ATLANTIC TELEGRAPH. Referring to other articles for details concerning the scien tific and mechanical principles of electro-telegraphy, the Atlantic cables may more espe cially be described here.
The possibility of laying an electric cable in the Atlantic, from Europe to America, was suggested by prof. Morse so far back as 1843; but it was not until 1854 that Mr. Cyrus Field and others discussed the means of practically realizing the idea. Lieut. Maury discovered that the bed of the Atlantic, between Ireland and Newfoundland, forms a kind of plateau, covered with soft ooze, favorably situated as a resting-place for a cable. In 1835, negotiations were carried on, partly in America, but chiefly in Eng land. to establish a company and raise capital; which objects were attained in 1856. The "New York and Newfoundland Telegraph company" connected Newfoundland with the mainland of America by cables and land-wires; but the " Electric Telegraph company" undertook,the laying of a cable from Newfoundland to Ireland, with a capital of i.',350,0•JO, in shares of £1000 each. A length of 2500 English miles of cable was ordered, and was completed by the summer of 1857. The conductor consisted of 7 fine copper wires, No. 22 gauge, twisted tightly together, forming a cord 15th in. thick, and weighing 107 lbs. per mile. This thickness was increased to ith in. by a core of three layers of gutta percha. Outside the core was a jacket of hempen yarn, saturated with pitch, tar, bees wax, and boiled linseed oil. The outer sheath consisted of 18 strands, each formed of 7 No. 22 iron wires. The whole diameter was about in., and the weight 1 ton per mile. In the manufacturing processes, the wires and yarns were twisted round each other by revolving drums and circular tables worked by steam-power; while the coatings of gutta-percha were applied by forcing the substance through dies which had the cop per conductor passing through their center. The Niagara and the Agamemnon, the one lent by the U. S. government and the other by the English, took 1250 in. of the
cable each, and steamed forth from Valentia (w. coast of Ireland) on Aug. 7, 1857. The Ifiagara paid out her portion of cable as she went. On the 11th, in an attempt to slacken the rate of paying out, the cable snapped, and the end sank in 2000 fathoms water, at 280 In. from Ireland. The appliances on board were not sufficient to remedy the disas ter, and the two ships returned to Plymouth, where the two portions of cable were placed in tanks until the next following year.
The Atlantic Telegraph company raised more capital, made 900 m. additional cable, and prepared for a new attempt in 1858. The Niagara and Agamemnon were again employed; but the submersion was to begin in mid-ocean, one ship proceeding eastward, and the other westward, after splicing the two halves of the cable. They left Valentia June 10; but it was not till the 26th that they could finish the splice and commence the submersion. On the 29th, a double breakage took place, and 144 in. of cable went to the bottom, wholly severed from the rest. The Agamemnon returned to England for improved appliances and further instructions; and &month was thus lost. On July 29, the two ships again spliced their two halves of cable in mid-ocean, and proceeded with their work without further disaster. On Aug. 6, the Agamemnon reached Valentia, and the Niagara Newfoundland, and exchanged congratulatory messages through the whole length or cable. Soon afterwards, greetings were exchanged between the queen and the president, and between many public bodies and official persons. The station at New foundland was connected by wires and cables with the general telegraphic system of America; and that at Valeutia with the general system of Europe. The cable continued working until Sept. 1, sending 129 niessages (of about 11 words each on an average) from England to America, and 271 from•America to England. The signals then ceased, and the cable became useless; it had been injured by the winter's sojourn at Plymouth.