WONDERS OF ELECTRICITY
By JAMES P. BOYD, A.M., L.B.
I. AT THE DAWN OF THE CENTURY.
When, in his “Midsummer Night’s Dream,” Shakespeare placed in the mouth of Puck, prince of fairies, the playful speech,—
In forty minutes,”
he had no thought that the undertaking of a boastful and prankish sprite could ever be outdone by human agency. Could the immortal bard have lived to witness the time when the girdling of the earth by means of the electric current became easier and swifter than elfin promise or possibility, he must have speedily remodeled his splendid comedy and denied to the world its delightful, fairy-like features.
An old and charming story runs, that Aladdin, son of a widow of Bagdad, became owner of a magic lamp, by means of whose remarkable powers he could bring to his instant aid the services of an all-helpful genie. When Aladdin wished for aid of any kind, he had but to rub the lamp. At once the genie appeared to gratify his desires. By means of the lamp Aladdin could hear the faintest whisper thousands of miles away. He could annihilate both time and space, and in a twinkling could transfer himself to the tops of the highest mountains. How the charm of this ancient story is lost in the presence of that marvelous realism which marks the achievements of modern electrical science!
The earliest known observations on that subtle mystery which pervades all nature, that silent energy whose phenomena and possibilities are limitless, and before which even the wisest must stand in awe, are attributed to Thales, a scholar of Miletus, in Greece, some 600 years B. C. On rubbing a piece of amber against his clothing, he observed that it gained the strange property of at first attracting and then repelling light objects brought near to it. His observations led to nothing practical, and no historic mention of electrical phenomena is found till the time of Theophrastus (B. C. 341), who wrote that amber, when rubbed, attracted “straws, small sticks, and even thin pieces of copper and iron.” Both Aristotle and Pliny speak of the electric eel as having power to benumb animals with which it comes in contact.
Thus far these simple phenomena only had been mentioned. There was no study of electric force, no recognition of it as such, or as we know it and turn it to practical account to-day. This seems quite strange when we consider the culture and power to investigate of the Egyptians, Phœnicians, Greeks, and Romans. True, a few fairy-like stories of how certain persons emitted sparks from their bodies, or were cured of diseases by shocks from electric eels, are found scattered through their literatures, but they failed to follow the way to electrical science pointed out to them by Thales. Even in the Middle Ages, when a few scientists and writers saw fit to speak of electrical phenomena as observed by the ancients, and even ventured to speculate upon them in their crude way, there were no practical additions made to the science, and the ground laid as fallow as it had done since the creation.
OLD FRANKLIN ELECTRICAL MACHINE.
(By permission of Franklin Institute.)
After a lapse of more than two thousand years from the experiment of Thales, Dr. Gilbert, physician to Queen Elizabeth (A. D. 1533–1603), took up the study of amber and various other substances which, when subjected to friction, acquired the property of first, attracting and then repelling light bodies brought near them. He published his observations in a little book called “De Magnete,” in the year A. D. 1600, and thus became the first author of a work upon electricity. In this unique and initial work upon simple electrical effects, the author added greatly to the number of substances that could be electrified by friction, and succeeded in establishing the different degrees of force with which they could be made to attract or repel light bodies brought near them.
Fortunately for electrical science, and for that matter all sciences, about this time the influence of Lord Bacon’s Inductive Philosophy began to be felt by investigators and scientific men. Before that, the causes of natural phenomena had not been backed up by repeated experiments amounting to practical proofs, but had been accounted for, if at all, by sheer guesses or whimsical reasons. Bacon’s method introduced hard, cold, constant experiment as the only sure means of finding out exactly the causes of natural phenomena; and not only this, but the necessity of series upon series of experiments, each based upon the results of the former, and so continuing, link by link, till, from a comparison of the whole, some general principle or truth could be drawn that applied to all. This inductive method of scientific research gave great impetus to the study of every branch of science, and especially to the unfolding of infallible and practical laws governing the phenomena of nature.
For very many years electrical experiments followed the lines laid down by Dr. Gilbert; that is, the finding of substances that could be excited or electrified by friction. By and by such substances came to be called electrics, and it became a part of the crude electrical science of the time to compute the force with which these electrics, when excited, attracted or repelled other substances near them. Among the ablest of these investigators were Robert Boyle, author of “Experiments on the Origin of Electricity,” Sir Isaac Newton, Otto von Guericke, and Francis Hawksbee, the last of whom communicated his experiments to the English Royal Society in 1705. Otto von Guericke used a hard roll of sulphur as an electric. He caused it to revolve rapidly while he rubbed or excited it with his hand. Newton and Hawksbee used a revolving glass globe in the same way, and thus became the parents of the modern and better equipped electrical machine used for school purposes.
The next step in electrical discovery, and one which marks an epoch in the history of the science, was made by Stephen Gray, of England, in 1729. To him is due the credit of finding out that electricity from an excited glass cylinder could be conducted away from it to objects at a remote distance. Though he used only a packthread as a conductor, he thus carried electricity to a distance of several hundred feet, and his novel discovery opened up what, for the time, was a brilliant series of experiments in England and throughout France and Germany. Out of these experiments came the knowledge that some substances were natural conductors of electricity, while others were non-conductors; and that the non-conductors were the very substances—glass, resin, sulphur, etc.—which were then in popular use as electrics. Here was laid the foundation of those after-discoveries which led to the selection of copper, iron, and other metals as the natural and therefore best conductors of electricity, and glass, etc., as the best insulators or non-conductors.
