after these interviews Lieutenant
Beecher of the United States Navy declared, in a paper
before the American Institute of Electrical Engineers on
May 28, that he believed the field of wireless telegraphy to
་
88
WIRELESS TELEGRAPHY.
.
be limited to the ocean; and Lieutenant Beecher is sup-
posed to be well acquainted with the Fessenden apparatus.
Overland Contracts in Alaska. The chief signal officer
of the United States Weather Bureau has contracted with
the Marconi Company for a circuit of one hundred and
sixty-five miles in an air-line from Bates Rapids in the in-
terior of Alaska to Fort Gibbon near the sea-coast. Ac-
cording to the map this must be almost entirely overland,
and presenting rather difficult conditions at that.
NEW MARCONI RECEIVER.
In a lecture in London on June 13, 1902, Mr. Marconi
reported that he had invented a receiver sufficiently sensi-
tive to allow of a transmission at the rate of thirty words
per minute.¹
:
GUARINI'S REPEATER.
An Italian scientist, Signor Guarini, seems to have
been partially successful in designing a wireless-telegraph-
repeater, its function being to pick up signals at a certain
distance and relay them onward with renewed strength.
WIRELESS TELEPHONY.
Telephoning without wires has not gained by the great
developments in its sister-art. Mr. A. F. Collins, an
American, reports that he has heard faint tones at a dis-
tance of three miles through what he terms the "earth-
bound-ether;" but he does not make public his methods
1 See Fig. 58 and accompanying description in Part IV., p. 165.
}
DESCRIPTIVE.
89
or devices. Telephonic waves are readily propagated
through space, but the difficulty is to confine them to
an intended recipient. Mr. Collins admits that the prob-
lem of making wireless telephony selective is one calcu-
lated to discourage the most sanguine investigator. The
inventions of Professor Pupin have decreased the first
cost of telephone equipment and increased the distance of
good transmission. Perhaps a multiplex transmission over
one small copper wire connecting the two points will even-
tually be the best device for selective telephony.
PRACTICABILITY.
Notwithstanding the great mass of positive evidence,
there are many conservative people who doubt that wire-
less telegraphy is or will be an art commercially practica-
ble. Public exhibitions have so often proved disappointing
that a great deal of disparaging testimony has circulated.
Also, there has lately become prominent the curious fact
that sunlight so interferes with wireless service, that to
overcome its effect, the energy necessary for transmission
during daylight must be several times that needed for the
same service at night; and despite previous statements
that the earth's curvature does not interfere with space
signalling, it now appears that for equal distances there
would be needed over a flat surface only one-third of the
energy now required; but these facts only indicate that
more power must be applied than was at first thought
needful. Always the public is looking for revolution in
an art and almost always, after the original discovery,
progress is made by a process of evolution from discoveries
already made. It may with comparative safety be pre-
dicted that this art, as have most others, will develop with
90
WIRELESS TELEGRAPHY.
step by step movements consisting mainly in the careful
and thorough application of comparatively small yet essen-
tial details, the principles of which are already well under-
stood, although their aggregate importance may not now
be fully realized.
To illustrate the foregoing by analogies, the two most
essential features in the development of wire telegraphy
have been the adoptions of screw-glass insulators and of
hard-drawn copper conductors; yet copper soft-drawn was
about the first thing tried (being soon abandoned for iron),
and the glass insulator at first without the screw threads
to fasten it to brackets or pins has been in use from the
outset. When the smooth-bore glass sprung off the pin,
as it often did, the wire lay against the wood-work and
lost part of its current. Again hard-drawn copper was
first used in the form of thin wires, and although it has
been known for more than a century that a telegraph
circuit may by the use of large wires be operated to
proportionally longer distances than by small ones, many
years elapsed before the telegraph companies seemed to
realize that fact. If we review telephone progress, it will
be found that one of its important steps, the transposition
of circuits to prevent cross-talk, was fully set forth twenty
years ago; but that it was ten years after that before such
transposition was systematized and made effective.
Professor Fleming, the scientific adviser to the Marconi
Company has recently in a series of lectures reviewed the
whole art of wireless telegraphy.
He has positively
asserted that communications may be carried on between
stations three thousand miles apart, and Professor Fleming
has had every opportunity by experiment and observation
upon which to base such an assertion.
.' ...

MAXWELL
MARCONI
BRANLY
HERTZ
LODGE
PART II.
INVENTORS AND INVENTIONS.
A CURIOUS feature in the record of Wireless Telegraphy
is the fact that while the press and public were hailing Mr.
Marconi as the only inventor of all that pertained to the
system by which he signaled across the ocean, the name
of an equally important patentee was hardly mentioned.
It is true that Professor Silvanus Thompson, an English
electrician of repute, had once or twice been quoted in
newspaper paragraphs as saying that the Marconi system
was a direct infringement upon American patents granted
to Professor Lodge; but the representatives of the Mar-
coni Company disparaged the statement, declaring that
Marconi had taken out eleven United States patents and
Lodge but one.
A careful search, including all of the year 1902, reveals
only ten patents issued to Marconi. One of these, how-
ever, has been reissued, and may have been counted in
addition. On the other hand, at the date of the transat-
lantic transmission by Marconi there had been on record
for several months the award of very important claims to
Professor Lodge by the most competent tribunal in the
world, the United States Patent Office.
It is not purposed to make this writing controversial,
much less to belittle Marconi's achievements. That in
91
י
92
WIRELESS TELEGRAPHY.
:
faith in himself and his project, in force of character and
ability to inspire confidence in others, he holds very high
rank, is indisputable; moreover, he must be recognized
as the maker of an epoch. At the same time, the historian
of this art would be remiss who did not endeavor so to sift
the evidence as to apportion to the man upon the pedestal
only his due, to the end that to other contributors might
come rightful credit.
In his "Evolution of the Electric Incandescent Lamp,"
the late Franklin Leonard Pope opens the preface of his
first edition with an essay upon the tendency of an
unthinking public to bestow its praise for a new invention
upon but one person. Mr. Pope, in 1889, when this was
written, was a recognized authority on patent matters, as
well as one of the foremost electrical engineers. He said:
"The outcome of a race of diligence between two independent but
equally meritorious inventors is perhaps as often as otherwise determined
by chance or accident. In this respect it may not inaptly be compared to
the result of a horse-race in which the fortunate winner carries off, not only
all the honors, but the purse as well, although his nose may have passed
under the wire barely an inch in advance of some of his no less deserving
competitors. It is a matter of common observation that when the fullness
of time arrives the discovery or invention for which the world has been
waiting is certain to be made. The critical student of affairs perceives that
however wonderful or however unexpected that invention may appear, it
is seldom that it is not found to be a necessary sequence of a long series of
other discoveries and inventions which have preceded it. Even in those
rare cases in which an improvement of indisputable novelty and originality
is made known to the industrial world, it is scarcely ever sufficiently per-
fected in its details to be capable of practical use until it has been worked
upon and improved by many hands and many minds.
"It has always been the way of the world to consider every such inven-
tion, especially when of a character to appeal to the minds of the masses,
or to identify itself closely with the everyday life of the community, as the
work of some particular individual, who, as it were by common consent, is
regarded as its sole originator and contriver, and upon him fame, honor and
INVENTORS AND INVENTIONS.
93
wealth are lavished without stint, in childlike unconsciousness of the
universal truth that inventions of this character are not made, but grow;
that they are not the fruit of momentary inspiration, but on the contrary are
the inevitable results which, from time to time, mark the slow but constant
progress of scientific and industrial evolution."
Another phase of popular treatment is reaction, which
often changes from adulation to indifference or positive
condemnation. Sinister congratulations from the Anglo-
American Cable Company were the immediate fruits of
Marconi's triumph in Newfoundland, and shortly after-
wards a meeting of the French Academy of Science
indulged in hostile criticism. The speakers at that meeting
contended that documentary evidence showed "that credit
for the invention of a wireless telegraph is due first to
Feddersen and Maxwell of England, then to Hertz of
Germany, but principally to Professor Branly, a French-
man, who invented the coherer; then to Professor Lodge
of England and Professor Popoff of Russia. Finally it
was pointed out that neither the French army nor the
German navy was using the Marconi system.”
Mr. Pope, in his "Evolution of the Electric Incandes-
cent Lamp," further says: "It is particularly desirable
that the line of demarcation between the improvements
which unquestionably involve invention, and those which
really exhibit nothing beyond an unusually high order of
mechanical or engineering skill, should be more distinctly
defined. The question at best is a difficult one; perhaps
in its application to individual cases the most difficult one
which the courts, sitting in patent cases, are ever called
upon to determine.”
Probably invention will be always more or less intangible,
and thus difficult of exact definition. Precedent, however,
94
WIRELESS TELEGRAPHY.
has firmly established the principle that inventive genius
must be something more than the manifestation of such
technical knowledge and skill as might reasonably be
expected of a person trained in any art. The inventor
must be the fortunate one who has moments of happy
inspiration leading to results never realized by hundreds
of faithful, patient plodders, straining to reach the same
goal. Like the true poet or artist, the inventor is born,
not made. As a practical test, in the case of an alleged
invention, the question might be raised whether, with well-
known appliances and principles and furnished with the
same facilities as were at the disposal of the applicant for
a monopoly, a hundred skilled mechanics or engineers
could have achieved the same result. If not, and if the
applicant has discovered new principles or devised novel
appliances, then he has made a true invention.
number of necessary qualifications the most important is
that originality which a thorough training in any one line
tends to deaden.
Of a
So far as the territory of the United States is con-
cerned, the claims allowed in a patent are to some extent
a warrant of monopoly to the inventor. The burden lies.
with the litigant opposing the patentee to show either that
the Patent Office did not possess all the information bear-
ing on the matter, or that possessing such information the
Office erred. It has become the practice of examiners to
give the applicant considerable latitude; and as at that
first tribunal there is no opposing counsel to break down
the case, it often happens that if a patent is subsequently
contested before a court it is pronounced invalid.
In the report of the Commissioner of Patents for 1892
appears the statement that,
INVENTORS AND INVENTIONS.
95
"Of 988 court cases reported in the Official Gazette of the Patent
Office between 1886 and 1892 wherein patents were in litigation, 436 pat-
ents were sustained and 522 were declared invalid in whole or in part. Of
the number declared invalid, 428 were by reason of some fault in the Pat-
ent Office, and 124 on account of evidence brought to light of which the
Office had no knowledge before granting the patents."
Again he says: Approaching the subject from another side, I am fur-
nished with the result of examinations as to the validity of the claims in
ten patents taken at random where searches in this office were made by a
well known law-firm. These patents contain fifty claims, of which thirty-
five were considered and were reported to be old.”
Patent Law from the point of view of an English
scientist is discussed by Professor Lodge, in his "Signal-
ling Through Space Without Wires," as follows:
"In the present state of the law in this country it appears to be neces-
sary for a scientific man whose investigations may have any practical bear-
ing, to refrain from communicating his work to any scientific society, or
publishing it in any journal, until he has registered it and paid a fee to the
Government under the so-called Patent Law. This unfortunate system is
well calculated to prevent scientific men in general from giving any atten-
tion to practical applications, and to deter them from any attempt to make
their researches useful to the community. If a scientific worker publishes
in the natural way, no one has any right in the thing published. It is
given away, and lies useless, for no one will care to expend capital upon a
thing over which he has no effective control. In this case practical devel-
opments generally wait until some outsider steps in and either patents some
slight addition or modification, or else, as sometimes happens, patents the
whole thing with some slight addition.
“If a scientific worker refrains from publishing and himself takes out a
patent, there are innumerable troubles and possible litigation ahead of him,
at least if the thing turns out at all remunerative; but the possibility is,
that in his otherwise occupied hands it will not so turn out until the period
of his patent right has expired.
"Pending a much-to-be-desired emendation of the law, whereby the
courts can take cognizance of discoveries or fundamental steps in an in-
vention communicated to and officially dated by a responsible scientific
society, and can thereafter award to the discoverer such due and moderate
recompense as shall seem appropriate when a great industry has risen on
the basis of that same discovery or fundamental invention; pending this
96
WIRELESS TELEGRAPHY.
much-to-be-desired modification of the law, it appears to be necessary to go
through the inappropriate and repulsive form of registering a claim to an
attempt at monopoly. The instinct of the scientific worker is to publish
everything, to hope that any useful aspect of it may be as quickly as possi-
ble utilized, and to trust to the instinct for fair play that he shall not be the
loser when the thing becomes commercially profitable. To grant him a
monopoly is to grant him more than a doubtful boon; to grant him the
privilege of fighting for his monopoly is to grant him a pernicious privilege
which will sap his energy, waste his time, and destroy his power of future
production."
THE CHAIN OF INVENTION.
Reference to Professor Dolbear's patent printed in the
appendix reveals a well defined transmission of electric
waves without wires in 1882; and the historical part of
this work records instances of wireless signaling nearly
half a century before that date. (See Achievement.)
Upon May 23rd, 1885, Mr. Thomas A. Edison filed
an application for a United States Patent, which was
finally issued upon December 29th, 1891, numbered
465,971. It differs from Dolbear's organization in that a
key is used to send out signals instead of a telephone to
transmit words. The receiving apparatus may be a tele-
phone or other recording apparatus. The Edison speci-
fication sets forth all the uses to which a wireless telegraph
may be put, such as transmitting signals from a shore to
moving vessels, signalling across bodies of water in lieu
of using submarine cables; and as well across land spaces.
It provides for the earth's curvature by interposing along a
route condensing surfaces so arranged that there shall be
always a clear air space between any surface and its im-
mediate neighboring ones in either direction.
It is reported that this patent has been purchased by
the Marconi interests. It has five years to run. The
first claim is as follows:
INVENTORS AND INVENTIONS.
97
"CLAIM I. Means for signalling between stations separated from each
other, consisting of an elevated condensing surface, or body at each station,
a transmitter operatively connected to one of said condensing surfaces for
varying its electrical tension in conformity to the signal to be transmitted
and thereby correspondingly varying the tension of the other condensing
surface; and a signal receiver operatively connected to said other conden-
sing surface substantially as described.
CLAIM 2 adds to the combination a condensing surface at such eleva-
tion that a straight line between said surfaces and the terminal surfaces
will avoid the curvature of the earth's surface. Claim 3 adds an induction
transmitter. Claim 4 brings in the secondary and the primary of an induc-
tion coil, a transmitting key, and a telephone receiver. Claim 5 has a new
combination of the elements previously noted."
All of these earlier transmissions, however, are supposed
to have been due to the propagation through space of
magnetic lines of force, or magnetic waves. The period
of ethereal transmission dates from the discoveries in 1886
of Professor Hertz, of Carlsruhe, Germany, who found
that a disruptive discharge of electricity across a spark-
gap produced a wave motion essentially different from the
magnetic movement. His receiver of these waves was a
piece of wire so bent as to bring its ends almost together.
(Fig. 48.) In the little space between the ends of the
bent wire he detected a response to the discharges from a
Ruhmkorff coil. These responses were in the form of
minute sparks. Between the spark-gap of the machine and
the bent wire there was no tangible conductor of any kind.
The adjective "Hertzian" in the patents of Lodge and of
Marconi are acknowledgements to the phyncist of Carlsruhe.
Contemporaneously with the work of Hertz, Professor
Calzecchi-Onesti, an Italian scientist, devised apparatus
consisting of a glass tube containing metal filings, and
revoluble on an axis. He found that a group of filings
which, under normal conditions, gave a very great resist-
ance to an electric current, became a good conductor if
98
WIRELESS TELEGRAPHY.
subjected to the secondary impulse that occurs when an
electric wire circuit is broken; but if, after the discharge
had ceased, the glass tube containing the filings was
turned over in such a way as to disarrange them, the
filings became again a highly resistant mass.
Branly's Discovery, 1891. In 1891 Professor Branly
of the Catholic Institute of Paris, made the discovery that
electric sparks across an air-gap caused filings to cohere,

VERTICAL WIRE
TREMBLER
MAGNET
CALL BELL
K
A
TAPPER
X
S'
COHERER
A
RELAY
S
+ |||||||
BATTERY B
Fig. 31.
EARTH
and also that a shock or tap imparted to the tube served to
decohere them. The coherer has since been commonly
called the "Branly tube." It would seem, however, that
in the matter of a tube of filings, Professor Onesti is more
properly entitled to the honor of being the originator.
Popoff's Early Devices. In April, 1895, Professor A.
Popoff, of the Cronstadt Torpedo School, described to
INVENTORS AND INVENTIONS.
99
the Russian Physico-Chemical Society of St. Petersburg
a device which he was using in connection with the study
of atmospheric electricity, and in December of the same
year he said in a note to that Society that he hoped to
make his apparatus applicable to telegraphic signaling.
Description of Fig. 31. There is shown in Fig. 31 the
organization used by Popoff. The line in the diagram
marked "vertical wire" was his exploring antenna for
atmospheric electrical manifestations. It may be explained
that the parts represented as separated at the point X are
in contact when the apparatus is at rest. When waves
from a distant point impinge upon the vertical wire they
pass through the coherer to earth, changing the coherer
from an insulating path to a conducting one. This change
causes a current to flow from battery B through the relay.
The relay magnet, thus becoming energized, pulls down
armature A which has been held upward by spring S,
making contact at Z. There results a division of current
at Y and Y', by which the trembler magnet is caused to
pull upward the armature A' and sound an alarm on the
call-bell. This upward movement of A' destroys the
contact at X, and spring S' draws down A', the mo-
mentum imparted to knob K serving to make it tap the
coherer.
Dr. Lodge as a Patentee. From the allowed claims of
his United States patents, Dr. Lodge would seem to con-
stitute the most important link in the chain of inventors of
wireless telegraphy. An inspection of his claims shows
that he is recognized as the originator of the "emitter,"
the single conducting body from which waves are sent into
་
•
100
WIRELESS TELEGRAPHY.
space; of the metal shield which protects the receiving
apparatus from damage or from operation by the trans-
mitter at the same station with it; of the automatic means
of decohering the trembler in a local circuit; of the com-
bination with a coherer and battery of a telegraphic
receiving instrument; and finally of the scheme of syn-
tonizing which attunes by adjustments of inductance and
capacity.
Professor Lodge's system has already been explained.
The official recognition of his inventions is recorded in his
United States patents numbered 674,846, the application
for which was filed December 20, 1897, and 609,154, for
which the application was filed in 1898. A reproduction
of the first is printed in full in the appendix of this work.
The data and claims of the second are as follows:
No. 609,154, Oliver J. Lodge, Liverpool, England, Dated August 16, 1898.
Application filed February 1, 1898.
CLAIM I. In a system of Hertzian-wave telegraphy, the combination,
with a pair of capacity areas, of a self-inductance coil inserted between them
electrically for the purpose of prolonging any electrical oscillations excited
in the system, and constituting such a system a radiator of definite fre-
quency or pitch.
CLAIM 2. In a system of Hertzian-wave telegraphy, the combination,
with a pair of capacity areas, of a self-inductance coil inserted between them
electrically for the purpose of prolonging any electrical oscillations excited
in the system, thus constituting the system a resonator or absorber of defi-
nite frequency or pitch, and a distant radiator of corresponding period
capable of acting cumulatively.
CLAIM 3. In a system of Hertzian-wave telegraphy, the combination,
with a pair of capacity areas, of electrical means having a spark-gap inserted
between them and serving to syntonize them, and means for bridging or
shunting the spark-gap, whereby the apparatus is adaptable for use at will.
either as a radiator or resonator.
CLAIM 4. In a system of Hertzian-wave telegraphy, the combination,
with a pair of capacity areas, of a number of self-inductance coils having
INVENTORS AND INVENTIONS.
ΙΟΙ
different amounts of self-induction, each of which is capable of being
switched in or out of circuit, serving to syntonize any such radiator to a
corresponding resonator or vice versa, whereby signaling may be effected
between any two or more correspondingly-attuned stations without disturb-
ing other differently-attuned stations.
CLAIM 5. In a system of Hertzian-wave telegraphy, the combination,
with a pair of capacity areas, of a variably-acting self-inductance coil, serv-
ing to syntonize such a radiator or resonator to any other such resonator
or radiator, whereby signaling may be effected between any two or more
correspondingly-attuned stations without disturbing other differently-attuned
stations.
CLAIM 6. In combination, a pair of capacity areas connected by a coil
of wire serving as the radiator in a system of Hertzian-wave telegraphy,
means for syntonizing such radiator, and means for charging it by aerial
disruption or impulsive rush.
CLAIM 7. In a system of Hertzian-wave telegraphy, the combination of
a pair of capacity areas such as h, h', means for syntonizing such capacity
areas, a receiving-circuit completed through one or both of such capacity
areas, and means for bridging over the discharge-gap between such capacity
areas when they are to be used as a receiver, whereby such capacity areas
are rendered adaptable for use at will either as a radiator or resonator.
CLAIM 8. In combination, in a system of syntonic Hertzian-wave tele-
graphy, a pair of capacity areas, a self-inductance coil and a secondary coil
surrounding said self-inductance coil, which secondary coil forms part of the
coherer-circuit substantially as and for the purpose set forth.
CLAIM 9. The combination, in the receiving-circuit of a system of Hertz-
ian-wave telegraphy, of a variably-acting self-inductance coil, connecting
the capacity areas, a coherer, a battery, a receiving instrument, and a shunt
across the coils thereof substantially as and for the purpose set forth.
Regarding
Declaration in Marconi's U. S. Patent.
priority in invention, a quotation from the specification of
the reissue of Marconi's first American patent is herewith
given. It may be explained that statements of this char-
acter embodied in a patent do not constitute official recog-
nition, such recognition being confined to the allowed
claims.¹
1 See pp. 102, 103, and 200.
102
WIRELESS TELEGRAPHY.
“I am aware of the publication of Professor Lodge of 1894 at London,
England, entitled 'The Work of Hertz,' and the description therein of
various instruments in connection with manifestations of Hertz oscillations.
I am also aware of the papers by Professor Popoff in the Proceedings of
the Physical and Chemical Society of Russia' in 1895 or 1896; but in
neither of these is there described a complete system or mechanism capable
of artificially producing Hertz oscillations, and forming the same into and
propagating them as definite signals, and reproducing, telegraphically, such
definite signals; nor has any system been described, to my knowledge, in
which a Hertz oscillator at a transmitting-station, and an imperfect-contact
instrument at a receiving-station, are both arranged with one terminal to
earth and the other elevated or insulated; nor am I aware that prior to my
invention any practical form of self-recovering imperfect-contact instrument
has been described. I believe that I am the first to discover and use any
practical means for effective telegraph transmission and intelligible reception
of signals produced by artificially formed Hertz oscillations."
INITIAL AMERICAN PATENT OF GUGLIELMO MARCONI.
For United States Patent No. 586,193, the application.
by Marconi was filed December 7, 1896. The patent was
issued July 13, 1897, with fifty-six claims, and remained as
the record until June 4, 1901, when it was reissued as
No. 11,913, in which the fifty-six claims were replaced by
twenty-four. The complete reissued record is reproduced
in the appendix of this work.
MARCONI'S UNITED STATES PATENTS.
an
Initial American Patent. Considering now the re-
issued claims of the initial American patent of Marconi,
the first one is a combination of the three elements,
imperfect contact, a current through it, and a receiving
instrument operated by the influence of distant oscilla-
tions on the contact. The second claim is also a combina-
tion of three elements,
an imperfect contact, a current
INVENTORS AND INVENTIONS.
103
through it, and means operated by the circuit to shake the
imperfect contact.
CLAIM 3. The third claim, while it combines as many as
seven elements, appears to be an essential one.
A spark-producer,
It reads:
An earth-connection to one end of the spark-producer,
An insulated conductor to the other end,
An imperfect contact,
An earth-connection to one end of the contact,
An insulated contact to the other end,
A circuit through the contact.
The important features of this combination, the use of
ground connections with the transmitter and the receiver,
is suggested by Dolbear's patent. (See Appendix.)
Metal Shield Around Receiver.¹ Marconi's second
patent, by filing of application, is No. 624,516. It has three
claims of length, each bringing forward as one element a
metallic box inclosing the receiver. The object of this is
to prevent injury to the receiver, on account of its close
proximity to the sparking appliance when both sender and
receiver are used at one station. Metal screens to protect
the receiver from a near-by transmitter are disclosed in
Marconi's initial American patent filed in 1896. The
same principle is also the subject of Professor Lodge's
third claim in No. 674,846, filed a year earlier than Mar-
coni's 624,516, and is fully described in Lodge's specifica-
tion. Consequently a broad claim was not possible at the
date of filing of the metal shield application.
Marconi's Third American Patent. Marconi, on Janu-
ary 5, 1899, filed an application for a U. S. patent which
1 See Figs. 69 and 70 in Part IV., with accompanying descriptions.
104
WIRELESS TELEGRAPHY.
was issued June 27, 1899, as No. 627,650.
Its first claim
is here broken into paragraphs to distinguish the different
elements.
CLAIM I.
In a receiver for electrical oscillations, the combination of
An imperfect contact (the coherer),
A local circuit through it,
An induction coil,
A capacity (either a condenser or the earth),
A conductor connected to one end of the primary of the coil (the high
wire),
A connection between the other end and the capacity (i.e., the primary
to earth),
Connections between the ends of the imperfect contact and the ends
of the secondary coil,
A condenser in one of the latter connections.1
There are eight claims, all of them in connection with
a receiver for electrical oscillations. Claim 2 adds to the
combination in No. 1 as protection to the coherer, choking
coils, which also appear in the initial Marconi American
patent. Claims 3, 4, 5, and 6 introduce an induction coil
in which the primary and secondary windings are each of
but a single layer; and claims 7 and 8 modify these layers
in that they are composed of wires not exceeding one-
fiftieth centimeter in diameter ( inch). Regarding
single-layer windings, Marconi himself in future patents
made continued modification.
1
125
MARCONI'S Fourth, Fifth, and sixTH AMERICAN PATENTS.
On June 13, 1899, Marconi filed an application which
was afterwards divided and finally issued in the form
of three U. S. patents, numbered respectively 647,007,
¹ Italicized words in parentheses supplied by the author as explanatory.
INVENTORS AND INVENTIONS.
105
647,008, and 647,009. In these specifications is much mat-
ter in common, the forty claims for the three patents being
made thus voluminous to cover technical points. Two
drawings have been selected, Fig. 32, the main illustra-
tion of both the first and third of the series, and Fig. 33,

