THE OCEAN CABLE.--The remaining department of Telegraphy is embodied in
the startling departure from ancient ideas of the possible which we know
as cable telegraphy, the messages by such means being _cablegrams_.
About these ocean systems there are many features not applying to lines
on land, though they are intended to perform the same functions in the
same way, with the same object of conveying intelligence in language,
instantly and certainly, but under the sea.
The marine cables are not simple wires. There is in the center a strand
of usually seven small copper wires, intended as the conductor of the
current. These, twisted loosely into a small cable, are surrounded by
repeated layers of gutta-percha, which is, in turn, covered with jute.
Outside of all there is an armor of wires, and the entire cable appears
much like any other of the wire cables now in common use with elevators,
bridges, and for many purposes. In the shallow waters of bays and
harbors, where anchors drag and the like occurrences take place, the
armor of a submarine cable is sometimes so heavy as to weigh more than
twenty tons to the mile.
There are peculiar difficulties encountered in sending messages by an
ocean cable, and some of these grow out of the same induction whose laws
are indispensable in other cases. The inner copper core sets up
induction in the strands of the outer armor, and that again with the
surrounding water. There is, again, a species of re-induction affecting
the core, so that faint impulses may be received at the terminals that
were never sent by the operators. All of these difficulties combined
result in what electricians term "retardation." It is one of the
departments of telegraphy that, like the unavoidable difficulties in all
machines and devices, educates men to their special care, and keeps them
thinking. It is one of the natural features of all the mechanical
sciences that results in the continual making of improvements.
The first impression in regard to ocean cables would be that very strong
currents are used in sending impulses so far. The opposite is true. The
receiving instrument is not the noisy "sounder" of the land lines. There
was, until recently, a delicate needle which swung to and fro with the
impulses, and reflected beams of light which, according to their number
and the space between them spelled out the message according to the Vail
dot-and-dash alphabet. Now, however, a means still more delicate has
been devised, resulting in a faint wavy ink-line on a long, unwinding
slip of paper, made by a fountain pen. This strange manuscript may be
regarded as the latest system of writing in the world, having no
relationship to the art of Cadmus, and requiring an expert and a special
education to decipher it. Those faint pulsations, from a hand three
thousand miles away across the sea, are the realization of a magic
incredible. The necromancy and black art of all antiquity are childish
by comparison. They give but faint indications of what they often
are--the messages of love and death; the dictations of statesmanship;
the heralds of peace or war; the orders for the disposition of millions
of dollars.
The story of the laying of the first ocean cable is worthy of the
telling in any language, but should be especially interesting to the
American boy and girl. It is a story of native enterprise and
persistence; perhaps the most remarkable of them all.
The earliest ocean telegraph was that laid by two men named Brett,
across the English Channel. For this cable, a pioneer though crossing
only a narrow water, the conservative officials of the British
government refused a charter. In August, 1850, they laid a single copper
wire covered with gutta-percha from Dover in England to the coast of
France. The first wire was soon broken, and a second was made consisting
of several strands, and this last was soon imitated in various short
reaches of water in Europe.
But the Atlantic had always been considered unfathomable. No line had
ever sounded its depths, and its strong currents had invariably swept
away the heaviest weights before they reached its bed. Its great
feature, so far as known, was that strange ocean river first noted and
described by Franklin, and known to us as the Gulf Stream. In 1853 a
circumstance occurred which again turned the attention of a few men to
the question of an Atlantic cable. Lieutenant Berryman, of the Navy,
made a survey of the bottom of the Atlantic from Newfoundland to
Ireland, and the wonderful discovery was made that the floor of the
ocean was a vast plain, not more than two miles below the surface,
extending from one continent to the other. This plain is about four
hundred miles wide and sixteen hundred long, and there are no currents
to disturb the mass of broken shells and unknown fishes that lie on its
oozy surface. It was named the "Telegraphic Plateau," with a view to its
future use. At either edge of this plateau huge mountains, from four to
seven thousand feet high, rise out of the depths. There are precipices
of sheer descent down which the cable now hangs. The Azores and Bermudas
are peaks of ocean mountains. The warm river known as the Gulf Stream,
coming northward meets the ice-bergs and melts them, and deposits the
shells, rocks and sand they carry on this plain. When it was discovered
the difficulty in the way of an Atlantic cable seemed no longer to
exist, and those who had been anxious to engage in the enterprise began
to bestir themselves.
