containing the elements was filled with sand, which was kept moist with
an electrolyte.]
XI
THE TELEPHONE, MOTOGRAPH, AND MICROPHONE
It is well known that to Mr. Alexander Graham Bell belongs the credit
for transmitting the articulate voice over an electric circuit by
talking against a diaphragm placed in front of an electromagnet.
But after Mr. Bell brought out the telephone Mr. Edison made some
remarkable improvements.
In the year 1875 Edison took up the study of harmonic telegraphs, in
addition to his other work, with the idea of developing a system of
multiple transmission by sending sound waves over an electric circuit.
One of the devices he then made is illustrated in an interesting
drawing on file at the Orange Laboratory, entitled "First Telephone
on Record." This device is described by Edison in a caveat filed in
the Patent Office January 14, 1876, a month before Bell filed his
application for patent.
Mr. Edison states, however, that while this device was crudely capable
of use as a magneto telephone, he did not invent it for transmitting
speech, but as an apparatus for analyzing the complex waves arising
from various sounds. He did not try the effects of sound waves produced
by the human voice until after Bell's discovery was announced, but then
found that this device was capable of use as a telephone.
This was a curious coincidence, but it must be understood that Mr.
Edison in his testimony and public utterances has always given Mr.
Bell full credit for the original discovery of transmitting articulate
speech over an electric circuit.
In order to understand the value of Edison's work in this field it
should be stated that, while Bell's telephone transmitted speech and
other sounds, it was only practicable for short lines. Bell had no
separate transmitter, but used a single apparatus both as transmitter
and receiver. This instrument was similar to the receiver used to-day,
having a metallic diaphragm placed near the pole of a magnet. The
vibrations of the diaphragm induced very weak electric impulses in the
magnetic coil. These impulses passed over the line to the receiving
end, energizing the magnet coil there, and, by varying the magnetism,
caused the receiving diaphragm to be similarly vibrated, and thus
reproduce the sounds. Under such conditions the telephone would be
practicable upon lines of only a few miles in extent, as the amount of
power generated by the human voice is necessarily quite limited.
The Western Union Company requested Edison to experiment on the
telephone so that it would be commercially practicable. He then went to
work with a corps of helpers, and, after months of hard work day and
night and the performance of many thousands of experiments, invented
the carbon transmitter. This, with his plan of using an induction coil
and constant battery current on the line, were the needed elements of
success, and it made the telephone a commercial possibility. Every
one of the many millions of telephones in use all over the world
to-day bears the imprint of Edison's genius in the employment of the
principles he then established.
What Edison accomplished was this: Instead of using one single
apparatus for transmitting and receiving, he made a separate
transmitter of special design. In this he used carbon, which varies
in electrical resistance with the pressure applied. The carbon was an
electrode in connection with the vibrating diaphragm, and was in a
closed circuit through which flowed a battery current. The vibrations
of the diaphragm caused variations of pressure on the carbon and
consequent variations in the current. These in turn resulted in
corresponding impulses in the receiving magnet, and the diaphragm of
the receiver was vibrated accordingly, thus reproducing the sounds.
Edison's plan also included the passing of the current through an
induction coil, the secondary of which was connected with the main
line. By this means electrical impulses of enormously high potential
are sent out on the main line to the receiving end.
Thus it will be seen that with Bell's telephone the sound-waves
themselves generate the electric impulses, which are hence extremely
weak. With Edison's telephone the sound-waves actuate an electric
valve, so to speak, and permit variations in a current of any desired
strength.
Mr. Edison's own story of his telephone work is full of interest: "In
1876 I started again to experiment for the Western Union and Mr. Orton.
This time it was the telephone. Bell invented the first telephone,
which consisted of the present receiver, used both as a transmitter
and a receiver (the magneto type). It was attempted to introduce
it commercially, but it failed on account of its faintness and the
extraneous sounds which came in on its wire from various causes.
