Part 4

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.]

Bourseul made plain the problem that was still before the investigator. And now comes one of the most remarkable episodes in the history of electricity,—a chapter of mingled shame and glory. In the village of Eberly’s Mills, Cumberland County, Pa., lived a genius by the name of Daniel Drawbaugh, who had made a study of telephony up to the very point Bourseul had left it. He had transmitted musical sound, sound of the voice, and other sounds in the same pitch. He had said that this was all that could be done till some means was discovered of holding up the constant onward flow of the electric current along a conducting wire by introducing into such flow a variable resistance such as would impart to simple pitch of voice the quality or _timbre_ of human speech. Drawbaugh achieved this in his simple workshop as early as 1859–60, according to evidence furnished to the United States Supreme Court at the celebrated trial of the cases which robbed him of the right to his prior invention. He did it by introducing into the circuit a small quantity of powdered charcoal confined in a tumbler, through which the current was passing. The charcoal, being a poor conductor and in small grains, offered just that kind of variable resistance to the current necessary to reproduce the tones and syllables of speech. He transmitted speech between his shop and house, and proved the success he had met with before audiences in New York and Philadelphia. But he neglected to care for the commercial side of his discovery, though many of his patents antedated those which contributed to deprive him of deserved honor and profit.

In 1861, Reis, of Germany, came into notice as the inventor of a telephone which transmitted sound very clearly, but failed to reproduce syllabified speech. However, the principle and shape of his transmitter and receiver were accepted by those who followed him. Two men now came upon the scene who had reached the conclusion already arrived at by Drawbaugh, and who became rivals over his head for the honor and profit of an invention by means of which the quality of the voice in speaking could be transmitted. These two were Elisha Gray, of Chicago, and Alexander Graham Bell, of Boston. Their respective devices seem to have been akin, and to have been presented to the patent office almost simultaneously; so nearly so, at least, as to make them a part of that long, costly, and acrimonious legal contention over priority of invention which did not end till 1887.

Both Bell and Gray reached the conclusion that the transmission of articulate speech was impossible unless they could produce electrical undulations corresponding exactly with the vibrations of the air or sound waves. They brought this similarity about by introducing a variable resistance into the electric current by means of an interposing liquid, just as Drawbaugh had done years before with his tumbler of powdered charcoal. Bell exhibited his instrument with comparative success at the Centennial Exhibition in 1876 in Philadelphia; but much had yet to be done to perfect a telephone of real commercial value.

The years 1877–78 were years of great activity among electricians, whose prime object was to perfect a telephone transmitter and receiver, by means of whose mutual operations at opposite ends of a circuit all the modulations of speech could be preserved and passed. To this end Berliner introduced into a transmitter or sender the then well-known principle of the microphone (Gr. _mikros_, small, _phone_, sound), which magnified the faint sounds by the variation in electrical resistance, caused by variation of pressure at loose contact between two metal points or electrodes. Edison quickly followed with a similar transmitter or sender, in which one of the electrodes was of soft carbon, the other of metal. Then came (1878) Hughes and Blake with senders, in which both of the electrodes were of hard carbon. Subsequently came other and rapid modifications of the sender, both in the United States and Europe, till the form of telephone now in popular use was arrived at, and which, strange to say, is, in its method of securing the necessary variable resistance in the circuit, quite like that employed by Mr. Drawbaugh; to wit, the introduction of fine carbon granules into a small metal cup just behind the vibrating diaphragm or disk of the sender. The circuit goes into the diaphragm in front, passing through the carbon granules and out through the back of the instrument. The action of talking into the sender causes the granules to be agitated, thus opening and closing the circuit and producing the conditions necessary to the transmission of articulate speech. The diaphragm or disk is the very thin covering of the cup containing the granules. It is sometimes made of carbon, but generally of hard metal, as steel. On being struck by the sound waves of the voice, it vibrates to correspond. The same vibrations are reproduced in the receiver at the opposite end of the circuit, and thus one listens to the phenomenon of transmitted human speech. The current for telephonic purposes is furnished by one or more batteries or cells, whose effect is heightened by the presence of an induction coil. The tendency now is to make “bipolars”—two contacts at the diaphragm—in place of a single contact. This style is becoming more in vogue in order to meet the demands of long-distance work. To each telephone is attached a generator or device for ringing a little bell as a signal that some one wishes to communicate. To such perfection have telephones been brought that it is quite possible to converse intelligibly at the distance of a thousand miles, with a less satisfactory service at twice or thrice that distance. The possibilities of clear speech-transmission at indefinite distance are without measure. Like the telegraph, the telephone has opened an immense and profitable industry, involving hundreds of millions of dollars. At the end of the century it is, unfortunately, monopolistic; but the time is near when a reasonable charge for service will enable every business house to communicate with its customers, and when even the remote corners of counties will be brought into touch with their capitals and with one another. Along the lines of civilizing contact the telephone fairly divides the wonders of the century with the telegraph, while for intimate intellectual communication it is a triumph of genius without parallel. It is the dispenser of speech in city, town, and village; in factory and mine, in army and navy; throughout government departments; and in Budapest, Hungary, it is a purveyor of general news, like the newspaper, for the “Telephone Gazette” of that city has a list of regular subscribers, to whom it transmits, at private houses, clubs, cafes, restaurants, and public buildings, its editorials, telegrams, local news, and advertisements.

