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Mr. T. H. Blakesley said that the 

 paper had considerable breadth ; but, like 

 a dangerous piece of water, it was 

 unequally deep. The subject was a very 

 large one, and perhaps the author had 

 not been able entirely to do justice to it, 

 even in his comparatively long paper. 

 Mr. Blakesley had himself done a good 

 deal of work in diagrams, and the first 

 remark he would make was that in Figs. 

 7, 8, and 9, the direction was continually 

 reversed. In Fig. 7 the motion of the 

 diagrams was supposed to be clockwise, 

 in Fig. 8 it was the reverse ; and in Fig. 

 9 it was supposed to be the same as in 

 Fig. 7. The advantage of a diagram 

 of that kind was that it not only repre- 

 sented the magnitude of certain quanti- 

 ties of electromotive force in general, but 

 the relative positions of their maximum 

 value. The author constantly called O 

 A the current. It was true he guarded 

 himself by saying that it was propor- 

 tional to the current ; but those who 

 read the paper might suppose that he 

 thought O A to be in phase with the 



