THE TELEPHONE.
PRELIMINARY SUGGESTIONS AND EXPERIMENTS OF BOURSEUL, REIS AND
DRAWBAUGH--FIRST SPEAKING TELEPHONE BY PROF. BELL--DIFFERENCES
BETWEEN REIS’ AND BELL’S TELEPHONES--THE BLAKE TRANSMITTER--
BERLINER’S VARIATION OF RESISTANCE, AND ELECTRIC UNDULATIONS BY
VARIATION OF PRESSURE--EDISON’S CARBON MICROPHONE--THE TELEPHONE
EXCHANGE--STATISTICS.
Τηλε (far), and φωνη (sound), are the Greek roots from which the word
telephone is derived. It has the significance of transmitting sound to
distant points, and is a word antedating the present speaking telephone,
although this fact is generally lost sight of in the dazzling brilliancy
of this latter invention. In the effort to hear better, the American
Indian was accustomed to place his ear to the ground. Children of former
generations also made use of a toy known as the “lovers’ telegraph”--a
piece of string held under tension between the flexible bottoms of two
tin boxes--which latter when spoken into transmitted through the string
the vibrations from one box to the other, and made audible words spoken
at a distance. These expedients simply made available the superior
conductivity of the solid body over the air to transmit sound waves. The
electro-magnetic telephone operates on an entirely different principle.
It is a marvelous creation of genius, and stands alone as the unique,
superb, and unapproachable triumph of the Nineteenth Century. For
subtilty of principle, impressiveness of action, and breadth of results,
there is nothing comparable with it among mechanical agencies. In its
wonderful function of placing one intelligent being in direct vocal and
sympathetic communication with another a thousand miles away, its
intangible and mysterious mode of action suggests to the imagination
that unseen medium of prayer rising from the conscious human heart to
its omniscient and responsive God. The telegraph and railroad had
already brought all the peoples of the earth into intimate communication
and made them close kin, but the telephone transformed them into the
closer relationship of families, and the tiny wire, sentient and
responsive with its unlimited burden of human thoughts and human
feelings, forms one of the great vital cords in the solidarity of the
human family.
It is a curious fact that many, and perhaps most, great inventions have
been in the nature of accidental discoveries, the by-products of thought
directed in another channel, and seeking other results, but the
telephone does not belong to this class. It is the logical and
magnificent outcome of persistent thought and experiment in the
direction of the electrical transmittal of speech. Prof. Bell had his
objective point, and keeping this steadily in view, worked faithfully
for the accomplishment of his object in producing a speaking telephone,
until success crowned his work. He probably did not realize at first the
full magnitude of the achievement, but looking at it from the end of the
Nineteenth Century, he might well exclaim in the language of Horace:
“_Exegi monumentum acre perennius_.”
Prof. Bell’s conception of the telephone dates back as far as 1874. His
first United States patent, No. 174,465, was granted March 7, 1876, and
his second January 30, 1877, No. 186,787. It is generally the fate of
most inventions, even of a meritorious order, to languish for many
years, and frequently through the whole term of the patent, before
receiving full recognition and adoption by the public, but the meteoric
brilliancy of this invention at its first public announcement astonished
the masses, and inspired the admiration of the savants of the world.
When exhibited at the Centennial Exhibition in Philadelphia, in 1876, it
was spoken of by Sir William Thomson, and Prof. Henry, as the “greatest
by far of all the marvels of the electric telegraph.”
[Illustration: FIG. 55.--PHILIP REIS’ TELEPHONE.]
It is always the fate of the author of any great invention to be
compelled to defend himself against the claims of others. It is one of
the failings of human nature to lay claim to that which somebody else
has obtained, and is an old story which finds its first illustration in
the squabbles of childhood. When a troop of prattling boys hunt
butterflies among the daisies, and some sharp-eyed youngster has
captured a prize, there are always others of his mates to cry, “I saw it
first,” and men are but grown-up boys. So in the history of the
telephone, Prof. Bell has found competitors for this honor, and it is
astonishing to know how close some of these prior experimenters came to
success without reaching it. In 1854 Bourseul, of Paris _suggested_ an
electric telephone, and in 1861 Philip Reis _devised_ an electric
telephone which would transmit musical tones. Daniel Drawbaugh, of
Pennsylvania, is alleged to have made an electric telephone in
1867-1868, and his claims against the Bell interests were fought
vigorously in the Patent Office, and in the courts, but without success.