e
E
K
C
J
r
A
α
Fig. 32.
the principal drawing in the second of the series. The
quotation here presented is common to all three of the
series:
“This invention relates to improvements in the apparatus described in
the specification of Patent No. 627,650, granted to me June 27, 1899. In
106
WIRELESS TELEGRAPHY.
that specification I described connecting the aerial conductor to a capacity
which may be the earth through the primary of an induction-coil, the ends
of the imperfect contact or sensitive tube being connected to the ends of the
secondary. In place of winding both the primary and secondary in single
layers, as claimed in that specification, the coils are now either made very
short (not much exceeding two centimeters in length) or else are wound in
sections. The number of turns in the successive layers of the secondary

k
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E
A
G
k
a
Fig. 33.
(and sometimes of the primary also) should diminish as the distance from
the center increases; but this, although preferable, is not essential. It is
also found desirable to connect direct to the sensitive tube or imperfect
contact (not through the condenser) the end of the secondary which is
farthest away from the nucleus or axial line of the coil.
In description of Figs. 32 and 33, a is the aerial conductor; b, a local
battery; c, a condenser; e, a connection to earth or other suitable capacity;
INVENTORS AND INVENTIONS.
107
j, a sensitive tube or imperfect contact; k are choking-coils, and ʼn a relay
working a signaling or other instrument. The diagrams of the coils are
greatly enlarged half-longitudinal sections, but are not strictly to scale.
In place also of showing the section of each coil or layer of wire as a longi-
tudinal row of dots or small circles, as it would actually appear, it is for
simplicity shown as a single continuous longitudinal straight line. A is the
end of the primary, which is connected to the aerial conductor a, and E is
the end connected to earth or a capacity. J is the end of the secondary,
which is directly connected to the sensitive tube or imperfect contact j, and
C is the end which is connected to it through the condenser. G is a glass
tube on which the coils are wound. The wires are preferably insulated by
a single covering of silk."
Claims 1, 2, and 16 fairly illustrate the inventive scope
of the first one of this group, No. 647,007, and are as
follows:
CLAIM I. In a receiver for electrical oscillations, the combination of
an imperfect electrical contact, a local circuit through it, an induction-coil,
the secondary of which consists of several layers, the number of turns in
the outer layers being less than in those next the primary, a capacity
connected to one end of the primary, a conductor connected to the other
end, and connections between the ends of the imperfect contact and the
ends of the secondary.
CLAIM 2. In a receiver for electrical oscillations, the combination of an
imperfect electrical contact, a local circuit through it, an induction-coil, the
secondary of which consists of several layers, the number of turns in the
outer layers being less than in those next the primary, a capacity connected
to one end of the primary, a conductor connected to the other end, con-
nections between the ends of the imperfect contact and the ends of the
secondary, and a condenser in one of the latter connections.
CLAIM 16. In a receiver for electrical oscillations, the combination of
an imperfect electrical contact, a local circuit through it, an induction-coil,
the primary of which consists of two wires connected in parallel, wound in
four layers, the first and second layers being formed of one wire and the
third and fourth of the other, the secondary of which consists of several
layers, the number of turns in the outer layers being less than in those next
the primary, and wound unsymmetrically with a lump at one end, a capacity
connected to one end of the primary, a conductor connected to the other
108
WIRELESS TELEGRAPHY.
end, connections between the ends of the imperfect contact and the ends
of the secondary, and a condenser in one of the latter connections.
Claims I, 2, and 4 of the second of the group are inserted
to show the distinctive features of that patent. Words are
Italicized by the author to mark a phrase which does not
occur in the first patent, but is found in all three of the
following claims:
CLAIM I. In a receiver for electrical oscillations, the combination of an
imperfect electrical contact, a local circuit through it, an induction-coil, the
secondary of which consists of several layers, the number of turns in the
outer layers being less than in those next the primary, a capacity connected
to one end of the primary, a conductor connected to the other end, connec-
tions between the ends of the imperfect contact and the ends of the sec-
ondary, and a condenser in the connection to the inner end of the secondary.
CLAIM 2. In a receiver for electrical oscillations, the combination of an
imperfect electrical contact, a local circuit through it, an induction-coil, the
secondary of which consists of several layers, the number of turns in the
outer layers being less than in those next the primary, and wound unsym-
metrically with a lump at one end, a capacity connected to one end of the
primary, a conductor connected to the other end, connections between the
ends of the imperfect contact and the ends of the secondary, and a con-
denser in the connection to the inner end of the secondary.
CLAIM 4. In a receiver for electrical oscillations, the combination of an
imperfect electrical contact, a local circuit through it, an induction-coil, the
primary of which consists of two wires connected in parallel, wound in two
layers, the secondary of which consists of several layers, the number of
turns in the outer layers being less than in those next the primary, and
wound unsymmetrically with a lump at one end, a capacity connected to
one end of the primary, a conductor connected to the other end, connec-
tions between the ends of the imperfect contact and the ends of the sec-
ondary, and a condenser in the connection to the inner end of the secondary.
Of the last of the series but one claim, the sixteenth, is
shown where the Italicized word "two" is its only distinc-
tion from claim 16 of the first of the series, in which the
word "four" is also found in Italics.
INVENTORS AND INVENTIONS.
109
CLAIM 16. In a receiver for electrical oscillations, the combination of
an imperfect electrical contact, a local circuit through it, an induction-coil,
the primary of which consists of two wires connected in parallel, wound in
two layers, the secondary of which consists of several layers, the number of
turns in the outer layers being less than in those next the primary, and
wound unsymmetrically with a lump at one end, a capacity connected to
one end of the primary, a conductor connected to the other end, connec-
tions between the ends of the imperfect contact and the ends of the sec-
ondary, and a condenser in one of the latter connections.
INVENTION OF IMPROVED TRANSMITTING
KEYS, SEVENTH
AND EIGHTH AMERICAN PATENTS OF MARCONI.
Patent No. 650,110, filed December 28, 1899, is a modi-
fication of No. 650, 109, filed on October 12 of the same
year. The diagram which illustrates the former is shown
as Fig. 77 in connection with "Keys," Part IV. The
difference between the two patents is that in the first a
connection is made from that electrode of the spark-gap
which connects with the high wire to an insulated back
terminal on the sending-key of the transmitting operator;
while in the second patent the high wire connecting
directly with the insulated back terminal of the transmit-
ting key does not make actual contact with the electrode
of the spark-gap, but, instead, is brought very near to it.
The first claim of 650, 109 is as follows:
CLAIM I. The combination of the primary and secondary of a sparking
appliance, a battery and key in circuit with the primary, an aerial conductor
connected to one terminal of the secondary, a receiver, means for connect-
ing the said terminal to the receiver, and a capacity connected to the other
terminal.
In the second claim there are substituted for the last
eight words of Claim I the words "and an earth connec-
tion connected to the other terminal."
The first claim of No. 650, 110 is as follows:
IIO
WIRELESS TELEGRAPHY.
CLAIM I. The combination of the primary and secondary of a spark-
ing appliance, a battery and key in circuit with the primary, an aerial con-
ductor led in close proximity to one terminal of the secondary, means for
connecting the said aerial conductor to the receiving instrument, and a
capacity connected to the other terminal.
The change of phrase noted in the companion patent,
whereby "capacity" is substituted for "earth connection,"
occurs here also.
C'
NINTH AMERICAN PATENT OF MARCONI.
R
A
In Fig. 34 there is shown a new set of connections in
which the secondary winding of a step-down induction coil
is divided into two parts, a condenser
is placed between the two parts, and
the relay circuit is connected to them
on each side of that condenser. This
diagram is the principal drawing of
U. S. Patent No. 668,315, issued on
February 19, 1901, the application for
which, however, was filed July 17, 1900.
While it is not the broadest claim,
No. 4 offers the best brief to illustrate
the invention. It is given here with
interpolated explanatory references as follows:

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CLAIM 4. In a receiver for electrical oscillations, the combination of
an induction coil, the secondary of which is wound in two parts (see j2,
Fig. 33), an aerial conductor connected to one end of the primary (A), a
capacity connected to the other end of the primary (E), a detector or
coherer connected to the outer ends of the secondary (T), a condenser
across the inner ends of the secondary (j3), a local circuit connected to the
condenser (BR), choking coils between the local circuit and condenser
(CIC2).
INVENTORS AND INVENTIONS.
III
No. 1, the broadest claim, has but five elements, and
reads as follows:
CLAIM I. In a receiver for electrical oscillations, the combination of an
induction-coil, the secondary of which is wound in two parts, an aerial con-
ductor connected to one end of the primary, a capacity connected to the
other end of the primary, a detector connected to the outer ends of the
secondary, and a local circuit connected to the inner ends of the secondary.
The wording of one part of the specification leads to the
belief that at the date of its filing, July 17, 1900, the in-
ventor was beginning to question the efficacy of the


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Fig. 35.
Fig. 36.
unsymmetrical winding advocated in former patents, al-
though he still gives to it, as Fig. 35, precedence in order
of description. The arrangement shown in Fig. 36, how-
ever, is spoken of as one from which "very good results have
been obtained." In it each half of the secondary consists
of one hundred and sixty turns in a single layer. The
specification states that in using coils in which the second-
ary winding consists of one layer, the inventor had noticed
that the best results were had when the length of the
secondary winding was approximately equal to the length
of the aerial conductor employed at the transmitting
station, an observation somewhat in line with Professor
Slaby's assertion that there is a law of transmission
which governs the length both of the emitter and the
antenna.¹
1 See in connection with Slaby, p. 58.
I 12
WIRELESS TELEGRAPHY.
*
:
DOUBLE WAVE-GATES. TENTH AMERICAN PATENT OF
MARCONI.
At this writing the final Marconi patent, so far as
known, is No. 676,332. The application was filed Febru-
ary 23, 1901, and it was issued on June II of the same
It relates to the employment of double emitters.
year.


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Fig. 37.
and antennae. These double conductors are shown either
as concentric cylinders separated by an appreciable air-
space, or as two distinct vertical wires, or as an aerial
terminal consisting of two conductors arranged concentri-
cally, the inner one being a solid wire covered with an
insulating substance, and the outer being a tube fitting
closely around the insulation of that which forms the core.
INVENTORS AND INVENTIONS.
113
The typical diagram is Fig. 37, in which it may be noted
that the inner conductor has one branch to earth and one
through an inductance and the spark-gap to the outer one.
In other drawings the patentee shows at the transmitting
station the wire connecting secondary coil c with induct-
ance i to the left as having a pointed top, and resting
against one of the coils of i, thus indicating that the
inductance may be varied. The scope of this final Mar-
coni patent may be shown by an analysis of its five claims
as follows:
CLAIM I. Element one, - Two aerial oscillation-producing conductors
insulated from each other. Element two, An inductance connected in
series with such conductors. Element three, — A producer of electric
oscillations (a Ruhmkorff coil, for instance). Element four, A signaling
instrument controlling the spark-producer (as a key in the primary
circuit).1
CLAIM 2. There is added to the combination in claim I a fifth element,
a connection from one of the emitters to the earth.
CLAIM 3. Element one of first claim is modified by the statement that
the two aerial oscillation-producing conductors are insulated from each
other.
CLAIM 4. Pertains to a receiving station and has four elements: One.
Two antennae insulated from each other. Two. An inductance con-
nected in series with the two antennae. Three. An imperfect electrical
contact.
CLAIM 5. Adds to the combination in claim 4 a connection from one
of the antennae to the earth.
There occurs in the specification of the patent now
under consideration the remark that while "Lodge shows
two large oscillation-producing conductors and an induct-
ance device connected between them," yet he does not
"use a plurality of aerial oscillation-producing conduc-
tors.
"2
1 Parenthetical phrases supplied by author.
2 See claims 6 and 8, Lodge's patent, No. 609,154, p. 101, Part II.
114
WIRELESS TELEGRAPHY.
THE WIRELESS TRANSMISSION PATENTS OF TESLA.
A number of inventions by Mr. Nikola Tesla have been
described at length in Part I. Their relation to the general
patent situation is, however, so complex, and may prove so
far reaching that anything like an exhaustive discussion of
such of his numerous patents as bear upon the art, would
occupy many times the space which can be allotted in this
work. Anything less than an exhaustive discussion would
not do the subject justice. It has, therefore, been thought
best to reproduce in the appendix, without any comment
whatever, the numbers, titles, dates of filing and represen-
tative claims, of such patents as may seem to give to the
inventor a monopoly of any of the methods and devices
necessary to the proper working of a wireless telegraph
system.
UNITED STATES PATENTS OF PROFESSOR REGINALD
A. FESSENDEN.
On August 12, 1902, there were issued to Professor
Fessenden thirteen United States patents, which are here
considered in the order of their filing as applications.
Fessenden's Initial United States Patents. - The first
two, filed December 15, 1899, and numbered 706,735 and
706,736, are companion patents, one concerning the meth-
ods and the other the devices of the same improvements.
The first claim of the method patent reads :
CLAIM I. "As an improvement in the art of transmitting signals elec-
trically by electromagnetic waves, the method herein described, which con-
INVENTORS AND INVENTIONS.
115
..
sists in the generation of electromagnetic waves at one station and trans-
forming the energy of the currents generated by such waves at the receiv-
ing-station into the energy of motion, that is without the necessary interpo-
sition of a secondary or auxiliary generator for the production of such
motion."
The auxiliary generator referred to as omitted is pre-
sumably the battery which in coherer organizations actu-
ates the relay. It will be observed that, as represented in
Fig. 55, Part IV., there is no source of energy whatever
at the receiving station.
To a feature of this invention attention is called by
another claim, as follows:
CLAIM 6. "As an improvement in the art of transmitting electrical en-
ergy by electromagnetic waves, the method herein described, which consists
in prolonging the oscillations of an energy-radiating conductor by energy
from a source external to the radiating-conductor and tuned to the period
of the radiating-conductor."
The external source here is condenser 18 in a shunt cir-
cuit around the spark-gap as shown in Fig. 44, Part IV.
Another novel feature is set forth in the ninth claim,
and explained by Fig. 53, Part IV., and the accompanying
description.
CLAIM 9.
"As an improvement in the art of transmitting electrical
energy, the method herein described, which consists in varying the con-
ductivity of a secondary circuit at the receiving-station by motion produced
by currents generated by electromagnetic waves.”
The Device Patent. The device patent 707,636 has
the same drawings as 706,735. Its claims cover in gen-
eral the means and combination of means which are used
in the methods specified and claimed in its mate.
►
116
WIRELESS TELEGRAPHY.
:
Fessenden's Patent for Electro-Magnetic Sending Con-
ductor. No. 706,737 was filed May 29, 1901. Here
No. 17 is a characteristic claim for a sending conductor.
CLAIM 17. “A sending-conductor for electromagnetic waves having low
resistance, small self-induction and great capacity."
An illustration of the above is found in reference num-
ber 1 of Fig. 38.
Another feature is the receiver of claim 12, which is
shown in Fig. 55, Part IV. The claim entire reads,


11
-10
F
E
Fig. 38.
2
CLAIM 12.
"A system for signaling by electromagnetic waves, having
in combination a conductor adapted to radiate waves of low frequency, and
a receiver dependent for its action upon a constant or independently-vary-
ing magnetic field and adapted to respond to currents produced by said
waves."
Fig. 38, as a whole, illustrates a system covered fairly
well by claim 21, which reads:
CLAIM 21. "A system for transmission of energy by electromagnetic
waves, including in combination a radiating-conductor and a source of alter.
nating electrical energy or potential, said radiating-conductor and source
being co-ordinated and relatively adjusted to radiate a substantially con-
tinuous stream of electromagnetic waves of substantially uniform strength.”
INVENTORS AND INVENTIONS.
117
Fessenden's U. S. Patent for Localizing by the Use of a
Plurality of Tuned Circuits. The features of No. 706,-
738, filed May 29, 1901, are well indicated by its claims I
and 5 here quoted, and as an illustrating diagram refer-
ence is had to Fig. 26, Part I.
CLAIM I. “In a system of signaling by electromagnetic waves, a receiv-
ing-conductor having a transforming device in series in the circuit, in com-
bination with a circuit including a translating device, and having a local
source of voltage and controlled by the transforming device and a source of
voltage so arranged that its voltage will oppose the voltage from the local
source operating the translating device.
CLAIM 5.
In a system of signaling by electromagnetic waves, a send-
ing-conductor adapted to maintain and to radiate persistent oscillations, in
combination with a receiving-conductor and one or more secondary circuits
controlled by the receiving-conductor, the ratio of inductance to capacity
being larger in a secondary circuit than in the sending-conductor, a wave-
responsive device included in a secondary circuit of a series, the several cir-
cuits being each tuned to correspond to the period of the sending-conductor."
Fessenden's United States Patent for Increasing the
Capacity of the Wave-Gate. The Fessenden patent
706,739 covers a device for surrounding the wave-gate
with a medium of specific inductive capacity higher than
air. Figs. 62 and 63 in Part IV. are respectively a plan
and an elevation, and are there fully described.
of the twenty claims may be quoted as follows:
The first
CLAIM I. "A conductor for radiating electromagnetic waves, in combi-
nation with a medium having an electrical constant on which the wave
length depends of a value greater than that of air arranged in suitable
relation to the conductor."
Fessenden's United States Patent for Localization by
Generating and Receiving Two Sets of Waves of Different
Periodicities. No. 706,740, filed September 28, 1901, is
an ingenious device for the localization of signals. It is
118
WIRELESS TELEGRAPHY.
described at length in connection with Fig. 28, Part I. Of
the nine claims two are sufficient for illustration.¹
CLAIM I. "In a system of signaling by electromagnetic waves, the
combination of a source of waves of different periodicities and two or
more receivers responsive respectively to the differing waves or impulses.
and a wave-responsive device operative when the waves or impulses attain
a certain predetermined phase relation.
CLAIM 6. In a system of signaling by electromagnetic waves, the com-
bination of means at the sending-station for generating two or more sets
of waves of different periodicities, and a wave-responsive device at the
receiving-station operative by the conjoint action of such set of waves."
Fessenden's Wireless Telephony.-The interesting claim
of Patent No. 706,747, filed September 27, 1901, is the
fourteenth referring to Wireless Telephony as follows:
CLAIM 14.
"In a system for transmission of speech by electromagnetic
waves, the combination at the sending-station of means for the practically
continuous generation of electromagnetic waves, a telephone-transmitter
for modifying the character of the waves or impulses, and a telephone-
receiver at the receiving-station responsive to currents generated by the
electromagnetic waves."
An illustration of the above is Fig. 27 in Part I., and
there described.
Fessenden's High Pressure Spark-Gap. - Professor Fes-
senden's Patent 706,741, filed November 5, 1901, is for
device to maintain a certain definite relation between the
resistance and the self-inductance and capacity of the send-
ing mechanism, regardless of the potential employed. It is
described at length in connection with Figs. 46 and 47,
Part IV. To indicate its patentable scope, two of its claims
are subjoined.
CLAIM 5.
"An apparatus for the generation of radiation, having in
combination a conductor for radiating electromagnetic waves, and sparking
¹ See in Part I. description of Tesla Patents, Nos. 723,188 and 725,605, and in Appendix
their dates and claims.
INVENTORS AND INVENTIONS.
119
terminals, all gaps between sparking terminals being occupied, by insulating
material under pressure greater than atmospheric pressure, substantially as
set forth.
CLAIM II. An apparatus for the generation of radiation having in
combination a conductor for radiating electromagnetic waves and spark-
ing terminals, all gaps between sparking terminals being occupied by
insulating material under pressure above a certain critical high pressure.”
In con-
Fessenden's Patent for a Selective System.
nection with "Keys" in Part IV., will be found as Figs.
74, 75, and 76, a reproduction of the third sheet of draw-
ings of the Fessenden Patent No. 706,742, filed June 6,
1902.
This document is long, containing five sheets of draw-
ings, six printed pages of specifications, and twenty-nine
claims.
To show its features, five of the claims follow:
CLAIM 5.
"In a system for signaling, &c., by electromagnetic waves,
the combination of a conductor adapted to radiate electromagnetic waves,
means for causing the radiation of electromagnetic waves from said con-
ductor, and means for modifying one or more of the characteristics of said
waves.
CLAIM 9. In a system of signaling by electromagnetic waves, the com-
bination of a conductor and a spark-gap with means for changing the
function of the conductor, i.e., from sending to receiving without bridging
or disconnecting the spark-gap.
CLAIM 16. In a system of signaling by electromagnetic waves, the
combination of a receiving-circuit, a series of receivers, and means shifting
any desired one of said receivers into and out of operative relation to the
receiving-conductor.
CLAIM 21. A system of signaling by electromagnetic waves, having in
combination a sending-conductor and a key provided with fingers adapted
to be brought into contact in succession with the sending-conductor at
different points.
CLAIM 26. A system of signaling by electromagnetic waves, having in
120
WIRELESS TELEGRAPHY.
combination therewith means for indicating to a third station during send-
ing or receiving that such sending or receiving station is busy."
Fessenden's Patent for Recording on Photographic Paper.
Patent No. 706,743, filed June 26, 1902, is for a method
of catching the signals on photographic paper, and at the
same time and in the same procedure applying chemicals
to fix and develop them. There are but three claims, which
are herewith reprinted.
CLAIM I. "As an improvement in the art of signaling by electro-
magnetic waves, the method herein described, which consists in producing
interpretable characters or symbols on a strip or film by chemical action
produced by currents generated by electromagnetic waves.
CLAIM 2. As an improvement in the art of signaling by electro-
magnetic waves, the method herein described, which consists in affecting a
sensitive strip or film by currents generated by electromagnetic waves.
CLAIM 3. As an improvement in the art of signaling by electromag-
netic waves, the method herein described, which consists in producing
interpretable characters or symbols on a strip or film by chemical action
induced by electric currents generated by electromagnetic waves."
Fessenden's Electromagnetic-Receiving-Device. No.
706,744, filed July 1, 1902, is for an electromagnetic
receiving-device. It is described at length in connection
with Fig. 59, Part IV. The first three claims are suffi-
ciently characteristic to show its patentable scope.
CLAIM I. "A receiver for currents produced by electromagnetic waves
consisting of a conductor having small heat capacity.
CLAIM 2. A receiver for currents produced by electromagnetic waves
consisting of a conductor having small radiating-surface.
CLAIM 3. A receiver for currents produced by electromagnetic waves
consisting of a conductor having low resistance and small heat capacity
substantially as set forth."
Fessenden's Patent for System. There will be found
in connection with Fig. 29, Part I., a long description of
INVENTORS AND INVENTIONS.
I2I
the invention embodied in No. 706,745, filed July 1, 1902.
The patent is for a system, and presumably presents the
culmination of Mr. Fessenden's labors. Of its thirty
claims the twenty-ninth may be quoted.
CLAIM 29.
"A system of signaling by electromagnetic waves, having at
the receiving-station a closed tuned secondary circuit and a constantly-re-
ceptive, current-operated, wave-responsive device, in combination with a
source of persistent radiation at the sending-station."
Fessenden's Wave-Chute Patent. — Professor Fessenden's
patent, No. 706,746, filed July 1, 1902, is for a wave-chute.
It is fully described in connection with wave-gates, and
illustrated by Figs. 64 and 65, Part IV. One claim is as
follows.
CLAIM 5.
"In a system for the transmission of energy by electromag-
netic waves, a sending-conductor for radiating such waves, and an artificial
ground connected to the lower end of the sending-conductor and connected
at its outer end to ground."
NOTICEABLE GROUP OF INVENTORS.
It is impossible within the limits of this volume to men-
tion, even briefly, all the inventions in this young art, for
they are already numbered by hundreds. There is a notice-
able group of inventors who assign, either directly or
indirectly, to the American Wireless Telegraph Company.
Among them Mr. A. F. Collins and Mr. Harry Shoe-
maker are prominent, the latter being especially prolific.
Unfortunately there is no public record of quantitative
results by which the merits of their inventions may be
measured.
122
་
WIRELESS TELEGRAPHY.
EHRET'S COMBINATION OF COHERER AND ANTI-COHerer.
The patent of Mr. Cornelius D. Ehret, already noticed
at some length as of promise,' is deserving of consideration
from an inventive standpoint. It is numbered 699,158.
The application was filed December 3, 1901, and the issue
is dated May 6, 1902. It contains twelve claims, all of
value. Three of them are herewith reprinted.
CLAIM I. "In a signaling system the combination of dissimilar wave-
responsive devices conjointly controlling a translating device.
CLAIM 7. In a receiver the combination of a coherer and an anti-
coherer conjointly controlling a translating device.
CLAIM 12. In a receiver the combination of a coherer and an anti-
coherer, a local circuit controlled by each, a coil of a relay included in each
circuit, said coils operating differentially on the magnetic circuit of each
relay, substantially as described."
PUPIN PATENTS.
Dr. M. I. Pupin, of Columbia University, has taken out
two United States patents for multiple telegraphy with
conductors. His claims, however, may have so broad a
scope as to cover the principle of selective signalling by
means of electrical resonance; and for this reason it is
reported that his rights have been purchased by the Mar-
coni interests. The numbers are respectively 707,007, and
707,008, and both were issued on August 12th, 1902.
Application for the first was filed February 23rd, 1894.
As an illustration of their bearing upon wireless telegraphy,
claim number one of the earlier patent (707,007) is here-
with quoted:
1 See p. 84 and Fig. 30 in Part I.
4
1
INVENTORS AND INVENTIONS.
123
"CLAIM I.
The method of distributing electrical energy which consists
in throwing upon a common conductor a number of alternate currents of
different frequencies and distributing the several energies of these currents
each selectively to a separate electrical device substantially as described."
SUMMARY.
There is in Part I an account of the transmission of
electric signals by Morse in 1842 across a body of water;
and a similar achievement by Lindsay some ten years later.
In the next decade James Clark Maxwell published his
interpretation of electrical phenomena as a propagation of
ether waves, differing from light only in the lesser number
of vibrations within a given unit of time. In 1882 Dol-
bear applied for a United States Patent for a method of
telephonic transmission across space without wires; and in
1885 Edison applied for one to cover methods and devices
similar to Dolbear's. It seems, however, that the true
period of invention in the field of ethereal transmission
extends from the discovery of the minute sparks in the
bent wire at Carlsruhe in 1886, to the reception of the
Poldhu signals at Cape Race in 1901; that the first trans-
mission was due to Hertz, and the discovery of the prop-
erties of the filings to Calzecchi-Onesti ; that the researches
of Branly gave to the world the laws which govern the
action of the coherer; that Lodge sealed the filings in a
vacuum, applied to the coherer thus improved the prin-
ciples of electrical resonance, and in a laboratory combined
the various elements which make a wireless telegraph ;
that Tesla discovered many of the laws governing high fre-
quencies and great pressures and devised means for the
production and effective insulation of high potentials; and
finally Marconi combined the results of these various dis-
coverers in a system by which signals were observed at the
distance of two thousand miles.
I24
WIRELESS TELEGRAPHY.