Of these the most active was the American, Cyrus W. Field. He began life
as a clerk in New York City. When thirty-five years old he became
engaged in the building of a land line of telegraph across Newfoundland,
the purpose of which was to transmit news brought by a fast line of
steamers intended to be established, and the idea is said to have
occurred to him of making a line not only so far, but across the sea. In
November, 1856, he had succeeded in forming a company, and the entire
capital, amounting to 350,000 pounds, was subscribed. The governments of
England and the United States promised a subsidy to the stockholders.
The cable was made in England. The _Niagara_ was assigned by the
United States, and the _Agamemnon_ by England, each attended by
smaller vessels, to lay the cable. In August, 1857, the Niagara left the
coast of Ireland, dropping her cable into the sea. Even when it dropped
suddenly down the steep escarpment to the great plateau the current
still flowed. But through the carelessness of an assistant the cable
parted. That was the beginning of mishaps. The task was not to be so
easily done, and the enterprise was postponed until the following year.
That next year was still more memorable for triumph and disappointment.
It was now designed that the two vessels should meet in mid-ocean, unite
the ends of the cable, and sail slowly to opposite shores. There were
fearful storms. The huge _Agamemnon_, overloaded with her half of
the cable, was almost lost. But finally the spot in the waste and middle
of the Atlantic was reached, the sea was still, and the vessels steamed
away from each other slowly uncoiling into the sea their two halves of
the second cable. It parted again, and the two ships returned to
Ireland.
In July they again met in mid-ocean. Europe and America were both
charitably deriding the splendid enterprise. All faith was lost. It was
known, to journalism especially, that the cable would never be laid and
that the enterprise was absurd. But it was like the laying of the first
land line. There was a way to do it, existing in the brains and faith of
men, though at first that way was not known. From this third meeting the
two ships again sailed away, the _Niagara_ for America, the
_Agamemnon_ for Valencia Bay. This time the wire did not part, and
on August 29th, 1858, the old world and the new were bound together for
the first time, and each could read almost the thoughts of the other.
The queen saluted America, and the president replied. There were salutes
of cannon and the ringing of bells. But the messages by the cable grew
indistinct day by day, and finally ceased. The Atlantic cable had been
laid, and--had failed.
Eight years followed, and the cable lay forgotten at the bottom of the
sea. The reign of peace on earth and good will to men had so far failed
to come and they were years of tumult and bitterness. The Union of the
United States was called upon to defend its integrity in a great war. A
bitter enmity grew up between us and England. The telegraph, and all its
persevering projectors, were almost absolutely forgotten. Electricians
declared the project utterly impracticable, and it began, finally, to be
denied that any messages had ever crossed the Atlantic at all, and Field
and his associates were discredited. It was said that the current could
not be made to pass through so long a circuit. New routes were spoken
of--across Bering's Strait, and overland by way of Siberia--and
measures began to be taken to carry this scheme into effect.
Amid these discouragements, Field and his associates revived their
company, made a new cable, and provided everything that science could
then suggest to aid final success. This new cable was more perfect than
any of the former ones, and there was a mammoth side-wheel steamer known
as the _Great Eastern_, unavailable as it proved for the ordinary
uses of commerce, and this vessel was large enough to carry the entire
cable in her hold. In July, 1865, the huge steamer left Ireland,
dropping the endless coil into the sea. The same men were engaged in
this last attempt that had failed in all the previous ones. It is one of
the most memorable instances of perseverance on record. But on August
6th a flaw occurred, and the cable was being drawn up for repairs. The
sound of the wheel suddenly stopped; the cable broke and sunk into the
depths. The _Great Eastern_ returned unsuccessful to her port.
Field was present on board on this occasion, and had been present on
several similar ones. There was, so far as known, no record made by him
of his thoughts. There were now five cables in the bed of the Atlantic,
and each one had carried down with it a large sum of money, and a still
larger sum of hopes. Yet the Great Eastern sailed again in July, 1866,
her tanks filled with new cable and Field once more on her decks. It was
the last, and the successful attempt. The cable sank steadily and
noiselessly into the sea, and on July 26th the steamer sailed into
Trinity Bay. The connection was made at Heart's Content, a little New
Foundland fishing village, and one for this occasion admirably named.
