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The result of this phenomenon is, that messages sent over one wire are liable to be received on all of the other wires, and, in the case of the telephone, this phenomenon is noticeable on cables one thousand feet long, and on a cable one mile long the parties on one wire can easily understand what those on the other wires are saying. The cable consisted of a strand of seven copper wires, one weighing 107 pounds a nautical mile or knot, covered with three coats of gutta-percha, weighing 261 pounds a knot, and wound with tarred hemp, over which a sheath of eighteen strands, each of seven iron wires, was laid in a close spiral. Many miles of this cable were laid, some with the lead pipe laid directly in the earth, some with it drawn again into iron pipes, and some carried through the sewers of the principal cities. Those cables laid directly in the earth soon failed, but those in iron pipes and the sewers continued to work, and from this grew the system now used in Paris. The route was especially selected through a low and marshy section of country, so that the pipes were almost constantly filled with water-this being the best possible condition for the preservation of the gutta-percha.

It was difficult to handle the wires without abrading the gutta-percha; and, when safely laid, the gutta-percha was attacked by coal-gas, vegetable growths, and the constituents of the soil. In 1855 the French government, having failed in their attempt to use gutta-percha wires, laid down a large number of bare wires in a trench filled in with bituminous compounds. 1. If an electric conductor be brought near to a large mass of conducting matter, as is a wire when it is taken down from a pole and buried in the earth, there appears in the current the phenomenon of retardation, by which each signal, instead of being sharp and distinct, is partly kept back, so that it overlaps and mingles with the next; the result is to limit the speed of working of the apparatus; or if, like the telephone, it be an apparatus in which the currents are necessarily extremely frequent, to confuse and destroy the signals altogether. At Marseilles the recorder acted in some respects like a barometer. The introduction of gutta-percha, in 1846, accordingly gave a new impetus to under-ground construction, and, though it took years of experimenting and millions of dollars, and though system after system failed in England, Germany, and the rest of Europe, there exists to-day a successful and durable system of under-ground telegraph wires connecting together the principal cities of the German Empire, besides many other under-ground lines in various parts of Europe.

His talent for electrical engineering was soon shown, and his progress was rapid; so that in 1852 he was appointed engineer to the Magnetic Telegraph Company, and in that capacity superintended the laying of lines in various parts of the British Isles, including in 1853 the first cable between Great Britain and Ireland, from Portpatrick to Donaghadee. In 1853 the Telegraph Company of England laid down a cable of ten gutta-percha-covered wires, in wooden troughs, along the high-road between London and Manchester, a distance of two hundred miles. This system, costing from eight to ten times that of a thoroughly built pole line, never worked satisfactorily, and soon had to be abandoned. It must be remembered, however, that these various systems have cost from ten to twenty times as much as similar overhead lines; that, for every mile of under-ground wire, there are many miles on poles; and that in Paris, which is the only city in the world having a complete under-ground system, there are unusual facilities for the running of wires, as sewers large enough to walk about in extend even under the less important streets of the city.

Since that, however, several lines have been built in England that have continued to work successfully; and in Germany successful under-ground cables have been laid down connecting together all of the principal cities of the empire. They were, however, soon replaced by pole lines. They were accordingly replaced by wires strung on poles, and the rest of the line was constructed in this way. Although neither expense nor pains were spared in the construction of this line, the cost being comparable with that of the Prussian system, two years had not elapsed before some of the wires ceased to work, and, though these were replaced and workmen kept constantly busy on the line, at the end of seven years the line was wholly abandoned in favor of overhead wires. 2. The second difficulty is called induction, and is noticed when two or more wires are run side by side and near together, as they necessarily are in an under-ground cable. This tube was laid in a trench by the side of the rail-road.

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