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nomenclature in the paper. Whether a 

 certain electromotive force should be 

 called " mean," " average," " equivalent," 

 the " square root of the mean squares," 

 or by any other name, might be a fit sub- 

 ject for discussion from a pure academic 

 point of view, but practical engineers 

 were satisfied with the terms ordinarily 

 in use, provided definitions were added 

 to prevent misunderstanding. The dia- 

 grams had not been designed with a view 

 of finding out everything which could 

 possibly be ascertained about alternators, 

 but simply as mental tools, perfected 

 only so far as necessary for the work of 

 designing alternators, but not further. 

 The statement in the paper, that there 

 was no self-induction in a bank of trans- 

 formers working glow-lamps, although 

 described as incorrect by Professor Ayr- 

 ton, had in reality been confirmed by the 

 remarks that gentleman had made, and 

 also by what fell from Mr. Mordey. Both 

 had said virtually the same thing, namely, 

 that the lag was nearly 180° between the 

 phases of primary and secondary current. 



