1886.] On a New Scale for Tangent (jralvanometers. 497 



Fig. 1, 



constant is about 3, that is, 3 amperes are required to produce the 

 unit deflection of 45°. 



The Post Office has for many years used a more sensitive and 

 portable form, having a constant of 0'00214, for testing wires, 

 batteries, and apparatus. Two scales have hitherto been engraved on 

 the dial of the instrument, ona in degrees and the other in tangent 



VOL. XL. 2 L 



