Page:Popular Science Monthly Volume 24.djvu/521

Rh system was at least ten times that of well-constructed overhead lines. By 1850 the earliest of these lines had failed, and by 1853 the entire system was replaced by pole lines. In 1852 asimilara similar [sic] cable was laid in Russia, between St. Petersburg and Moscow; this worked a few years and then failed. Between 1846 and 1852 many miles of somewhat similar cables were laid in France, but, excepting those laid in the sewers of Paris, they universally failed.

In 1854 quite a number of lead-covered cables were laid in Denmark, but these were soon obliged to be abandoned in favor of over-head lines. 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. 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.

During the same year the Electric Telegraph Company laid down a somewhat similar system between London, Manchester, and Liverpool, though iron and earthenware pipes were substituted for the wooden troughs. Some of these lines began to fail almost as soon as completed, while others were, by constant repairing and attention, kept working for nearly ten years, when the whole was finally abandoned and overhead lines put up.

The great trouble with all of these systems, whether in England or on the Continent, was due to water, which found its way to the conductors, and of course destroyed the insulation. 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. During this time many other shorter lines were constructed, but invariably with the same results.

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. The details of this work were very carefully carried out, and the experiment is of interest because similar plans are constantly being proposed to-day. This system, costing from eight to ten times that of a thoroughly built pole line, never worked satisfactorily, and soon had to be abandoned. In 1858 the administration decided to return to gutta-percha-covered cables laid in lead tubes. The reason of this was, that some of these cables laid in the sewers of Paris, in 1846, were still in good condition. 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