MAN'S CO-LABORER: THE DYNAMO 



Once for all, then, there is nothing unique, nothing 

 preternaturally marvelous, about the phenomena of 

 electricity. And indeed, it is interesting to note how 

 quickly we become accustomed to these phenomena, 

 and how little wonder they excite so soon as they cease 

 to be novel. Even imaginative people have long since 

 ceased to give thought to the trolley car; and within a 

 week of the opening of New York's subway the average 

 man came to regard it as much as a matter of course as 

 if he had been accustomed to it from boyhood. 



And yet, in another sense of the word, the electric 

 motor is a wonderful contrivance. As an example of 

 what man's ingenuity can accomplish toward trans- 

 forming the powers of nature and adapting them to his 

 own use, it is fully entitled to be called a marvel. More- 

 over, in the last analysis, we are as helpless to explain the 

 nature of electricity as we are to explain the nature 

 of gravitation. It is only the proximal phenomena of 

 the electric current that can be explained. These 

 phenomena, however, are full of interest. Let us 

 examine them somewhat in detail, allowing them to lead 

 us back from electric train to power-house and dynamo, 

 and from dynamo as far toward the mystery of electric 

 energy as present-day science can guide us. 



THE MECHANISM OF THE DYNAMO 



If we could look into the interior of a mechanism in 

 connection with the trucks beneath the car, we should 

 find an apparatus consisting essentially of coils of wire 

 adjusted compactly about an axis, and closely fitted 



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