<h2><SPAN name="CHAPTER_XV" id="CHAPTER_XV"></SPAN>CHAPTER XV.</h2>
<h3>TELEPHONY.</h3>
<p>In the foregoing chapters I have described
the method of transmitting musical tones
telegraphically and its applications to multiple
telegraphy, as well as to a mode of communicating
with a moving railroad-train. As
I stated in a former chapter, after discovering
a method of transmitting harmony as well as
melody, I had in mind two lines of development,
one in the direction of multiple telegraphy,
and the other that of the transmission
of articulate speech. I will not attempt to
give the names of all the people who have contributed
to the development of the telephone
(as this alone would fill a volume) but only
describe my own share in the work—leaving
history to give each one due credit for his
part. While I do not intend, here, to enter
into any controversy regarding the priority of
the invention of the telephone, I wish to say
that from the time I began my researches, in
the winter of 1873-4, until some time after I
had filed my specification for a speaking or
articulating telephone, in the winter of 1875-<span class="pagenum"><SPAN name="Page_135" id="Page_135"></SPAN></span>76,
I had no idea that any one else had done
or was doing anything in this direction. I
wish to say further that if I had filed my description
of a telephone as an application for
a patent instead of as a caveat, and had prosecuted
it to a patent, without changing a word
in the specification as it stands to-day, I
should have been awarded the priority of invention
by the courts. I am borne out in this
assertion by the highest legal authority. In
law, a <i>caveat</i> (Latin word, meaning "Let him
beware") is a warning to other inventors, to
protect an incomplete invention; whereas in
fact the invention to be protected may be
complete. An <i>application</i> for a patent is presumed
by the law to be for a completed invention;
but it may be, and very often is, incomplete.
It would often make a very great
difference if decisions were rendered according
to the facts in the case rather than according
to rules of law and practice, that sometimes
work great injustice to individuals.</p>
<p>As has been said in another chapter, in the
summer of 1874 I went to Europe in the interest
of the telephone, taking my apparatus,
as then developed, with me. I came home
early in the fall and resumed my experimental
work. Many interesting as well as amusing
things occurred during these experiments.</p>
<p>I remember that in the fall or early winter
of 1874 I was in Milwaukee with my apparatus<span class="pagenum"><SPAN name="Page_136" id="Page_136"></SPAN></span>
carrying on some experiments on a wire between
Milwaukee and Chicago. I had my
musical transmitter along, and one evening,
for the entertainment of some friends at the
Newhall House, a wire was stretched across
the street from the telegraph office into one
of the rooms of the hotel. A great number of
tunes were played at the telegraph-office by
Mr. Goodridge, who was my assistant at that
time, which were transmitted across the street,
as before stated. In those days it was a common
practice in telegraphy to use one battery
for a great number of lines. For instance,
starting with one ground-wire which connected
with, say, the negative pole of the battery,
from the positive pole two, three or a
half-dozen lines might be connected, running
in various directions, connecting with the
ground at the further end, thus completing
their circuits. For use in transmitting tones
across the street that evening we connected
our line-wire on to the telegraph company's
battery, which consisted of 100 or more cells,
and which had four or five more lines radiating
from the end of the battery to different
parts of Wisconsin. Our line was tapped on
to the battery (without changing any of its
connections) twenty cells from the ground-wire.
In transmitting, each vibration would
momentarily shut off these twenty cells from
the lines that were connected with the whole<span class="pagenum"><SPAN name="Page_137" id="Page_137"></SPAN></span>
battery. The effect of this (an effect that we
did not anticipate at the time) was to send a
vibratory current out on all the lines that
were connected with that single battery as
well as across the street. A great many familiar
tunes were played during the course of an
hour or two which, unconsciously for us, were
creating great consternation throughout the
State of Wisconsin, in many of the offices
through which these various lines passed.</p>
<p>Next morning reports and inquiries began
to come in from various towns and cities west,
northwest and north, giving details of the
phenomena that were noticed on the instruments
located in the various offices along the
lines. They reported their relays as singing
tunes; one party said he thought the instruments
were holding a prayer-meeting from the
fact that they seemed to be singing hymn-tunes
for quite a while, but this notion was
finally dissipated, because they grew hilarious
and sang "Yankee Doodle."</p>
<p>One operator, up in the pine woods of
northern Wisconsin, did not seem to take the
cheerful view of it that some of the others
did. He was sitting alone in the telegraph-office
that evening when he thought he heard
the notes of a bugle in the distance; he got
up and went to the door to listen, but could
hear nothing; but on coming back into the
room he heard the same bugle notes very<span class="pagenum"><SPAN name="Page_138" id="Page_138"></SPAN></span>
faintly. He was inclined to be somewhat
superstitious and grew very nervous; finally,
on looking around, he located the sound in his
relay, but this did not help matters with him.
