170 nature's 



As time passed on and the electric light and 

 electric railroad came into operation these dif- 

 ficulties were immensely increased, till now in 

 large cities the telephone companies are fast 

 being driven to the double-wire system, which 

 will soon become universal for telephonic pur- 

 poses the world over, except perhaps in a few 

 country places where there is freedom from 

 other systems of electrical transmission. To 

 successfully work the telephone and telauto- 

 graph through the same cables, these protective 

 devices against induction must be very care- 

 fully provided and maintained. 