{
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SOLOMON 18.
FIJI 18.
SAMOAN 18.
AUSTRALIA
NEW
ZEALAND
จ
C
A No A
A
San Francisco
U N
S
T NA
Washington
TE S
New Orleans
MEXIC
Gulf of
Mexico
CENTRAL
AMERICA
CUBA
JAMAICA❤
Fork
BERMUDA
SHAITI
→PORTO RICO
Sea
Caribbean
HAWAIIAN IS.
SOCIETY 18.
N
F
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BRITISH
ISLES Lon
Paris
FRANCE
AZORES
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AFRICA
(C. Verde
A
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TIC
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Pernambuco
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RICA
Valparaiso
Rio de Janeiro
Fig. 39.
Marconi's projected line of communication. England to New Zealand.
E.L.POATES, ENGR., N.Y.
THE COMPARATIVE MERITS.
125
PART III.
THE COMPARATIVE MERITS
OF WIRELESS TELEGRAPHY AND OF TELEGRAPHY
BY WIRES AND CABLES-AND THE COM-
MERCIAL OUTLOOK FOR EACH.
THE history of the useful arts is evidence of the fact
that each new development adapts itself to an especial
field; that old methods and devices, which seemed certain
to be supplanted by new, often continue to be employed
and even to multiply. The innumerable freight trains that
now rumble between Buffalo and Albany have not dis-
placed the mule and barge of Erie Canal; and notwith-
standing the existence of unnumbered freight-carrying iron
steamers, wooden vessels with sail power are still being
built on the Kennebec. Millions of electric lamps illumine
the streets, theatres, hotels, and residences of New York
City, yet "dollar gas" was very recently an issue in its
politics. The pedestrians of our larger cities are compelled
at each street crossing to calculate the relative speed of
machine-moved vehicles; yet the last United States Census
records twenty-two millions of horses and mules; and all
the harness factories in the country at this writing are
behind their orders. Telephone instruments are installed
in every nook and corner of the City of New York, their
126
WIRELESS TELEGRAPHY.
}
daily connections counting into thousands; yet the mes-
senger business of the American District Telegraph has
not decreased during the last seventeen years, and that
company is still paying dividends.
It is the purpose of this section to speculate as to the
influence that will be exerted by Wireless Telegraphy upon
its predecessors and competitors in the field of distant
communication. The new art has, of course, an exclusive
and profitable employment in signaling from ship to ship
on the ocean, and from ship to shore. The English
Marconi Company already derives a revenue from tolls for
communications between passengers on incoming steam-
ships and the near shores, receiving about two hundred and
fifty dollars a voyage from messages sent within a short
distance of either side of the Atlantic. The Lloyds have
adopted the system, and are requiring steamships that get
the best insurance rates to be equipped with it.
It is easy
to prophesy that in the immediate future the telegraphic
news of the world will be scattered like seed from the sower
over the whole Atlantic and may be picked up by any vessel
equipped with properly attuned apparatus; but that it will
render the present system of ocean cables obsolete is alto-
gether improbable.
The
Ocean Cables as a Means of Communication.
cables are an excellent medium for the transmission of
signals; they are in position; and the money that has
been expended to make and to place them cannot now
be recovered. Neither bonded indebtedness, nor other
form of financial obligation, will have any physical effect
upon the efficiency of the cables as a means of communi-
cation.
THE COMPARATIVE MERITS.
127
Expression of the Cable Company's Official. In this
connection may be quoted an article from the New York
Sun of March 4th, 1902, entitled "The Cable Company
Cheerful":
An expression of confidence in the ability of submarine cables to main-
tain their commercial supremacy in competition with wireless telegraphy
was made yesterday by George G. Ward, Vice-President and General Man-
ager of the Commercial Cable Company, in addressing as chairman the
annual meeting of that company's shareholders in this city. Mr. Ward
spoke as the representative of the officers of the company, who, he said,
while they "did not intend to belittle the credit due to Mr. Marconi," for
the advancement he has made in the field of wireless telegraphy, believed
that submarine cables would hold their supremacy, even should wireless
telegraphy "ever extend beyond its present experimental stage as regards
trans-Atlantic or other long-distance transmissions." Mr. Ward added:
"Our shareholders must not overlook the fact that it has taken the
Commercial Cable Company and its land line system some seventeen
or eighteen years to perfect their organization for the distribution and col-
lection of telegrams throughout the United States and the rest of the world.
Assuming that the Marconi system should become perfected so that it
could really compete in a commercial sense, and commercial requirements
are very exacting, it is fair to say that it would take as many years to put
the Marconi system in a position that would enable it to serve the public.
Messages are now transmitted across the Atlantic and answers received in
two and three minutes. A message experiencing a delay of ten or fifteen
minutes means the defeat of the object of the sender. A most important
point is the fact that 95 per cent of the Atlantic messages are expressed in
code or cipher language, the words or ciphers having no connected mean-
ing. The words or cipher groups frequently only differ from each other in
single letters, yet they have widely different meanings, and an error in the
transmission of one of their letters might have disastrous consequences.
These are some of the commercial exactions or demands made upon the
telegraphs. No one as yet even has pretended that the speed with which
messages may be transmitted by wireless apparatus even approaches the
speed of the aerial or submarine wire.
The company's net earnings for the year ended December 31, 1901,
amounted to $2,2 59,897, a decrease of $19,770 compared with 1900. After
payment of interest and dividends there was a balance of $409,538, against
$493,003 in 1900."
21
128
WIRELESS TELEGRAPHY.
Marconi's Belief. Herewith is reprinted by permission
from the Century Magazine, Marconi's own contention.
This item was published about the same time as that of
Vice-President Ward of the Cable Company:
Mr. Marconi believes that his system may become a formidable com¯
petitor against the ocean cables. To compete on land is not so easy,
as the lines there cost only one hundred dollars a mile, whereas the cables
cost one thousand dollars a mile, and require expensive steamers to repair
and maintain them. A transatlantic cable represents an initial outlay of at
least three million dollars, besides the cost of its maintenance. A Marconi
station can be built for sixty thousand dollars. Three of these, bringing
the two worlds into contact, will cost only one hundred and eighty thousand
dollars, while their maintenance should be insignificant. What his success
will mean can be best grasped by considering the extent of the property
which would be displaced thereby, although it is only since August 5th,
1858, that the first Atlantic cable was laid. There are now fourteen laid
along the Atlantic bed, and in the whole world seventeen hundred and sixty-
nine telegraph cables of various sizes, with a total length of almost one
hundred and eighty-nine thousand nautical miles, enough to girdle the
earth seven times. These require a great number of ocean-going cable
steamers for their laying and repairs, and while the total value of the cables
cannot be easily computed, it is known to be a fact that British capitalists
have one hundred million dollars invested in cable stocks."
Marconi has said to his English stockholders that
whereas the speed of the submarine cable is directly
affected by length of transmission, the wireless system is
not in the least affected by distance. That "it is just as
easy to work at high speed across the Atlantic or Pacific
as to work across the English Channel." He is confident
of establishing direct communication between England and
New Zealand.' He says that the curvature of the earth
does not affect the signals, and that ultimately he will be
able to send them all around the world.
Over the
Speed of Transmission over Ocean Cables.
German Cable from New York to the Azores, two sets of
1 See chart, Fig. 39, p. 124.
THE COMPARATIVE MERITS.
129
3
C
signals in opposite directions are simultaneously sent at a
rate of about seventy words per minute for each circuit of
a duplex transmission, making a total of one hundred and
forty words. This, it is said, is the best that is done over
any long submarine conductor. The principal limiting
factor in this signaling is a delaying influence due to
electrostatic capacity. Professor Pupin of Columbia Uni-
versity, who has exhaustively investigated this subject, has
pointed out that electrostatic capacity, being a storage of
power, is an advantage rather than a detriment if properly
controlled; and in pursuance of his plans for such control, it
is reported that the Bell Telephone Company has equipped
three circuits from New York to Chicago with "Pupin Coils,"
and that the results are an increase in the efficiency of speech-
communication equivalent to one hundred per cent.
Professor Pupin is sanguine that equally good results
will follow a similar treatment of ocean cables, but there is
no way of demonstrating this fact in actual practice except
by the construction of a new cable in conformity with his
design. He has been quoted in newspaper paragraphs as
saying that the ultimate possibility in submarine telegraphy
is a rate of one thousand words per minute; and while it
may be feasible to attain this speed it seems that condi-
tions other than those connected with induction
require for such rapid work both a larger conductor and
an increased mass of insulating material, thus entailing an
expense in construction which may prove prohibitive; and
that a safer estimate of probable future speed is five hun-
dred words per minute.
will
Progressive Invention in Cable Apparatus. It may be
said also that there is progressive invention in cable appa-
130
WIRELESS TELEGRAPHY.
ratus. Foresio Guarini, an Italian scientist of repute in
the field of wireless telegraphy, has suggested the coherer
as a device to be used in multiplexing ocean cables by
means of electrical resonance. Chemical telegraphy, here-
inafter explained, may also be mentioned in this connection.
The foregoing suggestions will serve to point the fact that
although etheric transmission has undoubtedly come to stay,
the possibilities of wave propagation through copper stili
offer alluring fields of research.
WIRELESS TELEGRAPHY OVERLAND.
Hertzian-wave signaling overland, though still in em-
bryo, will undoubtedly become an important factor.
Marconi believes a thousand miles in one span to be a
possible transmission. Guarini has been somewhat suc-
cessful in devising automatic repeaters which may double
or treble such a span. Fessenden predicts that a circuit
will eventually be worked from New York to Chicago.
A difficulty in making the comparison between wave
and wire signaling overland arises from the fact that the
land telegraph systems with wires seem to be far behind
their possibilities; which is to say that the telegraph com-
panies do not begin to do what they might; and in order
to present an intelligent view it is thought best to explain
at some length the present situation of commercial tele-
graphy on land.
Controversy in the Electrical World. There has re-
cently occurred in the correspondence department of the
Electrical World a controversy concerning the attitude of
132
WIRELESS TELEGRAPHY.
explained that in doing this work eight men are employed,
four in sending and four in receiving.
A circuit between Boston and New York, however, does
not furnish the most essential data, for it is but two hun-
dred and fifty miles in length. The great telegraphic
highways are the wires between New York and Chicago,
which are a thousand miles long. Upon these circuits the
quadruplex rate is likely to be nearer to sixty words per
wire per minute; but for the purposes of comparison we
may use the data given at eighty words, as it is certain that
this rate may not be exceeded.
The "Postal" engineer also stated that the public is not
finding fault with the present telegraphic service, to which
statement the reply may be made that the public is not
fully enlightened. He further stated that the night or
half-rate traffic "is naturally limited by reason of the splen-
did mail facilities between our principal cities."
Mail Service. Following are actual facts in regard to
mail service:
To transport a letter from a street box at 125th St. and
8th Avenue, New York City, to 39th Street and Cottage
Grove Avenue in Chicago, requires forty-five hours; con-
sequently the securing of an answer to an inquiry by such
means requires more than four full days.
A person in the business district of St. Louis desiring to
send a letter to New York at two in the afternoon may
just as well mail the letter at midnight. A letter regis-
tered on Thursday afternoon in St. Louis, with full postage,
was not delivered in the business district of New York
City until Monday morning.
First class mail matter deposited in the Post Office in
THE COMPARATIVE MERITS.
131
the Western Union Telegraph Company. This happening
is fortunate in that the participants are representative men
and have definitely announced their opinions. Professor
Pupin had published a letter which virtually stated that the
officials of the Western Union Telegraph Company were
impervious to suggestions from inventors or scientists.
The Electrical World editorially commenting upon this
letter took the ground that the telegraph authorities, as
compared with those in other electrical professions, had
been noticeably backward in developing their art. The
engineer of the Western Union Company replied that Pro-
fessor Pupin's lack of practical experience in telegraphy
probably accounted for his misapprehension.
The Morse System. He also said that nothing had
ever been found to equal what telegraphers call "Morse,"
a term used to define the method of reading signals by
sound which renders it possible to write down a message
as it is received, the telegram at the receiving end being
ready for delivery as soon as the sending operator has fin-
ished his work. It was further said that in times of emer-
gency and for some purposes the Wheatstone system had
value.
Speed of Quadruplex. -The engineer of the Postal Tel-
egraph Company gave some interesting data as to trans-
mission by Quadruplex (a species of "Morse") between
New York and Boston, by which it appears that the average
number of words sent over one wire by four operators is
four thousand nine hundred and fifty per hour, or a little
less than twenty-one words per minute per sender, or
eighty-four words per minute per wire. It may be
THE COMPARATIVE MERITS.
133
Detroit, Michigan, at six in the afternoon of Thursday,
will not be delivered down town in New York until Satur-
day morning.
Between the service just described for two cents and the
day rate of forty cents, and night rate of thirty cents for
ten word telegrams, the telegraph companies have never
been able to see an opportunity for employing at night
their idle wires.
DIFFERENT TYPES OF TELEGRAPH APPARATUS.
Besides the "Morse," there is telegraphic apparatus
known as the "Wheatstone," in which a paper ribbon is
first perforated and then sent through a machine, recording
at the distant end with ink marks upon paper tape; the
total speed of two sides of a "duplexed Wheatstone" is
about two hundred words per wire per minute.
There is also the Buckingham page-printer, which first
perforates a tape by means of a device like a typewriting
machine, feeds the messages through a transmitting ma-
chine, and produces at the distant end typewritten copies
at one hundred words per wire per minute.
Another device is the Murray page-printer, which practi
cally accomplishes the same results as the Buckingham
and attains about the same speed.
Another and recent device is the Rowland octoplex, by
which eight circuits are worked over one wire, each circuit
transmitting thirty words per minute, a total of two hun-
dred and forty words per wire per minute. The sending
is done by manipulating typewriters, typewritten copies
being automatically produced at the receiving station.
It is said that the Wheatstone and Buckingham appa-
134
WIRELESS TELEGRAPHY.
ratuses are both regularly employed by the Western Union
Telegraph Company, but the latter system was not men-
tioned by the company's engineer in the Electrical World
controversy. If the Murray is in business use that fact is
not known to the writer. The Rowland octoplex is said
to be employed in Germany.
All of these machines are complex in detail and costly
to construct. If there be considered, however, the total
investment of money in a copper wire one thousand miles
long and weighing perhaps four hundred pounds per mile,
together with the cost of planting poles, of attachments to
those poles, and the expense of patrol and maintenance,
the claims of inventors of telegraphic machines that their
apparatuses will pay for themselves in a short time seems
well founded. Either the Buckingham or Murray page-
printers, or the Rowland octoplex, are rated at a speed
much greater than that of quadruplexed Morse. All of
them save nearly fifty per cent in operating labor.
The officials, however, are obdurate, and while the equip-
ment of perhaps one wire with a new device is occasionally
allowed, the experiment seldom extends any further. The
result of such policy in the past has produced a great array
of abandoned machinery. After each trial, officials, engi-
neers, and operating force are further strengthened in their
admiration for the true and the tried; and the disappointed
inventors claim that to all arguments there is the same
response, and to all appeals the same denial, "There is
nothing like Morse.”
Morse Best Adapted to Certain Classes of Traffic. No
one denies that for the class of service that transmits orders
from the New York Produce Exchange to the Chicago
THE COMPARATIVE MERITS.
135
Board of Trade it seems impossible to find a substitute for
Morse. It is said that to the telegraphers in the Chicago
Trade Room even a typewriting machine is less facile than
the pen. They write upon a blank, using copying ink;
when the message has been written, a moist piece of paper
is laid over the blank, the two are then fed between the
rubber rollers of a wringer, and there is quickly in hand
the original message, which may be handed the consignee,
and an impression copy for the company's files.
There are classes of business which require the same
rapidity of delivery as do those of the grain and stock
brokers, and for which Morse seems best adapted. There
is, however, a traffic that comes from the general public
which is poorly handled. It is not so much the way this
class of business is being transmitted with present facilities
as a matter of what might be done with other and better
devices and with the lower tariffs those devices would
warrant.
The charges for sending miscellaneous telegrams are the
same as for those of the preferred class. Under favorable
conditions the telegraph companies may transmit an unpre-
ferred message fairly well; but if there be rain or wind or
excitement in Wall Street, or an election, or a political con-
vention, the wires are crowded; and having thus to contend
against frequent delays and high tariffs it is no wonder
that the number of these unfavored communications ist
comparatively small. As Mr. Delany, in one of the letters
of the recent discussion, has pointed out, there is no elas-
ticity, no reserve power in the present telegraph service.
For the class of business just described, low rates and the
adoption of some of the new possibilities in multiplex or in
chemical telegraphy would undoubtedly increase the re-
136
WIRELESS TELEGRAPHY.
ceipts of the telegraph companies and prove as well a boon
to the public.
Chemical Telegraphy. Almost coeval with Professor
Morse's inventions are those of Alexander Bain, who de-
clared as long ago as 1845 that by the chemical method
he could transmit two thousand words per minute. A
system based on this principle was tried by the Atlantic
and Pacific Telegraph Company in 1875. Its officials
made two mistakes, first ordering that it be used for all
kinds of traffic, and then that its use be entirely discontin-
ued. In the eighties the American Rapid Company tried
the system again, but that company was unsuccessfully
financed and soon collapsed.
The essential principle of chemical telegraphy is the
fact that an impression is made whenever a current of elec-
tricity passes from a metallic point resting upon chemically
treated moist paper to a conductor which connects with a
part of the same circuit from another point on the paper.
The action is electrolytic. A copper point leaves a red
mark, an iron one a deep blue. The number of signals is
governed by the volume of current, by the time of exposure,
and to some extent by the electrostatic capacity of the
conductor connecting the sending and receiving stations.
It may be expressed by the equation
N
ET
RK'
where N is the number of signals per unit of time, E the
electromotive force, T time, R resistance, and K capacity.
While the author is not exactly informed as to quantita-
tive results, it is safe to say that one five-thousandth of an
ampere flowing from an iron point and impressed upon the
THE COMPARATIVE MERITS.
137
sensitized paper for one second of time will leave a distinct
mark; and, conversely, that one-twentieth ampere unim-
peded by capacity is sufficient current to produce two
thousand words per minute, each word requiring from ten
to twenty marks.
Description of Chemical Telegraph Apparatus. — Fig. 40
is a diagrammatic view of a chemical telegraph circuit, P
being a source of current supply with one polarity, and N a
second source, having a polarity the reverse of the first.
B and B' are brushes terminating respectively conductors

N
B
F
F
C
RT
ST
oooo<B
F
F
B
P
Fig. 40.
from P and N. B″ and B'' are brushes on the surface of
the sending tape ST which are brought into contact with
B and B' by reason of the holes in the paper being moved
past them whenever the paper is pulled along by friction
rollers FF. The yoke y is of conducting material, and
consequently B" and B'' are electrically one piece which
is connected to the line. At the far station RT is the
chemically treated receiving tape, and resting upon it is an
iron pen C which is joined by insulating material ☛ to the
platinum faced strip C' called the spacing pen.
138
WIRELESS TELEGRAPHY.
Operation of Chemical Telegraph. Whenever a contact
is made between brush B and the line by reason of the
passing of one of the lower holes in tape ST, current flows
across RT from C to C' and colors the paper. After brush
B has passed a hole, the charge of electricity which has
become stored in the line flows to earth, and this secondary
flow of current tends to prolong the mark. Thus the
horizontal distance between a lower and an upper perfora-
tion impresses upon the sensitized paper either a long or a
short mark according as the distance between any lower
opening and its relative upper opening is long or short; for
whenever brush B' is presented to line, it neutralizes the
current flowing from C to C', and the pen C ceases to color
the paper.
Neutralizing Electrostatic Effects. The system of
positive and negative presentations is an improvement upon
the earlier methods, which used current of one polarity
only. Under the plan just illustrated, inductive influence
is partly neutralized; and by another and very simple
contrivance in connection with the apparatus, the details
of which the author is not at liberty to make public,
electrostatic capacity seems to be under absolute control.
Speed. -The speed of the chemical telegraph is marvel-
ous. Mr. Delany, the chief exponent of that kind of
transmission, has succeeded in recording in a laboratory,
and over an artificial line the equivalent of an ordinary
telegraphic circuit one hundred and twenty-five miles in
length, eight thousand words per minute. The author has
seen an initial force of one hundred and ten volts transmit
one thousand words per minute over an artificial line hav-
THE COMPARATIVE MERITS.
139
ing the resistance and electrostatic capacity of a circuit
between New York and Chicago. There is no reason why
machines should not be devised by which two thousand
words per minute may be sent with one hundred volts; nor
is there any insuperable obstacle to the use of five hundred
volts. Indeed the sending ten thousand words per minute
over a copper wire a thousand miles long weighing four
hundred pounds per mile is a possibility of the present
development. Chemical transmission is now used by the
Pennsylvania Railroad Company between Philadelphia and
Altoona, and over the circuit employed, Mr. Delany has
made a record of thirteen hundred words per minute. The
line measures in resistance about fourteen hundred ohms,
and is partly of iron wire.
There has been a plan for perforating paper tape by the
manipulation of a Morse Key; and, as the action of a
telegraph key is simply a down-and-up motion of a pivoted
lever, this action may be reproduced at a considerable
distance from the location of the sending operator. At the
distant point the tape may be fed into a transmitter, and it
may be reproduced by chemical signals over a second
circuit.
To illustrate the plan of operation, a telegram from New-
ark, New Jersey, for delivery at Milwaukee, Wisconsin,
under present conditions would be sent by Morse from
Newark to the main office in New York City, thence by
quadruplex to Chicago, thence by Morse to Milwaukee.
By the perforator and chemical telegraph the Newark
operator could make in the main office at New York a
tape which would be used to transmit the message from
New York to Chicago, where it would appear in the form
of Morse signals on a moist paper ribbon, and this might
140
WIRELESS TELEGRAPHY.
be handed to an operator in Chicago to be sent to Mil-
waukee by Morse.
In the first method the number of sets of human heads
and hands occupied with the message is six; in the latter
three, and consequently this latter presents just one-half
the chance for errors. Moreover, in the actual time of
passage the gain is considerable. The saving in plant, al-
lowing to the second method five thousand words per
minute, is as sixty to one over quadruplexed Morse; and
would be as forty to one over any of the type-printers.
So much space has been given to the chemical system
because of its development. It is wonderful that an organ-
ization so complete could have been perfected without the
experience that comes from daily use; and more wonder-
ful still, that having been thus perfected, it should be
entirely neglected by the telegraph companies.
Other Means of Rapid Signaling. There are undevel-
oped means of signaling, however, which to experts in
wireless telegraphy seem certain of future attainment.
Both Marconi and Fessenden are looking forward to ma-
chine transmission at a speed of five hundred words per
minute, and they are also hopeful of multiplexing wireless
circuits. Many of the obstacles, however, which loom up
in the future of wireless telegraphy do not present them-
selves in transmission by wire, and there is every reason to
suppose that a wire may not only be multiplexed many
times, but that each of the phantom circuits, as they are
called, may be made by machinery to convey some
hundreds of words per minute; always with more certainty
and speed than without the wires.
It is the apparent neglect of such great forces for which
THE COMPARATIVE MERITS.
141
the telegraph officials are held accountable by those ac-
quainted with the facts. Complication may not be urged,
because the chemical system, for example, is far simpler,
both in construction and operation, than is either the
duplex or the quadruplex or the typewriter devices. The
passage over a single wire of thousands of words per min-
ute is as well assured as is wireless telegraphy; and if
brought into regular commercial use it may prove a
greater public benefit. At present there is no outlook that
etheric signaling overland will ever attain to the tremen-
dous possibilities of telegraphy with wires.
וי

