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ALTHOUGH Mr. Edison has taken no
active part in the development of the more modern
wireless telegraphy, and his name has not
occurred in connection therewith, the underlying
phenomena had been noted by him many years in
advance of the art, as will presently be
explained. The authors believe that this
explanation will reveal a status of Edison in
relation to the subject that has thus far been
unknown to the public.
While the term "wireless telegraphy," as now
applied to the modern method of electrical
communication between distant points without
intervening conductors, is self-explanatory,
it was also applicable, strictly speaking, to
the previous art of telegraphing to and from
moving trains, and between points not greatly
remote from each other, and not connected
together with wires.
The latter system (described in Chapter
XXIII and in a succeeding article of this
Appendix) was based upon the phenomena of
electromagnetic or electrostatic induction
between conductors separated by more or less
space, whereby electric impulses of relatively
low potential and low frequency set up in. one
conductor were transmitted inductively across the
air to another conductor, and there received
through the medium of appropriate instruments
connected therewith.
As distinguished from this system, however,
modern wireless telegraphy--so called--has
its basis in the utilization of electric or ether
waves in free space, such waves being set up by
electric oscillations, or surgings, of
comparatively high potential and high frequency,
produced by the operation of suitable electrical
apparatus. Broadly speaking, these
oscillations arise from disruptive discharges of
an induction coil, or other form of oscillator,
across an air-gap, and their character is
controlled by the manipulation of a special type
of circuit-breaking key, by means of which long
and short discharges are produced. The electric
or etheric waves thereby set up are detected and
received by another special form of apparatus
more or less distant, without any intervening
wires or conductors.
In November, 1875, Edison, while
experimenting in his Newark laboratory,
discovered a new manifestation of electricity
through mysterious sparks which could be produced
under conditions unknown up to that time.
Recognizing at once the absolutely unique
character of the phenomena, he continued his
investigations enthusiastically over two mouths,
finally arriving at a correct conclusion as to
the oscillatory nature of the hitherto unknown
manifestations. Strange to say, however, the
true import and practical applicability of these
phenomena did not occur to his mind. Indeed,
it was not until more than TWELVE
YEARS AFTERWARD, in 1887,
upon the publication of the notable work of
Prof. H. Hertz proving the existence of
electric waves in free space, that Edison
realized the fact that the fundamental principle
of aerial telegraphy had been within his grasp in
the winter of 1875; for although the work of
Hertz was more profound and mathematical than
that of Edison, the principle involved and the
phenomena observed were practically
identical--in fact, it may be remarked that
some of the methods and experimental apparatus
were quite similar, especially the "dark box"
with micrometer adjustment, used by both in
observing the spark.[25]
There is not the slightest intention on the part
of the authors to detract in the least degree
from the brilliant work of Hertz, but, on the
contrary, to ascribe to him the honor that is
his due in having given mathematical direction
and certainty to so important a discovery. The
adaptation of the principles thus elucidated and
the subsequent development of the present
wonderful art by Marconi, Branly, Lodge,
Slaby, and others are now too well known to
call for further remark at this place.
Strange to say, that although Edison's early
experiments in "etheric force" called forth
extensive comment and discussion in the public
prints of the period, they seemed to have been
generally overlooked when the work of Hertz was
published. At a meeting of the Institution of
Electrical Engineers, held in London on May
16, 1889, at which there was a discussion
on the celebrated paper of Prof. (Sir)
Oliver Lodge on "Lightning Conductors,"
however; the chairman, Sir William Thomson
(Lord Kelvin), made the following remarks:
"We all know how Faraday made himself a cage
six feet in diameter, hung it up in mid-air in
the theatre of the Royal Institution, went
into it, and, as he said, lived in it and made
experiments. It was a cage with tin-foil
hanging all round it; it was not a complete
metallic enclosing shell. Faraday had a
powerful machine working in the neighborhood,
giving all varieties of gradual working-up and
discharges by `impulsive rush'; and whether it
was a sudden discharge of ordinary insulated
conductors, or of Leyden jars in the
neighborhood outside the cage, or
electrification and discharge of the cage
itself, he saw no effects on his most delicate
gold-leaf electroscopes in the interior. His
attention was not directed to look for Hertz
sparks, or probably he might have found them in
the interior. Edison seems to have noticed
something of the kind in what he called the
etheric force. His name `etheric' may,
thirteen years ago, have seemed to many people
absurd. But now we are all beginning to call
these inductive phenomena `etheric.' "
With these preliminary observations, let us now
glance briefly at Edison's laboratory
experiments, of which mention has been made.
