the whole domain of electrical science to new investigation, and
brought in their train a host of wonderful results, growing more and
more practical each year, and pointing the way more and more clearly to
the commercial value of electricity as a familiar, inexhaustible, and
irresistible power. Thus, in 1801, Nicholson showed that an electric
current from a voltaic pile would, when passed through salt water,
decompose the water and resolve it into its two original gases, oxygen
and hydrogen. In 1807, Sir Humphrey Davy, carrying electricity further
into the domain of chemistry, showed, by means of the electric current,
that various metallic substances embraced in the earth’s crust, and
before his time supposed to be elementary, were really dissoluble and
easily resolved into their component parts, whether solids, or gases,
or both. Two years later, in 1809, he made the equally momentous
discovery of something which was to prove a veritable _sit lux_, “Let
there be light,” for the nineteenth century, and illuminate it beyond
all others. Though it had been known almost from the date of the
first voltaic pile that, when the ends of its two conducting wires
were brought close together, a spark was seen to leap in a curved or
arc line from one wire to the other, which phenomenon was known as
the voltaic arc, it remained for Davy to exhibit this arc in all the
beauty of a brilliant light by using two charcoal (carbon) sticks or
electrodes, instead of the wires, at the point of close approach. Here
was the first principle of the after-evolved arc light to be found
by the end of the century in every large city, and to prove such a
source of comfort and safety for their millions of inhabitants. This
principle was simply that a stream of electricity pouring along a
conducting wire will, when interrupted by a substance such as carbon
(charcoal), which is a slow conductor, throw off a bright light at the
point of interruption. The phenomenon has been very aptly likened to a
running stream of water in whose bed a stone has been placed. The stone
obstructs the flow of water. The water remonstrates by an angry ripple
and excited roar. In Davy’s experiment with the pieces of charcoal,
both became intensely hot while the electricity was making its
brilliant arc leap from one to the other, and would, of course, soon
be consumed. He, therefore, in showing the principle of a permanent
luminant, failed to demonstrate its practical possibilities. These last
were not to be attained till the nineteenth century was well along, and
only after very numerous and very baffling attempts.
Between 1810 and 1830, many important laws governing electrical
phenomena were discovered, which tended greatly to render the
science more exact, and to give it commercial direction. Oersted, of
Denmark, discovered a means of measuring the strength and direction
of an electric current. Ampère, of France, discovered the identity
of electricity and what had before been called galvanism. Ritchie,
of England, made the first machine by which a continuous motion was
produced by means of the attractions and repulsions between fixed
magnets and electro-magnets. This machine was an early suggestion of
the dynamo and motor of the coming years of the century. It meant that
electricity was a source of power, as well as of other phenomenal
things.
In speaking of the electro-magnet in connection with Ritchie’s machine,
it is proper to say that the electro-magnet was probably discovered
between 1825 and 1830, but precisely by whom is not known. It differs
from the natural magnet, or the permanent steel horseshoe magnet, and
consists simply of a round piece of soft iron, called a core, around
which are wrapped several coils of fine wire. When an electric current
is made to pass through this wrapping of wire, called the helix, the
iron core becomes magnetized, and has all the power of a permanent
magnet. But as soon as the electric current ceases, the magnetic
power of the core is lost. Hence it is called an electro-magnet, or a
temporary magnet, to distinguish it from a permanent magnet.
[Illustration: INDUCTION COIL.]
While the discovery of the electro-magnet was very important in the
respect that it afforded great magnetic power by the use of a limited
or economic galvanic force, or, in other words, by the use of smaller
and fewer Voltaic batteries, it was not until Faraday began his
splendid series of electrical discoveries, in 1831, that a new and
exhaustless wellspring of electricity was found to lay at the door
of science. Faraday’s prime discovery was that of the induction of
electric currents, or, in other words, of manufacturing electricity
directly from magnetism. He began his experiments with what became
known as an induction coil, which, though then crude in his hands, is
the same in principle to-day. It consists of an iron core wrapped
with two coils of insulated wire. One coil is of very lengthy, thin
wire, and is called the secondary coil. The other is of short, thick
wire, and is called the primary. When a magnetic current is passed
through the primary coil, with frequent makes and breaks, it induces
an alternating current of very high tension in the secondary coil,
thus powerfully increasing its effects. In Faraday’s further study of
electric induction, he showed that when a conductor carrying a current
was brought near to a second conductor it induced or set up a current
in this second. So magnets were found to have a similar effect upon one
another.
[Illustration: MAGNETIC FIELDS OF FORCE.]
The secret of these phenomena was found to lie in the fact that
a magnet, or a conductor carrying a current, was the centre of a
field of force of very considerable extent. Such a field of force
can be familiarly shown by placing a piece of glass or white paper
sprinkled with fine iron filings upon the poles of a magnet. The
filings will be drawn into concentric circles, whose extent measures
the magnet’s field of force. So also the extent of the field of force
surrounding a conductor carrying a current may be familiarly shown.
