194 



THE WORLD '8 ADVANCE 



chipelagos, off the southeast coast of 

 [ndo-China. It is drawn from the trees 

 as a thin, milky fluid, which soon dis- 

 colors and rapidly becomes thick and 

 gummy. 



The. Heart of the Cable 



The copper wire which forms the core 

 of the cable must be the purest obtain- 

 able, or the flow of electricity will be 

 retarded, and the efficiency greatly low- 

 ered. The size of the. wire has quite as 

 great an influ- 

 ence upon the 

 conductivity ; 

 the smaller the 

 wire the greater 

 will be the re- 

 tarding effect. 

 To illustrate: a 

 copper wire 

 which weighs 

 loo pounds per 

 nautical mile is 



Consequently, the stranded core, in spite 

 of its greater cost, has been universally 

 adopted. 



Although there is no particular reason 

 why the bulk of submarine cable should 

 not be made in America, it is manufac- 

 tured almost exclusively in Europe. 

 Giant machines are used in stranding the 

 cores. As the wire emerges, it is coiled 

 in three-mile lengths on huge drums. 

 The process is completed by coating the 

 copper with an insulative and a protec- 

 tive covering of gutta percha and metal. 



The cable, 

 which lies along 

 the bottom of 

 the sea at a 

 depth of several 

 miles, is in no 

 particular 

 danger of de- 

 struction, and, in 

 consequence, i t 

 is small and 

 light. Giant fish 



The Sheaves of the Cable Steamer "Mackay-Bennett." At the Left: The Bow Cable Sheaves as Viewed 

 from Inboard. At the Right: Another View of the Bow Sheaves that are Used for Paying Out and 

 Picking Up Submarine Cables. In the Oval: The Stern Sheaves that are Used for the Same Purpose as 



Those at the Bow. 



not nearly so conductive as one which 

 weighs 200 pounds. In several of the 

 modern Atlantic cables 700 pounds of 

 copper are used every mile. 



Early in the career of electricity the 

 discovery was made that a conductor 

 made up of a number of strands of fine 

 wire possessed far more strength than a 

 solid conductor of the same weight. 



ordinarily do not penetrate to a depth of 

 more than several hundred fathoms, be- 

 cause of the pressure. Closer to shore, 

 however, the danger from this and other 

 sources is greater. 



Intemperate Workmen a Menace 

 The shore end of the cable is often 