With superstitious awe he listened to the instrument
for a few moments, while it gave out
the solemn tones of "Old Hundred," then it
suddenly jumped into a hilarious rendering of
"Yankee Doodle." This was too much for our
nervous friend, and hastily putting on his
overcoat, he left the office for the night.</p>
<p>On another occasion, when I was giving a
lecture in one of the cities outside of Chicago,
where exhibitions of music transmitted from
Chicago were given, one of the operators
along the line was very much astonished by
his switchboard suddenly becoming musical.
Orders had been given for the instruments in
all the local offices to be cut out of the particular
line that I was using. Hence the instrument
in this particular office was not in
the circuit through which the tunes were being
transmitted. The wire, however, ran
through his switchboard, and owing probably
to a loose connection, or an induced effect,
there was a spark that leaped across a short
space at each electrical pulsation that passed
through the line, thus reproducing the notes
of the various tunes played.</p>
<p>You will remember in one of the chapters
on sound (Volume II.), it is stated that a<span class="pagenum"><SPAN name="Page_139" id="Page_139"></SPAN></span>
musical tone is made up of a succession of
sounds repeated at equal intervals, and that
the pitch of the tone is determined by the number
of sound-impulses per second. Applying
this law to the sparks, you will be able to see
how the switchboard played tunes for the
operator.</p>
<p>In the foregoing experiments in transmitting
musical tones telegraphically, I used a
great many different varieties of receivers.
Some of them were designed with metal diaphragms
mounted over single electromagnets,
not unlike the receiver of an ordinary telephone.
These instruments would both transmit
and receive articulate speech when placed
in circuit with the right amount of battery to
furnish the necessary magnetism. However,
they were not used in that way at the time
they were first made—in 1874. These I called
common receivers, as they were designed to
reproduce all tones equally well. I designed
and constructed another form of receiver,
based somewhat upon the theory of the harmonic
telegraph.</p>
<p>This consisted of an electromagnet of considerable
size, mounted upon a wooden rod
about ten feet long. Mounted upon this rod
were also resonating boxes or tubes made of
wood of the right size to have their air-cavities
correspond with the various pitches of the
transmitting-reeds, so that each tone would be<span class="pagenum"><SPAN name="Page_140" id="Page_140"></SPAN></span>
re-enforced by some one of these air-cavities,
thus giving a louder and more resonant effect
to the musical notes.</p>
<p>Here were two types of receiver, one that
would receive one sound as well as another,
but none of them so loud, while the other was
constructed on the principle of selection and
re-enforcement, so that a particular note would
be sounded by the box having a cavity corresponding
to the pitch of the tone, and was
much louder and of much better quality than
I could get from the diaphragm receiver. One
of these receivers pointed to the harmonic
telegraph and the other to the speaking telephone.
I knew that I had a receiver that
would reproduce articulate speech or anything
else that could be transmitted.</p>
<p>My first conceptions of an articulate speech-transmitter
were somewhat complicated. I
conceived of a funnel made of thin metal having
a great number of little riders, insulated
from the funnel at one end and resting lightly
in contact with the funnel at the other end.
These riders were to be made of all sizes and
weights so as to be responsive to all rates of
vibration. In the light of the present day we
know that such an arrangement would have
transmitted articulate speech, but perhaps not
so well as a single point would do when properly
adjusted. My mind clung to this idea
till in the fall of 1875, when an observation I<span class="pagenum"><SPAN name="Page_141" id="Page_141"></SPAN></span>
made upon the street changed the whole course
of my thinking and solved the problem. The
incident I refer to took place in Milwaukee,
where I was then experimenting. One day
while out on an errand I noticed two boys with
fruit-cans in their hands having a thread attached
to the center of the bottom of each can
and stretched across the street, perhaps 100
feet apart. They were talking to each other,
the one holding his mouth to his can and the
other his ear. At that time I had not heard of
this "lovers' telegraph," although it was old.
