At the present time nearly all cables use the duplex system, that is, messages can be sent and received at the same time on one wire.
The speed of a cable is given in words per minute, the conventional number of five letters per word being understood, though in actual practice, owing to the extensive use of special codes, the number of letters per word is really between eight and nine, and this forms a considerable factor in the earning capacity of the cable, but the speed depends upon the length of the cable and the experience of the operator. Tests made over the Vancouver and Fanning Island section of the Pacific cable give 85 letters per minute with hand working and 100 letters a minute with automatic curb working, and approximately 168 letters a minute (84 letters each way) with duplex and curbed automatic working. This section of the cable is 3,455 nautical miles in length, the longest cable that has ever been laid, and about twice the length of the Atlantic cables. On shorter cables a greater speed can be attained.
CYRUS W. FIELD.
Cyrus W. Field.
Born in 1819, at Stockbridge, Mass., at the age of fifteen, he left home and became a clerk in a leading house in New York. At twenty-one he married and settled down in life as a wholesale paper merchant. Having been very successful he wished to retire, but yielded to the wishes of his junior partner and allowed his name to remain as the head of the firm. He withdrew, however, so far as to make a six months’ tour to South America, returning in 1853.
He was led to turn his attention to ocean telegraphy through an interview with Mr. Gisborne, who was then engaged in constructing a telegraph line across the Island of Newfoundland, and laying a submarine cable from there to Nova Scotia, in connection with a projected line of steamships to Ireland. It struck him that if a cable of such length could be laid there was nothing to hinder a still longer being carried from one side of the Atlantic to the other. Turning over this thought in his mind he consulted with Professor Morse and Lieutenant Maury, and receiving encouragement from them he devoted his energies in the enterprise in conjunction with his brother Dudley.
Other friends joined him, and the first Atlantic Telegraph Company was organized with a favorable charter, granting them the sole right for fifty years of landing a telegraph cable on Newfoundland and with a subsidy as soon as the line was completed.
The first thing was to connect the Continent with Newfoundland. This part of the scheme was successfully accomplished in 1856.