In these instances the filings brought within the fields of force are
magnetized. So would any other conducting substance be, and would
become capable of carrying away as an independent current that which
had been induced in it. Here we have the essential principle of the
modern dynamo-electric machine, commonly called simply dynamo. Faraday
actually constructed a dynamo, which answered very well for his
experiments, but failed in commercial results because the only source
of energy he could draw upon in his time was that supplied by the
rather costly voltaic cells.
During Faraday’s time and subsequently, electricians in Europe and the
United States were active in formulating further laws relative to the
nature, strength, and control of electrical currents, and each year was
one of preparation for the coming leap of electrical science into the
vast realm of commercial convenience and profit.
III. THE TELEGRAPH.
From the date of the discovery that electricity could be conducted
to a distance, dreams were indulged that it could be made a means of
communicating intelligence. In the eighteenth century, many attempts
were made to carry intelligent signals over electric wires. Some of
these were quite ingenious, but in the end failures, because the
old-fashioned frictional electricity was the only kind then known and
employed. Even after the discovery of the voltaic cell or battery,
which afforded an ample supply of chemical electricity to operate a
telegraphic apparatus, the time was not ripe for successful telegraphy,
for up till 1830 no battery had been produced that was sufficiently
constant in its operation to supply the kind of current required.
For feasible telegraphy, two important steps were yet necessary. One
was the discovery of the electro-magnet, 1825–30. The other was the
discovery of the Daniell’s battery or cell, in 1836, by means of which
a constant electric current could be sustained for a long time.
[Illustration: DANIELL’S CELLS.]
But even before these two indispensable requisites had been supplied
by human genius, much had been done to develop the mechanical methods
of conveying intelligence. In 1816, Ronalds, of England, constructed
a telegraph by means of which he operated a system of pith-ball
signals which could be understood. In 1820, Ampère suggested that the
deflection of the magnetic needle by an electric current might be
turned to account in imparting intelligence at a distance. In 1828,
Dyar, of New York, perfected a telegraph by means of which he made
tracings and spaces upon a piece of moving litmus paper, which tracings
and spaces could be intelligently interpreted through a prearranged
code. A little later, 1830, Baron Schilling constructed a telegraph
which imparted motion to a set of needles at either end.
[Illustration: MORSE TELEGRAPH AND BATTERY.]
From this time up to 1837, which last year was a memorable one in the
history of telegraphy, the genius of such distinguished men as Morse
in America, Wheatstone and Cooke in England, and Steinhill in Munich,
was brought to bear on the further evolution of the telegraph. While
all these names have been associated with the invention of the first
practical telegraph, it is impossible, with justice, to rob that of
Morse of the distinguished honor. Morse conceived his invention on
board the ship Surry, while on a voyage from Havre to New York, in
October, 1832. It consisted, as conceived, of a single circuit of
conductors fed by some generator of electricity. He devised a system
of signs, which was afterwards improved into the Morse alphabet,
consisting of dots or points, and spaces, to represent numerals. These
were impressed upon a strip of ribbon or paper by a lever which held
at one end a pen or pencil. The paper or ribbon was made to move along
under the pencil or pen at a regular rate by means of clockwork. In
accordance with these conceptions, Morse completed his instrument
and publicly exhibited it in 1835. He gave it further publicity, in
much improved form, in 1837. In this form it was entirely original in
the important respects that the ribbon or paper was made to move by
clockwork, while a pen or pencil gave the impressions, thus preserving
a permanent record of the message conveyed.
[Illustration: SAMUEL FINLEY BREESE MORSE.]
Though under systems less original and effective than that of Morse,
a first actual telegraph had been operated between Paddington and
Drayton, England, a distance of 13 miles, in 1839, and one at Calcutta,
India, for a distance of 21 miles, it was not until 1844 that the
world’s era of practical telegraphy actually set in under the Morse
system, which speedily superseded all others. In that year, amid the
jeers of congressmen and the adverse predictions of the press, Morse
erected the first American telegraph line in America, between Baltimore
and Washington, a distance of 40 miles, and, to the confusion of all
detractors, sent the first message over it on May 27 of that year. From
that date the fame of Morse was established at home, and soon became
world-wide. His system of telegraphy, with slight modifications, became
that of all civilized countries.
[Illustration: CYRUS W. FIELD.]