Then the lost cable of 1865 was found, raised and spliced.
In these later times, if a flaw should occur, science would locate it,
and go and repair it. Even if this were not true, the fact remains that
this last cable, and that of 1865, have been carrying their messages
under the sea for nearly thirty years. The lesson is that repeated
failures do not mean _final_ failure. There is often said to be a
malice, a spirit of rebellion, in inanimate things. They refuse to
become slaves until they are once and for all utterly subdued, and then
they are docile forever. Yet the malice truly lies in the inaptitude and
inexperience of men. Had Field and his associates known how to make and
lay an Atlantic cable in the beginning as well as they did in the end,
the first one laid would have been successful. The years were passed in
the invention of machinery for laying, and in improving the construction
of each successive cable. Many have been laid since then, certainly and
without failure. Men have learned how. [Footnote: At present the total
mileage of submarine cables is about 152,000 miles, costing altogether
$200,000,000. The length of land wires throughout the world is over
2,000,000 miles, costing $225,000,000. The capital invested in all
lines, land and sea, is about $530,000,000.]
Thirteen years were passed in this succession of toils, expenditures,
trials and failures. Field crossed the Atlantic more than fifty times in
these years, in pursuit of his great idea. At last, like Morse, he was
crowned with wealth, success, medals and honors. He was acquainted with
all the difficulties. It is now known that he knew through them all that
an ocean cable could finally be laid.
THE TELEPHONE.--The telegraph had become old. All nations had become
accustomed to its use. More than thirty years had elapsed--a long time
in the last half of the nineteenth century--before mankind awoke to a
new and startling surprise; the telegraph had been made to transmit not
only language, but the human voice in articulate speech. [Footnote: It
has been noted that Morse's idea was a _recording_ telegraph, that
being in his mind its most valuable point, and that this idea has long
been obsolete. In like manner, when the Telephone was invented there was
a general business opinion that it was perhaps an instrument useful in
colleges for demonstrating the wonders of electricity, but not useful
for commercial purposes _because it made no record_. "Business will
always be done in black and white" was the oracular verdict of prominent
and experienced business men. It may be true, but a little conversation
across space has been found indispensable. The telephone is a remarkable
business success.] The fact first became known in 1873, and was the
invention of Alexander G. Bell, of Chicago.
[Illustration: DIAGRAM OF TELEPHONE.--THE BLAKE TRANSMITTER.]
There were several, no one knows how many, attempts to accomplish this
remarkable feat previous to the success of Professor Bell. One of these
was by Reis, of Frankfort, in 1860. It did not embrace any of the most
valuable principles involved in what we know as the telephone, since it
could not transmit _speech_. Professor Bell's first operative
apparatus was accompanied by simultaneous inventions by Gray, Edison,
and others. This remarkable instance of several of the great
electricians of the country evolving at nearly the same time the same
principal details of a revolutionary invention, has never been fully
explained. The first rather crude and ineffective arrangements were
rapidly improved by these men, and by others, prominent among whom is
Blake, whose remarkable transmitter will be described presently. The
best devices of these inventors were finally embodied, and in the
resulting instrument we have one of the chiefest of those modern wonders
whose first appearance taxed the credulity of mankind. [Footnote: There
were, until a recent period, a line of statements, alleged facts and
reasonings, that were incredible in proportion to intelligence. The
occurrences of recent times have reversed this rule with regard to all
things in the domain of applied science. It is the ignorant and narrow
only who are incredulous, and the ears of intelligence are open to every
sound. All that is not absurd is possible, and all that is possible is
sure to be accomplished. The telephone, as a statement, _was_
absurd, but not to the men who worked for its accomplishment and finally
succeeded. The lines grow narrow. It requires now a high intelligence to
decide even upon the fact of absurdity within the domain of natural
law.]
In reality the telephone is simple in construction. Workmen who are not
accomplished electricians constantly erect, correct and repair the lines
and instruments. The machine is not liable to derangement. Any person
may use it the first time of trying, and this use is almost universal.