142
WIRELESS TELEGRAPHY.
-
Fig. 41. City of St. Johns, Newfoundland, where the first transatlantic signal by space telegraphy was received from England.
NOMENCLATURE.
143
PART IV.
APPARATUS.
NOMENCLATURE.
THE art which forms the subject-matter of this work
is young and its nomenclature limited. "Wireless Tele-
graphy" itself but a negative term is temporarily supplying
the need of a positive designation. Neither "radio-tele-
graphy" nor "wave-telegraphy" nor "etheric-transmission"
satisfies. "Hertzian-wave telegraphy" is of unwieldy
length and lacks euphony.
66
No single word suitably denotes every kind of instru
mentality affected by Hertzian or magnetic waves.
"Detector" has been used in another sense. Mr. Tesla
speaks of "sensitive-devices"; Mr. Fessenden and others
of a
"wave-responsive-device.' Responder" is too
closely identified with the DeForest system to be ac-
ceptable to competitors. "Resonator," to denote a receiv
ing device, is objectionable on account of its alliterative
and structural similarity with "radiator," a transmitter.
Antenna is an excellent name for the conducting termi-
nal that ends in air whenever the allusion is to a receiver
of waves; but it is not sufficiently aggressive to express
the opposite meaning. Emitter seems a good term for
designating anything that serves to send impulses outward.
The terminating conductor, however, being employed both

144
WIRELESS TELEGRAPHY.
as antenna and emitter, the necessity appears for that
which denotes both uses. Mr. Fessenden speaks of an
aggregation of five wires as a "harp." When the condi-
tions are applicable, "high wire" is a good term, but not
when cylinders or cones are used. The writer suggests as
a comprehensive title, one used in this work, "wave-gate."
For the instrument that acts by diverse resistances of
a sensitive device and thus translates the signals to a local
Yey Ph
Fig. 42.-Elevating the kite-supporting wave-gate at Signal Hill, St. Johns,
Newfoundland, December 12, 1901. X Marconi.
-
and more powerful circuit, no better name than "relay"
can be found: but to speak in that connection, of a "re
ceiver," is to confuse it with the sensitive device itself.
The circuit which contains a radio-receiver battery and
relay has occasionally been designated "local," not in-
trinsically a good term, and the less acceptable because to
telegraphers it implies a second organization in contra-
distinction to the connections of the main line.
NOMENCLATURE.
145
As suggested by Mr. Tesla's "sensitive-device," the
train of apparatus having the radio-receiver for one ele-
ment might properly be denoted the "sensitive circuit,"
and the battery which actuates the relay in that circuit
the "closing battery."
For the wires and apparatus in series with the relay
points, "recording-circuit," and for the energizing element
of that group, "recording battery," are designations that
should be clearly understood.
The terms "spark-producer," "oscillator," and "oscil-
lation-producer" are synonymously applied to all apparatus
that sends electric charges across the spark-gap.
"Induction-coil," the "primary" and "secondary" which
compose it, and the "key" used to bring into operation
the sparker, are terms well fixed in the public mind. The
contact which rapidly opens and closes in the primary
circuit is happily described in Marconi's patents as the
"trembler-break."
As both Professor Lodge and Signor Marconi, partly for
the purpose of broadening their patent claims, have in-
sisted that both the earth and the wave-gate are
(C capa-
cities," that term may not now be understood as confined
in meaning to a condenser or to a Leyden jar.
Ruhmkorff Coil.
TRANSMITTERS.
Before the advent of wireless
telegraphy the Ruhmhorff Coil was the standard spark-
producer. Referring to Fig. 43 as an illustration of that
coil, it may be described as follows:
In a position of rest the contact of spring T is in touch
with that of upright K. By the closure of the break at
switch S, battery B energizes circuit B-S-T-K, causing
146
WIRELESS TELEGRAPHY.
the iron coil I to become magnetic. The iron face of
spring T is attracted towards coil I, but as the movement
forward immediately breaks contact at a, I is demagne-
tized, and the spring T resuming its first position in con-
tact with K, coil I again becomes magnetized. On
account of the quickly changing conditions in coil I, there
occur continuous and rapid vibrations at point a.

G
о
E
D
D
I a
C
Fig. 43.
B
When, however, the current, after being made, is inter-
rupted at point a, there takes place an electric discharge
which is, in effect, a flow of current in an opposite direc-
tion to the charge which has just been made. This
reverse current, though of high pressure, is attenuated,
and has much less magnetic effect on the coil than the
initial one. It tends, however, slightly to magnetize coil
I at a time when that coil should be non-attractive: and it
TRANSMITTERS.
147
is also true that the high pressure generated is apt to burn
the contacts at a.
The function of condenser C is to give back its charge
with the same energy as that which emanates from the pri-
mary coil, thus neutralizing the bad effect of the primary
coil's discharge. It is seldom, however, that the adjust-
ments of the two forces are quite in balance, and conse-
quently there is generally more or less imperfect action at a.
Marconi's Spark-Producer. In Marconi's patent 11,913
is described a device which partially obviates the difficulty
of corrosive points, in that, by means of a small electric
motor, it causes one of the points of the vibrating break
continuously to revolve. The spark in this patent is shown
with an interposition of two balls in the center in an ebonite
casing. The distance between the center balls is one
twenty-fifth inch, and the inside distance between each of
the terminating electrodes and the center balls one and
one-half inches. The space between the two middle spheres
is filled with vaseline

oil. It is said that Mr.
Marconi afterward dis-
carded the center
globes and used a clear
space between elec-
trodes.
A Fessenden Trans-
mitter. Fig. 44
-
shows a trans-
mitter de-
signed by Mr.
18
Fig. 44.
148
WIRELESS TELEGRAPHY.
Fessenden, the patent for which was filed December 15,
1899. A distinctive feature is the condenser 18 bridging
the spark gap between electrodes 4-4. This arrange-
ment, the inventor says, is "for the purpose of maintain-
ing sustained radiation," for "this shunt circuit by reason
of its capacity stores up an additional amount of energy,
and when a spark passes across the gap, since the sending
conductor can radiate energy at a given rate, it must
continue to radiate for a long time in order to dissipate
this additional stored up energy."
A similar organization is shown in the Marconi patent
676,332, of later date than the Fessenden.¹
Alternating Current Dynamo Instead of Interrupter.
The interrupter in the primary coil of a direct current
sparking appliance being difficult of control with currents
of high potential, it is the practice in large installations to
employ steam power connected with an alternating current
dynamo, the voltage of which may be "stepped up" by
transformers; and where steam power is not available, but
energy is had from storage batteries, as in field operations,
direct current from the batteries may be made to turn an
electric motor by which an alternating current dynamo may
be kept in motion to furnish the primary coil with energy
to supply the spark gap.
Fessenden Dynamo as Direct Emitter. The use of a
dynamo for a direct emitter without the spark gap is shown
in Fessenden's patent 706,737. He claims that he is
able at once to produce a continuous train of radiant waves
of substantially uniform strength, as distinguished from
1 See Fig. 37 in Part II.
•
TRANSMITTERS.
149
the well-known systems wherein the spark-discharge starts
a train of waves of rapidly diminishing power, followed by
relatively long intervals of no radia-
tion. Fig. 45 is a diagram from the 1
Fessenden patent where I is a short
emitting wave-gate with large radia-
ting surface, 2 a tuning inductance,
3 an alternating current dynamo with
an earth connection..

2
www
Fig. 45.
DeForest Transmitter. The tran-
smitter of the DeForest system uses an alternating cur-
rent dynamo, a step-up transformer to increase the vol-
tage; and discharges across a gap in which is interposed
a detached conductor. The discharging electrodes and
the interposed member are of the same shape and size,
being disks of metal about one-quarter inch thick, and
upon the sides or faces about one and one-quarter inches
in diameter. The spark gaps upon each side of the middle
disk measure about one sixty-fourth inch.
The DeForest experts claim that with electrodes of a
surface relatively large as to the gap they get a "fat"
spark, and that such a spark produces better results at the
distant or responding end than would one of greater inten-
sity but less volume.
A Fessenden Transmitter. Figs. 46 and 47 are repro-
ductions from drawings in one of Mr. Fessenden's patents,
No. 706,641, filed November 5, 1901. The diagram of
curves, Fig. 46, is a graphic representation of comparative
efficiencies. The dots on horizontal line c indicate spark
potential in inches, the vertical line d radiation or effective
150
WIRELESS TELEGRAPHY.

result.
b is an
efficiency curve
α
C
Fig. 46.
which shows
results obtain-
ed under usual
conditions, viz.:
that within a
certain length
of spark, about
one inch, the
resultant radia-
6-
tion of electromagnetic waves is approximately proportional
to the length of spark; but that to increase the length of
spark beyond one inch will result in no practical increase
in radiation. The line
a is another efficiency
curve which is employed
to demonstrate that with
Mr. Fessenden's device,
the wave force d is ex-
actly proportional to
spark gap cat whatever
length the latter may be
prolonged.

Referring to Fig. 47,
10 is a rod pointed at
its lower end, surrounded
by an insulating sleeve
II, and so introduced
into the chamber 7 to
form one electrode of
2
10
-11
-7
11
8
5
the spark gap. The
Fig. 47.
TRANSMITTERS.
151
other electrode is the bottom plate of chamber 7, and thus
one of the discharging terminals is a point 4, and the
other a disk, 5. By means of pump 8, the air in chamber
7 is increased in pressure. It is found that when a certain
critical pressure is reached, which, for instance, may be
eighty pounds per square inch, the radiation for any length
of spark becomes strictly proportional to the applied force.
The term "radiation" in the foregoing explanation, and
as shown by the height of vertical line d of the curve dia-
gram, is an expression of an applied energy, that, if doubled
or trebled, doubles or trebles the distance from such energy
for which a wave-responsive device may be made to indi-
cate signals.
❤
152
WIRELESS TELEGRAPHY.
WAVE-RESPONSIVE-DEVICES.
Considering as a generic term either "sensitive-device,"
or "wave-responsive-device," or "radio-receiver," or "de-
tector," there may be made as classifications of it "coher-
ers," "anti-coherers," "micro-radiophones," and "mag-
netic-radio-receivers."
Coherers. If used without a qualifying word or prefix
the word coherer is now understood to indicate that form
of radio-receiver, which, being normally a high resistance,
is, under the influence of Hertzian-waves, changed to a low
resistance, becoming relatively a conductor, and remaining
electrically conductive after the subsidence of the wave
effect unless restored to its original state of resistivity by
some sort of mechanical impact.
Decoherence by Re-
Filings Tube of Calzecchi-Onesti.
volving. So long ago as 1886, Professor Calzecchi-
Onesti placed copper filings between two brass plates and
changed the electrical property of the filings from a state
of high resistance to one of low resistance by passing
through them the secondary impulse that occurs when an
electric circuit is broken. Afterward to facilitate decoher-
ence he inclosed the filings in a revoluble glass tube.
Branly's Filings. Tube Decoherence by Tapping.-
Branly, 1891, discovered that the filings could be rendered
conductive by the passage of electric sparks across an air-
gap in their vicinity, and that they could be decohered by
a slight jar.
纂
​WAVE-RESPONSIVE-DEVICES.
153
Lodge and Fitzgerald Needle and Tin-Foil. - Dr. Lodge,
in conjunction with Mr. Fitzgerald, made a coherer by
causing the point of a sewing-needle to rest upon a strip of
tin-foil. Later, this device was elaborated by contacting
the needle point with a flat spring which was fixed within
a clamp, the degree of pressure between point and spring
being regulated by adjusting screws.
Branly's Tripod of 1902.- Professor Branly in 1902
placed a tripod having sharp steel points slightly oxidized
upon a polished plane steel plate. A current of electricity
passing from tripod to plate is, under normal conditions,
subjected to a high resistance. This resistance is greatly
diminished by Hertzian-wave effect, and may be re-estab-
lished by so arranging a recording instrument, that imme-
diately after the wave effect is discontinued, it will jar the
plate.
Decoherence by Inversion.
In
Tesla's Filings Tube.
his patent No. 613,819, Mr. Tesla describes quite minutely
a form of filings coherer which is decohered by being
turned end for end, its position of rest being vertical. He
makes the particles as nearly as possible alike in size,
weight, and shape, having special tools to fashion them;
and then oxidizes them uniformly by placing the grains for
a given time in an acid solution of predetermined strength.
He prefers not to rarefy the atmosphere within the tube,
since by rarefaction it is rendered less constant in dielec-
tric property. He recommends an air-tight inclosure and
a rigorous absence of moisture. In another patent he
specifies decoherence by continuous revolution, instead of
by inversion, of the glass tube.
154
WIRELESS TELEGRAPHY.
The "Silver" Coherer. So far as is known by records
of practical tests the most sensitive type of the class under
consideration is the "silver" coherer. It is carefully
described in the American reissue patent No. 11,913 of
Marconi. Briefly the tube is one and one-half inches in
length, and one-twelfth inch internal diameter. Within
it are tightly plugged two pieces of silver wire, each one-
fifth inch long. The space between these plugs at center
is one-thirtieth inch. This minute space contains a pow-
der composed of ninety per cent of nickel filings, and ten
per cent of silver filings. The grains are as large as may
be produced with a coarse file, and are coated with an
almost imperceptible globule of mercury. The tube must
be sealed. A perfect vacuum is not essential, but is de-
sirable, and one of one-thousandth atmosphere has been
used. Sensitiveness to waves may be increased by using
a greater percentage of silver grains in the powder, or by
decreasing the distance between the silver stops.
Hertz Detector.
о
ANTI-COHERERS.
The first radio-receiver in which cause
and effect were observed and recognized
was devised by Hertz in 1886. It con-
sisted of a piece of wire, Fig. 48, bent into
circular form, a small disconnecting gap
being left in its circumference. If this de-
vice were suspended at some distance from
a sparking Ruhmkorff Coil, there being
no tangible connection between the coil and the circlet of
wire, minute sparks could be seen to fly across the air-gap
in the wire.

Fig. 48.
WAVE-RESPONSIVE-DEVICES.
155
Righi Detector. — Professor Righi obtained similar action
by holding at a few feet from a spark-producer a sheet of
glass covered with tin-foil, the metal being separated by a
fine diamond point into several longitudinal bands. Action
at the electrodes of the induction coil resulted in sparking
from band to band over the gaps in the tin-foil.
In 1899 a German scientist discovered that by placing a
drop of water upon the slit formed by the tin-foil edges of
the Righi bands, a very sensitive wave-detector was pro-
duced.
It is said the organizations just described differ from a
coherer, in that the action of waves causes their electrical
resistance to increase, an effect exactly opposite to that set
up in the coherer proper. They are, therefore, named
"anti-coherers,” and differing in principle, are declared not
to be subordinate to any patent claims which may cover a
coherer method. There is a report, however, that the
Marconi Company, presumably on the ground that the
alleged anti-coherer is an "imperfect contact," is preparing
to bring action for infringement against a competitor using
an anti-coherer.
DeForest Responder. The DeForest "responder" is
the most prominent type of anti-coherer. Fig. 49 illus-
trates the receiving apparatus in which A and A' are two
small brass rods, or wires, connected respectively to the
wave-gate and to the earth. D and D are hard rubber
tubes, into which is fitted the glass tube C. F and F' in-
dicate the position of adjusting screws which serve to
make greater or less the width of the gap which occurs at
G between electrodes A and A'. B is a battery, gen-
erally of two or three dry cells, and T is a telephone. The
156
WIRELESS TELEGRAPHY.
ends of the wires A and A' are smeared at the gap G with
a minute quantity of a paste which the inventor has named
'goo." By means of the adjusting screws F F' the ends
of A A' are first brought together within the tube, and

D
D
F
B
E
Fig. 49.
then slowly separated, until by repeated trials the amount
of space which is best for clear signals has been attained.
It will be understood that the "goo" thus bridges the
gap between the electrodes. Through a microscope the
paste is seen to lie in tiny globules which just touch one
WAVE-RESPONSIVE-DEVICES.
157
another, but under the action of impinging waves these
globules decompose and decohere, the effect being to
increase the electrical resistance of the closed circuit,
which, as in Fig. 49, contains a battery, a paste-filled gap
G, and a telephone receiver.
Now a telephone receiver gives forth audible sounds in
response to the slightest change in resistance, whether
diminished or augmented; and thus, whenever a long-
wave effect or a short-wave effect is produced at the
sending end, it is indicated at the receiving end by long
or short buzzing sounds in a telephone held or attached to
the ear of an operator.
Ehret System.Reference to the text and diagrams
which describe the system of Mr. Ehret¹ will serve to ex-
plain one use of an anti-coherer in connection with a relay.
MICRO-RADIOPHONES.
Carbon Powder Wave-Detector of 1897.—There is rec-
ord of the employment, about 1897, of a carbon powder
coherer by which Professor Jervis Smith of Oxford Uni-
versity, England, maintained communication over more
than a mile of space. So far as I can discover, this is the
earliest specimen of a type that is now known as the
micro-radiophone or micro-radio-receiver.
Popoff's Micro-Radiophone of 1900. In May, 1900,
Professor Popoff of Russia, as the result of experimenta-
tion, concluded that it was possible to eliminate the
1 See Fig. 30, Part I., and accompanying description.
158
WIRELESS TELEGRAPHY.
coherer and relay by substituting for both either a micro-
phonic arrangement of steel needles, having their extremi-
ties resting upon plates of carbon, or by mixing steel
filings and carbon powder.
The
Shoemaker's Steel and Carbon Wave-Detector.
steel and carbon powder type of Professor Popoff has been
the subject of many patented inventions, one of which, by
Mr. Shoemaker of Philadelphia, consists of a number of
steel balls in a horizontal line, the space between the balls
being filled with carbon powder.
Shoemaker and Pickard Needle and Carbon Wave-
Detector. Another invention was patented in the United
States, in August, 1902, by Messrs. Shoemaker and
Pickard. As expressed in the patent, -
"It comprises a wave-responsive-device whose essential elements are of
carbon and steel, respectively. A wave-responsive-device composed of
22
28
16
34
31
29
30
23 26
24
19
25
20
27
21
Fig. 50.
17
18
these materials has
the property of great
delicacy and sensi-

has
tiveness in respond-
ing to electrical ra-
diations, and
also the desirable
property of regaining
its normal condition after the cessation of influence of electrical waves.
"More specifically, our invention comprises carbon terminal blocks, in
contact with which are steel or iron needles, which serve to close the
circuit from one carbon block to the other. As an alternative, however, it
is to be understood that the terminal blocks may be of steel, and that car-
bon filaments or rods may contact with them to close the circuit.
"The wave-responsive-device herein described is connected with any of
the wireless signaling systems in the same relation as the numerous types
of wave-responsive-devices heretofore used.”
In Fig. 50, 16 is a glass tube or any suitable envelope, on the right-hand
WAVE-RESPONSIVE-DEVICES.
159
end of which is a metallic cap 17, through which is tapped the screw 18,
which at its left-hand end screws into the central insulating portion 19,
thereby clamping between said portion 19 and a brass nut 20 the carbon
disk 21.
22 is a metallic cap upon the left-hand end of the tube 16, and from
which extends into the tube rod 23, secured in said cap 22, and also into
insulating block 19, thereby clamping between said block 19 and a nut 24
the carbon disk 25.
32
25
-33
26 and 27 are disks of insulating material, which serve to center and
steady the device in tube 16. It is to be noticed that the disks of carbon
21 and 25 are slightly smaller in diameter than the tube 16
for the purpose of preventing their contact with said tube
during assemblage, inasmuch as such contact might serve
to destroy the disks, due to the fact that they are thin and
fragile. On to the left end of the cap 22 screws a cylin-
drical piece 28, forming between 28 and 22 a cavity 29,
designed to receive calcium chlorid or other desiccating material for keep-
ing the air or other gas within the tube 16 perfectly dry. Communication
between 29 and the interior of tube 16 is obtained by numerous holes, as
30. On the piece 28 is the binding-post 31, serving
as one terminal of the device, while cap 17 or screw
18 serves as the other terminal.
25
34
34
Fig. 52.
21
Fig. 51.

