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velous improvement; but not one of 

 those transformers was now at work ; all 

 had been exchanged for the ordinary 

 Gramme ring, with iron inside and cop- 

 per outside, because in this form the 

 electric circuit was short ; consequently, 

 the regulating power of the transformer 

 was better than it had been previously. 

 The other question raised about trans- 

 formers was whether a high or a low 

 frequency was advantageous. A fairly 

 high frequency was advisable ; but above 

 a certain limit, say 70 complete periods 

 per second, an increase of frequency did 

 not reduce the size of the transformer. 

 On the table there was one of his transfor- 

 mers, weighing 200 lbe., and feeding fifty 

 lamps, giving a weight of 4 lbs. per lamp. 

 It was built for a frequency of 70. The 

 Westinghouse transformer (taking the 

 figures from a paper by Professor Forbes 

 at the last meeting of the British Associa- 

 tion) was for forty lamps, and it weighed 

 160 lbs., or 4 lbs. per lamp. In that 

 case the frequency was 133 as against 

 his 70. That was a proof that the 