Mr. Orton wanted me to take hold of it and make it commercial. As I
had also been working on a telegraph system employing tuning-forks,
simultaneously with both Bell and Gray, I was pretty familiar with the
subject. I started in, and soon produced the carbon transmitter, which
is now universally used.
"Tests were made between New York and Philadelphia, also between New
York and Washington, using regular Western Union wires. The noises
were so great that not a word could be heard with the Bell receiver
when used as a transmitter between New York and Newark, New Jersey.
Mr. Orton and W. K. Vanderbilt and the board of directors witnessed
and took part in the tests of my transmitter. They were successful.
The Western Union then put the transmitters on private lines. Mr.
Theodore Puskas, of Budapest, Hungary, was the first man to suggest
a telephone exchange, and soon after exchanges were established. The
telephone department was put in the hands of Hamilton McK. Twombly,
Vanderbilt's ablest son-in-law, who made a success of it. The Bell
Company, of Boston, also started an exchange, and the fight was on,
the Western Union pirating the Bell receiver and the Boston company
pirating the Western Union transmitter. About this time I wanted to be
taken care of. I threw out hints of this desire. Then Mr. Orton sent
for me. He had learned that inventors didn't do business by the regular
process, and concluded he would close it right up. He asked me how much
I wanted. I had made up my mind it was certainly worth twenty-five
thousand dollars if it ever amounted to anything for central station
work; so that was the sum I had in mind to obstinately stick to and
get. Still it had been an easy job, and only required a few months,
and I felt a little shaky and uncertain. So I asked him to make me an
offer. He promptly said he would give me one hundred thousand dollars.
'All right,' I said, 'it is yours on one condition, and that is that
you do not pay it all at once, but pay me at the rate of six thousand
dollars a year for seventeen years--the life of the patent.' He seemed
only too pleased to do this, and it was closed. My ambition was about
four times too large for my business capacity, and I knew that I would
soon spend this money experimenting if I got it all at once; so I fixed
it that I couldn't. I saved seventeen years of worry by this stroke."
Edison continued his telephone work through a number of years and made
and tested many other kinds of telephones, such as the water telephone,
electrostatic telephone, condenser telephone, chemical telephone,
various magneto telephones, inertia telephone, mercury telephone,
voltaic pile telephone, musical transmitter, and the electromotograph.
The principle of the electromotograph was utilized by him in more
ways than one; first of all in telegraphy. Soon after the time he had
concluded the telephone arrangement just mentioned a patent was issued
to a Mr. Page. This patent was considered very important. It related to
the use of a retractile spring to withdraw the armature lever from the
magnet of a telegraph or other relay or sounder, and thus controlled
the art of telegraphy, except in simple circuits.
"There was no known way," remarks Edison, "whereby this patent could
be evaded, and its possessor would eventually control the use of what
is known as the relay and sounder, and this was vital to telegraphy.
Gould was pounding the Western Union on the Stock Exchange, disturbing
its railroad contracts, and, being advised by his lawyers that this
patent was of great value, bought it. The moment Mr. Orton heard
this he sent for me and explained the situation, and wanted me to go
to work immediately and see if I couldn't evade it or discover some
other means that could be used in case Gould sustained the patent. It
seemed a pretty hard job, because there was no known means of moving
a lever at the other end of a telegraph wire except by the use of a
magnet. I said I would go at it that night. In experimenting some
years previously I had discovered a very peculiar phenomenon, and that
was that if a piece of metal connected to a battery was rubbed over
a moistened piece of chalk resting on a metal connected to the other
pole, when the current passed the friction was greatly diminished. When
the current was reversed the friction was greatly increased over what
it was when no current was passing. Remembering this, I substituted a
piece of chalk, rotated by a small electric motor for the magnet, and
connecting a sounder to a metallic finger resting on the chalk, the
combination claim of Page was made worthless. A hitherto unknown means
was introduced in the electric art. Two or three of the devices were
made and tested by the company's expert. Mr. Orton, after he had had
me sign the patent application and got it in the Patent Office, wanted
to settle for it at once. He asked my price. Again I said, 'Make me
an offer.' Again he named one hundred thousand dollars. I accepted,
providing he would pay it at the rate of six thousand dollars a year
for seventeen years. This was done, and thus, with the telephone money,
I received twelve thousand dollars yearly for that period from the
Western Union Telegraph Company."