Elisha Gray’s claims perhaps came nearer to establishing for him a share
in the honor of inventing the speaking telephone than any other, for he
filed a caveat in the United States Patent Office upon the same day
(February 14, 1876), upon which Prof. Bell’s application for a patent
was made. But in the contest in the Patent Office with Gray, Edison,
Berliner, Richmond, Holcombe, Farmer, Dolbear, Volker, and others, it
was decided that Prof. Bell was the first to make a practically
effective speaking telephone, and this conclusion has been sustained by
the courts. Reis was a poor German school teacher at Friedrichsdorf, and
in 1860 he took a coil of wire, a knitting needle, the skin of a German
sausage, the bung of a beer barrel, and a strip of platinum, and
constructed the first electric telephone. A typical form of his
transmitter, see Fig. 55, was a box covered with a vibrating membrane E,
and provided with a mouth-piece at one side. A platinum strip F was
attached to the membrane or vibrating diaphragm E, and a platinum
pointed hammer G rested lightly on the platinum strip F. The hammer G
and platinum strip F were connected to the opposite ends of a wire,
which had in its circuit a battery and a receiver. Air vibrations in the
nature of sound waves in the box caused the diaphragm E to vibrate, and
a separating make-and-break contact between the platinum strip F and the
platinum point of hammer G caused a series of separate and distinct
broken impulses to traverse the battery circuit and be received upon the
receiver, which latter consisted of an iron rod with a coil of wire
around it. That Reis’ transmitter did alternately make and break the
circuit, seems clear from his own memoir. A translation from this
memoir, taken from the annual report (Jahresberichte) of the Physical
Society of Frankfurt am Main for 1860-1861, reads as follows:
“At the first condensation (of air vibrations) the hammer-shaped little
wire _d_ (G in our illustration), will be pushed back. At the succeeding
rarefaction it cannot follow the return vibration of the membrane, and
the current going through the little strip (of platinum) remains
interrupted so long as until the membrane driven by a new condensation
presses the little strip against _d_ (the hammer G) once more. In this
way each sound wave effects an opening and closing of the current.”
[Illustration: FIG. 56.--PROF. BELL’S TELEPHONE, MARCH 7, 1876.]
Reis evidently did not know how to make the vibrations of his diaphragm
translate themselves into exactly commensurate and correlated electric
impulses of equal rapidity, range, and quality. If he had done this, he
would have had a speaking telephone, but a make-and-break contact could
never do it, and hence he in his later instruments attached to them a
telegraphic key in order that the sending operator might communicate
with the receiving operator. If Reis’ telephone had been a speaking
telephone, this would have been unnecessary. Furthermore, it is
inconceivable how the intelligent, progressive, and scientific Germans
could have failed to have given to a speaking telephone in 1860 the
immediate honor and attention that it deserved. In America, the Bell
speaking telephone, invented in 1876, was known all over the civilized
world the same year. Reis’ broken contact circuit would transmit musical
tones, because musical tones vary chiefly in rapidity of vibration,
rather than in range, or quality, and the chattering contacts of Reis’
telephone would transmit musical tones because said contracts could be
adjusted to the practically uniform range of vibration. Prof. Bell,
however, had made a special study of articulate speech, and knew that
speech was not essentially musical, but was composed of an irregular and
discordant medley of vowel and consonant sounds, whose vibrations varied
not only in pitch or rapidity like musical tones, but also in the
quality or kind of vibrations as to range and loudness. In his
invention, therefore, he did not make and break the circuit as did Reis,
through the contact points, but he used the more sensitive plan of a
constantly closed circuit, and merely caused the current to undulate in
it by a principle of magnetic induction. This principle was first
discovered by Oersted, and developed into the well known fact that when
a piece of iron is moved back and forth from the poles of an
electro-magnet an induced current is made to oscillate in the helix of
the electro-magnet. The difference between Reis’ separating
make-and-break circuit, and the Bell continuous but undulating current,
might be illustrated by the difference between the impulses delivered by
the beating of the drum sticks on the head of a drum, on the one hand,
and the alternate pulling and slackening of a kite cord, on the other.
