OX TRANSIENT ELECTRIC CURRENTS. 351 



produces greater diminution of susceptibility as the magnetizing field 

 is taken greater. But consistently with the existence of a point 

 similar to the Villari reversal, and the diminution of magnetization in 

 weak fields, we should find increase of susceptibility in the direction 

 of compression when the magnetizing field is taken sufficiently great. 

 Of course, the increase of susceptibility in a given field will take 

 place only within a certain limit of compressional stress, beyond 

 which there is decrease. If this is really the case, the increase of 

 susceptibility in the direction of stretching must always be greater 

 than the increase in the direction of compression however greal the 

 magnetizing field is taken, for otherwise there would be reversal of 

 the direction of current. 



Xow examining the results of Professor Ewing on the mag- 

 netization of soft iron wire, I find that the increase of susceptibility 

 by loading is very small, when the field strength is over 10 unit-. 

 It is not thus improbable that when the field is taken sufficiently 

 great, the increase of susceptibility in the direction of compression 

 exceeds that in the direction of stretching, so that the current is 

 reversed. But this is quite contrary to the results of the present ex- 

 periments. On this account, it seems that twisting the wire does not 

 give rise to simple compression and extension along lines inclined at 

 45° to the normal plane section of the wire and perpendicular to the 

 radius. The molecular arrangement of the wire must also be affected 

 and give rise to additional changes in the transient current, which 

 cannot be ascribed to aeolotropy alone. 



In the experiments so far described, the wire was always twisted 

 in the magnetizing field between two extreme limits of twist. In 

 the experiments now to be described, the wire after being twisted 

 repeatedly to and fro, was kept in position at either extremity of the 

 range of twist, and the external magnetizing field was then suddenly 