Yet it is, from the view of any hour in all the past, an
incomprehensible mystery. A moment of reflection drifts the mind
backward and renders it almost incredible in the present. The human
voice, recognizable, in articulate words, is apparently borne for miles,
now even for some hundreds of miles, upon an attenuated wire which hangs
silent in the air carrying absolutely nothing more than thousands of
little varying impulses of electricity. Not a word that is spoken at one
end of it is ever heard at the other, and the conclusion inevitable to
the reason of even twenty years ago would be that if one person does not
actually hear the other talk there is a miracle. Probably this idea that
the voice is actually carried is not very uncommon. The facts seem
incomprehensible otherwise, and it is not considered that if that idea
were correct it _would_ be a miracle.
The entire explanation of the magic of the telephone lies in electrical
induction. To the brief explanation of that phenomenon previously given
the reader is again referred for a better understanding of what now
follows.
But, first, a moment's consideration may be given to the results
produced by the use of this appliance, which, as an illustration of the
way of the world was an innovation that, had it remained uninvented or
impossible, would never have been even desired. One third more business
is said now to be transacted in the average day than was possible
previously. Since many things can now go on together which previously
waited for direction, authority and personal arrangement, a man's
business life is lengthened one-third, while his business may mostly be
done, to his great convenience, from one place. It has given employment
to a large number of persons, a large proportion of whom are young
women. The status of woman in the business world has been, fortunately
or unfortunately, by so much changed. It has introduced a new necessity,
never again to be dispensed with. It has changed the ancient habits, and
with them, unconsciously, _the habit of thought_. Contact not
personal between man and man has increased. The _thought_ of others
is quickly arrived at. It has caused us to become more appreciative of
the absolute meanings and values of words, without assistance from face,
manner or gesture. Laughter may be heard, but tears are unseen. It has
induced caution in speech and enforces brevity. While none of its
conveniences are now noted, and all that it gives is expected, the
telephone, with all its effects, has entered--into the sum of life.
On the wall or table there is a box, and beside this box projects a
metal arm. In a fork of this arm hangs a round, black, trumpet-shaped,
hard rubber tube. This last is the receiving instrument. It is taken
from its arm and held close to the ear. The answers are heard in it as
though the person speaking were there concealed in an impish embodiment
of himself. Meantime the talking is done into a hole in the side of the
box, while the receiver is held to the ear. This is all that appears
superficially. An operation incredible has its entire machinery
concealed in these simplicities. It is difficult to explain the mystery
of the telephone in words--though it has been said to be simple--and it
is almost impossible unless the reader comprehends, or will now
undertake to comprehend, what has been previously said on the subject of
the production of magnetism by a current of electricity, as in the case
of the electro-magnet, and on the subject of induction and its laws.
It has been shown that electricity produces magnetism; that the current,
properly managed as described, creates instantly a powerful magnet out
of a piece of soft iron, and leaves it again a mere piece of iron at the
will of the operator. This process also will work backwards. An electric
current produces a magnet, and _a magnet also may be made to produce
an electric current_. It is one more of the innumerable, almost
universal, cases where scientific and mechanical processes may be
reversed. When the dynamo is examined this process is still further
exemplified, and when we examine the dynamo and the motor together we
have a striking example of the two processes going on together.
The application of this making of a current, or changing its intensity,
in the telephone, is apparently totally unlike the continuous
manufacture of the induced current for daily use by means of the steam
engine and dynamo. But it is in exact accord with the same laws. It
will, perhaps, be more readily understood by recalling the results of
the experiment of the two wires, where it was found that an _approach
to_, or a _receding from_, a wire carrying a current, produces
an impulse over the wire that has by itself no current at all. Now, it
must be added to that explanation that if the battery were detached from
that conducting wire, and if, instead of its being a wire for the
carrying of a battery current _it were itself a permanent magnet_,
the same results would happen in the other wire if it were rapidly moved
toward and away from this permanent magnet. If the reader should stretch
a wire tightly between two pegs on a table, and should then hold the
arms of a common horseshoe magnet very near it, and should twang the
stretched wire with his finger, as he would a guitar string, the
electrometer would show an induced alternate current in the wire. Since
this is an illustration of the principle of the dynamo, stated in its
simplest form, it may be well to remember that in this manner--with the
means multiplied and in all respects made the most of--a very strong
current of electricity may be evolved without any battery or other
source of electricity except a magnet. In connection with this
substitution of a magnet for a current-carrying wire, it must be
remembered that moving the magnet toward or from the wire has the same
result as moving the wire instead. It does not matter which piece is
moved.
