2?2 Messrs. H. .Nagaoka and K. Honda on Magnetostriction. 



magnetic east and west. When the current was made, the 

 magnetization of two similar bodies produced nearly the 

 same effect on the magnetometer in opposite sense ; thus the 

 deflexion of the magnetometer was so compensated that the 

 magnetometer could be placed very near the solenoids and 

 thereby rendered sensible to a slight change in the condition 

 of the magnetized body. In order to make the compensation 

 exact, the auxiliary solenoid S' was provided with levelling- 

 screws, and the brass tube containing the auxiliary magnet 

 with screw for adjusting the vertical position of the magnet. 

 The magnetizing solenoid was firmly fixed to the solid stone 

 pier, so that there was no risk of being disturbed by the 

 application of strong pressure to the vessel through bent 

 copper tubes ; it was also tested by means of a long thread 

 pendulum attached to the solenoid that no appreciable dis- 

 placement of the solenoid took place during the application 

 or removal of pressure. 



Fig. 3. 



TTTi 



i I I I 



r 



iT 



zS 



J 8 8 



S' 



M 



To make the reading of the magnetometer sensitive, it was 

 necessary to place the magnet in a position of maximum 

 deflexion ; this can be effected either by calculation for the 

 ovoid * or experimentally determined for other shapes. The 

 brass vessel was moved slowly up and down to such a position 

 that it was not affected by the small vertical displacement, 

 * Nagaoka, Wied. Ann. vol.lvii. p. 275 (1896 ). 