Up to this time an excited electric, such as a glass cylinder or wheel, had furnished the only source whence electricity had been drawn for purposes of experiment. But now another great step forward was taken by the momentous discovery that electricity, as furnished by the excited but quickly exhausted electric, could be bottled up, as it were, and so accumulated and preserved in large quantities, to be drawn upon when needed for experiment. It is not known who made this important discovery; but by common consent the storage apparatus, which was to play so conspicuous a part in after-investigations, was named the Leyden Jar or Phial, from the city of Leyden in Holland. It consisted of a simple glass jar lined inside and out with tinfoil to within an inch or two of the top, the tinfoil of the inside being connected by a conductor passing up through the stopper of the jar to a metallic knob on top. This jar could be charged or filled with electricity from a common electric, and it had the power of retaining the charge till the knob on top was touched by the knuckle, or some unelectrified substance, when a spark ensued, and the jar was said to be discharged. By conductors attached to the knob, guns were fired off at a distance by means of the spark, and it is said that Dr. Benjamin Franklin ignited a glass of brandy at the house of a friend by means of a wire attached to a Leyden jar and stretched the full width of the Schuylkill River at Philadelphia.
At this stage in the history of eighteenth century electricity there enters a character whose experiments in electricity, and whose writings upon the subject, not only brought him great renown at home and abroad, but perhaps did more to systematize the science and turn it to practical account than those of any contemporary. This was the celebrated Dr. Benjamin Franklin, of Philadelphia, Pa. He showed to the world that electricity was not created by friction upon an electric, but that it was merely gathered there, when friction was applied, from surrounding nature; and in proof of his theory he invaded the clouds with a kite during a thunder-storm, and brought down electricity therefrom by means of the kite-string as a conductor. The key he hung on the string became charged with the electric fluid, and on being touched by an unelectrified body, emitted sparks and produced all the effects commonly witnessed in the discharge of the Leyden jar.
Franklin further established the difference between positive and negative electricity, and showed that the spark phenomenon on the discharge of the Leyden jar was due to the fact that the inside tinfoil was positively electrified and the outside tinfoil negatively. When the inside tinfoil was suddenly drawn upon by a conductor, the spark was simply the result of an effort upon the part of the two kinds of electricity to maintain an equilibrium. By similar reasoning he accounted for the phenomenon of lightning in the clouds, and by easy steps invented the lightning-rod, as a means of breaking the force of the descending bolt, and carrying the dangerous fluid safely to the ground. Here we have not only a practical result growing out of electrical experiments, but we witness the dawn of an era when electricity was to be turned to profitable commercial account. The lightning-rod man has been abroad in the world ever since the days of Franklin.
Thus far, then, electrical science, if science it could yet be called, had gotten on at the dawn of the nineteenth century. No electricity was really known but that produced by friction upon glass, or some other convenient electric. Hence it was called frictional electricity by some, and static electricity by others, because it was regarded as electricity in a state of rest. Though a thing fitted for curious experiment, and a constant invitation to scientific research, it had no use whatever in the arts. An excited electric could furnish but a trivial and temporary supply of electricity. It exhausted itself in the exhibition of a single spark.
II. THE NEW NINETEENTH CENTURY ELECTRICITY.
By a happy accident in 1790, Galvani, of Bologna, Italy, while experimenting upon a frog, discovered that he could produce alternate motion between its nerves and muscles through the agency of a fluid generated by certain dissimilar metals when brought close together. Though this mysterious fluid came to be known as the galvanic fluid, and though galvanism was made to perpetuate his name, it was not until 1800 that Volta, another Italian, showed to the scientific world that really a new electricity had been found.
FRANKLIN INSTITUTE, PHILADELPHIA.
(From photo furnished by Institute.)
Volta constructed what became known as the galvanic pile, but more largely since as the voltaic pile, which he found would generate electricity strongly and continuously. He used in its construction the dissimilar metals silver and zinc, cut into disks, and piled alternately one upon the other, but separated by pieces of cloth moistened with salt water. This simple generator of electricity was the forerunner of the more powerful batteries of the present day, and which are still popularly known as voltaic cells or batteries.
But the importance of Volta’s discovery did not lay more in the construction of his electrical generator than in the great scientific fact that chemistry now became linked indissolubly with electricity and electrical effects. The two novel and charming sciences, hitherto separate, were henceforth to coöperate in those majestic revelations and magnificent possibilities which so signally distinguish the nineteenth century. By means of greatly improved voltaic cells or batteries, that is, by jars containing acid in which were suspended dissimilar metals, electricity could be produced readily and in somewhat continuous current. By increasing the number of these cells or jars or batteries, and connecting them with conductors, the current could be made stronger and more effective. In contradistinction to the old frictional or static electricity, the new became known as chemical or current electricity.
As was to have been expected, Volta’s invention and discovery excited 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.
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.
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.
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.
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.
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.
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.
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.
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.”
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.
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.