Oh the first manifestation of the unusual
phenomena in November, 1875, Edison's
keenness of perception led him at once to believe
that he had discovered a new force. Indeed,
the earliest entry of this discovery in the
laboratory note-book bore that caption. After
a few days of further experiment and
observation, however, he changed it to
"Etheric Force," and the further records
thereof (all in Mr. Batchelor's
handwriting) were under that heading.
The publication of Edison's discovery created
considerable attention at the time, calling
forth a storm of general ridicule and
incredulity. But a few scientific men of the
period, whose experimental methods were careful
and exact, corroborated his deductions after
obtaining similar phenomena by repeating his
experiments with intelligent precision. Among
these was the late Dr. George M. Beard, a
noted physicist, who entered enthusiastically
into the investigation, and, in addition to a
great deal of independent experiment, spent much
time with Edison at his laboratory. Doctor
Beard wrote a treatise of some length on the
subject, in which he concurred with Edison's
deduction that the phenomena were the
manifestation of oscillations, or rapidly
reversing waves of electricity, which did not
respond to the usual tests. Edison had observed
the tendency of this force to diffuse itself in
various directions through the air and through
matter, hence the name "Etheric" that he had
provisionally applied to it.
Edison's laboratory notes on this striking
investigation are fascinating and voluminous,
but cannot be reproduced in full for lack of
space. In view of the later practical
application of the principles involved,
however, the reader will probably be interested
in perusing a few extracts therefrom as
illustrated by facsimiles of the original
sketches from the laboratory note-book.
As the full significance of the experiments
shown by these extracts may not be apparent to a
lay reader, it may be stated by way of premise
that, ordinarily, a current only follows a
closed circuit. An electric bell or electric
light is a familiar instance of this rule.
There is in each case an open (wire) circuit
which is closed by pressing the button or turning
the switch, thus making a complete and
uninterrupted path in which the current may
travel and do its work. Until the time of
Edison's investigations of 1875, now under
consideration, electricity had never been known
to manifest itself except through a closed
circuit. But, as the reader will see from the
following excerpts, Edison discovered a
hitherto unknown phenomenon--namely, that
under certain conditions the rule would be
reversed and electricity would pass through space
and through matter entirely unconnected with its
point of origin. In other words, he had found
the forerunner of wireless telegraphy. Had he
then realized the full import of his discovery,
all he needed was to increase the strength of the
waves and to provide a very sensitive detector,
like the coherer, in order to have anticipated
the principal developments that came many years
afterward. With these explanatory
observations, we will now turn to the excerpts
referred to, which are as follows:
"November 22, 1875. New
Force.--In experimenting with a vibrator
magnet consisting of a bar of Stubb's steel
fastened at one end and made to vibrate by means
of a magnet, we noticed a spark coming from the
cores of the magnet. This we have noticed often
in relays, in stock- printers, when there were
a little iron filings between the armature and
core, and more often in our new electric pen,
and we have always come to the conclusion that it
was caused by strong induction. But when we
noticed it on this vibrator it seemed so strong
that it struck us forcibly there might be
something more than induction. We now found
that if we touched any metallic part of the
vibrator or magnet we got the spark. The larger
the body of iron touched to the vibrator the
larger the spark. We now connected a wire to
X, the end of the vibrating rod, and we found
we could get a spark from it by touching a piece
of iron to it, and one of the most curious
phenomena is that if you turn the wire around on
itself and let the point of the wire touch any
other portion of itself you get a spark. By
connecting X to the gas-pipe we drew sparks
from the gas-pipes in any part of the room by
drawing an iron wire over the brass jet of the
cock. This is simply wonderful, and a good
proof that the cause of the spark is a TRUE
UNKNOWN FORCE."