In addition to the above, it should be stated that not only will an
induced current be set up in the wire, but also _the magnetism in the
magnet will be increased or diminished as the tremblings of the wire
cause it to approach or recede from it_. Therefore if a wire be led
away from each pole of a permanent magnet, and the ends united to form a
circuit, an induced current will appear in this wire if a piece of soft
iron is passed quickly near the magnet.
There is an essential part of the telephone that it is necessary to go
outside of the field of electricity to describe. It is undoubtedly
understood by the reader that all sound is produced by vibrations, or
rapid undulations, of the surrounding air. If a membrane of any kind is
stretched across a hoop, and one talks against it, so to speak, the
diaphragm or membrane will be shaken, will vibrate, with the movement of
the air produced by the voice. If a cannon be fired all the windows
rattle, and are often broken. A peal of thunder will cause the same jar
and rattle of window panes, manifestly by what we call
"sound"--vibrations of the air. The window frame is a "diaphragm." The
ear is constructed on the same principle, its diaphragm being actually
moved by the vibrations of air, being what we call hearing. With these
facts about sound understood in connection with those given in
connection with the substitution of a magnet for a battery current, it
is entirely possible for any non-expert to understand the theory of the
construction of the telephone.
In the Bell telephone, now used with the Blake transmitter [which
differs somewhat from the arrangement I shall now describe] a bar magnet
has a portion of its length wound with very fine insulated wire. Across
the opposite end of this polarized [Footnote: "Polarized" means
magnetized; having the two poles of a permanent magnet. The term is
frequently used in descriptions of electrical appliances. Instead of
using the terms _positive_ and _negative_, it is also
customary to speak of the "North" or the "South" of a magnet, battery or
circuit.] magnet, crosswise to it, and very close, there is placed a
diaphragm of thin sheet iron. This is held only around its edge, and its
center is free to vibrate toward and from the end of this polarized
magnet. This thin disc of iron, therefore, follows the movements, the
"soundwaves," of the air against it, which are caused by the human
voice. We have an instance of apiece of soft iron moving toward, and
away from, a magnet. It moves with a rapidity and violence precisely
proportioned to the tones and inflections of the voice. Those movements
are almost microscopic, not perceptible to the eye, but sufficient.
The approaching and receding have made a difference, in the quality of
the magnet. Its magnetism has been increased and diminished, and the
little coil of insulated wire around it has felt these changes, and
carried them as impulses over the circuit of which it is a part. In that
circuit, at the other end, there is a precisely similar little insulated
coil, upon a precisely similar polarized magnet. These impulses pass
through this second coil, and increase or diminish the magnetism in the
magnet round which it is coiled. That, in turn, affects by magnetic
attraction the diaphragm that is arranged in relation to its magnet
precisely as described for the first. The first being controlled as to
the extent and rapidity of its movements by the loudness and other
modifications of the voice, the impulses sent over the circuit vary
accordingly. As a consequence, so does the strength of the magnet whose
coil is also in the circuit. So, therefore, does its power of attraction
over its diaphragm vary. The result is that the movements that are
caused in the first diaphragm by the voice, are caused in the second by
an _attraction_ that varies in strength in proportion to the
vibrations of the voice speaking against the first diaphragm.
This is the theory of the telephone. The sounds are not carried, but
_mechanically produced_ again by the rattle of a thin piece of iron
close to the listener's ear. The voice is full, audible, distinct, as we
hear it naturally, and as it impinges upon the transmitting diaphragm.
In reproduction at the receiving instrument it is small in volume;
almost microscopic, if the phrase may be applied to sound. We hear it
only by placing the ear close to the diaphragm. It will be seen that
this is necessarily so. No attempts to remedy the difficulty have so far
been successful. There is no means of reproducing the volume of the
voice with the minute vibrations of a little iron disc.
In actual service an electro-magnet is used instead of, or in addition
to, the bar magnets described above. A steady flow from a battery is
passed through an instrument which throws this current into proper
vibrations by stopping the flow of the current at each interval between
impulses. There is a piece of carbon between the diaphragm and its
support. The wires are connected with the diaphragm and its support, and
the current passes through the carbon. When the diaphragm vibrates, the
carbon is slightly compressed by it. Pressure reduces its resistance,
and a greater current passes through it and over the wires of the
circuit for the instant during which the touch remains. This is the
Blake transmitter. It should be explained that carbon stands low on the
list of conductors of electricity. The more dense it is, the better
conductor. The varying pressures of the diaphragm serve to produce this
varying density and the consequent varying impulses of the current which
effect the receiving diaphragm.