As was to be expected in a century so full of enterprise as the
nineteenth, a science so attractive, so useful to civilization, so
commercially valuable, so full of possibilities, as telegraphy, could
not remain at rest. Everywhere it stimulated to improvement and new
invention and discovery; and as the century progressed, it witnessed
in steady succession the wonders of what became known as duplex
telegraphy, that is, the sending of different messages over the same
wire at the same time. Again, the century witnessed the invention of
quadruplex telegraphy, that is, the sending of four separate messages
over the same wire, two in one direction and two in another. This was
followed by the invention of Gray’s _harmonic system_, by means of
which a number of messages greater than four are transmitted at the
same time over the same wire; and this again by Delaney’s _synchronous
multiplex system_, by means of which as many as 72 separate messages
have been sent over the same wire at the same time, either all in one
direction, or some in one direction and the rest in an opposite.
For a time successful telegraphy was limited to overland spaces, the
conductors or wires, consisting of iron or copper, being insulated
where they passed the supporting poles. In the cities, supporting
poles proved to be unsightly and dangerous, and they were succeeded
by underground conduits carrying insulated wires. In 1839, we read of
what may be reckoned the first successful experiment in telegraphing
under water by means of an insulated wire, or cable, as a conductor.
The experiment was tried at Calcutta, and under the river Hugli. In
1842, Morse experimented at New York with an under-water cable, and
showed that a successful submarine telegraphy was practical. In 1848,
a cable, insulated with gutta-percha, was laid under water between New
York and Jersey City, and successfully operated. In 1851, a submarine
cable was laid and successfully operated under the English Channel.
An enterprising American, Cyrus W. Field, of New York, now took up
the subject of submarine telegraphy, and suggested a cable under the
ocean between Ireland and Newfoundland. One was laid in 1857, but it
unfortunately parted at a distance of three hundred miles from land. A
second was laid under Mr. Field’s auspices in 1858, but the insulation
proved faulty, and after working imperfectly for a month, it gave out
entirely.
[Illustration: OCEAN CABLE.]
These disasters, though furnishing much valuable experience, checked
the enterprise of submarine telegraphy for a number of years. Not
until 1861, when a deep-sea cable was successfully laid and operated
between Malta and Alexandria, and in 1864, when one was laid across the
Persian Gulf, did enterprise gain sufficient courage to dare another
attempt to cable the Atlantic. In 1865, that attempt was made. Again
the cable broke, but this did not dissuade from another and successful
attempt in 1866. This signal triumph was the forerunner of others,
equally important to international commerce and the world’s diplomacy.
Countries far apart, and isolated by oceans, have, by means of deep-sea
cables, been brought into intimate relation, and made sharers of one
another’s intelligence, enterprise, and civilizing instincts. What
the overland telegraph has done toward bringing local states and
communities into contact, the submarine cable has done for the remote
nations.
In form, an ocean cable differs much from the simple wire which
constitutes the conductor of an overland or even underground telegraph.
It is made in many ways, but mostly with a central core of numerous
copper wires, which are more flexible than a single wire. These are
thickly covered with an insulating material, such as gutta-percha,
after first being heavily wrapped in tarred canvas or like material.
The central cores may be one, two, three, or even more in number. Where
a cable is likely to be subjected to the abrasion of ship-bottoms,
rocks, or anchors, it has an outer covering or guard composed of
closely united steel wires. In submarine telegraphy, the instruments
used in sending and receiving the message are very much more ingenious,
delicate, and costly than in overland telegraphy.
Whereas at the beginning of the nineteenth century electric telegraphy
was an unknown science, and even up to the middle of the century was
of limited use and doubtful commercial value, nevertheless the end of
the century witnesses in its growth and application one of its most
stupendous marvels. From the few miles of overland wires in 1844, the
total mileage of the century has expanded to approximately 5,000,000,
and the submarine to 170,000. A single company (the Western Union) in
the United States operates 800,000 miles of wire, conveying 60,000,000
messages per year, while throughout the world more than 200,000,000
messages per year serve the purposes of enlightened intercourse. The
capital employed reaches many hundreds of millions of dollars.
The close of the nineteenth century opened possibilities in telegraphy
that may be classed as startling in comparison with its previous
attainments. It would seem that the intervention of the familiar
conducting wire is not absolutely necessary to the transmission of
intelligence. The old and well-established principle of induced
currents has lately been turned to account in what is termed
“telegraphy without wires.” As an instance, a telegraph wire, when
placed close alongside of a railroad track, will take up and convey to
and from the stations the induced pulsations of a magneto-telephone
placed within a passing car, and connected to the metallic roof of the
car. This system has been put to practical use on at least one railway,
and pronounced feasible.
But a greater marvel than this springs from the discovery of Hertz,
about 1890, that every electrical discharge is the centre of
oscillations radiating indefinitely through space. The phenomenon
is likened to the dropping of a stone in a placid lake. Concentric
undulations of the water are set up,—little waves,—which gradually
enlarge in diameter, and affect in greater or less degree the entire
surface. Could an apparatus be invented to detect and direct the
oscillations made in space by an electric generator,—to perceive, as
it were, the ether undulations, just as the eye notes those on the
lake’s surface?