"November 23, 1815. New
Force.--The following very curious result
was obtained with it. The vibrator shown in
Fig. 1 and battery were placed on insulated
stands; and a wire connected to X (tried both
copper and iron) carried over to the stove about
twenty feet distant. When the end of the wire
was rubbed on the stove it gave out splendid
sparks. When permanently connected to the
stove, sparks could be drawn from the stove by a
piece of wire held in the hand. The point X of
vibrator was now connected to the gas-pipe and
still the sparks could be drawn from the
stove."
. . . . . . . . .
"Put a coil of wire over the end of rod X and
passed the ends of spool through galvanometer
without affecting it in any way. Tried a
6-ohm spool add a 200-ohm. We now tried
all the metals, touching each one in turn to the
point X." [Here follows a list of metals and
the character of spark obtained with each.]
. . . . . . . . .
"By increasing the battery from eight to twelve
cells we get a spark when the vibrating magnet is
shunted with 3 ohms. Cannot taste the least
shock at B, yet between carbon points the spark
is very vivid. As will be seen, X has no
connection with anything. With a glass rod four
feet long, well rubbed with a piece of silk over
a hot stove, with a piece of battery carbon
secured to one end, we received vivid sparks
into the carbon when the other end was held in
the hand with the handkerchief, yet the
galvanometer, chemical paper, the sense of
shock in the tongue, and a gold-leaf
electroscope which would diverge at two feet from
a half- inch spark plate-glass machine were not
affected in the least by it.
"A piece of coal held to the wire showed faint
sparks.
"We had a box made thus: whereby two points
could be brought together within a dark box
provided with an eyepiece. The points were
iron, and we found the sparks were very
irregular. After testing some time two
lead-pencils found more regular and very much
more vivid. We then substituted the graphite
points instead of iron."[26]
. . . . . . . . .
After recording a considerable number of other
experiments, the laboratory notes go on to
state:
"November 30, 1875. Etheric
Force.--We found the addition of battery to
the Stubb's wire vibrator greatly increased the
volume of spark. Several persons could obtain
sparks from the gas-pipes at once, each spark
being equal in volume and brilliancy to the spark
drawn by a single person.... Edison now
grasped the (gas) pipe, and with the other
hand holding a piece of metal, he touched
several other metallic substances, obtained
sparks, showing that the force passed through
his body."
. . . . . . . . .
"December 3, 1875. Etheric
Force.--Charley Edison hung to the
gas-pipe with feet above the floor, and with a
knife got a spark from the pipe he was hanging
on. We now took the wire from the vibrator in
one hand and stood on a block of paraffin
eighteen inches square and six inches thick;
holding a knife in the other hand, we drew
sparks from the stove-pipe. We now tried the
crucial test of passing the etheric current
through the sciatic nerve of a frog just killed.
Previous to trying, we tested its sensibility
by the current from a single Bunsen cell. We
put in resistance up to 500,000 ohms, and
the twitching was still perceptible. We tried
the induced current from our induction coil
having one cell on primary,, the spark jumping
about one-fiftieth of an inch, the terminal of
the secondary connected to the frog and it
straightened out with violence. We arranged
frog's legs to pass etheric force through. We
placed legs on an inverted beaker, and held the
two ends of the wires on glass rods eight inches
long. On connecting one to the sciatic nerve
and the other to the fleshy part of the leg no
movement could be discerned, although brilliant
sparks could be ob- tained on the graphite
points when the frog was in circuit. Doctor
Beard was present when this was tried."
. . . . . . . . .