In the successive impacts on the head of a drum there could not be so
sensitive a transfer of motion to the lower head of the drum as there
would be transferred to the kite by the movement of the hand holding the
kite cord. Reis’ plan resembled the broken drum beats, and Bell’s the
kite cord, which always preserved a certain amount of tension. Bell
accomplished his object by the means shown in Figs. 56 and 57, in which
Fig. 56 represents his first patent of March 7, 1876, and Fig. 57 his
second patent of January 30, 1877. In both cases the current was a
continuously closed one, and was not alternately made and broken as by
the separating contacts of Reis. Prof. Bell caused the vocal air
vibrations to undulate or oscillate the continuously closed circuit by
the principle of magnetic induction as follows (see Fig. 56): He caused
diaphragm _a_, when spoken against, to vibrate the armature _c_ in front
of the electro-magnet _b_, but without touching it, and as the armature
approached and receded from the electro-magnet it induced an undulating
but never broken current in the helix of this electro-magnet and along
the line to and through the helix of the electro-magnet _f_ at the
distant receiver, and this undulating current, influencing the armature
_h_, which touched the diaphragm _i_ but not the electro-magnet,
produced in the attractive influence of the magnet on this armature and
diaphragm, vibrations of the same rapidity, range, and quality as those
vocal vibrations that acted upon the first diaphragm _a_. In other
words, the sequence of transference was air vibrations in A, mechanical
vibrations of diaphragm _a_, electrical undulations traversing the line,
induced vibrations in armature _h_ and diaphragm _i_, and air vibrations
again resolved back into sounds of articulate speech, the same as those
spoken into A. It will be perceived that in the Bell telephone both
transmitter and receiver were of identical construction. This is better
shown in Fig. 57 of his later patent, in which the horizontal line below
the electro-magnet on one side represents a metal transmitting
diaphragm, and the horizontal line under the electro-magnet at the other
side was the receiving diaphragm. Not only were the sounds thus
reproduced, but as the circuit was continuous and never broken by any
separating contacts, the extreme sensitiveness of the electric
vibrations set up by magnetic induction was such that the discordant and
irregular quality of the vibrations of articulate speech were
transferred and reproduced with exact fidelity, as well as the musical
tones, and this rendered the speaking telephone a success. In later
telephones the current is actually transmitted through the contacting
points, but this only became practicable after the carbon microphone
transmitter was invented, in which the essential undulations of the
electric current were produced in another way, _i. e._, by the
application of the important discovery that the varying of the pressure
on carbon, by vibration, varied its conductivity, and in this way
produced the same result of undulating a current without breaking it.
This in no wise detracts from the value of the principle of the
continuous undulating current discovered and employed by Prof. Bell,
between which and the breaks of the hard platinum points of Reis there
is a difference as wide as the difference between success and failure.
[Illustration: FIG. 57.--PROF. BELL’S TELEPHONE, JANUARY 30, 1877.]
The form in which Prof. Bell’s telephone was placed before the public
was not that shown in the patents, but it quickly assumed the well-known
shape of an elongated cylinder forming a handle, with a flaring
mouth-piece at one end. This development in form is credited to Dr.
Channing in 1877, and it is the familiar form to-day, whose internal
construction is shown in Fig. 58. The handle is made of hard rubber, and
the cap or mouth-piece, which is screwed thereon, is also of hard
rubber. The diaphragm A, of thin ferrotype plate, is clamped at its
edges between the cap, or mouth-piece, and the handle. The compound
magnet B is composed of four thin flat bar magnets, arranged in pairs on
opposite sides of the flat end of the soft iron pole piece _c_ at one
end, and the soft iron spacing piece _d_ at the other end, the magnets
being clamped to these pieces with like poles all in one direction. The
end of the pole piece _c_ extends to within 1/100 to 2/100 of an inch of
the diaphragm, or as near as possible so that the diaphragm does not
touch it when it vibrates. On the pole piece _c_ is placed a wooden
spool on which is wound silk-covered wire (No. 34, Am. W. G.). This wire
fills the spool, and its ends are soldered to two insulated wires which
pass through a flexible rubber disc _f_ below the spool and extend
respectively to the two binding posts at the opposite end of the handle.
The current passes from one binding post and its connecting wire,
through the wire on the spool, and thence to the other connecting wire
and binding post. When used as a transmitter, vocal vibrations acting
mechanically on the diaphragm A produce undulatory vibrations by
magnetic induction in the spool of wire, which are transmitted to the
other end of the line; and when used as a receiver, the undulatory
vibrations from the remote end of the line produce mechanical vibrations
in the diaphragm, which set up air vibrations that are reproductions of
articulate sounds.
