256 Major R. L. Hippisley. 



the equation to the (B, H) curve of the particular core under 

 consideration. This will be of the form 



where n is one less than the number of observed simultaneous values 

 of B and H from which the equation is calculated ; whence 



(4), 



and substituting in the equation 



dt 



we get 



E-R; 



di = dt (6), 



which is easily integrable ; and integrating between the proper 

 limits we get after reduction 



E 



E 



E 2 



E ?i-1 



E 



E 2 



E 



E 2 



5a 5 L 5 + 



E- 8 



-_ 



E"" 3 



^ 



11 



&c., to '/?/-f-l terms 



(7). 



The corresponding equation when the E.M. b 1 . is removed and the 

 current is dying away is 



^ 



tne /b/zj/3, &c., being the coefficients of the powers of H in the 

 equation to the descending (B, H) curve, which is, of course, different 

 to the ascending curve. 



