SUBMARINE CABLES. 



defect happened to exist at any point of the first coat it would be 

 covered by the second, the chances against a defect occurring at 

 the same point of both coatings amounting to an impossibility. 



80. The conducting wire thus invested, or so many of them as 

 it is intended to deposit, are then twisted together, and surrounded 

 with a mass of spun yarn, soaked with grease and tar, so as to 

 form a compact rope. Around this rope are then twisted a number 

 of stout iron wires, sometimes coated on the surface with zinc, or 

 as it has been called, galvanised. The cable is then complete, and 

 is fabricated in one continued length sufficient to extend from 

 shore to shore, or from bank to bank. Perspective side views of 

 the several cables, and transverse sections of them in their full 

 size, are given in the figures indicated in the first column of the 

 following table, the number of conducting wires insulated by the 

 gutta-percha and included within the cables, the number of 

 surrounding iron wires, the total length from coast to coast, and 

 the weight of the cables per mile respectively being indicated in 

 the other columns. 



153 