A very natural outgrowth of the telephone was that curious invention known as the phonograph (Gr. _phone_, sound, and _graphein_, to write). It is not only an instrument for writing or preserving sound, but for reproducing it. As a simple recorder of sound, it was an instrument dating as far back as 1807, when Dr. Young showed how a tuning-fork might be made to trace a record of its own vibrations. But Young’s thought had to go through more than half a century of slow evolution before the modern phonograph was reached; for in the phonautograph of Scott, the logographs of Barlow and Blake, and the various other attempts up to 1877 to make and preserve tracings of speech, there were no successful means of reproducing speech from those tracings hit upon.

[Illustration: A GRAPHOPHONE.]

In that year (1877), Edison, in striving to make a self-recording telephone by connecting with its diaphragm or disk a stylus or metal point which would record its vibrations upon a strip of tinfoil, accidentally reversed the motion of the tinfoil so that the tracings upon it affected the stylus or tracing-point in an opposite direction. To his surprise, he found that this reverse motion of the tinfoil, tickling, as it were, the stylus oppositely, reproduced the sounds which had at first agitated the diaphragm. It was but a step now to the production of his matured phonograph in 1878. He made a cylinder with a grooved surface, over which he spread tinfoil. A stylus or fine metal point was made to rest upon the tinfoil, so as to produce a tracing in it, following the grooves in the cylinder when the latter was made to revolve. This stylus was connected with the diaphragm of an ordinary telephone transmitter. When one spoke into the transmitter, that is, set the diaphragm to vibrating, the stylus impressed the vibratory motions of the diaphragm, or, in other words, the waves of the exciting sound, in light indentations upon the tinfoil. In order to reproduce the sounds thus registered in the tinfoil of the cylinder, it was made to revolve in an opposite direction under the point of the stylus, and as the stylus was now affected by precisely the same indentations it had first made in the tinfoil, it carried the identical vibrations it had recorded back to the diaphragm of the telephone, and thus reproduced in audible form the speech that had at first set the diaphragm to vibrating. The speech thus reproduced was that of the original speaker in pitch and quality. Ingenious and wonderful as Edison’s machine was, it was susceptible of improvement, and soon Bell and others came forward with a phonograph in which the recording cylinder was covered with a hardened wax. This was called the graphophone. Again, Berliner improved upon the phonograph by using for his tracing surface a horizontal disk of zinc covered with wax. By chemical treatment, the tracings made in the wax were etched into the zinc, and thus made permanent. Edison made further and ingenious improvements upon his phonograph by attaching hearing tubes for the ear to the sound receiver, and by the employment of an electric motor to revolve the wax cylinder. By the attachment of enlarged trumpets and other devices, every form of modern phonograph has been rendered capable of reproducing in great perfection the various sounds of speech, song, and instrument, and has become a most interesting source of entertainment.

V. DYNAMO AND MOTOR.

Dynamo is from the Greek _dunamis_, meaning power. Motor is from the Latin _motus_, or _moveo_, to move. Dynamo is the every-day term applied to the dynamo-electric machine. Motor is the every-day term applied to the electric motor. The dynamo and motor are quite alike in principle of construction, yet direct opposites in object and effect. Perhaps it might be well to designate both as dynamo-electric machines, and to say that, when such machine is used for the conversion of mechanical energy or power of any kind into electrical energy or power, it is a dynamo. When a reverse result is sought, that is, when electrical energy or power is to be converted into mechanical energy or power, the machine that is used is a motor. In practical use for most purposes they are brought into coöperation, the dynamo being at one end of an electric system, making and sending forth electricity, the motor being at the other end, taking up such electricity and running machinery with it. Both machines were epoch-making in the midst of a wondrous century, and both were results of those marvelous evolutions in electrical science which characterized the earlier years of the century.