A year or two later the electromotograph principle was again made
use of in a curious manner. The telephone was being developed in
England, and Edison had made arrangements with Colonel Gouraud, his old
associate in the automatic telegraph, to represent his interests.
A company was formed, a large number of instruments were made and
sent to London, and prospects were bright. Then there came a threat
of litigation from the owners of the Bell patent, and Gouraud found
he could not push the enterprise unless he could avoid using what was
asserted to be an infringement of the Bell receiver.
He cabled for help to Edison, who sent back word telling him to hold
the fort. "I had recourse again," says Edison, "to the phenomenon
discovered by me some years previous, that the friction of a rubbing
electrode passing over a moist chalk surface was varied by electricity.
I devised a telephone receiver which was afterward known as the
'loud-speaking telephone,' or 'chalk receiver.' There was no magnet,
simply a diaphragm and a cylinder of compressed chalk about the size
of a thimble. A thin spring connected to the center of the diaphragm
extended outwardly and rested on the chalk cylinder, and was pressed
against it with a pressure equal to that which would be due to a weight
of about six pounds. The chalk was rotated by hand. The volume of sound
was very great. A person talking into the carbon transmitter in New
York had his voice so amplified that he could be heard one thousand
feet away in an open field at Menlo Park. This great excess of power
was due to the fact that the latter came from the person turning the
handle. The voice, instead of furnishing all the power, as with the
present receiver, merely controlled the power, just as an engineer
working a valve would control a powerful engine.
"I made six of these receivers and sent them in charge of an expert on
the first steamer. They were welcomed and tested, and shortly afterward
I shipped a hundred more. At the same time I was ordered to send twenty
young men, after teaching them to become expert. I set up an exchange
of ten instruments around the laboratory. I would then go out and get
each one out of order in every conceivable way, cutting the wires of
one, short-circuiting another, destroying the adjustment of a third,
putting dirt between the electrodes of a fourth, and so on. A man would
be sent to each to find out the trouble. When he could find the trouble
ten consecutive times, using five minutes each, he was sent to London.
About sixty men were sifted to get twenty. Before all had arrived,
the Bell Company there, seeing we could not be stopped, entered into
negotiations for consolidation. One day I received a cable from Gouraud
offering 'thirty thousand' for my interest. I cabled back I would
accept. When the draft came I was astonished to find it was for thirty
thousand pounds. I had thought it was dollars."
After the consolidation of the Bell and Edison interests in England the
chalk receiver was finally abandoned in favor of the Bell receiver--the
latter being more simple and cheaper. Extensive litigation with
newcomers into the telephone field followed, and Edison's carbon
transmitter patent was sustained by the English courts, while Bell's
was declared invalid.
In America, the competition between the Western Union and Bell
companies, which had been keen and strenuous, was finally brought to
an end under an agreement, the former company agreeing to retire from
the telephonic field and the latter company agreeing to stay out of the
telegraphic field. Through its ownership of Edison's carbon transmitter
invention, the Western Union company came to enjoy an annual income of
several hundred thousand dollars for some years as a compensation for
its retirement from telephony under this agreement.
The principle involved in Edison's carbon-transmitter gave birth to
another interesting device called the microphone, by means of which
the faintest sounds could be very plainly heard. For instance, the
footsteps of a common house-fly make a loud noise when the hearing
is assisted by the microphone. As every one knows, the microphone is
universally used in our modern radio.
This invention was claimed at the time for Professor Hughes, of
England. Whatever credit might be due to him for the form he proposed,
a standard history ascribes two original forms of the microphone to
Edison, and he himself remarks: "After I sent one of my men over to
London especially to show Preece the carbon transmitter, when Hughes
first saw it, and heard it--then within a month he came out with the
microphone, without any acknowledgment whatever. Published dates will
show that Hughes came along after me."