"December 5, 1875. Etheric
Force.--Three persons grasping hands and
standing upon blocks of paraffin twelve inches
square and six thick drew sparks from the
adjoining stove when another person touched the
sounder with any piece of metal.... A
galvanoscopic frog giving contractions with one
cell through two water rheostats was then placed
in circuit. When the wires from the vibrator
and the gas- pipe were connected, slight
contractions were noted, sometimes very plain
and marked, showing the apparent presence of
electricity, which from the high insulation
seemed improbable. Doctor Beard, who was
present, inferred from the way the leg
contracted that it moved on both opening and
closing the circuit. To test this we
disconnected the wire between the frog and
battery, and placed, instead of a vibrating
sounder, a simple Morse key and a sounder
taking the `etheric' from armature. The spark
was now tested in dark box and found to be very
strong. It was then connected to the nerves of
the frog, BUT NO MOVEMENT OF
ANY KIND COULD BE DETECTED
UPON WORKING THE KEY, although
the brilliancy and power of the spark were
undiminished. The thought then occurred to
Edison that the movement of the frog was due to
mechanical vibrations from the vibrator (which
gives probably two hundred and fifty vibrations
per second), passing through the wires and
irritating the sensitive nerves of the frog.
Upon disconnecting the battery wires and holding
a tuning-fork giving three hundred and
twenty-six vibrations per second to the base of
the sounder, the vibrations over the wire made
the frog contract nearly every time.... The
contraction of the frog's legs may with
considerable safety be said to be caused by these
mechanical vibrations being transmitted through
the conducting wires."
Edison thought that the longitudinal vibrations
caused by the sounder produced a more marked
effect, and proceeded to try out his theory.
The very next entry in the laboratory note-book
bears the same date as the above (December 5,
1875), and is entitled "Longitudinal
Vibrations," and reads as follows:
"We took a long iron wire one-sixteenth of an
inch in diameter and rubbed it lengthways with a
piece of leather with resin on for about three
feet, backward and forward. About ten feet
away we applied the wire to the back of the neck
and it gives a horrible sensation, showing the
vibrations conducted through the wire."
. . . . . . . . .
The following experiment illustrates notably the
movement of the electric waves through free
space:
"December 26, 1875. Etheric
Force.--An experiment tried to-night gives
a curious result. A is a vibrator, B, C,
D, E are sheets of tin-foil hung on
insulating stands. The sheets are about twelve
by eight inches. B and C are twenty-six
inches apart, C and D forty-eight inches and
D and E twenty-six inches. B is connected to
the vibrator and E to point in dark box, the
other point to ground. We received sparks at
intervals, although insulated by such space."
With the above our extracts must close,
although we have given but a few of the
interesting experiments tried at the time. It
will be noticed, however, that these records
show much progression in a little over a month.
Just after the item last above extracted, the
Edison shop became greatly rushed on telegraphic
inventions, and not many months afterward came
the removal to Menlo Park; hence the
etheric-force investigations were side-tracked
for other matters deemed to be more important at
that time.
Doctor Beard in his previously mentioned
treatise refers, on page 27, to the views of
others who have repeated Edison's experiments
and observed the phenomena, and in a foot-note
says:
"Professor Houston, of Philadelphia, among
others, has repeated some of these physical
experiments, has adopted in full and after but a
partial study of the subject, the hypothesis of
rapidly reversed electricity as suggested in my
letter to the Tribune of December 8th, and
further claims priority of discovery, because he
observed the spark of this when experimenting
with a Ruhmkorff coil four years ago. To this
claim, if it be seriously entertained, the
obvious reply is that thousands of persons,
probably, had seen this spark before it was
DISCOVERED by Mr. Edison; it had
been seen by Professor Nipher, who supposed,
and still supposes, it is the spark of the extra
current; it has been seen by my friend, Prof.
J. E. Smith, who assumed, as he tells me,
without examination, that it was inductive
electricity breaking through bad insulation; it
had been seen, as has been stated, by Mr.
Edison many times before he thought it worthy of
study, it was undoubtedly seen by Professor
Houston, who, like so many others, failed to
even suspect its meaning and thus missed an
important discovery. The honor of a scientific
discovery belongs, not to him who first sees a
thing, but to him who first sees it with expert
eyes; not to him even who drops an original
suggestion, but to him who first makes, that
suggestion fruitful of results. If to see with
the eyes a phenomenon is to discover the law of
which that phenomenon is a part, then every
schoolboy who, before the time of Newton, ever
saw an apple fall, was a discoverer of the law
of gravitation...."