Fig. 51 represents a plan view of one of the car-
bon disks
as, for example, 25
as, for example, 25 — which shows sym-
metrically-arranged small holes 32, while the inner
large hole 33 permits the passage of the rods 18 or 23.
In Fig. 52 are shown the two carbon disks 21 and 25, supporting
between them the needles 34.
This Shoemaker and Pickard organization is an elabora-
tion of the Popoff microphonic receiver of 1900, and is
typical of its class.
-
Fessenden. Silver Ring and Knife-edge Contact.
Fig. 53 illustrates a radio-receiver designed by the United
States Government expert, Mr. Fessenden. 7 repre-
sents a coil of wire which is a magnetic field for an arma-
ture 8, the latter being made preferably in the form of a
160
WIRELESS TELEGRAPHY.
•
silver ring. Ring 8 is balanced upon two knife edges 13
and 13', one of which, as 13, is formed of a good electrical
conductor, for example, silver; and the other, 13', is out of
circuit. A carbon block 14 is so arranged that the por-
tion between it and knife edge 13 of the ring 8 forms part
of an electrical circuit. Waves passing from the gate 6 to
the earth and energizing field coil 7 will cause the ring 8
to press upon the carbon block 14, thereby increasing the
conductivity of the contact between 8 and 14.
61
"When using a telephone-receiver as a recording instru-
ment, the generator 15 is preferably of a character capable
of producing an
alternating cur-
rent, as such cur-
rent causes a
constant vibra-
tion of the dia-
phragm, the
vibrations in-
creasing in in-
tensity with an
increased flow

of current in
15
16
14
13
8
13'
Fig. 53.
the circuit. This increase in intensity of action with in-
creased flow of current is characteristic of this form of
receiver. In this it is sharply differentiated from such
devices as the coherer, which either give a strong indica-
tion or do not give any. This characteristic is advanta-
geous in that if the signal sent say a dot be too weak
to give an action of the full intensity, it may still in most
cases be read and not missed entirely, which is of value in
sending code-messages."
WAVE-RESPONSIVE-DEVICES.
161
*
The Code-Message Trouble. The above allusion to
code-messages" was probably first suggested by a
declaration of the ocean cable companies that the Marconi
Company could not transmit code-messages,—an idea now
prevalent among inventors competing with the Marconi
Company. Why the transmission of dots should not be
necessary in ordinary messages has not been made clear;
nor why there should be obstacles to the passage of code-
messages which are sent by telegraphic signals exactly
like other messages.
Mr. Fessenden's description of Fig. 53 includes the
alternate use of a telegraphic sounder as a recording in-
strument in place of the telephone (16) shown; but it is
hardly possible that a sounder in such position can have
been successfully employed in practice.
Marconi's Opinion of Non-Tapping Coherers.
In a
paper read before the Royal Institution of London in
CARBON
CONNECTING
WIRE
MERCURY
IRON
GLASS

CARBON
CONNECTING
WIRE
MERCURY
GLASS
Fig. 54.
June, 1902, Signor Marconi says of non-tapping coherers,
that they are not sufficiently reliable for commercial work;
that under the influence of strong waves or of atmospheric
discharges they cohere permanently; and that there is an
unpleasant tendency to suspend action in the middle of a
telegram; moreover, that as their resistance is continually
varying, it is difficult to syntonize the circuits of which
they form a part.
162
WIRELESS TELEGRAPHY.
Italian Navy Radio-Receiver.-The radio-receiver adopted
by the Italian navy, a result of the combined efforts of its
experts, is a composite of the coherer and the microphone
receiver. It is used in connection with a circuit syntonized
in the usual way by capa-

city
The
and self-induction.
marked
illustration,
Fig. 54, seems sufficiently
to describe it.
BARAAAAAAAAAA
8
•MOME
M
19
Fig. 55.
6
MAGNETIC-RADIO-
RECEIVERS.
In the class of magnetic-
radio-receivers Mr. Fes-
senden has evolved three
distinct types and Mr.
Marconi one.
A Fessenden Magneto-
Receiver. Fig. 55 is an
illustration of one of Mr.
Fessenden's magneto-re-
ceivers, in which 7 and 7
represent field coils con-
nected respectively to
wave-gate 6 and to earth.
8 is an armature so sus-
pended that the reaction of the current induced in 8 when-
ever the coils 7 are energized will cause 8 to move.
Such
movement may be made observable by reflection of a
WAVE-RESPONSIVE-DEVICES.
163
beam of light from the mirror 9
upon a scale. The slight move-
ment of the mirror is seen in the
larger movement of the spot.
Another of Mr. Fessenden's
devices is shown in Fig. 56, in
which 10 is the wave-gate of a re-
ceiving station; 12 is a fine steel
wire held under tension between
the poles of magnet 13; 14 is

15
14
Fig. 56.
12
10
a contact normally disconnected from wire 12 by the inter-
action of currents.
A Second Magneto-Receiver by Fessenden.
L10
Fig. 57.
Fig. 57 is

a diagrammatic representation from Mr. Fes-
senden's patent, No. 706,747, in which 10 is
the antenna, II a coil having one terminal con-
nected to the antenna 10, and the other ter-
minal grounded. A telephone diaphragm 12,
adapted to vibrate in unison with changes of
current produced by waves radiated from the
12 sending station, is suitably supported in oper-
ative relation to the coil II; and the apparatus
at the receiving station is tuned in harmony
with the emitter of the sending station.
Marconi's Hysteresis Detector. -At this
writing a description of the new Marconi re-
ceiver has been published, but no authorized
illustration of it has been printed. In Fig.
58 an attempt is made to follow in diagram the
164
WIRELESS TELEGRAPHY.
La
Marconi text. The discovery upon which this new appa-
ratus is based is the fact that hysteresis is decreased by
the action of Hertzian waves.
Hysteresis Defined. -- Whenever iron is subjected to
changes in magnetic strength or magnetic polarity it gen-
erates and radiates heat. This phenomenon is called
"hysteresis," and the amount of heat dissipated as loss by
reason of such changes is known as "hysteresis loss."
-
Changes of Polarity in Iron. How Produced. Differ-
ences in polarity may occur from movements of the iron
itself, as when the armature of a dynamo revolves; or from
the movements of a magnet, as when a dynamo field is
caused to move about a stationary armature; or from
changes in the exciting cause, as when an alternating cur-
rent is made to pulsate through a transformer.
Quantitative Effects. - Quantitatively, hysteresis effect
depends upon the amount of iron under influence; upon
the quality of the metal, wrought-iron or steel being more
affected than soft iron; upon the density of magnetism in
the iron; and upon the rapidity of the movements which
cause the changes in magnetic direction or magnetic
power.
—
Theory. Theoretically, it has been explained that heat
is generated by friction as the molecules of iron in mag-
netic action turn over and thus rub against one another.
Description of Marconi Magnetic Detector. Referring
to Fig. 58, upon a core C, which consists of fine iron wires,
WAVE-RESPONSIVE-DEVICES.
165
A
are wound one or two layers B of thin insulated copper
wires. Over this winding B, is an insulating coating G;
around the insu-
lating envelope
a bobbin FF;
and upon the
bobbin a wind-
ing of small in-

sulated wires,
D. The ends of C
the winding B
are connected
respectively to
the antenna A
B
D
יד
B
D
M
W
and the earth at
E; and the ends
of the winding
Fig. 58.
D to the telephone T. One face of the core C is pre-
sented to, and magnetized by, the magnet M. Upon being
revolved by clock work, W, the movements of M cause
constant reversals in the polarity of core C, and conse-
quently a certain hysteresis effect is produced. Whenever
this effect is modified by the influence of Hertzian waves,
an audible record of such waves is made on the tele-
phone receiver.
Practical Results From Marconi Magnetic Detector.-
For some time the form of detector just described has
been in successful operation over a distance of one hun-
dred and nine miles of sea surface, and forty-three miles of
high land, a total of one hundred and fifty-two miles.
Marconi seems to think it is more sensitive and more re-
166
WIRELESS TELEGRAPHY.
..
1
Less electromotive force
liable than a filings coherer.
than with a coherer is required at the sending station; its
resistance is uniform; and many of the precautions and
delicate adjustments necessary where a coherer is used
may be neglected with the hysteresis detector.
Coherer Organization Needed to Call. So far, however,
in order to "call," it has been necessary to use with the
new receiver, a coherer, relay, and bell. The only suc-
cessful indicator of signals in connection with it is a tele-
phone receiver. If, as the tests seem to indicate, a visual
record can be made and retained, Mr. Marconi thinks
it will be possible to transmit several hundred words per
minute.
A Wave-Responsive-Device by Fessenden. It may be
assumed that the result of Mr. Fessenden's labors for the
United States Government, so far as wave-responsive-
devices are concerned, is the subject of his patent No.
706,744, for which application was made on June 6, 1902,
from the laboratory at Manteo, North Carolina. In patent
No. 706,745, the inventor claims that with the device so
fully described in 706,744 "messages at the rate of thirty
words per minute were sent and received over a distance of
fifty miles, from Cape Hatteras to Roanoke Island, using
at the sending end a spark only one thirty-second of an
inch long." This form of radio-receiver from the Fessenden
patents cannot be included in any of the four classifications
just discussed. The patentee himself describes it as “a
current-actuated wave-responsive-device consisting of a con-
ductor having a small heat capacity and arranged in a
vacuum."
WAVE-RESPONSIVE-DEVICES.
167
Description of Fessenden's Heat-Receiver. - Fig. 59 is
a diagrammatic illustration
reproduced from Mr. Fes-
senden's patent 706,744, in
which 17 is a glass bulb.
Into it are sealed two lead-
ing-in conductors of plati-
num wire, 16 16. 18 is a
silver shell having at its
top a glass brace 19, hold-
ing the wires 16 16. The
platinum wires, except at
the tip 14, are coated with
silver. The tip 14 which
is left uncoated is a minute
part, being but a few hun-
dred thousandths of an inch
in length. Having small
volume and capacity, the
loop 14 is capable of being
quickly raised in tempera-
ture an appreciable amount,
and it is equally capable
of quick cooling, thus pro-
ducing rapid changes in
electrical resistance.

16
19
14
Fig. 59.
167
18
17
168
WIRELESS TELEGRAPHY.
WAVE-GATES.
Marconi's Early Experiments in England. In England,
about August, 1896, Mr. Marconi transmitted signals over-
land a distance of two miles. No ground connection
either at the sending or receiving stations was used.
Adoption of High Wire and Earth Terminal. The next
steps in the Marconi system were the adoption of an ele-
vated terminal and an earth terminal. On May 11, 1897,
Marconi, who was conducting experiments at Lavernock
Point, England, failed of results. His receiving apparatus
was set upon a cliff sixty feet above the level of the sea.
Here was erected a pole ninety feet in height capped with
a cylinder of zinc six feet long and three feet in diam-
eter. An insulated copper wire was fastened to the cap,
led down the pole, and from it made connection to one end
of the coherer. The other end of the coherer was con-
nected to a wire which was dropped down the cliff and
dipped in the sea.
Communication Established by Better Earth and Longer
Wave-Gate. Both on that day and on the following, at-
tempts at transmission were unsuccessful; but on May 13,
the coherer and other receiving instruments having been
carried to the bottom of the cliff, communication was at
once established. The antenna by the change to the
bottom of the cliff had been lengthened to one hundred
and fifty feet. The earth connection had been strength-
ened by the elimination of such resistance as was furnished
by sixty feet of wire.
WAVE-GATES.
169
!
Lodge's Early "Collecting Wire." In Dr. Lodge's first
patent, filed December 20, 1897, his wave-gate served for
the reception of impulses, and was called by the inventor a
"collecting wire." Presumably it was but a few feet in
length. Quoting from that patent: "In some cases I find
that any bare wire, or a connection to earth direct or
through the system of gas or water pipes, will serve suffi-
ciently well as a collector or as an assistance to the insu-
lated collector."
1
Lodge Emitter. Lodge devised a form of emitter in
which electricity was "supplied to a single conductor a
suddenly or disruptively by a couple of positive and nega-
tive sparks from knobs b and c. A partial metallic inclos-
ure d could be used to diminish waves in an undesired
direction. There seems to have been no extension into
space from the sphere a; nor any switching communication
between the sending and receiving sides of his apparatus.
A Supposed Law.
When virtue was found to exist in
an elevated wire, Mr. Marconi made a number of experi-
ments from which he deduced the law that the distance
over which signals could be transmitted varied as the
square of the height of the vertical conductors.
Lodge's Cones. It was soon found, however, that no
such law existed, and the attention of experts in wireless
telegraphy was next given to devising wave-gates lower in
height but greater in surface area. Dr. Lodge, in his
United States patent filed February 1, 1898, says: "I
prefer for the purpose of combining low resistance with
1 Lodge patent, Appendix II.
170
WIRELESS TELEGRAPHY.
great electrostatic capacity, cones, or triangles, or other
such diverging surfaces, with the vertices adjoining and
their larger areas spreading out into space." Manifestly
such a construction as is shown in Fig. 25, Part I., would
be especially weak to resist wind pressure, and so the
inventor recommended a modification in the form of a
roof, as illustrated in Fig. 21, Part I.
Marconi's Thick Copper Cable. In a patent filed Janu-
ary 5, 1899, Marconi describes two wave-gates. The first
was an insulated cable consisting of seven strands, each
strand made of seven copper wires, each one millimeter in
diameter, thus making the total diameter of the cable, the
number of wires being forty-nine, nine millimeters, or
thirty-six hundredths of an inch. This copper cable was
suspended vertically from a height of one hundred and
thirty feet.
Marconi's Iron Netting. The second was a galvanized
wire netting two feet broad and one hundred and thirty
feet long, the top of the netting being about one hundred
and ten feet from the ground.
Marconi's Observations on Wave-Gates in May, 1901.-
In a paper before the Royal Society of Arts of London,
May 15, 1901, Signor Marconi said: "The original elevated
straight wire which was used as a transmitter was a very
good radiator of electric waves; but its electric oscillations
died away with great rapidity, though very powerful while
they lasted. If a radiator be used giving off much less
energy at each vibration, but emitting a series of waves
1
WAVE-GATES.
171
:
over an extended period, then it will only affect a resonator
tuned to that particular frequency. It will take some
time, measured in thousandths of a second, for the radi-
ator to set up a swinging electric force in the receiver
sufficient to break down the insulation of the coherer."
He further observed, in the same paper, that "early in
1900 the vertical wire was replaced by the zinc cylinder
oscillators." The zinc cylinders are illustrated in Part II.
as Fig. 37, and in the text accompanying that figure are
described at length.
41
6
5
4
-7
Fessenden's Wave-Gates of Low Resistance and Large
Capacity. In May, 1901, Mr. Fessenden,
who had evidently been working along the
same lines as Marconi, filed two patent appli-
cations whose subject matter chiefly concerned
radiating conductors of low resistance and
large capacity. Two of these are shown in
Figs. 60 and 61. The inventor describes
them as "sending conductors for electromag-
netic waves," and says that they have a large
capacity distributed with substantial uniform-
ity over the radiating portion, and that this
capacity is so adjusted that the waves radiated
from the conductors have a low frequency.
These conductors, it will be observed, differ
from the Lodge cones in that, except for the
enlargement in Fig. 61, they are uniform in
figure.

4
7
5
5
6
5
8
-7
Fig. 60.
Mr. Fessenden says it has been held that the capacity
of the upper portion of a conductor of uniform cross sec-
tion is much lower than that of the middle or lower por-
:
172
WIRELESS TELEGRAPHY.
tion; but that by actual measurements he has found this
not to be the case, the upper portions having practically
the same capacity as the lower. Further, he
says, that when far from the ground the capa-
city of a conductor with respect to that ground
is dependent not upon its distance from the
earth, but upon its size and shape. Of the en-
largement (17) in the middle of the sending
conductor shown in Fig. 61, the inventor says.~~

"The effect of locally increasing the superficial area of
the sending-conductor, or of locally increasing the capacity
Fig. 61.
by any other suitable means, is to produce two or more
sets of waves of different periodicities, the periodicity of the first being
dependent upon the electrical constants of the sending-conductor as whole,
and the periodicity of the other depending upon the position and amount
of localized increase of capacity, in the same way as by attaching a weight
or spring to a piano wire between its extremities additional vibrations in
the wire are created.”
Fessenden's Wave-Gates of High Specific Inductive Capa-
city. Figs. 62 and 63 are from the Fessenden patent
706,739. The first is a sectional elevation, and the second


7
"
I
2
3
I
2
3
Fig. 62.
Fig. 63.
a plan of a sending conductor similar in configuration to
that shown in Fig. 61, but now surrounded by a coil of
WAVE-GATES.
173
wire, between the turns of which is supplied an insulating
medium of high specific inductive capacity. "By this
means," the patent declares, "it is possible to increase the
capacity of the conductor without altering its height, and
yet without altering the relation between the wave length
and the medium and the length of the conductor. In other
words, to obtain the same effect as is produced in air by
increasing the height of the conductor"; or, again, “that
all the functions or desirable results incident to the employ-
ment of a long high conductor can be attained by a rela-
tively short low conductor."
In Figs. 62 and 63 reference number I indicates the
radiating portion proper; 2 may consist of a coil of insu-
lated iron wires of No. 40 Brown & Sharpe gauge. The
wires in the coil are maintained under tension, the turns
being spaced a distance apart approximately one-fourth the
diameter of the wire. The spaces between the wires 2
may be filled with an insulating material of high specific
inductive capacity,' such as rubber, indicated by a black
mass in the figure; 3 is a reflecting plate formed of metal
and arranged on the side of the conductor opposite that
facing the direction in which the waves are to travel;
44 are spark knobs; 7 is an enlargement for a purpose
similar to reference number 17 of Fig. 61. Of 7 the
inventor says, it may be a band of conducting material,
and that such a construction affords means for adjust-
ing the capacity by adding or removing bands, or by
changing their position along the conductor. The main
advantage, and a matter of especial necessity to the Fes-
senden system, is that this device enables the operator to
obtain long waves from a short conductor, thereby avoid-
ing the expense involved in the erection of high masts.
1 See p. 183.
174
WIRELESS TELEGRAPHY.
Another Fessenden inven-
Fessenden's Wave-Chute.
tion is for a "wave-chute," called also an "artificial
ground." Of this device Fig. 64 is an elevation and Fig.
65 a plan. In those illustrations reference numbers 2

2
13
13
13
11
13-
1000
000
ПО
Fig. 64.
are longitudinal wires in the wave-chute; and 3, trans-
verse wires connecting together wires 2; II is a metallic
guy rope or chain for supporting the mast. In one of
his descriptions of the wave-chute the inventor says:
INVENTOR'S DESCRIPTION OF WAVE-CHUTE. -"I have found that it
is essential for the proper sending and receipt of these waves that the sur-
face over which they are to travel should be highly conducting, more espe-

2
2
-3
3
Fig. 65.
cially in the neighborhood of the point where the waves are generated. I
have found that this highly-conducting-portion of the surface should pref-
erably extend to at least a distance from the origin equal to a quarter wave
length of the wave in air, and in the direction toward the station or sta-
tions to which it is desired to send the waves. Where the sending-station
is in a city or similar place where the waves may be cut off by high build-
ings or high trees, this highly-conducting path should be extended still
WAVE-GATES.
175
farther, until it passes beyond the limits of the obstacle, and there the
highly-conducting portion, which may be in the form of a strip of metal or
other conductor, or of a number of wires, is connected to ground."
and, further, that "on rocky shores," as an instance, "salt
spray sometimes dashes, rendering the ground surface near
the station a conducting one which was previously an insu-
lating one; and in such case an artificial ground makes the
conditions constant in all weathers."
Preventing Absorption of Waves into Iron or Steel Guys.
"That it is preferable in such places to employ iron
chains or iron wire ropes, and that such iron or steel guys
would in general absorb waves rapidly," therefore he coats
them and the mast with a non-magnetic film, such as zinc
or lead, thus rendering their resistance to the currents pro-
duced by electromagnetic waves of the frequency used so
low that there is little absorption. It is desirable that the
guys be insulated from the ground, and "in order to ren-
der it certain that the natural period of the mast and guys
is different from that of the electromagnetic waves, said
mast and guys may be wrapped or encircled with one or
more coils or turns (13) of iron strips, or wire, preferably
insulated, thus increasing the inductance and natural
period of the mast and guys, and permitting the employ-
ment of conducting materiale.g., iron or steel in the
mast and guys.
As shown in Fig. 64, the coils or turns
may be either formed locally, i.e., extending a short dis-
tance along the mast or guys, or such coils or turns
may extend continuously along such parts.
"While the coating of the mast and guys with non-mag-
netic material need not necessarily be used with the coils
or turns, it is preferred in most cases to both coat the
mast and guys with non-magnetic material and also to
176
WIRELESS TELEGRAPHY.
employ the coils or turns of magnetic wire or strips, which
may be formed of nickel or other magnetic material. No.
40 Brown & Sharpe gauge of wire is a size suitable for the
purpose."
Probable Law or Wave-Propagation Through Space. -
It seems natural and probable that the dissipation of
energy in wave-propagation through space follows laws
analogous to those that govern the conduction of electrical
currents along wires, that the amount of loss is inversely
proportional to the cross-sectional area of the conducting
medium and to the
square of the applied

pressure. If etheric
waves are radiated in.
Fig. 66.
straight lines, then the
cross-sectional area of a
wireless conductor is the
product of the height and
the mean horizontal peri-
phery of the wave-gate.
It is also true that the
amount of energy which
may be transferred from
the surface of the send-
ing conductor to the
other is modified by the resistance to vibrations of the
carrier which conveys those vibrations from the initial
source of wave generation to the emitting surfaces.
The Marconi Wave-Gates at Poldhu and Glacé Bay.
Figs. 66, 67, and 68 are, respectively, illustrations of the
WAVE-GATES.
177
!!
Marconi Company's wave-gates at Poldhu, England, and at
Glacé Bay, Cape Breton. Fig. 68 carries out the idea of

Fig. 67.
Professor Lodge, referred to at some length in Part II.,
and also mentioned in the present part in connection with
Lodge's wave-gate.
M

00
Fig. 68.
Cape Breton is an island and politically a part of the prov-
ince of Nova Scotia. It is twelve miles from Sydney, and
178
WIRELESS TELEGRAPHY.
separated from the main land by the Strait of Canso.
Each of the four towers, shown in the Glacé Bay picture,
are two hundred and fifteen feet high. They form a
square, each side of which is two hundred feet in length.
Between the eastern towers and the sea the ground is
absolutely bare of soil. The structures are composed of
strong steel timbers bolted together and firmly anchored
in foundations of cement concrete. At different heights
depend from the towers hundreds of steel guys (not shown
in the picture) secured to the rocky surface of the ledge
from a few feet to fifty yards from their respective bases.
SHIELDS.
179
SHIELDS.
A device peculiar to Wireless Telegraphy is the metal
shield used to protect the coherer from the strong waves
of a transmitter in close proximity at the same station.
Fig. 69 shows one of Dr. Lodge's devices, which he thus
describes :
COHERER SENSITIVE TO LOCAL AS WELL AS DISTANT OSCILLATIONS.
"Á coherer is sensitive not only to the desired impulse arriving from a

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Fig. 69.
distance and conveyed to it by the collectors, but it is also liable to respond
to any local sparks or electric surgings in its neighborhood, especially to
oscillations in an adjacent emitter. It may be protected from all these by
complete inclosure in a flawless metallic box."
PROTECTION BY METALLIC COVERING. "For the purpose of protect-
ing the coherer from undesired disturbance, therefore, I inclose it (some-
times with all coils, wires, batteries, and the like connected to it) in a
metallic covering or case, as shown in Fig. 69, leaving only one or
180
WIRELESS TELEGRAPHY.
more round holes or short tubes w for the collector terminal or terminals
to enter by, and for vision or other needful purpose requiring an aperture,
for through round holes of moderate size large electric waves do not
readily pass, whereas through chinks or long slits, no matter how infinitely
narrow, they can pass with ease. They likewise pass in by means of any
insulated wire which enters the box; but through any wire which is thor-
oughly joined to the metal wall of the box where it enters the waves cannot
pass."
DESCRIPTION OF FIG. 69. — "In the particular arrangement shown
in Fig. 69 a single terminal h is employed which is insulated from the cas-
ing by tube w, and is connected to one terminal only of the coherer. This
construction is effective and desirable in certain cases, and it is found that
the Hertzian waves pass in readily through the single wire. Hence it is
not absolutely necessary to remove the terminal h from its aperture when
it is not being used for the purpose of establishing communication and
enabling waves from the collector to enter the box and reach the coherer.
The only part of the coherer or detector portion outside the box is
the index or needle mirror z of the telegraphic receiving instrument em-
ployed, which is acted upon and deflected by its coil g inside acting
magnetically through the metal wall.
"When the plan of withdrawing the terminals of the box is adopted, it
is sufficient to put the coherer above mentioned alone in the box."
Marconi's Shield.
Marconi's organization for shielding
his coherer is illustrated in Fig. 70.
His own description is as follows:
"When both instruments are employed at the same station, it is found
that the sensitive tube or sensitive imperfect contact is liable to injury by
its close proximity to the sparking appliance. In order to obviate this
objection, I inclose the receiver containing the sensitive tube or sensitive
imperfect contact in a box of metal having only a small opening into it,
and I employ the same conductor and earth-plate for both instruments.
The earth-plate is permanently connected to one terminal of the sparking
appliance and to the outside of the box. The insulated conductor can be
connected by a plug either to the other terminal of the sparking appliance
or to the other end of the imperfect contact.
64
According to my present invention I inclose the receiver in a metallic
box A. One-twentieth of an inch is a suitable thickness for the metal.
7
SHIELDS.
181
1
The inside of the box is connected by a wire A' to the relay-circuit, and its
outside by wires A2 A3 to one terminal of the telegraphic instrument ½ and
earth E, respectively.
The

other branch of the relay-
circuit is connected by a
wire A4, insulated from the
box, to the other terminal
of the instrument h.
"B is a coil on the wire
A4 and outside the box. It
is protected from mechani-
cal injury by a wooden case
C; but this may be omitted.
The coil B may contain
about twenty yards of wire
one seventy-fifth of an inch
in diameter and have one
hundred and twenty turns.
"The wire is insulated
with gutta-percha D, which
is covered with tin-foil F,
E
D B
Fig. 71.
A
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Fig. 70.
b
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as shown in Fig. 71. The tin-foil is in electric connection with
the box. The coil B prevents oscillations of the transmitter
from reaching the coherer at the same station through the
wire A¹. The aerial conductor u can be connected by a flex-
ible conductor, plug G', and spring-contacts H and H' either to one of the
balls e for transmitting or to one end of the tube j for receiving. The
other end of the tube j is connected by a wire J to the inside of the box."
182
WIRELESS TELEGRAPHY.
CONDENSERS, INDUCTANCE-COILS
AND KEYS.
To round out this division of the work and to furnish
means of ready reference, there is presented here a brief
account of important principles and devices connected
with Wireless Telegraphy, which, however, are neither
novel nor peculiar to it.
Condensers. When a source of electrical current is
connected to a conductor, a long wire for instance, and
that conductor is insulated both along its course and from
a return wire or from the earth, it will become charged.
Suppose instead of a long wire the conductor be a small
sheet of tin-foil positively charged, and suppose another
sheet of tin-foil negatively charged be placed near the first
one, say, by gluing the two sheets upon opposite sides of
a glass plate, then the amount of charge which may be
Fig. 72.
spread upon the tin-foil
sheets will be greatly in-
creased. The total quan-
tity of electricity which

may thus be stored depends upon the area of the surfaces
in the metal, upon the nearness to each other of the two
oppositely charged sheets, which is to say the thinness of
insulation between them, and also upon the composition of
the insulating medium or "dielectric." Suppose two tin-
foil sheets are joined together at their edges and interlaced
with and insulated from two other sheets connected at the
edges, then a diagrammatic expression would be as in Fig.
72, that diagram being the accepted symbol for a condenser.
Multiplication of sheets increases, in direct proportion,
CONDENSERS, INDUCTANCE-COILS AND KEYS. 183
the capacity of the condenser for the storage of electricity.
The amount stored is also more or less according to the
"specific inductive capacity" of the insulating medium-
the "dielectric." If the effect of dry air be taken as 1,
that of rubber is equivalent to 3, of sulphur to 4, of mica
to 7, and of glass to 9. For convenience and economy
condensers are usually made of tin-foil plates separated by
sheets of paraffined paper and sealed in a wood box.
Marconi's Condenser. Marconi describes as follows
the condenser used in connection with his earlier forms of
apparatus for "tuning" the circuit. "It was composed
of six tin-foil (or copper) plates connected to each terminal,
each plate being 1.97 inches by 1.18 inches, the plates
being insulated by paraffined paper, .067 inch thick. Its
capacity measurement was one-fourth of one microfarad."
Tesla Condenser. As has been shown already, the con-
denser plays a very important part in Tesla's wireless
transmissions. In his sun motor patent shown in Fig. 15,
Part I., he uses mica as a dielectric, and treats the condens-
ers by a process of his own invention, consisting in inclos-
ing the device in an air-tight receptacle, exhausting the air
from the receptacle, introducing into a vessel containing
the device an insulating material rendered fluid by heat,
and when this material has permeated the interstices of
the condenser subjecting the whole to pressure which is
maintained until the material has cooled and solidified.
Improvements. - Other inventors have improved this
process by so contriving the method of filling that the
molten insulating material solidifies first in the interior
184
WIRELESS TELEGRAPHY.
parts of the condenser and then on its edges. Paraffin
wax is the principal ingredient of the insulating material
in these later inventions.
INDUCTANCE COILS.
Illustration of Lines of Magnetic Force. Suppose a
piece of cardboard be held horizontally so that iron filings
will rest upon its surface, and that it be pierced through
its center by a vertical copper wire. If the free ends of