The carbon transmitter has not been the only way in which Edison has
utilized the peculiar property that carbon possesses of altering
its resistance to the passage of current according to the degree of
pressure brought to bear on it.
For his quadruplex system he constructed a rheostat, or resistance box,
with a series of silk disks saturated with plumbago and well dried. The
pressure on the disks can be regulated by an adjustable screw, and in
this way the resistance of the circuit can be varied.
He also developed a "pressure," or carbon, relay, by means of which
signals of variable strength can be transferred from one telegraphic
circuit to another. The poles of the electromagnet in the local or
relay circuit are hollowed out and filled up with carbon disks or
powdered plumbago.
If a weak current passes through the relay the armature will be but
feebly attracted and will only compress the carbon slightly. Thus the
carbon will offer considerable resistance and the signal on the local
sounder will be weak.
If, on the contrary, the incoming current be strong, the armature
will be strongly attracted, the carbon will be more compressed, thus
lowering the resistance and giving a loud signal on the local sounder.
Another beautiful and ingenious use of carbon was made by Edison in an
instrument invented by him called the tasimeter. This device was used
for indicating most minute degrees of heat, and was so exceedingly
sensitive that in one case the heat of rays of light from the remote
star Arcturus showed results.
The tasimeter is a very simple instrument. A strip of hard rubber rests
vertically on a platinum plate, beneath which is a carbon button, under
which again lies another platinum plate. The two plates and the carbon
button form part of an electric circuit containing a battery and a
galvanometer. Hard rubber is very sensitive to heat, and the slightest
rise of temperature causes it to expand, thus increasing the pressure
on the carbon button. This produces a variation in resistance shown by
the swinging of the galvanometer needle.
This instrument is so sensitive that with a delicate galvanometer the
heat of a person's hand thirty feet away will throw the needle off the
scale.
XII
MAKING A MACHINE TALK
If one had never heard a phonograph, it would seem as though it would
be impossible to take some pieces of metal and make a machine that
would repeat speaking, singing, or instrumental music just like life.
So, before the autumn of 1877, when Edison invented the phonograph, the
world thought such a thing was entirely out of the question. Indeed,
Edison's own men in his workshop, who had seen him do some wonderful
things, thought the idea was absurd when he told them that he was
making a machine to reproduce human speech.
One of his men went so far as to bet him a box of cigars that the thing
would be an utter failure when finished, but, as every one knows,
Edison won the bet, for the very first time the machine was tried it
repeated clearly all the words that were spoken into it.
A story has often been told in the newspapers that the invention was
made through Edison's finger being pricked by a point attached to a
vibrating telephone diaphragm, but this is not true.
The invention was not made through any accident, but was the result
of pure reasoning, and in this case, as in many others, fact is more
wonderful than fiction. Mr. Edison's own account of the invention of
the phonograph is intensely interesting.
"I was experimenting," he says, "on an automatic method of recording
telegraph messages on a disk of paper laid on a revolving platen,
exactly the same as the disk talking-machine of to-day. The platen had
a spiral groove on its surface, like the disk. Over this was placed
a circular disk of paper; an electromagnet with the embossing point
connected to an arm travelled over the disk, and any signals given
through the magnets were embossed on the disk of paper. If this disk
was removed from the machine and put on a similar machine provided
with a contact point the embossed record would cause the signals to be
repeated into another wire. The ordinary speed of telegraphic signals
is thirty-five to forty words a minute; but with this machine several
hundred words were possible.
"From my experiments on the telephone I knew of the power of a
diaphragm to take up sound vibrations, as I had made a little toy which
when you recited loudly in the funnel would work a pawl connected to
the diaphragm; and this, engaging a ratchet-wheel, served to give
continuous rotation to a pulley. This pulley was connected by a cord
to a little paper toy representing a man sawing wood. Hence, if one
shouted: 'Mary had a little lamb,' etc., the paper man would start
sawing wood. I reached the conclusion that if I could record the
movements of the diaphragm properly I could cause such records to
reproduce the original movements imparted to the diaphragm by the
voice, and thus succeed in recording and reproducing the human voice.