The transmitter, as above described, is in the square box, and its round
black diaphragm may be seen behind the round hole into which one talks.
[Footnote: Shouting into a telephone doubtless comes of the idea,
unconscious, that one is speaking to a person at a distance. To speak
distinctly is better, and in an ordinary tone.] The receiver is the
trumpet-shaped tube which hangs on its side, and is taken from its hook
to be used. The call-bell has nothing to do with the telephone. It is
operated by a small magneto-generator,--a very near relative of the
dynamo-the current from which is sent over the telephone circuit (the
same wires) when the small crank is turned. Sometimes the question
occurs: "Why ring one's own bell when one desires to ring only that at
the central office?" The answer is that both bells are in the same
circuit. If the circuit is uninterrupted your bell will ring when you
ring the other, and a bell at each end of your circuit is necessary in
any case, else you could not yourself be called.
When the receiving instrument is on its hook its weight depresses the
lever slightly. This slight movement _connects_ the bell circuit
and _disconnects_ the telephone circuit. Take it off the hook and
the reverse is effected.
The long-distance telephone differs from the ordinary only in larger
conductors, improved instruments, and a metallic circuit--two wires
instead of the ordinary single wire and ground connections.
[Illustration: TELEAUTOGRAPH TRANSMITTING INSTRUMENT.]
THE TELAUTOGRAPH.--This, the latest of modern miracles in the field of
electricity, comes naturally after the telegraph and telephone, since it
supplements them as a means of communication between individuals. It
also is the invention of Prof. Elisha Gray, who seems to be as well the
author of the name of his extraordinary achievement. It is not the first
instrument of the kind attempted. The desire to find a means of writing
at a distance is old. Bain, of Edinburgh, made a machine partially
successful fifty years ago. Like the telegraph as intended by Morse,
there was the interposition of typesetting before a message could be
sent. It did not write, or follow the hand of the operator in writing,
though it did reproduce at the other end of the circuit in facsimile the
faces of the types that had been set by the sender. It was a process by
electrolysis, well understood by all electricians. Several of this
variety of writing telegraphs have been made, some of them almost
successful, but all lacking the vital essential. [Footnote: The lack of
_one vital essential_ has been fatal to hundreds of inventions.
Inventors unconsciously follow paths made by predecessors. The entire
class of transmitting instruments must dispense with tedious
preliminaries, and must use _words_. Vail accomplished this in
telegraphy. Bell and others in the telephone, and Gray has borne the
same fact in mind in the present development of the telautograph.] In
1856 Casselli, of Florence, made a writing telegraph which had a
pendulum arrangement weighing fourteen pounds. Only one was ever made,
but it resulted in many new ideas all pertaining to the facsimile
systems--the following of the faces of types--and all were finally
abandoned.
The invention of Gray is a departure. The sender of a message sits down
at a small desk and takes up a pencil, writing with it on ordinary paper
and in his usual manner. A pen at the other end of the circuit follows
every movement of his hand. The result is an autograph letter a hundred
miles or more away. A man in Chicago may write and sign a check payable
in Indianapolis. Personal directions may be given authoritatively and
privately. As in the case of the telephone, no intervening operator is
necessary. No expertness is required. Even the use of the alphabet is
not necessary. A drawing of any description, anything that can be traced
with a pen or pencil, is copied precisely by the pen at the receiving
desk. The possibilities of this instrument, the uses it may develop, are
almost inconceivable. It might be imagined that the lines drawn would be
continuous. On the contrary, when the pen is lifted by the writer at the
sending desk it also lifts itself from the paper at that of the
receiver.
The action of the telautograph depends upon the variations in magnetic
strength between two small electro-magnets. It has been seen that an
electro-magnet exerts its attractive force in proportion to the current
which passes through its coil. To use a phrase entirely non-technical,
it will "pull" hard or easy in proportion to the strength of the passing
current. This fact has been observed as the cause of action in the
telephone, where one diaphragm, moved by the air-vibrations caused by
the voice, causes a varying current to pass over the wire, attracting
the other diaphragm less or more as the first is moved toward or away
from its magnet. In the telautograph the varying currents are caused not
by the diaphragm influenced by the voice, but _by a pencil moved by
the hand_.
