Submarine Cables. 15? 



The failure of this first cable served to teach 

 manufacturers and engineers how to construct 

 cables with reference to the conditions under 

 which they are to be used. It was found that 

 in the deep sea a much smaller and less ex- 

 pensive cable could be used than would answer 

 at the shore ends, where the water is shallow. 

 The shore ends of an ocean cable are made 

 v. -ry large, as compared to the deep-sea por- 

 tions, so as to resist the effect of the waves and 

 other interfering obstacles. It was further 

 learned that the most successful mode of trans- 

 mitting signals through the cable was with a 

 small battery of low voltage, and by the use of 

 very delicate instruments for receiving the 

 messages. It is not possible to employ such 

 instruments on cables as are used on land- 

 lini-s. while it would not be a difficult feat to 

 transmit even twice the distance over land- 

 strung on poles, using the ordinary Morse 

 :aph. 



The water of the ocean is a conductor, as 

 well as the heavy armor that surrounds the 

 insulation of the cable. When a current is 

 transmitted through the conducting wires, in 

 the miter of the cable, they set up a counter- 

 charge in the armor and the water above it, 

 -hat a< an electrified cloud will induce a 

 ehar^e in the e;irth under it. of an opposite 

 nature. This countercharge, being so close to 



the conducting wire. h;i- a rel;;r<ling effect 



