In the same year that Oersted made his brilliant discovery, M. Arago detected another law, which furnished a second method by which the electric current could be made to tell its tale. He announced to the French Academy the fact so pregnant in its consequences, that the fluid possessed the power of imparting magnetism to steel or iron; and shortly afterwards our own countryman, Sturgeon, invented the first electro-magnet, by coiling around a piece of soft iron a great length of fine insulated copper wire, the ends of which communicated with a battery. Figure 5 will give a rough idea of this instrument. The wire U B A, when it reaches the cylinder K L, is wound many times round it, and returns to the battery at V. As long as the current is passing, the soft iron becomes a magnet and attracts the iron armature P; but directly the circuit is broken its magnetic power ceases, and P, by the action of a spring, flies back. It will at once be seen that by alternately making and breaking the circuit, which can be done as fast as the hand can move the handle of a lever, an up and down movement of the armature P will take place, and this is the principle of action in Wheatstone’s electro-magnetic dial instrument and Morse’s recording telegraph, so extensively used in America. The general modus operandi of the latter, which is a contrivance of singular merit and efficiency, can be easily understood. At the station at which the message is received, a poised iron lever has a metal pin on its upper surface at one end, and an armature on its under surface at the other end. When the magnet, which is placed beneath the armature, attracts and draws it down, the pin at the opposite extremity is raised, and presses against a strip of paper, which is moved between the metal point, and a roller supported above it, at a uniform rate by means of clock-work. The pin or style will then make a simple dot, or trace lines of variable length upon the paper, according as the electric current is kept up only for a single instant, or for a longer period. “The impressions on the paper,” says Dr. Turnbull, “resemble the raised printing for the blind.” Out of these dots and lines an alphabet is formed similar to that which we have given in a subsequent page, when speaking of the chemical telegraph at Bain. The instrument of Morse requires only a single wire to work it, and is, says the Abbé Moigno, “an excellent telegraph, very simple, very efficacious, and very rapid in its transmissions. A practised clerk can indent on an average seventeen words a minute, which is consequently as many as a skilful writer could transcribe with a pen. It is, moreover, a great advantage to have fixed on a band of paper the messages which the needle telegraphs merely figure in the air.”
Since the year 1821 the principles of action of two of the working telegraphs of the present day were known to scientific men, and the question naturally arises, how was it that it still took so many years to make the telegraph a working fact? The answer is, that the combination of circumstances necessary to bring it to perfection had not arisen. What interest had practical men in carrying out the dreams of philosophers? No one imagined that it would ever become a necessary social engine, or that it would pay “seven per cent.” to a public Company. The patronage of the Government could alone have been looked to by any of the proposers of the new method of telegraphy, and the sort of encouragement received from this quarter may be judged from the fact that when Mr. Ronalds attempted to draw the attention of some of the officials to the working of his instrument, they did not even deign to pay it a visit, but returned for answer, “That the telegraph was of no use in time of peace, and that the semaphore in time of war answered all the required purposes.” The occasion that suddenly ripened the invention and brought it into practical operation was the introduction of railroads. Were it not for the universal spread of this new means of locomotion, the telegraph might still have remained in that limbo from which so many discoveries have never emerged. The vast advantage to a railroad of a method of conveying signals instantaneously throughout its entire length was at once seen, and the continuity of its property, together with the protection afforded by its servants, presented facilities for its introduction and maintenance which had never before occurred.
A problem of great scientific interest as well as of practical importance in connection with the electric telegraph had still to be solved. The experiments of Dr. Watson on Shooter’s Hill, in the middle of the last century, proved, it is true, that a shock of electricity passed along a four mile circuit without any appreciable loss of time, but nothing was definitely known about the speed at which it really travelled. This difficult question was answered by Professor Wheatstone. His beautiful investigations on the subject were made by means of a very rapidly revolving mirror, upon which the passage of the electric fluid, at different and distant parts of a severed wire, was indicated by sparks, which appeared as lines of light on the rapidly turning glass, on the same principle that a bit of lighted charcoal whirled round and round in the air appears as a circle of fire. By this instrument, which we cannot render intelligible to the general reader, but for a fuller account of which we refer him to the Philosophical Transactions of 1834, he made it evident to the eye that one spark or leap of the electric fluid did occur before the other—thus proving that its transit along the wire was a matter of time. The manner in which he took measure of this infinitesimal period was extremely ingenious. By attaching a hollow piece of metal—a metallic humming-top as it were—to the spindle of his revolving mirror, and at the same time directing a current of air against it, he was enabled to test its speed by the pitch of the sound produced: this once known, the measuring of time that elapsed between the different sparks was easy. Thus he forced the lightning to tell how fast it was going. His admirably-contrived apparatus has since proved of considerable use to philosophers in measuring very minute parts of time, and scientific men can now with the greatest ease ascertain the period a flash of light takes to traverse a distance of 50 feet—and light, be it remembered, travels at the speed of 200,000 miles a second!
