CHANGE OF ELASTICITY BY MAGNETIZATION. J 



o. Our method of measurement was similar to that of Stevens 

 and Dorsey, as shown in the annexed figure. 



A and B were two magnetizing coils of the same dimensions-,, 

 which rested horizontally in a co-axial line. FG was a stout brass 

 rod of rectangular section extending between tAvo fulcrums ; it was 

 also supported at the midde point by another fulcrum. The coils 

 can, therefore, be moved independently of the bar. LM was a rod to 

 be tested placed in the axial line of the coils. It was supported at 

 L and M bv two fulcrums : one of them was an ordinary wedsfe 

 fixed to the brass rod, while the other consisted of a cylinder, which 

 could rotate about its own axis. (^ was the weight suspended from 

 the middle of the bar. At the center of the bar, a fine copper wire, 

 the diameter of which was about 0.08mm, was soldered and stretched 

 vertically upwards by means of a weak spring P. This wire was 

 wound once round a rotating cylinder, to which a small mirror was 

 attached, and then stretched upwards, as used in Hertz's dynamometer.* 



* Hertz .lüstniuientenkunde, 3, 17, 1883 ; Gt^sauimelte Werke Ba. 1. 



