Mr. Charles Wheatstone, F.R.S., and Professor of Experimental Philosophy in King's College at the time of that interview, had made considerable advances in the scientific part of the enterprise. At the commencement of his career as a maker and seller of musical instruments in London, he was led to investigate the science of sound; and from his researches in that direction, he was led—much as Herschel was led—to devote himself to optics, and to study the philosophy of light. He was the first to point out the peculiarity of binocular vision, and to describe the stereoscope, which has since become so popular an instrument. Gradually, however, his thoughts and researches came to be steadfastly directed to the application of electricity to the communication of signals. In determining the rate at which the electric current travels through a wire he had laid down, he made an important stride towards the end in view. He proved by a series of most ingenious experiments, that one spark of electricity leaps on before another, and that its progress is a question of time. He found that electricity travels through a copper wire as fast as, if not faster, than light, that is, at the rate of 200,000 miles in a second; but through an iron wire, electricity moves at the rate of only 15,400 miles in a second. In 1836 Mr. Wheatstone had begun experiments in the vaults of King's College, with four miles of wire, properly insulated, and was working out the details of a telegraph, the scientific principles of which he had already laid down. He had discovered an original method of converting a few wires into a considerable number of circuits, so that the greatest number of signals could be transmitted by a limited number of wires, by the deflection of magnetic needles. Mr. Wheatstone, however, was somewhat backward in the mechanical parts of the scheme, and the meeting between him and Cooke was therefore of the greatest benefit to both, and an admirable illustration of the old proverb, that two heads are better than one. Had they never been brought together,—had they kept on working out their own ideas apart—each would, no doubt, have been able to produce an electric telegraph; but a great deal of time would have been lost, and their respective efforts less complete and valuable than the one they effected in conjunction. Cooke wanted sound, scientific knowledge; Wheatstone wanted mechanical ingenuity; and their union supplied mutual deficiencies. A partnership was immediately formed between them. Before their combined genius all difficulties vanished; and in the June of the same year they were able to take out a patent for a telegraph with five wires and five needles. Their respective shares in its invention are clearly marked out by Sir J. Brunel and Professor Daniell, who, as arbiters between the two upon that delicate question, gave the following award in 1841:—
"Whilst Mr. Cooke is entitled to stand alone as the gentleman to whom this country is indebted for having practically introduced and carried out the electric telegraph as a useful undertaking, promising to be a work of national importance; and Professor Wheatstone is acknowledged as the scientific man whose profound and successful researches had already prepared the public to receive it as a project capable of practical application,—it is to the united labours of two gentlemen so well qualified for mutual assistance, that we must attribute the rapid progress which this important invention has made during the five years since they have been associated."
Shortly after the taking out of a patent, wires were laid down between Euston Square Terminus and Camden Town Station, on the North-Western Railway; and the new telegraph was subjected to trial. Late in the evening of the 25th July 1837, in a dingy little room in one of the Euston Square offices, Professor Wheatstone sat alone, with a hand on each handle of the signal instrument, and an anxious eye upon the dial, with its needles as yet in motionless repose. In another little room at the Camden Town Station, Mr. Cooke was seated in a similar position before the instrument at the other end of the wires, along with Mr., now Sir Charles Fox, Robert Stephenson, and some other gentlemen. It was a trying, agitating moment for the two inventors,—how Wheatstone's pulse must have throbbed, and his heart beat, as he jerked the handle, broke the electric current, and sent the needles quivering on the dial; in what suspense he must have spent the next few minutes, holding his breath as though to hear his fellow's voice, and almost afraid to look at the dial lest no answer should be made; with what a thrill of joy must each have seen the needles wag knowingly and spell out their precious message,—the "All's well; thank God," that flashed from heart to heart, along the line of senseless wire. "Never," said Wheatstone, "did I feel such a tumultuous sensation before, 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 practicable beyond cavil or dispute."
A few days before this trial of the telegraph in London, Steinheil, of Munich, is said to have had one of his own invention at work there; and it is a difficult question to decide whether he or Cooke and Wheatstone were the first inventors. It is, however, a question of no consequence, as each worked independently. Since the first English electric telegraph was patented, there have been a thousand and one other contrivances of a similar kind taken out; but it may be doubted whether, for practical purposes, the original apparatus, with the improvements which its own inventors have made on it, is not still the best of them all.
