362 H. XAGAOKA. 



experiments, the eritieal point may have been passed. But Professor 

 Ewing in discussing the transient current as due to aeolotropic mag- 

 netic susceptibility takes the pulling stress only into account, and 

 completely ignores the effect in the direction of compression. As I 

 have already pointed out, compression must play an important part 

 in changing the amount of the transient current, ft is the difference 

 of magnetization in the directions of compression and of stretching 

 that gives rise to the transient current, if the phenomena is entirely 

 due to aeolotropic susceptibility. Thus, although the Villari critical 

 point has been passed, the current may How in the same direction so 

 long as the corresponding compressional stress produces greater 

 decrease of susceptibility than in the direction of stretching. Again 

 the current can reverse its sign even when the Villari critical point 

 has not been passed, provided compression produces greater increase in 

 the magnetism of the iron wire examined. The scantiness of experi- 

 mental data in this branch of research does not admit us to draw 

 any definite conclusion on the subject under discussion. To see 

 whether the application of very large twist reverses the direction of 

 the transient current, I had recourse to direct experiment rather than 

 to mere reasoning on scanty resources. With this object in view, I 

 subjected an iron wire 1.54 mm. thick, and 27 cm. long to fore 

 and back twistings through an angle of 3(>0 o . The twist thus 

 applied amounted to 13° per cm., and must correspond to great com- 

 pressional and stretching stresses. On reversing the magnetizing 

 current and observing the transient current, it was found that the 

 direction was always the same and determined by the direction of 

 stretching ; nor did the current due to this large twist show any 

 notable decrease as compared with currents due to smaller twists as the 

 comparison of the following readings with the same wire for smaller 

 twists will show. 



