374 II. NAGAOKA. 



of curve III. Fig. XL with any one given in Fig. IX. will .show 

 that this must also be the case with nickel. 



Another point of difference between these two methods is the 

 difference in the position of the Wendepunkt, and the initial form of 

 the curve before reaching the Wendepunkt. In the experiments made 

 by Midden twisting, the Wendepunkt occurs in weaker magnetizing 

 fields as the twist is increased; but it is otherwise when the mag- 

 netizing force is reversed. In this ease, the Wendepunkt gradually 

 shifts into higher regions of the magnetizing field. The first increase 

 of the twisting transient current, as the magnetizing force is increased, 

 takes place more rapidly for greater twist ings ; but when the direc- 

 tion of the magnetizing force is reversed, the same increase takes 

 place more rapidly for the smaller twist. This fact is evident from 

 the examination of the curves L, IL, III. in Fig. IX. and I., II. in 

 Fig. XI. The curve for r=±90° lies at first below the curve for 

 r = ±30°, while the curve for r =±180° lies, at the outset, below the 

 curves for these other angles of twist. 



When the wire is subjected to longitudinal stress, the curve 

 undergoes a slight alteration. The initial part of the curve lies 

 below the curve for the unloaded wire, but the current increases 

 steadily, and finally reaches the Wendepunkt, which occurs at a 

 hjo-her field than in the case of wires under no longitudinal stress. 

 As the longitudinal stress is increased, the current becomes smaller 

 in weak magnetizing fields, but it increases steadily witli the increase 

 of the magnetizing force so that the curve ultimately cuts the curve.' 

 for no longitudinal stress. At the same time the Wendepunkt of the 

 curve is shifted into stronger fields. Similar results have been 

 obtained for the twisting transient current. 



In the experiment made by suddenly twisting the nickel wire, 

 it was seen that with the angle of twist then applied, the current was 