By this experiment it appeared that electricity travels through a copper-wire with at least the velocity of light through the celestial space, though the recent experiments made for Professor Bache, director of the national survey of America, have proved that the velocity of the current through suspended iron wires is not more than 15,400 miles per second. The philosophic proof of the marvellous rate at which the electric current moved, doubtless turned many minds once more in the direction of the long sought for telegraph, and it is not surprising that the eminent elucidator of the fact was among the number. A short time after this he insulated four miles of wire in the vaults of King’s College, on which he performed most of his subsequent experiments.[34] Thus in the silence of these gloomy vaults, as early as 1836, the lightning that was to flash with intelligence round the world—the nervous system so shortly destined to spread itself through two hemispheres, string together continents and islands, and carry human thought under the wide-spreading seas, was slowly being trained to the service of man by one of the most distinguished of the many philosophers who have contributed to the development of this branch of science.
Following up his experiment, Professor Wheatstone worked out the arrangements of his telegraph, and having associated himself in 1837 with Mr. Cooke, who had previously devoted much time to the same subject, a patent was taken out in the June of that year in their joint names. Their telegraph had five wires and five needles; the latter being worked upon the face of a lozenge-shaped dial inscribed with the letters of the alphabet, any one of which could be indicated by the convergence of two of the needles. This very ingenious instrument could be manipulated by any person who knew how to read, and did not labour under the disadvantage of working by a code which required time to be understood. Immediately upon the taking out of the patent, the directors of the North Western Railway sanctioned the laying down of wires between the Euston Square and Camden Town stations, and towards the end of July the telegraph was ready to work.
Late in the evening of the 25th of that month, in a dingy little room near the booking-office at Euston square, by the light of a flaring dip-candle, which only illuminated the surrounding darkness, sat the inventor, with a beating pulse and a heart full of hope. In an equally small room at the Camden Town station, where the wires terminated, sat Mr. Cooke, his co-patentee, and among others, two witnesses well known to fame, Mr. Charles Fox and Mr. Stephenson. These gentlemen listened to the first word spelt by that trembling tongue of steel which will only cease to discourse with the extinction of man himself. Mr. Cooke in his turn touched the keys and returned the answer. “Never did I feel such a tumultuous sensation before,” said the Professor, “as when all alone in the still room I heard the needles click, and as I spelled the words I felt all the magnitude of the invention, now proved to be practical beyond cavil or dispute.” The telegraph thenceforward, as far as its mechanism was concerned, went on without a check, and the modifications of this instrument, which is still in use, have been made for the purpose of rendering it more economical in its construction and working, two wires at present being employed, and in some cases only one.
A frequently renewed and still unsettled controversy has arisen upon the point of who is to be considered the first contriver of the telegraph in the form which made it available for popular use. Two names alone are now put forward to dispute the claim with Wheatstone—Steinheil of Munich and Morse of New York.
From a communication of M. Arago to the French Academy of Sciences, it appears that the telegraph of Steinheil was in operation, for a distance of seven miles, on the 19th of July, 1837, the same month in which Wheatstone put his own contrivance to the test upon the North Western Railway. But besides that the patent of Wheatstone was taken out in the preceding June, and was itself founded upon previous and thoroughly successful experiments, there is another material circumstance which gives him a claim to priority over Steinheil, viz., that the latter published no description of his instrument until August, 1838, that he altered and improved it in the interval, and that the only accounts we have of his contrivance describe its amended and not its original form. It was, however, a very meritorious performance, and, in addition to its other excellences, Steinheil was the first who employed the earth to complete the circuit—a most important fact, which we shall explain hereafter. Still his telegraph was inferior in its mechanical arrangements to that of Wheatstone, and the inventor himself soon abandoned it in favour of a modification of the instrument of Morse.
Morse dates his claim to the invention of the telegraph from the year 1832, when the first idea of such an instrument, he tells us, struck him as he was returning home from Havre in the ship Sully. A fellow-passenger, Professor Jackson, it appears, was in the habit of amusing himself, in common with the rest of the passengers, with some accounts of the wonders of electricity; and when Morse later developed his contrivance, Professor Jackson not only claimed it as a plagiarism from his own conversation, but added that Morse was so ignorant as to ask, upon hearing the term Electro-Magnetism, “In what does that differ from ordinary Magnetism?” The telegraph was at best, on the part of both of them, a crude idea; and it was not till September, 1837, that Professor Morse was able to exhibit his still imperfect machinery in action. He ultimately succeeded, as we have before stated, in producing a telegraph of first-rate excellence; and, out of 15,000 miles of wire which had been erected by 1852 in the United States, 12,124 were worked on the system of Morse.
The question of priority is, in our opinion, after all, of no sort of importance, at least as regards the rival claims of Wheatstone and Steinheil. When the progress of science has prepared the way for a great discovery, two geniuses will occasionally take the step together, because each is able to take the step of a giant. It was thus that the Calculus was found out by both Newton and Leibnitz, and the place of Neptune in the heavens by both Adams and Leverrier. It was the same with the telegraph. The investigations of Wheatstone and Steinheil were entirely independent of each other, and it cannot lessen the merit of either that there was a second man in Europe who was equal to the task.