OCEAN TELEGRAPH WIRE.

New Zealand Times, Volume XXIX, Issue 4183, 17 August 1874, Page 3

OCEAN TELEGRAPH WIRE.

(From the New York Herald, May 20.) The new ocean cable between our shores and England promises to defy all the submarine enemies and to stand the severest strains that may test it. The cable eaters of the deep sea, so long despised by scientific men, are ho insignificant obstructionists to tho enterprise of modem ocean telegraphy. On the Atlantic cable which was raised by the steamship Hibernia a year ago (when a fault was indicated about two hundred miles from Brest), tho .uplifted strand was perforated by mollusks in its outer covering, and coated with their shells. This cable had been laid in 1869, and in the intervening time the marine life had penetrated the outer covering and had passed between the iron wires to the gutta percha core. Here alone they were foiled, and in vain made their attack on a substance which resisted their indentations and proves itself the most important shield of the ocean cable. In the new cable of the Direct United States Company, to be laid by the steamship Faraday, this agent is to play a more extensive part than in any former structure of the kind. The core of the new strand is composed of a thick copper wire, encircled by eleven very fine copper wires, served with four coatings of gutta percha. These percha coatings, instead of being applied, as formerly, in long narrow strips of india rubber are put on from tho soft mass of the gum, while yet fresh from the steam heating process, and in a dough-like condition. The pliability of tho Direct Company’s wire is somewhat sacrificed to the superior conductivity it will possess, owing to the greater thickness of tho central copper wire. To make tho central wire proof against attack it is not only insulated by the gum shield, but by Manila hemp, which adds strength also. The whole core is sheathed by ton iron wires, each of which is hemp coated, and each hemp coating thoroughly steeped in the tar preparation, which seems to serve nearly as good a purpose as tho gutta percha. Tliese, having been all put together, are wrapped in Italian hemp for double security. The most exhaustive tests

with Thomson’s reflecting galvanometer have been made of the splendid wire on board the Faraday. Its immense strength will undoubtedly secure it against any possibility of strain or fracture from the action of any submarine current, or from attrition against the ledges of any submarine furrow over which it may be deposited. If successfully laid it will insure, in almost any probability, perfect and uninterrupted telegraphic communication, whatever fate might befall the present lines.