In 1891, Professor Branley found that the electric vibrations in ether
could be detected by means of fine metallic filings. No matter how good
a conductor of electricity the metal in mass might be, when reduced
to fine filings or powder it offered powerful resistance to a passing
current; in other words, became a very poor conductor. An electric
discharge or spark near the filings greatly decreased their resistance.
If the filings were jarred, their original resistance was restored.
Branley placed his filings in a tube, into either end of which wires
were passed. These were connected with a galvanometer. Ordinarily, the
resistance of the filings was such as to prevent a current passing
through them, and the galvanometer remained unaffected. But when an
electric spark was emitted near the tube, the resistance was so much
decreased that the current passed readily through the filings, and was
detected by the galvanometer. This is simply equivalent to saying that
the discharge of the electric spark made the filings to cohere and
become a better conductor than when lying loosely in the tube. Here,
then, was opportunity for an instrument which had but to regulate the
number of sparks and indicate the presence of the electric waves in
order to produce dots and dashes similar to those used in the common
telegraph. Such an instrument was brought nearest to perfection by
Signor Marconi, a young Italian, in 1896. With it he succeeded in
sending electric waves through ether or space, and without the use of
wires, a distance of four miles, upon Salisbury Plain, England. Later,
he transmitted messages by means of space (wireless) telegraphy across
Bristol Channel, a distance of 8.7 miles, and subsequently across the
English Channel, a distance of 18 miles. Mr. W. J. Clarke, of America,
has improved upon Marconi’s methods of space telegraphy, and shown some
remarkable results. Whether space telegraphy will eventually supersede
that by wires is one of the problems that time only can solve. But
such are the possibilities of electrical science that we may well be
prepared for more wonderful revelations than any yet made.
[Illustration: THE GREAT EASTERN LAYING AN OCEAN CABLE.]
IV. HELLO! HELLO!
Telegraph (Gr. _tele_, far, and _graphein_, to write) implies the
production of writing at a distance by means of an electric current
upon a conductor. Telephone (Gr. _tele_, far, and _phone_, sound)
implies the production of sound at a distance by the same means, though
the word telephone was in early use to describe the transmission of
sound by means of a rod or tightly stretched string connecting two
diaphragms of wood, membrane, or other substance. This last plan of
transmitting sound came to be known as the string telephone, and it
retained this name until the invention of the electric telephone.
Like the electric telegraph, the electric telephone was an evolution.
The string telephone, in the hands of Wheatstone, showed, as early as
1819, that the vibrations of the air produced by a musical instrument
were very minute, and could be transmitted hundreds of yards by means
of a string armed with delicate diaphragms. But while the string
telephone served to confirm the fact that sounds are vibrations of
the atmosphere which affect the tympanum of the ear, it remained but
a toy or experimental device till after electric telegraphy became
an accepted science, that is, in the year 1837 and subsequently. One
of the earliest steps toward the evolution of the electric telephone
was taken by Mr. Page, of Salem, Mass., in 1837, who discovered
that a magnetic bar could emit sounds when rapidly magnetized and
demagnetized; and that those sounds corresponded with the number of
currents which produced them. This led to the discovery, between
1847 and 1852, of several kinds of electric vibrators adapted to the
production of musical sounds and their transmission to a distance.
All this was wonderful and momentous, but a little while had still
to elapse before one arose bold enough to admit the possibility of
transmitting human speech by electricity. He came in 1854, in the
person of Charles Bourseul, of Paris, who, though as if writing
out a fanciful dream, said, “We know that sounds are produced by
vibrations, and are adapted to the ear by the same vibrations which
are reproduced by the intervening medium. But the intensity of the
vibrations diminishes very rapidly with the distance, so that it is,
even with the aid of speaking-tubes and trumpets, impossible to exceed
somewhat narrow limits. Suppose that a man speaks near a movable disk,
sufficiently flexible to lose none of the vibrations of the voice, that
this disk alternately makes and breaks the current from a battery,
you may have at a distance another disk, which will at the same time
execute the same vibrations.”
[Illustration: A STRING TELEPHONE.]
Bourseul further showed that the sounds of the voice thus reproduced
would have the same pitch, but admitted that, in the then present
state of acoustic science, it could not be affirmed that the syllables
uttered by the human voice could be so reproduced, since nothing was
known of them, except that some were uttered by the teeth, others by
the lips, and so on. The status of the telephone then, according to
Bourseul, was that voice could be reproduced at a distance at the pitch
of the speaker, but that something more was needed to transmit the
delicate and varied intonations of human speech when it was broken into
syllables and utterances. To transmit simply voice was one thing; to
transmit the _timbre_ or quality of speech was another.
[Illustration: THOMAS ALVA EDISON.]