Edison took out only one patent on
long-distance telegraphy without wires. While
the principle involved therein (induction) was
not precisely analogous to the above, or to the
present system of wireless telegraphy, it was a
step forward in the progress of the art. The
application was filed May 23, 1885, at
the time he was working on induction telegraphy
(two years before the publication of the work of
Hertz), but the patent (No.
465,971) was not issued until December
29, 1891. In 1903 it was purchased
from him by the Marconi Wireless Telegraph
Company. Edison has always had a great
admiration for Marconi and his work, and a warm
friendship exists between the two men. During
the formative period of the Marconi Company
attempts were made to influence Edison to sell
this patent to an opposing concern, but his
regard for Marconi and belief in the fundamental
nature of his work were so strong that he refused
flatly, because in the hands of an enemy the
patent might be used inimically to Marconi's
interests.
Edison's ideas, as expressed in the
specifications of this patent, show very clearly
the close analogy of his system to that now in
vogue. As they were filed in the Patent
Office several years before the possibility of
wireless telegraphy was suspected, it will
undoubtedly be of interest to give the following
extract therefrom:
"I have discovered that if sufficient elevation
be obtained to overcome the curvature of the
earth's surface and to reduce to the minimum the
earth's absorption, electric telegraphing or
signalling between distant points can be carried
on by induction without the use of wires
connecting such distant points. This discovery
is especially applicable to telegraphing across
bodies of water, thus avoiding the use of
submarine cables, or for communicating between
vessels at sea, or between vessels at sea and
points on land, but it is also applicable to
electric communication between distant points on
land, it being necessary, however, on land
(with the exception of communication over open
prairie) to increase the elevation in order to
reduce to the minimum the induction-absorbing
effect of houses, trees, and elevations in the
land itself. At sea from an elevation of one
hundred feet I can communicate electrically a
great distance, and since this elevation or one
sufficiently high can be had by utilizing the
masts of ships, signals can be sent and received
between ships separated a considerable distance,
and by repeating the signals from ship to ship
communication can be established between points
at any distance apart or across the largest seas
and even oceans. The collision of ships in fogs
can be prevented by this character of
signalling, by the use of which, also, the
safety of a ship in approaching a dangerous coast
in foggy weather can be assured. In
communicating between points on land, poles of
great height can be used, or captive balloons.
At these elevated points, whether upon the
masts of ships, upon poles or balloons,
condensing surfaces of metal or other conductor
of electricity are located. Each condensing
surface is connected with earth by an electrical
conducting wire. On land this earth connection
would be one of usual character in telegraphy.
At sea the wire would run to one or more metal
plates on the bottom of the vessel, where the
earth connection would be made with the water.
The high-resistance secondary circuit of an
induction coil is located in circuit between the
condensing surface and the ground. The primary
circuit of the induction coil includes a battery
and a device for transmitting signals, which may
be a revolving circuit-breaker operated
continually by a motor of any suitable kind,
either electrical or mechanical, and a key
normally short-circuiting the circuit-breaker
or secondary coil. For receiving signals I
locate in said circuit between the condensing
surface and the ground a diaphragm sounder,
which is preferably one of my electromotograph
telephone receivers. The key normally
short-circuiting the revolving
circuit-breaker, no impulses are produced in
the induction coil until the key is depressed,
when a large number of impulses are produced in
the primary, and by means of the secondary
corresponding impulses or variations in tension
are produced at the elevated condensing surface,
producing thereat electrostatic impulses. These
electrostatic impulses are transmitted
inductively to the elevated condensing surface at
the distant point, and are made audible by the
electromotograph connected in the ground circuit
with such distant condensing surface."
The accompanying illustrations are reduced
facsimiles of the drawings attached to the above
patent, No. 465,971.
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