﻿116 Dr. W. H. Eccles on the Effect of Electrical 



first derived curve, of the corresponding cyclic curve. To 

 assist in picturing the magnetic state of the iron there is 

 plotted on each diagram the proper hysteresis loop. These 

 loops were obtained by independent experiments with the 

 earth's field controlling the magnetometer-needle. (Reducing 

 factor for I is 67*5). 



Fig. 6. — The dotted curve shows spark-effect. 



In these figures the abscissas for all the curves are milli- 

 amperes (multiply by 0'0696 to get C.Gr.S. field). The figures 

 have been so constructed that, except in the cyclic curves, 

 equal ordinates on the different figures represent absolutely 

 equal effects. The reducing factors for the spark-effect 

 curves are as given in connexion with Table I. In all the 

 slope curves the ordinates give at once very approximately 

 the change of intensity of magnetization per "001 C.G.S. 

 increment of field. But the ordinates of the cyclic curve are 

 reduced 21 times in fig. 3, 12 times in fig. 4, 63 times in 

 fig. 5, 84 times in fig. 6 ; and are thus not directly com- 

 parable with one another or with the companion curves. 



Returning to the spark-effect and the gradient curves, 

 however, it is seen that the spark-effect is by no means a 