To show how these movements may be caused let us imagine a case that may
occur in nature. It is an interesting mechanical study. There is an
upright rush or reed growing in the middle of a running stream. The stem
of this rush has elasticity naturally; it has a tendency to stand
upright; but it bends when there is a current against it. It is easy
enough to imagine it bending down stream more or less as the current is
more or less strong.
Imagine now another stream entering the first at right angles to it, and
that the rush stands in the center of both currents. It will then bend
to the force of the second stream also, and the direction in which it
will lean will be a compromise between the forces of the two. Lessen the
flow of the current in one of the streams, and the rush will bend a
little less before that current and swing around to the side from which
it receives less pressure. Cut off either of the currents entirely, and
it will bend in the direction of the other current only. In a word,
_if the quantity or strength of the current of both streams can be
controlled at will, the rush can be made to swing in any direction
between the two, and its tip will describe any figure desired, aided, of
course, by its own disposition to stand upright when there is no
pressure_.
Let us imagine the rush to be a pen or pencil, and the two streams of
water to be two currents of electricity having power to sway and move
this pencil in proportion to their relative strength, as the streams did
the rush. Imagine further that these two currents are varied and changed
with reference to each other by the movements of a pen in a man's hand
at another place. It is an essential part of the mechanism of the
telautograph, and the movement is known among mechanicians as
"compounding a point."
Gray, while using the principles involved in compounding a point, seems
to have discarded the ways of transmitting magnetic impulses of varying
strength commonly in use. His method he calls the "step-by-step"
principle, and it is a striking example of what patience and ingenuity
may accomplish in the management of what is reputedly the most elusive
and difficult of the powers of nature. The machine was some six years in
being brought into practical form, and was perfected only after a long
series of experiments. In its operation it deals with infinitesimal
measurements and quantities. The first attempts were on the "variable
current" system, which was later discarded for the "step-by-step" plan
mentioned.
In writing an ordinary lead pencil may be used. From the point of this
two silk cords are extended diagonally, their directions being at right
angles to each other, and the ends of these cords enter openings made
for them in the cast iron case of the instrument on each side of the
small desk on which the writing is done.
Inside the case each cord is wound on a small drum which is mounted on a
vertical shaft. Now if the pencil-point is moved straight upward or
downward it is manifest that both shafts will move alike. If the
movement is oblique in any direction, one of the shafts will turn more
than the other, and the degree of all these turnings of each shaft in
reference to the other will be precisely governed by the direction in
which the pencil-point is moved.
[Illustration: DIAGRAM OF MECHANICAL TELAUTOGRAPH. BOW-DRILL
ARRANGEMENT.]
Now, suppose each shaft to carry a small, toothed wheel, and that upon
these teeth a small arm rests. As the wheel turns this arm will move as
a pawl does on a ratchet. Imagine that at each slight depression between
the ratchet-teeth it breaks a contact and cuts off a current, and at
each slight rise renews the contact and permits a current to pass. This
current affects an electro-magnet--one for each shaft--at the receiving
end, and each of these magnets, when the current is on, attracts an
armature bearing a pawl, which, being lifted, allows the notched wheel,
upon which it bears, to turn _to the extent of one notch_. The
arrangement may be called an electric clutch, that may be arranged in
many ways, and the detail of its action is unimportant in description,
so that it be borne in mind that _each time a notch is passed in
turning the shaft by drawing upon or relaxing the cords attached to the
pencil-point_, an impulse of electricity is sent to an electro-magnet
and armature which allows _a corresponding wheel and its shaft to turn
one notch, or as many notches, as are passed at the transmitting
shaft_. In moving the pencil one inch to one side, we will suppose it
permits the shaft on which the cord is wound to turn forty notches. Then
forty impulses of electricity have been sent over the wire, the clutch
has been released forty times, and the shaft to which it is attached has
turned precisely as much as the shaft has which was turned, or was
allowed to turn, by the cord wound upon it and attached to the pencil.
It will be remembered that the arrangement is double. There are two
shafts operated by the writer's pencil--one on each side of it. Two
corresponding shafts occupy relative positions in respect to the
automatic pen of the receiving instrument. There are two circuits, and
two wires are at present necessary for the operation of the instrument.
