Electricity 



less, and perforce will more and more exclude heat 

 from the chain of transformations which issue 

 in the locomotive's flight, in the whirl of factory 

 and mill. Thus in some degree is allayed the 

 fear, never well grounded, that when the coal 

 fields of the globe are spent civilization must 

 collapse. As the electrician hears this forebod- 

 ing he recalls how much fuel is wasted in con- 

 verting heat into electricity. He looks beyond 

 either turbine or shaft turned by wind or tide, 

 and, remembering that the metal dissolved in 

 his battery yields at his will its full content of 

 energy, either as heat or electricity, he asks, 

 Why may not coal or forest tree, which are but 

 other kinds of fuel, be made to do the same ? 



One of the earliest uses of light was a means of 

 communicating intelligence, and to this day the 

 signal lamp and the red fire of the mariner are as 

 useful as of old. But how much wider is the field 

 of electricity as it creates the telegraph and the 

 telephone ! In the telegraph we have all that 

 a pencil of light could be were it as long as an 

 equatorial girdle and as flexible as a silken thread. 

 In the telephone for nearly two thousand miles 

 the pulsations of the speaker's voice are not only 

 audible, but retain their characteristic tones. 



In the field of mechanics electricity is decidedly 

 preferable to any other agent. Heat may be 

 transformed into motive power by a suitable 

 engine, but there its adaptability is at an end. 

 An electric current drives not only a motor, but 

 every machine and tool attached to the motor, 

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