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secohm. There was also an apparatus on 

 the table familiar to some members, called 

 a secohmmeter, for comparing two self- 

 inductions. It rapidly alternated the 

 battery connections and the galvanom- 

 eter connections of a Wheatstone's 

 bridge, and it rendered the measurement 

 of self-induction, which before two years 

 ago usually had been very unsensitive, 

 having had to be effected with single 

 impulses, as sensitive as the ordinary 

 measurement of resistance with a Wheat- 

 stone's bridge. With a combination of 

 those two instruments the coefficient of 

 self-induction could at once be measured 

 with accuracy, without any other appa- 

 ratus except the ordinary Wheatstone's 

 bridge. Fig. 32 showed symbolically 

 the arrangement for measuring a coeffi- 

 cient of self-induction L 2 . G C and B C 

 were the galvanometer and battery com- 

 mutators of the secohmmeter, which were 

 rotated by turning the handle H. Bal- 

 ance for steady currents having been first 

 obtained, the secohmmeter handle was 

 rotated at any convenient speed, and the 