[Illustration: FIG. 58.--LONGITUDINAL SECTION OF BELL TELEPHONE.]
Although the Bell telephone is both a transmitter and receiver, in
practice a more sensitive and better form of transmitter has taken its
place. That most generally used and best known is the “Blake
transmitter,” which was brought out about 1880. This employs two
important elements. The first is the carbon microphone, which is a means
for producing the undulations in the current by the variations in
pressure on carbon contacts, and the second is an induction coil
operated by a local battery, whose primary circuit passes through the
contacts of the carbon microphone, and whose secondary circuit passes
over the line. These fundamental elements of the Blake transmitter were
the inventions of Berliner and Edison, and were made in 1877. The broad
idea of producing electric undulations by varying the pressure between
electrodes by vocal vibrations, was a large bone of contention in the
Patent Office between various inventors. An application for a patent for
the same was filed in the Patent Office by Emile Berliner, June 4, 1877,
which was contested in an interference by Gray, Edison, Richmond,
Dolbear, Holcombe, Prof. Bell, and others. After fourteen years of
litigation the patent was finally awarded to Berliner. The patent
granted to him November 17, 1891, No. 463,569, is a valuable one, and
has become the property of the American Bell Telephone Company. The
application of a low resistance conductor (carbon) in a microphone was
invented by Edison as early as 1877, but his patent, No. 474,230, did
not issue until May 3, 1892, on account of the interference with
Berliner on the broader principle.
[Illustration: FIG. 59.--BLAKE TRANSMITTER.]
[Illustration: FIG. 60.--DIAGRAM OF CIRCUITS IN BLAKE TRANSMITTER.]
The Blake transmitter takes its name from the inventor of its mechanical
features, who has assembled in it the fundamental principles of Berliner
and Edison in a sensitive and practical mechanical construction, covered
by minor patents, dated November 29, 1881. It is the little box in the
middle of the familiar telephone outfit into which the talking is done.
Its internal construction is shown in Fig. 59. To the rear of the door
is secured the cast iron circular ring A, inside of which lies the
Russia iron diaphragm B, cushioned at its edges with a rubber band. A
circular seat a little larger than the diaphragm is formed in the iron
ring, and on this seat the diaphragm rests. A short, thin metal plate
attached to the ring A on the right hand side clamps the diaphragm in
position by resting squarely on the rubber edge of the diaphragm. Its
function is like that of a hinge, which allows the diaphragm to freely
swing inward. A steel damping spring is secured to the ring at the
opposite edge of the diaphragm, and has its free end provided with a
rubber glove on which is cemented a thin piece of fluffy woolen
material. The padded end of the damping spring rests against the
diaphragm and prevents excessive vibration. The iron ring A has at its
bottom a projection holding an adjusting screw, and to a similar top
projection is attached by screws a brass spring, from which depends
another casting C, supporting the microphone apparatus, which is best
shown in the diagram, Fig. 60. In this diagram A is one terminal of the
battery connected by wire S to the hinge H of the box. From the other
leaf of the hinge the wire M passes to K, where it is soldered to the
upper end of a German silver spring I. At K this spring is clamped and
insulated from the iron work by two pieces of hard rubber. On the lower
end of the spring I is soldered a short piece of thick platinum wire,
whose ends are rounded into heads, one of which bears against the
diaphragm N, and the other against the carbon button J. This button is
attached to a small brass weight, and is supported by a spring R,
clamped at its upper end to the metal support T. This spring is
surrounded its entire length by rubber tubing to deaden vibration. The
transmitter is adjusted by screw O, which, acting upon casting T, brings
the carbon button, the platinum heads, and also the diaphragm N, against
each other with a regulated pressure. The current passes from the part K
to the spring I, the platinum head, carbon button J, and its supporting
spring R, to metal casting T, and ring V, thence by wire L to the lower
hinge G, by wire P to the primary of the induction coil, and thence by
wire Y to binding post B, the two binding posts A B being the two
battery terminals. The secondary wire E of the induction coil has its
ends connected by wires X and W with the two binding posts C B, which
are the line terminals, or one the line terminal and the other the
ground connection. It will thus be seen that the primary current passes
through the transmitter, and the secondary traverses the line. The most
familiar forms of the telephone are those seen in Figs. 61 and 62, but
the ideal form is rigged in a cabinet or little room, which excludes all
extraneous interfering sounds.
