18G 



the current," and accordingly defined the 

 mechanical output of the machine as 

 " the product O A and O D." As far as 

 lie could make out, O A was the resultant 

 •electromotive force obtained by the 

 addition of the terminal and induced 

 electromotive forces E, andE, and by the 

 author's own showing (Fig. 7) the current 

 ought to be the resultant of this and of 

 the electromotive force due to self-induc- 

 tion, that was, it ought to coincide with 

 O R ; or assuming the terminal resistance 

 to be one, it would be equal to O R. 

 Accordingly, the mechanical work gener- 

 ated would be the product of O R and O 



D, namely, E. I. cos B O F, I standing 

 for the current. Moreover, he should 

 prefer assuming some definite position of 



E, to start from as being more conforma- 

 ble to reality, aud letting E shift about, 

 thereby altering the positions and magni- 

 tudes of the other quantities. There 

 would then be perfect agreement between 

 the author's diagram and the geometrical 

 solution of the same problem explained 

 by him in a paper, " On the difficulties in 