Fig. 73.
that wire above and below the card be connected to the
poles of a battery, the filings will arrange themselves in
radiating lines as in Fig. 73. The influences which ema-
nate from the wire are named magnetic lines of force, and
the area over which such influences are exerted is a mag-
netic field.
CONDENSERS, INDUCTANCE-COILS AND KEYS. 185
Induction Between Two Circuits. If a second wire
with its ends joined together, to make an endless loop, be
brought into a magnetic field, there will be developed in
this loop an electric current. If, while the two wires are
in proximity, either the loop or the battery circuit be
moved or the pressure in the battery circuit be varied, or
the lines of force are passed across the loop, or the loop
cuts them, or any electrical change is made, an electric
circuit is set up in the loop.
Induction and Counter-Force in a Coil. If a portion
of a wire in a charged circuit be wound in a coil, the lines
of force which may emanate from any one turn are cut by
the wires of the other turns, and so a varying current may
produce an inductive effect in that coil. The counter
pressure thus created tends to stop the development of the
flowing current, because the induced force is opposite in
direction to the initial one; but if the flowing current be
broken or weakened or strengthened, or in any way
changed in direction or in force, then the secondary
stream takes the same direction as the primary one, and,
as both work together, there is a surge or impulse due
to the sudden release of energy that has previously been
bound.
One Coil is Placed Within Another. It is the usual
practice to place in the interior of a coil of one circuit
turns of wire which are part of another. This arrange-
ment secures the best results that may be had with coils
alone, but a still greater effect is had by placing an iron
core within the inner coil.¹
1 The analogy of inductive effect to the load upon a vibrating spring has been illus-
trated by Fig. 7, p. 29, Part I.
186
WIRELESS TELEGRAPHY.
'.
One of Marconi's Inductance Coils. Mr. Marconi, de-
scribing an inductance, says:
Primary. — “The primary is wound upon a glass tube
.635 cm. (about inch) in diameter. This primary wind-
ing consists of two parallel windings of two hundred turns
each of copper wire .012 cm. in diameter (about .005 inch,
or No. 36, B. & S. Gauge), the wire being insulated by a
single covering of silk. The resistance of these two wind-
ings in parallel is about 3.1 ohms."
Secondary. The secondary winding consists of 800
turns of a wire .005 cm. (.002 inch) in diameter, having a
resistance of about 140 ohms, and wound either over or
under the primary winding.
Another Marconi Winding. Another Marconi induc-
tance coil has the secondary wound directly upon a glass
tube .3 inch diameter, the copper wire being .002 inch
diameter with a single silk covering, and making three
hundred and seventy-five turns about the tube with a
resistance of seventy-nine ohms. Over this secondary
is wound the primary of copper wire .005 inch in diameter
with a single silk wrapping. Resistance seven and one-
tenth ohms. Each of the four windings described consists
of a single layer.
-
TRANSMITTING KEYS
KEYS IN SECONDARY CIRCUIT AND
CONTACTS IN OIL.
In the initial American patent of Marconi, filed Decem-
ber, 1896, it is said that when working with large amounts
CONDENSERS, INDUCTANCE-COILS AND KEYS. 187
of energy it is better to keep the primary circuit in con-
stant operation and to interrupt the discharge of the
secondary; moreover, that in such cases the contacts of

4
3
Fig. 74.
the key should be immersed in oil, lest, owing to the
length of the spark, the current continue to pass after the
contacts have been separated. In the DeForest system
the key contacts are also made in oil.

T
8
8
100
10
ca
3
.7
Fig. 75.
Fessenden Key-Contacts. One of Mr. Fessenden's
inventions in keys is illustrated by a plan view, Fig. 74,
and sectional views, Fig. 75 and Fig. 76.
In this transmission it is intended to keep the generator
in continuous operation, the manipulation of the key
throwing the sending conductor out of tune with the
188
WIRELESS TELEGRAPHY.
receiving circuit of the distant station by short-circuiting
more or less of the tuning device.
Referring to the figures, switch 3 is employed to render
the generator inoperative while the apparatus is being used
as a receiver; 5 indicates one or more connected pairs of
parallel wires to form a tuning grid; 6 indicates movable
contacts adapted to connect electrically the wires or con-
ductors of each pair; 7 is a box containing sufficient oil to

7.
10 8-
Fig. 76.
cover the wires to a depth of about one inch ; 8 are spring
arms; 9 are adjusting blocks mounted in arms in the cover
of the box; and 10, 10a, Iob, Ioc, Iod are fingers arranged
to be brought into successive contact with one or more of
the wires of the grid, thus to shunt more or less of the
capacity and self-inductance of the sending circuit.
MARCONI'S TRANSMITTING KEY AND LIGHTNING-GUARD.
In Fig. 77 is shown a key arrangement devised by Mar-
coni for two objects, first, because the wave-gate is often
charged with atmospheric electricity which, when it is
shifted from the transmitting to the receiving circuit, is
liable to impart to the operator and to the coherer an
injurious shock; and, second, to prevent the accidental
CONDENSERS, INDUCTANCE-COILS AND KEYS. 189
operation of the transmitter when the aerial conductor is
connected to receiver. The arm of the key is prolonged
beyond its pivot, and carries an insulated contact which is
permanently connected to the aerial conductor. Below
this contact on the base of the instrument is the terminal
of the receiver. The arm is so arranged that immediately

