Atlantic Telegraph. The union of the Old and New Worlds by means of the electric telegraph, probably the boldest feat of electric engineering ever projected, was first suggested by Professor Morse in 1843. Various reasons prevented his ideas taking practical shape, the principal obstacle being the unknown depth of the Atlantic and the supposed rocky nature of the bottom. When, however, Lieutenant Maury of the United States navy discovered that between Ireland and Newfoundland the bed of the ocean was nearly level and covered with soft ooze, and Mr Cyrus Field and others had thoroughly discussed the practical methods, a company was formed for the purpose in 1856, to which the governments of Great Britain and the United States gave liberal guarantees.
This company, after a fruitless attempt to lay an electric cable in 1857, finally succeeded in 1858.
The cable, 2500 miles long, and weighing one ton per mile, was composed of seven fine copper wires, cased in gutta-percha, contained in a casing of hemp saturated with pitch, beeswax, and oil, the outer sheath being composed of eighteen strands of seven iron wires each. It was taken, in equal portions, on board H.M.S. Agamemnon (91 guns) and the United States frigate Niagara, spliced in mid-ocean, and finally landed; the one end by the Agamemnon at Valentia, Ireland; the other by the Niagara at Trinity Bay, Newfoundland.
The result was not encouraging. The current obtained through the wire was so weak that a congratulatory message from the Queen to the president, consisting of 90 words, took 67 minutes to transmit. After a few more messages the cable became useless.
In consequence of this failure, it was not until 1865 that capital was found to make another attempt. This time the cable was made still heavier, and the whole length, 2300 miles, weighing 4000 tons, was shipped on board one vessel, the Great Eastern. The paying-out journey was commenced at Valentia, but when the vessel was 1064 miles from that port, the cable broke from an accidental strain. After a fruitless effort to fish up the broken cable from the bottom, it was abandoned for the season. In 1866 another line, so modified in construction as to be both lighter and stronger than the previous one, was successfully laid by the Great Eastern. The 1865 cable was then, by means of the same vessel, grappled for, and brought up from a depth of two miles, spliced, and completed to Trinity Bay.
The practicability of laying an electric wire across the Atlantic being thus demonstrated, many lines have been projected, and several of them carried out. In 1869 a French company laid a line from Brest to St Pierre, off the south of Newfoundland. In 1873 a line was begun from Lisbon to Pernambuco in South America. This line, by means of a duplicate line from London to Lisbon, brings this country into direct communication with the whole of South America. Other two cables were laid from Valentia to Trinity Bay in 1874 and 1875. The latter, made by the Messrs Siemens, weighed only 880 pounds per mile, being the lightest cable planned for Atlantic telegraphy. One from Penzance to St Pierre was laid in 1879; another from England to Panama was completed in 1882; and in 1884 Messrs Bennett and Mackay's line was laid from Valentia to Torbay in Nova Scotia.
Altogether there have been laid across the Atlantic 15 cables, 3 of which are quite dead, 9 are in good working order, and 3 good for some purposes. When the first line was opened the rates were £20 for 20 words of 5 letters each, and 20s. for every 5 letters extra. The following year those rates were halved, and by successive reductions reached in August 1869 the rate of £1, 10s. for 10 words, and 3s. per word extra without restriction of number of letters. The rate is now from 1s. to 1s. 8d. a word, subject to occasional fluctuations from disputes among the competing lines. One of these disputes caused in 1887 a reduction of the rates to 6d. per word on the part of all companies except one, which charged 1s. Still, even at the cheapest rates, long messages are very expensive. To obviate this as far as possible, several code and cipher schemes have been devised for transmitting lengthy messages by a comparatively small number of words. These schemes, subject to certain regulations, have been accepted by the post-offices and telegraph companies. The whole Atlantic system is worked in connection with the ordinary telegraph system of the world, and, with the lines to India and Australia, may be said to bring the uttermost ends of the earth within speaking distance.
See article TELEGRAPH for an account of the science and methods employed, and for the subject of Submarine Telegraphy.