16 



AKT. 14.— K. HONDA AND S. SHIMIZU 



Annealed cobalt bar. 



The effect of torque. To study the effect of torque, it is convenient 

 to keep the longitudinal field constant and to vary tlie circular field; 

 for thougli the application of the longitudinal field is always accom- 

 panied by the twist due to the change of rigidity, the passage of a 

 longitudinal current does not cause any appreciable twist; lience by 

 varying the circular field, it is not necessary to apply the correction 

 due to the change of rigidity. The torcpie was given by means of the 

 suspended weights as in the experiment on the change of rigidity by 

 magnetization. Keeping the longitudinal field constant, we found 

 that in all cases the effect of torque diminishes the twist by an amount 

 wiiich is nearly ])roportional to the torque. Figs. 17, 18, 19, 20 

 show the f'-eneral feature of the decrease of twist due to torque. In 

 soft iron and annealed cobalt, the effect is very small, but in nickel 

 and cast cobalt, it is considerable. 



In a paper on mutual relations between torsion and magnetism, 

 Professor Najraoka and one of our members liave obtained from 

 Kirchhoff's theory the result that for given longitudinal current and 

 field, the amouiit of (wist is inversely proportional to the scjuare of 

 the radius of the ferromagnetic win;. It is interesting to notice that 