It remains to describe the manner of operating the automatic pen by
connection with its two shafts which are turned by the step-by-step
arrangement described, precisely as much and at the same time as those
of the transmitting instrument are.
[Illustration: WORK OF THE TELAUTOGRAPH. COLUMBIAN EXPOSITION, 1893.]
To each shaft of the receiving instrument is attached an aluminum
pen-arm by means of cords, each arm being fixed, in regard to its shaft,
as a bow drill is in regard to its drill. These arms meet in the center
of the writing tablet, V-shaped, as the cords are with relation to the
writer's pencil in the sending instrument. A small tube conveys ink from
a reservoir along one of the pen-arms, and into a glass tube upright at
the junction of the arms. This tube is the pen. Now, let us imagine the
pencil of the writer pushed straight upward from the apex of the
V-shaped figure the cords and pencil-point make on the writing desk.
Then both the shafts at the points of the arms of the V will rotate
equally. [Footnote: See diagram of mechanical Telautograph, and of bow
drill. In the latter, in ordinary use, the stick and string; rotate the
spool. Rotating the spool will, in turn, move the stick and string, and
this is its action in the pen-arms of the Telautograph.] The number of
impulses sent from each of these shafts, by the means explained, will be
equal. Each of the shafts of the receiving instrument will rotate alike,
and each draw up its arm of the automatic pen precisely as though one
took hold of the points of the two legs of the V, and drew them apart to
right and left in a straight line. This moves the apex of the V, with
its pen, in a straight line upward at the same time the writer at the
sending instrument pushed his pencil upward. If this one movement,
considered alone, is understood, all the rest follow by the same means.
This is, as nearly as it may be described without the use of technical
mechanical terms, the principle of the telautograph. It must be seen
that all that is necessary to describe any movement of the sender's
pencil upon the paper under the receiving pen is that the rotating
upright shafts of the latter should move precisely as much, and at the
same time, with those two which get their movement from the wound cords
and attached pencil-points in the hand of the writer.
Only one essential item of the movement remains. The shafts of both
instruments must be rotated by some separate mechanical agency, capable
of being automatically reversed. By an arrangement unnecessary to
explain in detail, the pencil of the writer lifted from the paper
resting on the metallic table which forms the desk; results in the
automatic lifting of the pen from the paper at the receiving desk.
* * * * *
Prof. Elisha Gray was born in 1835, in Ohio. He was a blacksmith, and
later, a carpenter. But he was given to chemical and mechanical
experiments rather than to the industries. When twenty-one, he entered
Oberlin College, remaining there five years, and earning all the money
he spent. He devoted his time chiefly to studies of the physical
sciences. As a young man he was an invalid. Later he was not remarkably
successful in business, failing several times in his beginnings. His
first invention was a telegraph self-adjusting relay. It was not
practically successful. Afterwards he was employed with an electrical
manufacturing company at Cleveland and Chicago. Most of his earlier
inventions in the line of electrical utility are not distinctively
known. He has never been idle, and they all possessed practical merit.
For many years before he was known as the wizard of the telautograph, he
was foremost in the ranks of physicists and electricians. He is not a
discoverer of great principles, but is professionally skillful and
accomplished, and eminently practical. His every effort is exerted to
avoid intricacy and clumsiness in machinery. In 1878 he was awarded the
grand prize at the Paris Exposition, and was given the degree of
Chevalier and the decorations of the Legion of Honor by the French
Government, and again in 1881, at the Electrical Exposition at Paris, he
was honored with the gold medal for his inventions. He secured the
degree of A.M. at Oberlin College, and was the recipient of the degree
of Ph.D. from the Ripon (Wis.) College. For years he was connected with
those institutions as non-resident Lecturer in Physics. Another
University gave him the degree of LL.D. He is a member of the American
Philosophical Society, the Society of Electrical Engineers of England,
and the Society of Telegraph Engineers of London. He received an award
and a certificate from the Centennial Exposition for his inventions in
electricity.
The same lesson is to be gathered from his career, so far, that is given
by the life of every noted American. It means that money, family,
prestige, have no place as leverages of success in any field. The rule
is toward the opposite. The qualities and capacities that win do so
without these early advantages, and all the more surely because there is
an inducement to use them. There is no "luck."