t 672 ] 



SJtrS 



LXXI. A Resistance Comparator. By R. A. Lehfeldt *. 



OBJECTING to sliding contacts on account of the thermo- 

 electric effects they tend to introduce, and irregularities 

 slide- wires often show when a good deal used, I have designed 

 this comparator without any. It consists of two coils of 99 

 ohms each (ocfg) connected by twenty coils of 0*1 ohm each. 



D 



" Galv. 



The latter are arranged circularly, so that a switch connected 

 to the galvanometer may be set on any one of the intervening 

 studs. When the comparator is to be used in the ordinary 

 way, to make a simple Wheatstone's bridge, the terminals d e 



* Communicated by the Phvsical Society : read March 13. 1903, 



