CHAPTER VII 



ELECTRICITY 



SECTION I 



THE NATURE OF ELECTRICITY 



151. Electrical Energy. The question, What is elec- 

 tricity? has never been fully answered. Many things 

 have been learned about its behavior, but with all 

 their study men have never been able to discover what 

 it is. For convenience we often speak of currents 

 of " electricity," charges of " electricity," etc., as though 

 it were a form of matter ; but though we may do this, 

 it must be borne in mind that we do not know anything 

 which proves it beyond a doubt. 



While men have been seeking to learn the nature of 

 electricity, however, they have discovered many things 

 which enable us to make it very useful. Particularly 

 important is the fact that it possesses energy which may 

 be made to do work for us when it is properly controlled. 

 In this study we shall consider not so much the nature 

 of electricity as the means by which electrical energy may 

 be made useful to man. We shall seek to learn some- 

 thing about electrical energy along three general lines, 

 how it can be produced, how it may be controlled, 

 and what are its effects. The study of these matters 

 will doubtless show us much that is of interest as well 

 as of importance. 



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