It is said to have been used in China 2000
years ago.</p>
<p>The two boys seemed to be conversing in a
low tone with each other and my interest was
immediately aroused. I took the can out of
one of the boy's hands (rather rudely as I remember
it now), and putting my ear to the
mouth of it I could hear the voice of the boy
across the street. I conversed with him a moment,
then noticed how the cord was connected
at the bottom of the two cans, when, suddenly,
the problem of electrical speech-transmission
was solved in my mind. I did not have an opportunity
immediately to construct an instrument,
as I had a partner who was furnishing
money for the development of the harmonic
telegraph and would not listen to any collateral
experiments. I remember sitting down
by this partner one day and telling him what I<span class="pagenum"><SPAN name="Page_142" id="Page_142"></SPAN></span>
could do in the way of transmitting speech
through a wire. I told him I thought it would
be very valuable if worked out. He gave me a
look that I shall never forget, but he did not
say a word. The look conveyed more meaning
than all the words he could have said, and I
did not dare broach the subject again.</p>
<p>However, as soon as I found opportunity,
without saying a word to anybody except my
patent lawyer, I filed a description, accompanied
by drawings, of a speaking telephone
which stands in history to-day as the first
complete description on record of the operation
of the speaking telephone. It described
an apparatus which, when constructed, worked
as described, and it is a matter of history that
the first articulate speech electrically transmitted
in this country was by a transmitter
constructed on the principle described, and almost
identically after the drawings in my
caveat. While the transmitter described in
this caveat was not the best form, it would
transmit speech, and it contained the foundation
principle of all the telephone transmitters
in use to-day.</p>
<p>There are two methods of transmitting
speech. One is known as the magneto method
and the other that of varying the resistance of
the circuit. My first transmitter was devised
on the latter principle.<span class="pagenum"><SPAN name="Page_143" id="Page_143"></SPAN></span></p>
<p>I append to this extracts from my specification
filed Feb. 14, 1876:</p>
<div class="blockquot"><p><i>To All Whom It May Concern:</i>—Be it known that I, Elisha
Gray of Chicago, in the County of Cook and State of Illinois,
have invented a new art of transmitting vocal sounds telegraphically,
of which the following is a specification: It is
the object of my invention to transmit the tones of the human
voice through a telegraphic circuit, and reproduce them
at the receiving-end of the line, so that actual conversations
can be carried on by persons at long distances apart. I have
invented and patented methods of transmitting musical impressions
or sounds telegraphically, and my present invention
is based upon a modification of the principle of said
invention, which is set forth and described in letters patent
of the United States, granted to me July 27, 1875, respectively
numbered 166,095 and 166,096, and also in an application for
letters patent of the United States, filed by me, Feb. 23,
1875. * * * My present belief is that the most effective
method of providing an apparatus capable of responding to
the various tones of the human voice is a tympanum, drum,
or diaphragm, stretched across one end of the chamber, carrying
an apparatus for producing fluctuations in the potential
of the electric circuit and consequently varying in its
power. * * * The vibrations thus imparted are transmitted
through an electric circuit to the receiving-station, in which
circuit is included an electromagnet of ordinary construction,
acting upon a diaphragm to which is attached a piece of
soft iron, and which diaphragm is stretched across a receiving
vocalizing chamber <i>C</i>, somewhat similar to the corresponding
vocalizing chamber <i>A</i>.</p>
<p>The diaphragm at the receiving-end of the line is thus
thrown into vibrations corresponding with those at the
transmitting-end, and audible sounds or words are produced.</p>
<p>The obvious practical application of my improvement will
be to enable persons at a distance to converse with each
other through a telegraphic circuit, just as they now do in
each other's presence, or through a speaking-tube.</p>
<p><span class="pagenum"><SPAN name="Page_144" id="Page_144"></SPAN></span></p>
<p>I claim as my invention the art of transmitting vocal
sounds or conversations telegraphically through an electric
circuit.</p>
</div>
<p>This specification was accompanied by cuts
of the transmitter and receiver connected by
a line-wire and showing one person talking to
the transmitter and another listening at the receiver.
These cuts may be seen in various
books on the subject of telephony.</p>
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