78 SUBMAKINE CABLE LAYING AND EEPAIRING. 



always adopted. The only disadvantage of absolute closenesa 

 is the difficulty in coiling and uncoiling, especially when the 

 wires are of steel as in deep-sea cables ; and it has been found 

 that some small amount of clearance between the wires is 

 necessary to give the cable sufficient flexibility for handling 

 and coiling. This condition is now met by the addition of a 

 serving of cotton tape around each sheathing wire, or by 

 making the inner serving so heavy that the sheathing wires 

 cannot butt against each other. Separate taping, the basis 

 of a patent due to the late Mr. Matthew Gray, is undoubtedly 

 the better expedient, because a double advantage is gained — 

 namely, longer life of the wires due to prevention of corrosion 

 by this covering, and greater flexibility of the cable, while the 

 value of the complete arch is sufficiently retained. In many 

 cases both these ideas are embodied — that is, the sheathing 

 wires are separately taped and the inner yarn serving is made 

 sufficiently full to allow the sheathing wires to lie slightly 

 apart instead of pressing closely together. By this means, and 

 the employment in a deep-sea cable of a sufficient number of 

 wires, say, 14 or 15 wires of No. 13 size, the wires are free to 

 slide past each other in coiling or bending, and there is no 

 liability to kink. About 5 per cent, should be added to the 

 theoretical diameter of pitch circle to produce the required 

 effect. Before taping the wires are pickled in hot preservative 

 compound and the cotton tape is impregnated with the same. 

 The main cable of the 1894 Anglo-American Telegraph Co. had 

 the sheathing wires individually taped in this manner, and was 

 described in detail by Mr. Arthur Dearlove in The Electrician 

 for October 12th of that year. 



Speaking of cables of low specific gravity, a sheath without 

 any iron in it, and composed entirely of hemp, was introduced 

 several years ago by Trott and Hamilton, and a considerable 

 amount of cable thus protected was manufactured. The idea 

 was that the cable might be easily recovered in deep water, but 

 being so light there was the difficulty of knowing when it had 

 been hooked by the grapnel soon enough to prevent the 

 grapnel being carried right through it. In fact, the ordinary 

 dynamometer indication of the presence of the cable on the 

 grapnel was inapplicable. A piece of this cable 48 nauts in 

 length was inserted in the mid-Atlantic portion of the 1869 



