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the current must therefore do work in 

 flowing against this counter electromotive 

 force. It is this work thus absorbed by 

 the fixed coils which partly reappears as 

 mechanical work of rotation given out by 

 the armature, the rest being dissipated 

 in heat as in the case of an ordinary 

 motor. The action here explained is in 

 reality not quite so simple, because self- 

 induction and the reaction of the arma- 

 ture field have to be taken into account ; 

 but, in the absence of all experimental 

 data, it is not worth while to attempt a 

 closer investigation. The author has 

 thought it expedient to explain the funda- 

 mental principle of this type of motor, as 

 the investigation might prove useful to 

 those who are about to experiment with 

 similar machines. He regrets that he is 

 unable to place before the institution 

 details of the Tesla motor, as constructed 

 by the Westinghouse company; but as 

 these details are only partially worked 

 out, and secured by patents, this com- 

 pany naturally prefer to withhold them 

 for the present. 