[Illustration: FIG. 61.--WALL TELEPHONE.]
[Illustration: FIG. 62.--DESK TELEPHONE.]
With the Bell receiver and the Blake transmitter a good practical
telephone system may be constructed, but the improvements which have
been made in the short life of the telephone are beyond adequate
description, or even mention. They relate to the call bell, the battery,
the switchboard, meters for registering calls, conductors, conduits,
connections, lightning arresters, switches, anti-induction devices,
repeaters, and systems. Among those most prominently identified with its
development are Bell, Edison, Berliner, Hughes, Gray, Dolbear and
Phelps. The activity in this field is best illustrated by the fact that
the art of telephony, begun practically in 1876, has at the end of the
Nineteenth Century grown into some 3,000 United States patents on the
subject.
[Illustration: FIG. 63.--TELEPHONE EXCHANGE.]
That which has given the telephone its greatest commercial value is the
“exchange” system, by which at a central office any member of a
telephonic community may be instantly put into communication with any
other member of that community. For this purpose, see Fig. 63, a
continuous switchboard is arranged along the side of a large room and
occupies most of that side of the wall. It comprises a great array of
annunciator drops, spring jacks with plug seats, and connecting cords
with metal plugs at their opposite ends. Each subscriber is connected to
his own spring jack and annunciator drop, and his call to central
office (from his magneto-bell) throws down the annunciator drop which
bears the number of his telephone, and announces to the attendant his
desire to communicate with another. To insure the attention of the
attendant, a tiny electric lamp is by the same action lighted directly
in front of her, which acts as a pilot signal to call her attention to
the drop. The attendant now puts a plug in that spring jack, which
automatically restores the drop, and she then asks the number which the
subscriber wants, and, upon ascertaining this, puts the plug at the
other end of the connecting cord into the spring jack of the subscriber
wanted, and by this action disconnects her own telephone. As every
telephone subscriber has in the central office an apparatus exclusively
his own, it will be seen that a telephone community of several thousands
of subscribers involves an imposing array of multiple connections, and a
great expense in construction. Girls are chosen as exchange attendants
because their voices are clearer. Every telephone jack, however, does
not have its Jill, for each girl has charge of a hundred or more jacks,
and wears constantly on her head a telephone of special shape, embracing
her head like a child’s hoop comb, but terminating with an ear-piece at
one end that covers one ear. She is too busy to waste time in adjusting
an ordinary telephone to her ear, and so wears one of special design all
the time.
In the twentieth annual report of the American Bell Telephone Company,
for the year 1899, the number of telephones in use January 1, 1900, by
that company alone, in the United States, was 1,580,101; the miles of
wire were 1,016,777, and the daily connections for persons using the
telephone were 5,173,803. The gross earnings of the company were
$5,760,106.45, and it paid in dividends $3,882,945. The total number of
exchange stations of the Bell Company in the principal countries of the
world are: United States, 632,946; Germany, 212,121; Great Britain,
112,840; Sweden, 63,685; France, 44,865; Switzerland, 35,536; Russia,
26,865; Austria, 26,664; Norway, 25,376. The United States has nearly
85,000 more than all the others put together.
Since the expiration of the Bell patents many smaller companies have
sprung up, and the number of telephones in use has more than doubled in
the last five years. Long distance telephony is now carried on up to
nearly 2,000 miles, and one may to-day lie in bed in New York and listen
to a concert in Chicago, and the vocal exchange of business and social
intercourse between cities has become so large a feature of modern life
as to justify the organization of a great company for this service
alone.
In the Old Testament, Book of Job, xxxviii. chapter, 35th verse, it is
written: “Canst thou send lightnings that they may go and say unto
thee--‘Here we are?’” For thousands of years this challenge to Job has
been looked upon as a feat whose execution was only within the power of
the Almighty; but to-day the inventor--that patient modern Job--has
accomplished this seemingly impossible task, for at the end of this
Nineteenth Century of the Christian Era, the telephone makes the
lightning man’s vocal messenger, tireless, faithful, and true, knowing
no prevarication, and swifter than the winged messenger of the gods.