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Fig. 77.
after its release by the operator, subsequent to the send-
ing of a message, it turns about upon its pivot, bringing
the above-mentioned contact and terminal together, so
connecting the receiver with the aerial conductor.
In the drawing b' and b4 indicate the contacts of an
ordinary Morse key and a high insulating handle. The
extension arm b has an insulated contact b2. When the
key is released by the operator its longer arm falls by its
own weight, the contact b2 descending upon the con-
tact b3.
190
APPENDIX I.
T
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Holololot
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Plate I.
Reproduction of drawing accompanying United States Patent of Amos E. Dolbear,
dated October 5, 1886.
No. 350,299,
[See p. 96.]
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APPENDIX I.
UNITED STATES PATENT OFFICE.
AMOS EMERSON DOLBEAR, OF SOMERVILLE, MASSACHUSETTS,
ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE DOLBEAR
ELECTRIC TELEPHONE COMPANY, OF NEW JERSEY.
MODE OF ELECTRIC COMMUNICATION.
Specification forming part of Letters Patent No. 350,299, dated
October 5, 1886.
Application filed March 24, 1882. Serial No. 56,264. (No model.)
To all whom it may concern :
Be it known that I, AMOS EMERSON DOLBEAR, of Somerville, in
the county of Middlesex and State of Massachusetts, have invented a
new Mode of Electric Communication, of which the following is
a full, clear, concise, and exact description, reference being had to
the accompanying diagram, forming a part hereof.
My invention relates to establishing electric communication be-
tween two or more places without the use of a wire or other like
conductor; and it consists in connecting the transmitting-instrument
with a ground the potential of which is considerably above the
normal, and the receiving-instrument with a ground the potential
of which is considerably below the normal, the result being that an
impulse from the transmitter sufficient to cause the receiver to give
intelligible signals is transmitted through the earth without the need
of any circuit, such as has heretofore been deemed essential.
In the diagram, A represents one place (say Tufts College), and B
a distant place (say my residence).
C is a wire leading into the ground at A, and D a wire leading into
the ground at B.
G is a secondary coil, one convolution of which is cut, the ends
thus formed being connected with the poles of the battery ƒ', which
191
192
APPENDIX I.
has a number of cells sufficient to establish in the wire C, which is
connected with one terminal of the secondary coil G, an electro-
motive force of, say, one hundred volts. G in this instance also rep-
resents an induction-coil, T being a microphone-transmitter, ƒ its
primary circuit, and f' its battery — that is, the battery ƒ not only
furnishes the current for the primary circuit, but also charges or elec-
trifies the secondary coil G and its terminals C and H'.
Now, if words be spoken in proximity to transmitter T, the vibra-
tion of its diaphragm will disturb the electric condition of the coil G,
and thereby vary the potential of the ground at A, and the variations
of the potential at A will cause corresponding variations of the
potential of the ground at B, and the receiver R at B will reproduce
the words spoken in proximity to transmitter T, as if the wires C D
were in contact or connected by a third wire. Electric communica-
tion may be thus established between points certainly more than half
a mile apart; but how much farther I cannot now say.
There are various well-known ways of electrifying the wire C to a
positive potential far in excess of a hundred volts, and the wire D to
a negative potential far in excess of a hundred volts.
In the diagram, H H' H² represent condensers, the condenser H'
being properly charged to give the desired effect. The condensers H
and H2 are not essential, but are of some benefit; nor is the con-
denser H' essential when the secondary G is otherwise charged. I
prefer to charge all these condensers, as it is of prime importance
to keep the grounds of wires C and D oppositely electrified, and
while, as is obvious, this may be done by either the batteries or the
condensers, I prefer to use both.
The main difficulty in utilizing my invention on a large scale is
that when there are many spots corresponding to A and B signals
transmitted from any A will go to the nearest B, or to several B's,
depending upon proximity and other causes. One method of obviat-
ing this difficulty is to use a given A only during a certain assigned
time for communicating with a certain B, the particular B being
arranged to receive communications only during the assigned time.
Thus, if there were ten B's within a given area, then the first B might
be used for the first hour, the second B for the next hour, and so on,
and the first A for the first five minutes of the first hour, the second
A for the next five minutes, and so on, so that either one of the A's
might have free communication with the first B, each for its assigned
time during the first hour, and either A with the second B, each for
its assigned five minutes of the second hour, and so on.
APPENDIX I.
193
In practice there will be of course both a receiver and transmitter
at A and B, proper switches being used to bring either into use, as
will be well understood without description.
I have spoken only of telephone-instruments, as these give the
best results; but any electric instruments may be used capable of
utilizing the currents passing through the earth from C to D, and the
strength of such currents can be largely increased by increasing the
positive potential of C and the negative potential of D. It will also
be obvious that if the end of coil G (shown in the diagram as con-
nected with one armature of condenser H') be grounded, and the end
shown grounded be connected with the condenser, then C will be
minus, and D must therefore be made plus.
What I claim is
The art above described of communicating by electricity, consist-
ing in first establishing a positive potential at one ground and a nega-
tive at another; secondly, varying the potential of one ground by
means of transmitting apparatus, whereby the potential of the other
ground is varied; and, lastly, operating receiving apparatus by the
potential so varied, all substantially as described.
Witnesses:
G. B. MAYNADIER,
JOHN R. SNOW.
AMOS EMERSON DOLBEAR.
APPENDIX II.
UNITED STATES PATENT OFFICE.
OLIVER JOSEPH LODGE, OF LIVERPOOL, ENGLAND.
ELECTRIC TELEGRAPHY.
Specification forming part of Letters Patent No. 674,846, dated
May 21, 1901.
Application filed December 20, 1897. Serial No. 662,688. (No model.)
To all whom it may concern :
Be it known that I, OLIVER JOSEPH LODGE, a subject of the
Queen of Great Britain, residing at Liverpool, in the county of Lan-
caster, England, have invented certain new and useful Improvements
in Electric Telegraphy, of which the following is a specification.
My invention relates to electric telegraphy; and it consists mainly
in utilizing certain processes and combinations of apparatus whereby
I am enabled to demonstrate the presence of, and to indicate in a
receiving-circuit the reception of, what are known as "Hertzian
waves" emitted from any suitable apparatus at a distance from the
receiving-circuit and propagated through space. Thus after a suc-
cession of electrical surgings of predetermined duration have been
caused to emanate from the emitter in accordance with the Morse or
other code of telegraphic signaling the same are taken up in the
receiver-circuit and so rendered intelligible, and a telegraphic system
is thus obtained.
My invention relates, further, to certain improvements in connec-
tion with the emitting apparatus, and comprises the other improve-
ments hereinafter more particularly described and claimed.
The annexed drawings, which are diagrammatic representations,
illustrate my invention.
194
APPENDIX II.
195
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Plate II.
Reproduction of drawing accompanying United States Patent of Oliver Joseph Lodge,
No. 674,846, dated May 21, 1901.
196
APPENDIX II.
Figure 1 shows the essential parts of one form of emitting appara
tus. Fig. 2 illustrates one form, and Fig. 3 an alternative arrange-
ment, of the apparatus and assembly of parts which constitute my
receiving-circuit. Fig. 4 shows a form of "coherer," and likewise
serves to illustrate a means for the automatic breaking down of the
cohesion resulting from the reception of waves by the coherer, as
hereinafter fully described. Fig. 5 illustrates an alternative form of
coherer, and Fig. 6 a still further modified form thereof and an alter-
native means of breaking down cohesion. Fig. 7 shows the coherer
and other parts incased within a metallic covering, as hereinafter
described.
As emitter of the Hertzian waves for the purpose of this invention
I may employ any known or suitable device in which a condenser or
Leyden jar or other electric capacity consisting either of a pair of
insulated plates or of a single plate and the earth is charged by an
electrical machine (such as Wimshurst's), or a Ruhmkorff induction-
coil, or a battery, or any other well-known means, to a high potential
and then discharged suddenly with a spark between suitably arranged
and prepared surfaces in air or in any medium, such as oil.
In Fig. 1 I have shown a form of emitter in which electricity is
supplied to a single conductor a (shown as a sphere, but which may
be of dumb-bell or any other shape) suddenly or disruptively by a
couple of positive and negative sparks from knobs b and c and there
left to oscillate and emit waves. A partial metallic inclosure d may
be used to diminish waves in undesired directions. Both of these
arrangements are my invention. The more usual plan hitherto has
been to charge two conductors by a pair of leading-wires and let them
spark into each other.
Referring now to Figs. 2 and 3, my receiving-circuit consists, essen-
tially, of a coherer e, a battery for other suitable source of electrical
energy, and a telegraphic receiving instrument g, all in electrical con-
nection, as shown. There is added to these latter a collecting-wire
h, of any desired length, as shown in Fig. 2, or else a form of Hertz-
ian resonator, as shown at i in Fig. 3, the function of either of which
is to collect and to convey to the coherer the Hertzian waves produced
at a distance, as aforesaid. In some cases I find that any bare wire
or a connection to earth direct or through the system of gas or water-
pipes, as shown at j in Fig. 2, will serve sufficiently well as a collector
or as an assistance to the insulated collector.
The coherer consists, essentially, of an organism whose electrical
resistance diminishes under the influence of Hertzian waves, but
APPENDIX II.
197
which returns to its former amount when the cohered condition
brought about by the electrical influence is broken down by mechan-
ical tremor.
One suitable form of coherer is illustrated in Fig. 4, which was
introduced (for other purposes) by Branly previous to the year 1894.
This arrangement consists of a pair of metallic points k, embedded in
metallic grains or powder / within a glass tube m; but it will be un-
derstood that I may employ any other equivalent device. For exam-
ple, I may seal the filings up in vacuum, as indicated in Fig. 5, which
I have discovered increases and prolongs its sensitiveness, or I may,
as illustrated in Fig. 6, use a coherer consisting of a needle-point »,
resting lightly on a flat plate or spring o, fixed in a clampy, the de-
gree of pressure being obtained by the adjustment-screws p and q.
On the arrival of Hertzian waves more complete contact or cohesion
is set up between the particles of powder or between the point n
and spring or other light metallic contact o, and so allows more cur-
rent from the battery ƒ to flow through the telegraphic receiving in-
strument (indicated at g, Figs. 2, 3, and 7); but then before the
coherer is again in a fit state to receive fresh impulses, the said cohe-
sion must be destroyed. Now according to my invention I provide
for this being effected by an automatic vibrator. This mechanical
vibration may consist of a succession of jars or knocks or taps, which
may be produced by electrical means, as in an electric trembling bell
(see r in Fig. 4), or by clockwork (see Fig. 6). In the last-mentioned
figure, s and t represent two wheels of a clockwork-train. Upon the
arbor (or on a disk mounted thereon) of the wheel s is a series of
serrations or the like u (shown exaggerated in the drawings), which
as the wheel rotates effects the vibration of the lever or spring o
either directly or indirectly through the stand. Such a tapper as is
used in dentistry also serves very well for my purpose.
A coherer is sensitive not only to the desired impulse arriving from
a distance and conveyed to it by the collectors, but it is also liable to
respond to any local sparks or electric surgings in its neighborhood,
especially to oscillations in an adjacent emitter. It may be protected
from all these by complete inclosure in a flawless metallic box.
For the purpose of protecting the coherer from undesired disturb-
ance, therefore, I inclose it (sometimes with all coils, wires, batteries,
and the like connected to it) in a metallic covering or case, as shown
at in Fig. 7, leaving only one or more round holes or short tubes w
for the collector terminal or terminals to enter by, and for vision or
other needful purpose requiring an aperture, for through round holes
198
APPENDIX II.
of moderate size large electric waves do not readily pass, whereas
through chinks or long slits, no matter how infinitely narrow, they can
pass with ease. They likewise pass in by means of any insulated
wire which enters the box; but through any wire which is thoroughly
joined to the metal wall of the box where it enters the waves cannot
pass.
In the particular arrangement shown in Fig. 7 a single terminal h
is employed which is insulated from the casing by tube w and is con-
nected to one terminal only of the coherer. This construction is
effective and desirable in certain cases, and it is found that the Hertz-
ian waves pass in as readily through the single wire, affecting the
coherer in the same way as in the case of the earthed circuit through
jin Fig. 2. Hence it is not absolutely necessary to remove the ter-
minal И from its aperture when it is not being used for the purpose
of establishing communication and enabling waves from the collector
to enter the box and reach the coherer; for these same terminals h
or j may when they are raised completely plug with metallic con-
tinuity, as shown at x, the small holes through which they can freely
afterward be lowered.
The only part of the coherer or detector portion outside the box
(shown in Fig. 7) is the index or needle mirror z of the telegraphic
receiving instrument employed, which is acted upon and deflected by
its coil g inside acting magnetically through the metal wall.
When the plan of withdrawing the terminals of the box is adopted,
it is sufficient to put the coherer above mentioned alone in the box.
What I claim, and desire to secure by Letters Patent of the United
States, is:
1. In a system of Hertzian-wave telegraphy, an emitter consisting
of a single conducting body and means for suddenly and disruptively
communicating opposite electric charges thereto, whereby oscilla-
tions are set up in said body, and waves are emitted, substantially as
described.
2. In a system of Hertzian-wave telegraphy, an emitter comprising
a single conductor supplied with opposite electricities by a pair of
knobs connected to the terminals of a high-potential source.
3. In a system of Hertzian-wave telegraphy, the combination with
an emitter, of a partial metallic inclosure serving to lessen the emis-
sion of Hertzian waves in undesired directions.
4. A coherer comprising a variable electrical contact sealed in
vacuum.
5. In a receiver for Hertzian-wave signaling systems, the combina-
APPENDIX II.
199
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¿
tion of the following instrumentalities: a coherer, a base or support
upon which it is mounted, and a vibrator mounted in proximity to the
coherer, and adapted to agitate its elements.
6. In the receiving-circuit of a system of Hertzian-wave telegraphy,
the combination, with a coherer, of automatic means to successively
break down the cohesion caused in said coherer by such Hertzian
waves.
7. In combination, in the receiving-circuit of a system of Hertzian-
wave telegraphy, a coherer, a battery, a telegraphic receiving instru-
ment, and automatic means to successively break down the cohesion
caused in said coherer by such Hertzian waves.
8. 1. combination, in the receiving-circuit of a system of Hertzian-
wave telegraphy, a coherer, a battery, a telegraphic receiving instru-
ment, automatic means to successively break down the cohesion
caused in said coherer by such Hertzian waves, and means serving
to collect and convey to the coherer Hertzian waves produced at a
distance.
In testimony whereof I have hereunto subscribed my name.
OLIVER JOSEPH LODGE.
Witnesses:
WM. PIERCE,
WM. G. MURRAY.
APPENDIX III.
UNITED STATES PATENT OFFICE.
GUGLIELMO MARCONI, OF LONDON, ENGLAND, ASSIGNOR, BY MESNE
ASSIGNMENTS, TO MARCONI'S WIRELESS TELEGRAPH
COMPANY, LIMITED, OF ENGLAND.
TRANSMITTING ELECTRICAL IMPULSES AND SIGNALS
AND APPARATUS THEREFOR.
Specifications forming part of Reissued Letters Patent No. 11,913,
dated June 4, 1901.
Original No. 586,193, dated July 13, 1897. Application for reissue filed April 1, 1901.
Serial No. 53,896.
To all whom it may concern:
Be it known that I, GUGLIELMO MARCONI, a subject of the King
of Italy, residing and having a post-office address at 18 Finch Lane,
Threadneedle Street, London, England, have invented certain new
and useful Improvements in Transmitting Electrical Impulses and
Signals and in Apparatus Therefor, of which the following is a
specification.
According to this invention electrical signals, actions, or manifes-
tations are transmitted (through the air, earth, or water) by means of
oscillations of high frequency, such as have been called "Hertz
rays" or "Hertz oscillations." All line-wires may be dispensed
with. At the transmitting-station I preferably employ a Ruhmkorff
coil, having in its primary circuit a Morse key or other signaling
instrument and at its poles appliances for producing the desired
oscillations. The Ruhmkorff coil may, however, be replaced by any
other source of high-tension electricity. When working with large
amounts of energy, it is, however, better to keep the coil or trans-
200
APPENDIX III.
201
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Plate III.
Reproduction of first sheet of drawings accompanying United States Patent of
Guglielmo Marconi, No. 11,913. (A reissue.)
202
APPENDIX III.
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Plate IV.
Reproduction of second sheet of drawings accompanying United States Patent of
Guglielmo Marconi, No. 11,913. (A reissue.)
APPENDIX III.
203
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Plate V.
Reproduction of third sheet of drawings accompanying United States Patent of
Guglielmo Marconi, No. 11,913. (A reissue.)
204
APPENDIX III.
former constantly working for the time during which one is trans-
mitting, and instead of interrupting the current of the primary
interrupting the discharge of the secondary. In this case the con-
tacts of the key should be immersed in oil, as otherwise, owing to the
length of the spark, the current will continue to pass after the
contacts have been separated. At the receiving-station there is a
local-battery circuit containing any ordinary receiving instrument
and an appliance for closing the circuit, the latter being actuated by
the oscillations from the transmitting-station. When transmitting
through the air, and it is desired that the signal should only be sent
in one direction, I place the oscillation-producer at the transmitting-
station in the focus or focal line of a reflector directed to a receiv-
ing-station, and I place the circuit-closer at the receiving-station in a
similar reflector directed toward the transmitting-station. When
transmitting signals by the aid of earth connections, I connect one
end of the oscillation-producer and one end of the circuit-closer to
earth and the other ends to plates preferably electrically tuned with
each other in the air and insulated from earth.
Figure 1 is a diagrammatic front elevation of the instruments at
the transmitting-station when signaling through the air, and Fig. 2 is
a vertical section of the transmitter. Fig. 2ª is a longitudinal section
of the oscillator to a larger scale. Fig. 3 shows a detail of the
trembler-break on a larger scale. Fig. 4 is a diagrammatic front
elevation of the instruments at the receiving-station. Fig. 5 is an
enlarged view of the receiver. Fig. 6 shows a modification of the
tube j. Fig. 7 shows the detector. Fig. 8 is a full-sized view of
the liquid resistance. Figs. 9 and 10 show modifications of the
arrangements at the transmitting-station. Fig. 11 shows a modifica-
tion of the arrangements at the receiving-station.
Referring now to Fig. 1, a is a battery, and b an ordinary Morse
key closing the circuit through the primary of a Ruhmkorff coil c.
The terminals c' of the secondary circuit of the coil are connected to
two metallic balls dd, fixed by heat or otherwise at the ends of
tubes d' d', Fig. 2a, of insulating material, such as ebonite or vulcan-
ite. e e are similar balls fixed in the other ends of the tubes d'. The
tubes d'fit tightly in a similar tube d², having covers d³, through
which pass rods dª, connecting the balls d to the conductors. One
(or both) of the rods d¹ is connected to the ball d by a ball-and-
socket joint and has a screw-head upon it working in a nut in the
cover d³. By turning the rod, therefore, the distance of the balls e
apart can be adjusted. d5 represents holes in the tube d², through
APPENDIX III.
205
which vaseline, oil, or like material is introduced into the space
between the balls e.
The balls & and e are preferably of solid brass or copper, and the
distance they should be apart depends on the quantity and electromo-
tive force of the electricity employed, the effect increasing with the
distance so long as the discharge passes freely. With a coil giving
an ordinary eight-inch spark, the distance between e and e should, to
assure good results, be from one twenty-fifth to one-thirtieth of an
inch, and the distance between d and e about one and one-half
inches. Other conditions being equal, the larger the balls the greater
is the distance at which it is possible to communicate. I have gen-
erally used balls of solid brass of four inches diameter, giving oscilla-
tions of ten inches length of wave.
If a very powerful source of electricity giving a very long spark be
employed, it is preferable to divide the spark-gap between the central
balls of the oscillator into several smaller gaps in series. This
may be done by introducing between the big balls smaller ones of
about half an inch diameter, held in position by ebonite frames.
I find that the regularity and power of the discharge of an ordi-
nary Ruhmkorff coil with a trembler-break on its primary is greatly
improved by causing one of the contacts of the vibrating break to
revolve rapidly. I do this preferably by having a revoluble central
core c², Fig. 3, in an ordinary screw c³, which is in communication
with platinum contacts. I cause the said central core, with one of
the platinum contacts attached to it, to revolve, preferably, by con-
necting it to a small electric motor c. This motor can be worked by
the same circuit that works the coil, or, if necessary, by a separate
circuit. The connections are not shown in the drawings. By this
means the platinums are kept smooth, and any tendency to stick is
removed. They last, also, much longer. At the receiving-station
is a battery whose circuit includes an ordinary telegraphic instru-
ment (or it may be a relay or other apparatus which is desired to
work from a distance) and a circuit-closer.
In Fig. 4, g is the battery, and ʼn a telegraphic instrument on the
derived circuit of a relay 1.
The appliance I employ as a circuit-closer is shown at Fig. 5, and
consists of a glass tube j, containing metallic powder or grains of
metal, each end of the column of powder being connected to a
metallic plate k of suitable length to cause the system to resonate
electrically in unison with the electrical oscillations transmitted.
The glass tube may be replaced in some places by one of gutta-
•
206
APPENDIX III.
percha or like material. Two short pieces j², preferably of thick
silver wire of the same diameter as the internal diameter of the
tube j, so as to fit tightly in it, are joined to two pieces of platinum
wire j³. The tube is closed and sealed onto the platinum wires j³ at
both ends.
Many metals can be employed for producing the powder or
filings; but I prefer to use a mixture of two or more different
metals. I find hard nickel to be the best metal, and I prefer to add
to the nickel filings, about ten per cent of hard-silver filings, which
increase greatly the sensitiveness of the tube to electric oscillations.
By increasing the proportion of silver powder or grains the sensitive-
ness of the tube also increases; but it is better for ordinary work not
to have a tube of too great sensitiveness, as it might be influenced by
atmospheric or other electricity. The sensitiveness can also be
increased by adding a very small amount of mercury to the filings
and mixing up until the mercury is absorbed.
The mercury must not be in such a quantity as to clot or cake the
filings. An almost imperceptible globule is sufficient for a tube. In-
stead of mixing the mercury with the powder one can obtain the same
effects by slightly amalgamating the inner surfaces of the plugs
which are to be in contact with the filings. Very little mercury must
be used, just sufficient to brighten the surface of the metallic plugs
without showing any free globules. The size of the tube and the
distance between the two metallic stops may vary under certain
limits. The greater the space allowed for the powder the larger and
coarser ought to be the filings or grains.
I prefer to make my sensitive tubes of the following size: The
tube j is one and one-half inches long and one-tenth or one-twelfth
of an inch in internal diameter. The length of the stops j² is about
one-fifth of an inch, and the distance between the stops is about one-
thirtieth of an inch. I find that the smaller the space between the
stops in the tube the more sensitive it proves; but the space cannot
under ordinary circumstances be excessively shortened without in-
juring the fidelity of the transmission.
The metallic powders ought not to be fine, but, rather, as coarse
as can be produced by a large and rough file.
All the very fine powder ought to be removed by blowing or
sifting.
The powder ought not to be compressed between the stops, but
rather, loose, and in such a condition that when the tube is tapped
the powder may be seen to move.
APPENDIX III.
207
The tube must be sealed; but a vacuum inside it is not essential.
A slight vacuum, however, results from having heated it while sealing
it. Care must also be taken not to heat the tube too much in the
center when sealing it, as it would oxidize the surfaces of the silver
stops and also the powder, which would diminish its sensitiveness.
I use in sealing the tubes a hydrogen and air flame. A vacuum is,
however, desirable, and I have used one of about one one-thousand th
of an atmosphere, obtained by a mercury-pump. It is also necessary
for the powder or grains to be dry and free from grease or dirt, and
the files used in producing the same ought to be frequently washed
and dried, and used when warm.
If the tube has been well made, it should be sensitive to the
induction of an ordinary electric bell when the same is working at
one to two yards or more from the tube.
In order to keep the sensitive tube j in good working order, it is
desirable, but not absolutely necessary, not to allow more than one
milliampere to flow through it when active. If a stronger current is
necessary, several tubes may be put in derivation between the tuned
plates; but this arrangement is not quite as satisfactory as the single
tube. It is necessary when using tubes of the type I have described
not to insert in the circuit more than one coil of the Leclanche type,
as a higher electromotive force than 1.5 volts is apt to pass a current
through the tube even when no oscillations are transmitted. I can,
however, construct tubes capable of working with a much higher
electromotive force. Fig. 6 shows one of these tubes. In this tube
instead of one space or gap filled with filings there are several spaces
separated by sections of tight-fitting silver wire. A tube thus con-
structed, observing also the rules of construction of my tubes in
general, will work satisfactorily if the electromotive force of the
battery in circuit with the tube is equal to 1.2 volts multiplied by the
number of gaps. With this tube, also, it is well not to allow a
current of more than one milliampere to pass.
The tube j may be replaced by other forms of imperfect electrical
contacts.
The plates are of copper or aluminium or other metal, about
half an inch or more broad, about one-fiftieth of an inch thick, and
preferably of such a length as to be electrically tuned with the electric
oscillations transmitted. The means I adopt for fixing the length
of the plates is as follows: I stick a rectangular strip of tin-foil m
(see Fig. 7) about twenty inches long (the length depends on the
supposed length of wave that one is measuring), by means of a weak
208
APPENDIX III.
solution of gum, onto a glass plate m'. Then by means of a very
sharp penknife or point, I cut across the middle of the tin-foil, leav-
ing a mark of division 2. If this detector is held in the proximity
(four or five yards) and parallel with the axis of the oscillator in
action it will show little sparks at m². If the length of the pieces of
tin-foil approximates to the length of wave emitted from the oscil-
lator, the spark will take place between them at a certain distance
from the transmitter, which is a maximum when they are of suitable
length. By shortening or lengthening the strips, therefore, it is easy to
find the length most appropriate to the length of wave emitted by the
oscillator. It is desirable to try this detector in the focus or focal
line of the reflector. The length so found is the proper length for
the plates k, or rather these should be about half an inch shorter on
account of the length of the sensitive tube j, connected between
them.
Instead of the tuned plates, k tubes or even wires may be em-
ployed.
ƒ is a cylindrical parabolic reflector made by bending a metallic
sheet, preferably of brass or copper, to form and fixing it to metallic
or wooden ribs ƒ'.
7 is a cylindrical parabolic reflector similar to that used at the
transmitting-station.
The reflectors applied to the receiver and transmitter ought to be,
preferably, in length and opening, the double at least of the length of
wave emitted from the oscillator.
It is slightly advantageous for the focal distance of the reflector at
the receiving-station to be equal to one-fourth or three-fourths of the
wave length of the oscillation transmitted.
I have hitherto only mentioned the use of cylindrical reflectors;
but it is also possible to use ordinary concave reflectors, preferably
parabolic, such as are used for projectors.
It is not essential to have a reflector at the transmitters and re-
ceivers; but in their absence the distance at which one can communi-
cate is much smaller.
When no oscillations are sent from the transmitting-station, the
tube j does not conduct the current and the local-battery circuit is
broken; but when the powder or tube is influenced by the electrical
oscillations from the transmitter it conducts and closes the circuit.
I find, however, that when once started the powder in the tube con-
tinues to conduct even when the oscillations from the transmitter
have ceased; but if it be shaken or tapped the circuit is broken. A
APPENDIX III.
209
tube well prepared will instantly interrupt the current passing
through it at the slightest tap, provided it is inserted in a circuit
in which there is little self-induction and small electromotive
force, such as a single cell, and where the effects of self-induction
have been removed by one of the methods which I will presently
describe.
The two plates k communicate with the local circuit through two
very small coils k', which I will call "choking-coils," formed by
winding a few inches of very thin and insulated copper wire around
a bit of iron wire about an inch and a half long. The object of these
choking-coils is to prevent the high-frequency oscillation induced
across these plates by the transmitter from dissipating itself by run-
ning along the local-battery wires, which might weaken its effect on
the sensitive tubej. These choking-coils may, however, be some-
times replaced by simple thin wires. They may also be connected
directly to the tube j. The local circuit in which the sensitive tube j
is inserted, contains a sensitive relay », preferably wound to a resis-
tance of about twelve hundred ohms. This resistance need not be
necessarily that of the relay, but may be the sum of the resistance of
the relay and another additional resistance. The relay ought to be
one possessing small self-induction.
The plates k, tube j, and coils k' are fastened by means of wire
stitches o' to a thin glass tube o, preferably not longer than twelve
inches, firmly fixed at one end to a strong piece of timber o². This
may be done by means of wood or ebonite grasping-screws.
I do the tapping automatically by the current started by the tube,
employing a trembler p on the circuit of the relay similar in con-
struction to that of an electric bell, but having a shorter arm. This
vibrator must be carefully adjusted. Preferably the blows should be
directed slightly upward to prevent the filings from getting caked.
In place of tapping the tube, the powder can be disturbed by slightly
moving outward and inward one or both of the stops j², the trembler
being replaced by a small electromagnet (or magnets) whose arma-
ture is connected to the stop.
I ordinarily work the telegraphic receiver h (or other instruments)
by a derivation, as shown, from the circuit which works the trembler
p. They can also, however, be worked in series with the trembler.
When working ordinary sounders or Morse apparatus, a special
adjustment of the same is sometimes needed to enable one to obtain
dots and dashes. Sometimes it is necessary to work the telegraphic
instruments or relays from the back stops of the first relay, as is done
210
APPENDIX III.
in some systems of multiple telegraphy. Such adjustments are known
to telegraphic experts.
By means of a tube with multiple gaps it is possible to work the
trembler and also the signaling or other apparatus direct on the cir-
cuit which contains the tube; but I prefer, when possible, to work-
with the single-gap tube and the relay, as shown. With a sensitive
and well-constructed trembler it is also possible to work the trembler
with the single-gap tube in series with it without the relay.
In derivation on the terminals of the relay n is placed an ordinary
platinoid resistance double-wound (or wound on the "bight," as it
is sometimes termed) coil g of about four times the resistance of the
relay, which prevents the self-induction of the winding of the relay
from affecting the sensitive tube.
The circuit actuated by the relay contains an ordinary battery r of
about twelve cells and the trembler p, the resistance of the winding
of which should be about one thousand ohms, and the core ought
preferably to be of soft iron, hollow and split lengthwise, like most
electromagnets used in telegraph instruments. In series or deriva-
tion from this circuit is inserted the telegraphic or other apparatus,
which one may desire to work. It is desirable that this instrument
or apparatus, if on a derivation, should have a resistance equal to the
resistance of the trembler p. A platinoid resistance h' of about five
times the resistance of the instrument is inserted in derivation across
the terminals of the instrument and connected as close to the same as
possible. In derivation across the terminals of the trembler is
placed another platinoid resistance p', also of about five times the
resistance of the trembler. A similar resistance p² is inserted in a
circuit connecting the vibrating contacts of the trembler. In deriva-
tion across the terminals of the relay-circuit it is well to have a liquid
resistance s, which is constituted of a series of tubes, one of which is
shown full size in Fig. 8, filled with water acidulated with sulfuric
acid. The number of these tubes in series across the said terminals
ought to be about ten for a circuit of fifteen volts, so as to prevent, in
consequence of their counter electromotive force, the current of the
local battery from passing through them, but allowing the high-ten-,
sion jerk of current generated at the opening of the circuit in the
relay to pass smoothly across them without producing perturbing
sparks at the movable contact of the relay. It is also necessary to
insert a platinoid resistance in derivation on any apparatus one may
be working on the local circuits. These resistances ought also to be
inserted in derivation on the terminals of any resistance which may
be apt to give self-induction.
APPENDIX III.
21I
I find it convenient when transmitting across long distances to
make use of the transmitter shown in Fig. 9.
tt are two poles connected by a rope t', to which are suspended,
by means of insulating-suspenders, two metallic plates 22, prefer-
ably in the form of cylinders closed at the top, connected to the
spheres e (in oil or other dielectric, as before) and to the other balls
18 in proximity to the spheres c', in communication with the coil or
transformer c. The balls are not absolutely necessary, as the
plates 12 may be made to communicate with the coil transformer by
means of thin insulated wires. The receiver I adopt with this trans-
mitter is similar to it, except that the spheres e are replaced by the
sensitive tube j and plates k, while the spheres are replaced by
the choking-coils k', in communication with the local circuit. It may
be observed that, other conditions being equal, the larger the plates
at the transmitter and receiver, and the higher they are from the
earth, and to a certain extent the farther apart they are the greater is
the distance at which correspondence is possible.