From being used merely to carry railway messages, the telegraph was brought into the service of the general public; the advantages of such almost instantaneous communication were readily appreciated; and eight years after Messrs. Cooke and Wheatstone took out their patent, lines of telegraph to the extent of 500 miles were in operation in England upon the original plan. In 1855 telegraphic correspondence had become so general, that the Electric Telegraph Company was started to supply the demand. In that establishment the Needle Telegraph of Wheatstone and Cooke is the one generally used, with the Chemical Recording Telegraph of Bain for special occasions. By means of the latter, blue lines of various lengths, according to an alphabet, are drawn upon a ribbon of paper, and as many as 20,000 words can be sent in an hour, though the ordinary rate is 100 per minute. In the purchase of patent rights alone, the Company have spent £170,000, and they are every year adding to the length of their wires. In June 1850 they had 6730 miles of wires, and despatched 29,245 messages a year. In December 1853 they had 24,340 miles of wires, and despatched 212,440 messages a-year. Their lines now extend over a much larger mileage, and convey a greatly increased number of messages. The Magnetic Telegraph Company have also a large extent of wires, and do a considerable business.
III.—THE SUBMARINE TELEGRAPH.
The land telegraph having had such success, the next step was to carry the wires across the deep, and link continent to continent,—an all-important step for an island kingdom such as ours, with its legion of distant colonies. The success of a submerged cable between Gosport and Portsmouth, and of one across the docks at Hull, proved the feasibility of a water telegraph, at least on a small scale, and it was not long before more ambitious attempts were made. On the 28th of August 1850, a cable, 30 miles long, in a gutta percha sheathing, was stretched at the bottom of the straits between Dover and Cape Grisnez, near Calais. Messages of congratulation sped along this wire between England and France; and although a ridge of rocks filed the cable asunder on the French coast, the suspension of communication was only temporary. The link has once more been established, and is in daily use. The first news sent by the wire to England was of the celebrated coup d'etat of the 2d December, which cleared the way for Louis Napoleon's ascent of the throne. Numerous other cables have since been sunk beneath the waters; complete telegraphic communication has just been established between England and India, and will, no doubt, before long be extended to Australia.
The greatest enterprise of this kind, however, still remains unaccomplished—that is, the laying of the Atlantic cable. A company was started in 1856 to carry out this great enterprise, the governments of Great Britain and the United States engaging to assist them, not only with an annual subsidy of £10,000 a-year for twenty-five years, but to furnish the men and ships required for laying the cable from one side of the Atlantic to the other. The chief difficulty which engaged the attention of Mr. Wildman Whitehouse and the other agents of the notable enterprise was the enormous size of the cable which, it was thought, would be necessary. The general belief at that time was, that the greater the distance to be traversed, the larger must be the wire along which the electric current was to pass, and that the rate of speed would be in proportion to the size of the conductor. Mr. Whitehouse, however, thought it would be as well to begin by making sure that this was really the case, and that a monster cable was essential; and after some three thousand separate observations and experiments, was delighted to find that the difficulty which stared them in the face was imaginary. Instead of a large cable transmitting the current faster than a small one, he ascertained beyond a doubt, that the bigger the wire, the slower was the passage of the electricity. It would be needful, therefore, to make the cable only strong enough to stand the strain of its own weight, and heavy enough to sink to the bottom. A single wire would have been quite sufficient, but a strand of seven wires of the finest copper was used for the cable, so that the fracture of one of them might not interfere with the communication,—as long as one wire was left intact the current would proceed. A triple coating of gutta percha, to keep the sea from sucking out the electricity, and a thick coating of iron wire, to sink the cable to the bottom and give it strength, were added to the copper rope, and then the cable was complete. No less than 325,000 miles of iron and copper wire were woven into this great cable,—as much as might be wound thirteen times round the globe; and its weight was about a ton per mile. The length of the cable was 18,947 miles—some 600 miles being allowed to come and go upon, in case of accidents.
The end of July 1857 was selected for the sailing of the ships that were to lay the cable, as fogs and gales were then out of season, and no icebergs to be met with. On the 8th of August, the Agamemnon (English) and Niagara (American), with four smaller steamers to attend them, and each with half of the mighty cable in her hold, got up their steam and left Valentia Harbour. One end of the cable was carried by a number of boats from the Niagara on shore, where the Lord-Lieutenant was in waiting to receive it, and place it in contact with the batteries, which were arranged in a little tent upon the beach. A slight accident to the cable for a little while delayed the departure of the ships; but by the 10th they had got 200 miles out to sea, and so far the cable had been laid successfully. Messages passed and repassed between the ships and the shore. The next day the engineer discovering that too much cable was being paid out, telegraphed to the people on board to put a greater grip on it; the operation was clumsily managed, and the cable snapped, sinking to a depth of 12,000 feet.