372 H. XAGA.OKA. 



compressional stresses are increased, the change in magnetization in 

 both directions becomes very small. In fact, we should expect the 

 transient current to increase with the twisting, and to have no max- 

 imum if the current be due simply to aeolotropy. The preceding 

 experiments in constant magnetizing field show that this is really the 

 case. On the other hand, when the magnetizing" field is made to 

 vary, the current reaches a maximum. Looked at from the point of 

 view of aeolotropy, this would mean that the arithmetical sum of the 

 increase of the magnetization in the direction of compression and the 

 decrease of magnetization in the direction of stretching reaches a 

 maximum value at a certain magnetizing field, a conclusion which 

 agrees with the experiments of Ewing. Thus aeolotropic magnetic 

 susceptibility in the directions of stretching and of compression not 

 only explains the direction of the current, but also some of its general 

 characteristics. 



The transient current produced by reversing the direction of the 

 magnetizing force was examined in the same manner as in the case 

 of iron. With the wire kept twisted, the magnetizing force was 

 reversed many limes, and immediately thereafter, the reading of the 

 first swing due i<> the next reversal was taken. This was done with a 

 series of gradually increasing values of the magnetizing force. Out of 

 numerous experiments, \ give only five of the curves (Fig. XI) taken 

 with the thick wire and four (Fig. X 1 1) obtained with the thin. 

 For I he thick wire : — 



Curve I. for r = ± 30° 

 If. „ r = ± 90° 



III. .. r = ±18l>° 



IV. „ r = ± 00° (loaded I kg.) 

 ,, V. ,, r = ± 60° ( ., 8 kg.) 



For the thin wire : — 