When transmitting with connections to the earth or water, I use a
transmitter as shown in Fig. 10. I connect one of the spheres d to
earth E, preferably by thick wire, and the other to a plate or elevated
conductor u, carried by a pole v and insulated from earth; or the
sphere d may be omitted and one of the spheres e be connected to
earth, and the other to the plate or conductor u. At the receiving-
station, Fig. TI, I connect one terminal of the sensitive tube j´to earth
E, also by a thick wire, and the other to a plate or elevated conductor
w, preferably similar to u. The plate w may be suspended on a pole
x, and must be insulated from earth. The larger the plates of the
receiver and transmitter, and the higher from the earth the plates are
carried the greater is the distance at which it is possible to communi-
cate. When using the last-described apparatus, it is not necessary
to have the two instruments in view of each other, as it is of no con-
sequence if they are separated by mountains or other obstacles. At
the receiver it is possible to pick up the oscillations from the earth or
water without having the plate w. This may be done by connecting
the terminals of the sensitive tube j to two earths preferably at a
certain distance from each other and in a line with the direction from
which the oscillations are coming. These connections must not be
entirely conductive, but must contain a condenser of suitable capa-
city — say one square yard of surface. Balloons can also be used
instead of plates on poles, provided they carry up a plate or are
themselves made conductive by being covered with tin-foil. As the
212
APPENDIX III.
height to which they may be sent is great, the distance at which com-
munication is possible becomes greatly multiplied. Kites may also
be successfully employed, if made conductive by means of tin-foil.
The apparatus above described is so sensitive that it is essential
either that the transmitters and receivers at each station should be at
a considerable distance from each other or that they should be
screened from each other by stout metal plates. It is sufficient to
have all the telegraphic apparatus in a metal box and any exposed
part of the circuit of the receiver inclosed in metallic tubes which are
in electrical communication with the box. Of course the part of the
apparatus which has to receive the radiation from the distant station
must not be inclosed, but possibly screened from the local transmitter
by means of metallic sheets. When working through the earth or
water, the local receiver must be switched out of circuit when the
transmitter is at work, and this may also be done when working
through air.
The operation of my apparatus and system of communication or
signals is as follows: The Ruhmkorff coil or other source of high
tension electrically capable of producing Hertz oscillations being in
circuit with a signaling instrument -- such as a Morse key, for
instance the operator by closing the circuit in the way commonly
employed for producing dots and dashes in ordinary telegraphy will
cause the oscillator to produce either a short or a more prolonged
electric discharge or spark or succession of sparks, and this will
cause a corresponding short or more prolonged oscillation in the sur-
rounding medium corresponding in duration to the short or longer
electrical impulse which in ordinary telegraphy produces a dot or
dash.
Such oscillations of defined character will thereupon be
propagated as such throughout the medium and will affect a properly-
constructed instrument at a distant receiving-station. At such sta-
tion the imperfect-contact instrument is in circuit with a relay, and
when oscillations from the transmitting-station reach and act upon
such imperfect contact its resistance is reduced, and the circuit is
thereby closed during the continuance of the oscillation and for a
length of time corresponding thereto. The closing of the relay-cir-
cuit causes the sounder or other signal apparatus to act in accord-
ance with the particular oscillation received, and the oscillation also
immediately starts the action of the shaking or tapping device, which
so shakes the powder in the imperfect-contact instrument as to cause
it to break circuit as soon as the oscillation ceases which has closed
the circuit and produced a movement of the signaling instrument
#
APPENDIX III,
213
corresponding thereto. I am therefore enabled to communicate sig-
nals telegraphically without wires by thus artificially forming oscilla-
tions at the transmitting-station into definite signals by means of a
signaling instrument and receiving and reading the same at a receiv-
ing-station by an imperfect-contact instrument, which when acted
upon by such defined oscillations operates, first, to close the circuit
in accordance with the received oscillation and produce a correspond-
ing movement of the receiving instrument, relay, or sounder, and also
to operate a shaking device to automatically reopen the circuit
immediately after the reception of each oscillation, thereby preserv-
ing the results of its defined character in the action of the receiver.
All the details specified herein of construction of the sensitive
tube and its connections are desirable for great efficiency; but the
fundamental features of my system of transmission are not restricted
to such details.
I am aware that the sensitiveness of various apparatus, including
tubes containing filings, to more or less distant electrical disturbances
has been observed in a general way, and that it has also been pro-
posed to disturb the conducting of such filings by various instru-
mentalities for shaking the tubes containing the same. I am also
aware that the use of tubes containing metallic powders of several
separate kinds has been described or suggested in connection with
certain experiments relating to so-called "coherers," but I am not
aware that the utility of a mixture of metallic powders has ever previ-
ous to my invention been ascertained and utilized for the purpose of
obtaining the required degree of sensitiveness in such an instrument.
I am aware of the publication of Professor Lodge of 1894, at Lon-
don, England, entitled "The Work of Hertz" and the description
therein of various instruments in connection with manifestations of
Hertz oscillations. I am also aware of the papers by Professor Popoff
in the Proceedings of the Physical and Chemical Society of Russia
in 1895 or 1896; but in neither of these is there described a complete
system or mechanism capable of artificially producing Hertz oscilla-
tions and forming the same into and propagating them as definite
signals and capable of receiving and reproducing, telegraphically,
such definite signals; nor has any system been described, to my
knowledge, in which a Hertz oscillator at a transmitting-station and
an imperfect-contact instrument at a receiving-station are both
arranged with one terminal to earth and the other elevated or insu-
lated; nor am I aware that prior to my invention any practical form
of self-recovering imperfect-contact instrument has been described.
י
•
214
APPENDIX III.
I believe that I am the first to discover and use any practical
means for effective telegraphic transmission and intelligible recep-
tion of signals produced by artificially-formed Hertz oscillations.
What I claim is
1. In an apparatus for communicating electrical signals by means
of a producer of Hertz oscillations and a signaling instrument, the
combination, in the receiver, of an imperfect electrical contact, a cir-
cuit through the contact, and a receiving instrument operated by the
influence of such oscillations on said contact, substantially as and
for the purpose described.
2. In an apparatus for communicating electrical signals by means
of a producer of Hertz oscillations and a signaling instrument, the
combination, in the receiver, of an imperfect electrical contact, a cir-
cuit through the contact, and means, controlled by said circuit, oper-
ating to shake the contact, substantially as and for the purpose
described.
3. The combination, in an apparatus for communicating electrical
signals, of a spark-producer at the transmitting-station, an earth con-
nection to one end of the spark-producer, an insulated conductor
connected to the other end, an imperfect electrical contact at the
receiving-station, an earth connection to one end of the contact, an
insulated conductor connected to the other end, and a circuit through
the contact, substantially as and for the purpose described.
4. The combination, in an apparatus for communicating electrical
signals, of a spark-producer at the transmitting-station, an earth con-
nection to one end of the spark-producer, an insulated conductor
connected to the other end, an imperfect electrical contact at the
receiving-station, an earth connection to one end of the contact, an
insulated conductor connected to the other end, a circuit through the
contact, and means, controlled by the circuit, for shaking the contact,
substantially as and for the purpose described.
5. The combination, in an apparatus for communicating electrical
signals, of a spark-producer at the transmitting-station, an earth con-
nection to one end of the spark-producer, an insulated conductor
connected to the other end, an imperfect electrical contact at the
receiving-station, choking-coils connected to each end of the contact,
an earth connection to one end of the imperfect contact, an insulated
conductor connected to the other end, and a circuit through the coils
and contact, substantially as and for the purpose described.
6. The combination, in an apparatus for communicating electri-
cal signals by means of a producer of Hertz oscillations and a
APPENDIX III.
215
signaling instrument, an imperfect electrical contact at the receiving-
station, choking-coils connected to the contact, a circuit through
the coils and contact, and means, controlled by the circuit and
operating to shake the contact, substantially as and for the purpose
described.
7. The combination, in an apparatus for communicating electrical
signals by means of a producer of Hertz oscillations and a signaling
instrument, an imperfect electrical contact at the receiving-station,
means, connected to each end of the contact, to prevent the oscilla-
tion from dissipating itself, a circuit through said means and contact,
and means, controlled by the circuit and operating to shake the con-
tact, substantially as and for the purpose described.
8. The combination, in an apparatus for communicating electrical
signals, of a spark-producer at the transmitting-station, an earth con-
nection to one end of the spark-producer, an insulated conductor con-
nected to the other end, a tube containing metallic powder at the
receiving-station, an earth connection to the powder and an insulated
conductor also connected therewith, and a circuit through the pow-
der, substantially as and for the purpose described.
9. The combination, in an apparatus for communicating electrical
signals, of a spark-producer at the transmitting-station, an earth con-
nection to one end of the spark-producer, an insulated conductor con-
nected to the other end, a tube containing metallic powder, and an
insulated conductor also connected therewith, a circuit through the
powder and means, controlled by the circuit, for shaking the powder,
substantially as and for the purpose described.
10. The combination, in an apparatus for communicating electri-
cal signals, of a spark-producer at the transmitting-station, an earth
connection to one end of the spark-producer, an insulated conductor
connected to the other end, a tube containing metallic powder at the
receiving-station, choking-coils connected to the powder, an earth
connection to the powder and an insulated conductor also connected
herewith, and a circuit through the coils and powder, substantially
as and for the purpose described.
11. The combination, in an apparatus for communicating electri-
cal signals, of a producer of Hertz oscillations, electrically connected
with a signaling instrument at the transmitting-station, a tube con-
taining metallic powder at the receiving-station, choking-coils con-
nected to the powder, a circuit through the powder, and means,
controlled by said circuit, for shaking the powder, substantially as
and for the purpose described.
216
APPENDIX III.
12. The combination, in an apparatus for communicating electri-
cal signals, of a producer of Hertz oscillations, electrically connected
with a signaling instrument at the transmitting-station, a tube con-
taining metallic powder at the receiving-station, choking-coils and
earth connection through condensers connected to the powder, and
means, controlled by the circuit, for shaking the powder, substantially
as and for the purpose described.
13. The combination, in an apparatus for communicating electri-
cal signals, of a producer of Hertz oscillations, electrically connected
with a signaling instrument at the transmitting-station, a tube con-
taining metallic powder at the receiving-station, electrically-tuned
devices connected to the powder, a circuit through the powder, and
means, controlled by said circuit, for shaking the powder, substan-
tially as and for the purpose described.
14. In a receiver for electrical oscillations, the combination of an
imperfect electrical contact, tuned metallic plates connected to it, a
circuit through the contact, and means, controlled by the circuit, for
shaking the contact.
15. In a receiver for electrical oscillations, the combination of an
imperfect electrical contact, choking-coils connected to the contact, a
circuit through the coils and contact, and means, controlled by the
circuit, for shaking the contact.
16. In a receiver for electrical oscillations, the combination of an
imperfect electrical contact, tuned metallic plates and choking-coils
connected to the contact, a circuit through the same, and means, con-
trolled by the circuit, for shaking the contact.
17. In a receiver for electrical oscillations, the combination of
a tube containing a mixture of metallic powders, a circuit through
the same, and means, controlled by the circuit, for shaking the
powder.
18. In a receiver for electrical oscillations, the combination of a
tube containing a metallic powder or powders and mercury, a circuit
through the same, and means, controlled by the circuit, for shaking
the powder.
19. In a receiver for electrical oscillations, the combination of a
tube, metallic plugs in the tube, metallic powder between the plugs,
metallic plates connected to the plugs, choking-coils connected to the
plugs, and a circuit through the coils, plugs, and powder.
20. In a receiver for electrical oscillations, the combination of a
tube, metallic plugs in the tube, metallic powder between the plugs,
metallic plates connected to the plugs, choking-coils connected to the
APPENDIX III.
217
plugs, a circuit through the coils, plugs, and powder, and means,
controlled by the circuit, for shaking the powder.
21. In a receiver for electrical oscillations, the combination of a
tube, metallic plugs in the tube, a mixture of metallic powder and
mercury between the plugs, choking-coils connected to the plugs, a
circuit through the coils, plugs, and powder, and means, controlled
by the circuit, for shaking the powder.
22. In a receiver for electrical oscillations, the combination of an
imperfect electrical contact, choking-coils connected to the contact,
a circuit through the coils and contact, a relay controlled by the cir-
cuit, and means, controlled by the relay, for shaking the contact.
23. In a receiver for electrical oscillations, the combination of an
imperfect electrical contact, a circuit through the contact, an electric
trembler shaking the contact, and means for preventing the self-
induction of the trembler from affecting the contact.
24. The combination of a transmitter capable of producing electri-
cal oscillations or rays of definite character at the will of the operator,
and a receiver located at a distance and having a conductor tuned to re-
spond to such oscillations, a variable-resistance medium in circuit with
the conductor, whose resistance is altered by the received oscillations,
means, controlled by the received oscillations, for restoring the re-
sistance medium to its normal condition after the reception of such
oscillations, and means for rendering the received oscillations mani-
fest.
In witness whereof I have hereunto signed my name, at 18 Finch
Lane, in the city of London, the 29th day of January, in the year
1901.
In presence of –
SAMUEL FLOOD PAGE,
GUGLIELMO MARCONI.
Hubert WILLOUGHBY CORBY.
APPENDIX IV.
REPRESENTATIVE CLAIMS RELATING
TO WIRELESS TRANSMISSION.
FROM THE UNITED STATES PATENTS OF NIKOLA
TESLA IN CHRONOLOGICAL ORDER
OF FILING APPLICATIONS.
U. S. Patent No. 462,418, Nov. 3, 1891; filed Feb. 4, 1891.
I. The method of electrical conversion here described, which
consists in discharging a condenser or conductor possessing capa-
city and maintaining a succession of intermittent or oscillating dis-
ruptive discharges of said conductor into a working circuit con-
taining translating devices.
2. In a system of electrical conversion, the combination of a
generator or source of electricity and a line or generating circuit
containing a condenser or possessing capacity, and a working cir-
cuit operatively connected with the generating circuit through one
or more air-gaps or breaks in the conducting medium, the electri-
cal conditions being so adjusted that an intermittent or oscillating
disruptive discharge from the generating into the working circuit
will be maintained, as set forth.
U. S. Patent No. 454,622, June 23, 1891; filed April 25, 1891.
2. The method of producing an electric current for practical
application, such as for electric lighting, which consists in gener-
ating or producing a current of enormous frequency and inducing
by such current in a working circuit, or that to which the light-
ing devices are connected, a current of corresponding frequency
and excessively high potential, as set forth.
3.
The method of producing an electric current for practical
1 See page 114.
218
APPENDIX IV.
219
application, such as for electric lighting, which consists in charging.
a condenser by a given current, maintaining an intermittent or
oscillatory discharge of said condenser through or into a primary
circuit, and producing thereby in a secondary working-circuit in
inductive relation to the primary very high potentials, as set forth.
U. S. Patent No. 568,176, Sept. 22, 1896; filed April 22, 1896.
1. The apparatus herein described for converting direct currents
into currents of high frequency, comprising in combination a cir-
cuit of high self-induction, a circuit controller adapted to make
and break such circuit, a condenser into which the said circuit
discharges when interrupted, and a transformer through the pri-
mary of which the condenser discharges as set forth.
2. The combination of a source of direct current and a circuit
therefrom, choking-coils in said circuit, means for making and
breaking the circuit through said coils, a condenser around the
point of interruption in the said circuit and a transformer having
its primary in circuit with the condenser as set forth.
3. The combination with a circuit of high self-induction and
means for making and breaking the same, of a condenser around
the point of interruption in the said circuit, and a transformer the
primary of which is in the condenser-circuit as described.
U. S. Patent No. 568,178, Sept, 22, 1896; filed June 20, 1896.
1. The method of regulating the energy delivered by a system
for the production of high-frequency currents and comprising a
supply circuit, a condenser, a circuit through which the same dis-
charges and means for controlling the charging of the condenser
by the supply circuit and the discharging of the same, the said
method consisting in varying the relations of the frequencies of
the impulses in the circuits comprising the system, as set forth.
2. The method of regulating the energy delivered by a system
for the production of high frequency currents comprising a supply-
circuit of direct currents, a condenser adapted to be charged by
the supply-circuit and to discharge through another circuit, the
said method consisting in varying the frequency of the impulses
of current from the supply circuit, as set forth.
3. The method of producing and regulating electric currents of
high frequency which consists in directing impulses from a supply
circuit into a charging circuit of high self-induction, charging a
220
APPENDIX IV.
condenser by the accumulated energy of such charging circuit,
discharging the condenser through a circuit of low self-induction,
raising the potential of the condenser discharge and varying the
relations of the frequencies of the electrical impulses in the said
circuits, as herein set forth.
U. S. Patent No. 568,179, Sept. 22, 1896; filed July 6, 1896.
I. The method herein described of producing electric currents
of high frequency, which consists in generating an alternating cur-
rent, charging a condenser thereby during determinate intervals of
each wave of said current, and discharging the condenser through
a circuit of low self-induction, as herein set forth.
4. The combination with a source of alternating current, a
charging-circuit in which the energy of said current is stored, a
circuit-controller adapted to interrupt the charging-circuit at de-
terminate points in each wave, a condenser for receiving on the
interruption of the charging circuit, the energy accumulated therein,
and a circuit into which the condenser discharges when connected
therewith by the circuit-controller, as set forth.
U. S. Patent No. 568,180, Sept. 22, 1896; filed July 9, 1896.
1. The combination with a source of current, of a condenser
adapted to be charged thereby, a circuit into which the condenser
discharges in a series of rapid impulses, and a circuit controller
for effecting the charging and discharge of said condenser, com-
posed of conductors movable into and out of proximity with each
other, whereby a spark may be maintained between them and the
circuit closed thereby during determined intervals, as set forth.
·
U. S. Patent No. 577,670, Feb. 23, 1897; filed Sept. 3, 1896.
I. The combination with a source of electric energy, of a plu-
rality of condensers and a discharge circuit therefor, a motive de-
vice and a circuit-controller operated thereby and adapted to
direct the energy of the source into the condensers and connect
them with the discharge-circuit successively and in alternation, as
set forth.
U. S. Patent No. 577,671, Feb. 23, 1897; filed Nov. 5, 1896.
1. The improvement in the manufacture of electrical devices
such as condensers, which consists in inclosing the device in an
APPENDIX IV.
221
air-tight receptacle, exhausting the air from the receptacle, intro-
ducing into a vessel containing the device an insulating material-
rendered fluid by heat, and then when said material has perme-
ated the interstices of the said device, subjecting the whole to
pressure, and maintaining such pressure until the material has
cooled and solidified, as set forth.
U. S. Patent No. 645,576, March, 20, 1900; filed Sept. 2, 1897.
2. The method herein before described of transmitting electrical
energy, which consists in producing at a generating station a very
high electrical pressure, conducting the current caused thereby to
earth and to a terminal at an elevation at which the atmosphere
serves as a conductor therefor, and collecting the current by a
second elevated terminal at a distance from the first.
5. The method herein before described of transmitting electri-
cal energy through the natural media, which consists in producing
between the earth and a generator-terminal elevated above the
same, at a generating station, electrical impulses of a sufficiently-
high electromotive force to render elevated air strata conducting,
causing thereby current impulses to pass, by conduction, through
the air strata, and collecting or receiving at a point distant from the
generating station, the energy of the current impulses by means of
a circuit synchronized with the impulses.
U. S. Patent No. 649,621, May 15, 1900; filed Sept. 2, 1897.
3. The combination with a transmitting instrument comprising
a transformer having its secondary connected to ground and to an
elevated terminal respectively, and means for impressing electri-
cal oscillations upon its primary, of a receiving instrument com-
prising a transformer having its primary similarly connected to
ground and to an elevated terminal, and a translating device con-
nected with its secondary, the capacity and inductance of the two
transformers having such values as to secure synchronism with
the impressed oscillations, as set forth.
5. The combination with a transmitting coil or conductor con-
nected to ground and an elevated terminal respectively, and means
for producing electrical currents or oscillations in the same, of a
receiving coil or conductor similarly connected to ground and to
an elevated terminal and synchronized with the transmitting coil
or conductor, as set forth.
222
APPENDIX IV.
8. The combination with a transmitting coil or conductor con-
nected to ground and to an elevated terminal respectively, and
adapted to cause the propagation of currents or oscillations by
conduction through the natural medium, of a receiving-circuit sim-
ilarly connected to ground and to an elevated terminal, and of a
capacity and inductance such that its period of vibration is the
same as that of the transmitter, as set forth.
9. The transmitting or receiving circuit herein described, con-
nected to ground and an elevated terminal respectively, and ar-
ranged in such manner that the elevated terminal is charged to
the maximum potential developed in the circuit, as set forth.
10. The combination with a transmitting coil or conductor con-
nected to ground and to an elevated terminal respectively of a
receiving-circuit having a period of vibration corresponding to that
of the transmitting circuit and similarly connected to ground and
to an elevated terminal and so arranged that the elevated terminal
is charged to the highest potential developed in the circuit, as set
forth.
U. S. Patent No. 611,719, Oct. 4, 1898; filed Dec. 10, 1897.
2. The combination with a closed receptacle, of a circuit-con-
troller contained therein and means for maintaining within said
receptacle an inert atmosphere under pressure.
4. The combination with a circuit controlling mechanism, one
part or terminal of which is a conducting fluid, such as mercury,
of a receptacle inclosing the same and means for maintaining an
inert gas under pressure in the receptacle.
U. S. Patent No. 613,809, Nov. 8, 1898; filed July 1, 1898.
7. The combination with a source of electrical waves or dis-
turbances and means for starting and stopping the same, of a ves-
sel or vehicle, propelling and steering mechanism carried thereby,
a circuit containing or connected with means for controlling the
operation of said mechanism and adjusted or rendered sensitive
to the waves or disturbances of the source, as set forth.
U. S. Patent No. 685,953, Nov. 5, 1901; filed June 24, 1899.
2 The method of transmitting and utilizing electrical energy
herein described, which consists in producing electrical disturb-
ances or effects capable of being transmitted to a distance through
APPENDIX IV.
223
the natural media, charging a condenser at a distant receiving
station with energy derived from such effects or disturbances, and
using for periods of time, predetermined as to succession and dura-
tion, the potential energy so obtained to operate a receiving device.
7. The method herein described of producing arbitrarily varied
or intermitted electrical disturbances or effects, transmitting such
disturbances or effects to a distant receiving station, establishing
thereby a flow of electrical energy in a circuit at such station, se-
lecting or directing the impulses in said circuit so as to render
them suitable for charging a condenser, charging a condenser with
the impulses so selected or directed, and discharging the accumu-
lated potential energy so obtained into, or through a receiving
device.
U. S. Patent No. 685,954, Nov. 5, 1901; filed Aug. 1, 1899.
4. The method herein before described of utilizing effects or dis-
turbances transmitted through the natural media, which consists
in controlling, by means of such effects or disturbances, the charg-
ing of an electrical condenser from an independent source, and
discharging the stored energy through a receiving circuit.
U. S. Patent No. 685,012, Oct. 22, 1901; filed March 21, 1900.
6. In a system for the transmission of energy, a series of trans-
mitting and receiving circuits adapted to vibrate freely, in combi-
nation with means for artificially maintaining the same at a low
temperature, as set forth.
U. S. Patent 725,605, April 14, 1903; filed July 16, 1900.
1. In a system for the transmission of electrical energy, the
combination with means for producing two or more distinctive
kinds of disturbances or impulses, of receiving circuits, each tuned
to respond to the waves or impulses of one kind only, and a re-
ceiving device dependent for operation upon the conjoint action.
of the several receiving circuits, as set forth.
7. The combination with a plurality of transmitter elements,
each adapted to produce a series of impulses or disturbances of a
distinctive character, and means for controlling and adjusting the
same, of a receiver having a plurality of sensitive circuits each
tuned so as to be affected by one of the series of impulses only,
and dependent for operation upon the conjoint action of all of said
circuits, as set forth.
224
APPENDIX IV.
8. The combination with a transmitter adapted to produce a
series of electrical impulses or disturbances of distinctive character
and in a given order of succession, of a receiving apparatus com-
prising tuned circuits responding to such impulses in a correspond-
ing order, and dependent for operation upon the conjoint action
of said elements, as set forth.
12. In a system for the transmission of electrical energy, the
combination with a transmitting apparatus comprising a trans-
former and means for impressing upon the secondary element of
the same oscillations or impulses of different character, of a re-
ceiving apparatus comprising a plurality of circuits each tuned to
the impulses of one kind emitted by the secondary of the trans-
mitting transformer, and a receiver dependent for operation upon
the conjoint action of the receiving circuits, as set forth.
13. In a system for the transmission of electrical energy, the
combination with a transmitting apparatus comprising a trans-
former and means for impressing upon the secondary elements of
the same oscillations or impulses of different periodicities and in
a given order of succession, of a receiving apparatus comprising a
plurality of circuits each tuned to respond to the transmitted im-
pulses of one period, and a receiver dependent for operation upon
the conjoint action of the receiving circuits, as set forth.
16. In a system for the transmission of electrical energy, the
combination with a transmitter adapted to produce electrical waves
or oscillations varying in character in a predetermined order, of a
receiving instrument responsive to said oscillations and dependent
for operation upon the action thereof in a corresponding order, as
set forth.
U. S. Patent 723,188, March 17, 1903; filed July 16, 1900.
1. The method of operating distant receivers which consists in
producing and transmitting a plurality of kinds or classes of elec-
trical impulses or disturbances, actuating by the impulses or dis-
turbances of each kind or class one of a plurality of circuits tuned
to respond to impulses of such kind or class and operating or con-
trolling the operation of a receiver by the conjoint action of two
or more of said circuits, as set forth.
3. The method of signaling which consists in producing a plu-
rality of series of impulses or disturbances differing from each
other in character and order of succession, exciting by the im-
pulses of each series one of a plurality of receiving-circuits tuned
APPENDIX IV.
225
....
:
to respond exclusively thereto and controlling by the conjoint.
action of such circuits a local circuit, as set forth.
9. The improvement in the art of transmitting electrical energy
which consists in operating or controlling a receiving mechanism
by a series or group of electrical impulses of different periodici-
ties and of a predetermined order of succession.
U. S. Patent No. 11,865; a reissue Oct. 23, 1900. Original filed
Aug. 14, 1900.
1. The method of insulating electric conductors herein described
which consists in imparting insulating properties to material sur-
rounding or contiguous to the said conductors by the continued
action thereon of a gaseous cooling agent, as set forth.
U. S. Patent No. 685,958, Nov. 5, 1901; filed March 21, 1901.
I. The method of utilizing radiant energy, which consists in
charging one of the armatures of a condenser by rays or radia-
tions, and the other armature by independent means, and dis-
charging the condenser through a suitable receiver, as set forth.
INDEX.
Achievement (section of this book),
II.
Anti-coherers, 154-157.
Apparatus (division of this work)
(Part IV.), 143.
Appendix, 190.
Argentina and Italy, Wireless Com-
munication between, projected,
22.
Ayrton, Professor, Prophecy, 3.
Barthélemy, Abbé, Prophetic Writ
ing, 2.
Branly, Prof.
Hertzian-wave-coherer, 17, 153.
Inventor of Filings tube Coherer,
93, 98.
Portrait, opp. 91.
Tripod Coherer, 153.
Cables, Ocean.
Cost, 128.
Earnings, 127.
Mileage, gross, 128.
Number, 128.
Transmitting speed, 128.
Chemical Telegraphy (by Wire),
136.
Description and Diagram, 137.
Speed of Transmission, 138.
Circuits, Wireless Telegraph, 26.
Coherers.
Descriptions, 152, 154.
Collins, A. F., Wireless Telephony,
88.
Comparative Merits of Wire and
Space Telegraphy (a division
of this work), 125.
Condensers.
Description, 182.
Function in Ruhmkorff Coil, 147.
Marconi's Condenser, 183.
Tesla's Condenser, 183.
Condensers, Inductance Coils and
Keys (a section of this book), 182.
Crookes, Sir William, 3.
Davy, Sir Humphry, 4, 5.
DeForest System, 87.
DeForest Responder, 156, 157.
DeForest Transmitter, 149.
Descriptive (a section of this book),
38.
Discovery (a section of this book), 4.
Dolbear, Prof. Amos E.
Application for patent, 1882, 15.
Mentioned, 96.
U.S. Patent (in full), 191.
Edison, Patent of 1891, 96.
Singing Telephone, 13, 14.
Signalling to moving train, 1885,
15.
Equipment, Wireless, Cost of, 128.
Explanatory (a section of this book),
24.
226
INDEX.
227
Faraday, Michael, 4, 6.
Feddersen Experimentalist, 4, 7, 93.
Fessenden, Prof. Reginald H.
Heat Receiver, 166, 167.
Interview with, 69.
Inventive Record, 114-122.
Prediction of Overland Trans-
mission, 130.
Specialist for U. S. Weather
Bureau, 66.
Transmitters, 147–151.
Wave-Responsive-Devices, 166–
167.
Wireless Telegraph Apparatus,
Tests, 67.
Gale, L. D., Experiments for Pro-
fessor Morse, 12.
Galileo's prediction, 1, 2.
Guarini, Foresio.
Suggestion for
Multiplexing
Ocean Cables with Coherers,
130.
Wireless Telegraph Automatic
Repeaters, 88, 130.
Heat Receiver, Fessenden, 167.
Henry, Joseph, 4, 6, 7, 11.
Helmholtz, Hermann, 4, 6, 7.
Hertz, Heinrich.
Anti-coherer, 154.
Career as physicist, 8, 9.
Crowning achievement, 1
15.
Discoveries, 97.
Mentioned, 93.
Portrait, opp. 91.
Pupil of Helmholtz, 4.
Holy Writ, Quotation from, 1.
Huyghens, Dutch Philosopher,
Originator of Undulatory The-
ory of Light, 4, 5, 7.
Hysteresis defined, 164.
Hysteresis, Detector of, Marconi
165.
Inductance-Coils, 184.
Inventors and inventions (a division
of this book) (Part II.), 91.
Inventions in Wireless Telegraphy.
Summary, 123.
Italy and Argentina, Wireless Tele-
graph projected between, 22.
Kelvin, Lord, Physicist, 4, 7.
Keys, Transmitting, Fessenden and
Marconi, 186-189. .
Lesarge, Pioneer in Electric Teleg-
raphy, II.
Light, Theories of, 5, 7.
Localization of Wireless Telegraph
Signals, 33.
Lindsay, James Bowman, 2, 12, 13.
Lodge, Dr. Oliver Joseph.
Biographical, 15.
Discoverer, 4.
Early Experiments with Coherer,
17.
Patents, 99, 100, 101, 194.
Portrait, opp. 91.
Signalling Instrument of 1889, 16.
System Described, 63.
System, Diagram of, 64.
Magnetic Radio Receivers, 162, 166.
Mail Service, Speed of Transmis
sion, 132.
Marconi.
Biographical, 18.
Patents, 91, 101-113, 200-217.
Maxwell, James, Clerk, 4-8, 93, 123.
Portrait, opp. 91.
Methods, Old vs. New, 121.
228
Micro Radiophones, 157–162.
Morse, Prof. S. F. B., 11, 12.
Muirhead, Alexander, 3.
Newton, Sir Isaac, 5.
Nomenclature, 143.
Non-tapping Coherers.
INDEX.
See Micro Radiophones and
Magnetic Radio Receivers.
Onesti, Calzecchi, 15, 97, 152.
Overland Transmission, 87.
Patents, Validity of Report of Com
missioner for 1892, 95.
See also Dolbear, Ehret, Fessen-
den, Lodge, Marconi.
Poldhu Station, 18-21, 176. See
also Frontispiece.
Pope, Franklin Leonard, 92, 93.
Popoff, Count, 17.
Apparatus of April, 1895. Dia-
gram and Description, 94-95,
98-99.
Micro Radiophone of 1900, 157.
Practicability, Commercial, of Wire-
less Telegraphy, 89.
Preece, Sir Wm. H., Early Experi-
ments in Wireless Telegraphy,
14, 15.
Prophecy (section of this book), 1.
Pupin, Dr. M. I., 129, 131.
Patent, 118.
Resonance, Electrical, Theory, 27.
Resonance, Electrical, Practice, 31.
Responder, DeForest, 155.
Ruhmkorff Coil, Diagram and De-
scription, 145-147.
Shields for Wireless Telegraph Re-
ceivers, 179-181.
Signals, Telegraphic, Illustration of,
Frontispiece and 25.
Slaby, Dr., of Germany, 56–62.
Speeds of Signal Propagation by
Wireless and by Cables Com
pared, 36.
7
Steinheil, Early Telegrapher, 11.
Strada, Prophecy of, A.D. 1617, 2.
Telegraph, Electric, Record of, 11.
Overland, Cost of, 128.
Telephony, Wireless, 88.
Terms, in Wireless Telegraphy.
See Nomenclature.
Tesla.
Biographical, 38.
Concatenated Tuned Circuits,. 48.
Conversion, Electrical, by Con-
denser Discharges, 45.
Filings, Tube Coherer, 153.
Long Distance Power
mission, 39–43•
Long Island Plant, opp. 53.
Mentioned, 4.
Trans-
Patent Claims, 114, 218-225.
Portrait, opp. 43.
Prediction of 1893, 3.
Telautomata, 44.
Transmitter of High Potentials,
42.
Sun Motors, 53.
Transmission (Transatlantic), Fron-
tispiece and 18-21.
Transmission (Wireless), not affect-
ed by distance, 128.
Tuning (Electrical), 27.
(See also Resonance.)
Tuned Circuits, 48.
United States Government.
Wireless Stations, 66.
..
INDEX.
229
Practice Tests, 67.
Proposals for Wireless Tele-
graphs, 68.
Work of Weather Bureau, 66.
Wave-Gates (section of this book),
168.
Wave-Responsive-Devices (section
of this book), 152.
Western Union Telegraph Com
pany's Controversy with Dr.
Pupin, 131.
Wire Telegraphy.
Types and Apparatus, 133.
Young, Dr. Thomas, 5.
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