This time the cable was destined to have a long and useful life, and later in the same year the 1865 cable was recovered, spliced to a new length, and safely brought to land, so that there were now two links between the Old World and the New. It was estimated that the total cost of completing the great undertaking, including the cost of the unsuccessful attempts, was nearly two and a half millions sterling. Since 1866 cable-laying has proceeded very rapidly, and to-day telegraphic communication exists between almost all parts of the civilized world. According to recent statistics, the North Atlantic Ocean is now crossed by no less than 17 cables, the number of cables all over the world being 2937, with a total length of 291,137 nautical miles. Before describing the actual working of a submarine cable, a few words on cable-laying may be of interest. Before the cable-ship starts, another vessel is sent over the proposed course to make soundings. Galvanized steel pianoforte wire is used for sounding, and it is wound in lengths of 3 or 4 nautical miles on gun-metal drums. The drums are worked by an engine, and the average speed of working is somewhere about 100 fathoms a minute in descending, and 70 fathoms a minute in picking up. Some idea of the time occupied may be gained from a sounding in the Atlantic Ocean which registered a depth of 3233 fathoms, or nearly 3½ miles. The sinker took thirty-three minutes fifty seconds in descending, and forty-five minutes were taken in picking up. The heavy sinker is not brought up with the line, but is detached from the sounder by an ingenious contrivance and left at the bottom. The sounder is fitted with an arrangement to bring up a specimen of the bottom, and also a sample of water; and the temperature at any depth is ascertained by self-registering thermometers.