256 Mr Peake, A Novel Instrument for Illustrating 



where H = strength of magnetic field, 



a = cross-section of specimen, 

 and I = effective length of specimen between magnetic poles. 



Fig. 6. 



One division of H scale = '00836 radians, 

 therefore = "00886 x 2*8 radians, 



fju = 2,100, as determined by ballistic method. 



Hence from (2) E- 2jl00 x W836 x 2-8 " ill ' 



The weight of the specimen was 1*14 grammes, the specimen 

 was of uniform section and of specific gravity 7*78, hence 



,1-14 

 ""7-Y8" 



