Engineering Wonders of the World
Volume III

THE LAYING OF SUBMARINE CABLES. 375 Fig. 32.—TESTING-ROOM ABOARD SHIP (T.S. ‘ COLONIA ). that continuity is maintained from end to end, and that the electrical insulation is satisfactory. In addition to Electrical sjgnais are exchanged, at pre-determined time intervals, between the ship and the shore hut from which the cable has been laid. Occasional brief messages are also included in the routine. CONCLUSION. Perhaps the most recent striking develop- ment in submarine telegraphy is the All- British Pacific Cable, in deep water, far distant from trade routes or The World’s forejgn shores. This runs into Cable System, ^pths of four miies jn places ; and just as the first Atlantic cable was considered at the time 44 a wild freak of people that were to be pitied,” so also this first Pacific cable was similarly spoken of by some, mainly on account of the great length (3,458 nautical miles) of one of its sections. It was, however, laid (in 1902) without a hitch. The useful life of a cable may be nowadays as much as forty years, after which it is usually better to replace the line than to attempt to again repair it. In the present day cables have no history. It must not, however, be supposed from this that we do not have occasional minor mishaps nowadays. Moreover, even though our mate- rials are so vastly superior to what the pioneers had at hand, there are still the usual eventu- alities, many of which, as has been shown, are scarcely under control. By far the greater proportion of the cables