"Instead of using a disk I designed a little machine, using a cylinder
provided with grooves around the surface. Over this was to be placed
tin-foil, which easily received and recorded the movements of the
diaphragm. A sketch was made, and the piece-work price, eighteen
dollars, was marked on the sketch. I was in the habit of marking the
price I would pay on each sketch. If the workman lost, I would pay
his regular wages; if he made more than the wages, he kept it. The
workman who got the sketch was John Kruesi. I didn't have much faith
that it would work, expecting that I might possibly hear a word or so
that would give hope of a future for the idea. Kruesi, when he had
nearly finished it, asked what it was for. I told him I was going to
record talking, and then have the machine talk back. He thought it
absurd. However, it was finished; the foil was put on; I then shouted
'Mary had a little lamb,' etc. I adjusted the reproducer, and the
machine reproduced it perfectly. I was never so taken back in my life.
Everybody was astonished. I was always afraid of things that worked
the first time. Long experience proved that there were great drawbacks
found generally before they could be made commercial; but here was
something there was no doubt of."
No wonder that John Kruesi, as he heard the little machine repeat the
words that had been spoken into it, ejaculated in an awe-stricken tone:
"Mein Gott im Himmel!" No wonder the "boys" joined hands and danced
around Edison, singing and shouting. No wonder that Edison and his
associates sat up all night fixing and adjusting it so as to get better
and better results--reciting and singing and trying one another's
voices and listening with awe and delight as the crude little machine
repeated the words spoken or sung into it.
The news quickly became public, and the newspapers of the world
published columns about this wonderful invention. Mr. Edison was
besieged with letters from every part of the globe. Every one wanted
to hear this machine; and in order to satisfy a universal demand for
phonographs to be used for exhibition purposes he had a number of them
made and turned them over to various individuals, who exhibited them to
great crowds around the country. These were the machines in which the
record was made on a sheet of tin-foil laid around the cylinder.
They created great excitement both in America and abroad. The
announcement of a phonograph concert was sufficient to fill a hall with
people who were curious to hear a machine talk and sing.
In the next year, 1878, Edison entered upon his experiments in electric
lighting. His work in this field kept him intensely busy for nearly ten
years, and the phonograph was laid aside as far as he was concerned.
He had not forgotten it, however, for he had fully realized its
tremendous possibilities very quickly after its invention. This
is shown by an article he wrote for the _North American Review_,
which appeared in the summer of 1878. In that article he predicted
the possible uses of the phonograph, many of which have since been
fulfilled.
[Illustration: MR. EDISON AT THE CLOSE OF FIVE DAYS AND NIGHTS
OF CONTINUED WORK IN PERFECTING THE EARLY WAX-CYLINDER TYPE OF
PHONOGRAPH--JUNE 16, 1888
This is the longest continuous session of labor he ever performed.]
In 1887, having finished the greatest part of his work on the electric
light, he turned to the phonograph once more. Realizing that the
tin-foil machine was not an ideal type and could not come into common
use, he determined to re-design it, and make it an instrument that
could be handled by any one.
This meant the design and construction of an entirely different type of
machine, and resulted in the kind of phonograph with which every one is
familiar in these modern days. One of the chief differences was the use
of a wax cylinder instead of tin-foil, and, instead of indenting with a
pointed stylus, the record is cut into the wax with a tiny sapphire,
the next hardest jewel to a diamond.
Into his improvements of the phonograph Mr. Edison has put an enormous
amount of time and work. He has never lost interest, but has worked on
it more or less through all the intervening years up to the present
time. Even during recent years he has expended a prodigious amount of
energy in improving the reproducer and other parts, spending night
after night, and frequently all night, at the laboratory.