3 ART. 12. -K. HONDA, S. SHIMIZU. AND S. KUSAKABE : 



The rotation of the cvlindcr \v;is oh.served ])y means of a vertical «cale 

 and a telesco[)e. 



The dimensions of eacli part of our arrangement were as 

 follows ;- — 



Length of each coil — 39.90 cm, 



Its internal diameter = 5.80 cm, 



4-n =393.5, 



Distance between the coils in air^ = 2.5 cm for iron and steel, 



r 



i= 2.( 



gap i = 2.0 cm for nickel and cobalt, 



i|= 59.9 

 1= 21. 5« 



Distance between two fulci'ams^ = 59.91 cm for iron and steel, 



L and M / = 21.59 cm for nickel and cobalt, 



Diameter of the rotating cylinder = 0.172 cm, 

 Scale distance ==2G1.3cm. 



The sensibility of our apparatus was such that the displacement 

 of one division of the imaii^e of the vertical scale in the field of the 

 telescope corresponded to a change of depression of 1.72xlO"^cm in 

 the middle of our ferromagnetic rod. It was neccessary to protect the 

 mirrcjr and the thin copper wire from air currents in order to prevent 

 minute vibrations (jf the mirror. 



The measurements were conducted in the followins; order. The 

 bar to be tested was placed in the axial line of the coils and then 

 loaded by a weight. The tension of the fine copper wire was then 

 suitably adjusted by means of a screw fixed to the support K, and the 

 inirroi' was directed towards the telescope. This adjustment was 

 effected as in the experiment described in the preceding paper. To 

 begfin with, a current through the coils was made or broken and the 

 working of the arrangement tested. The bar was then demagnetized 

 nnd the initial reading taken. A current was then passed through 

 the coils and the corresponding deflection noted. These processes 

 were repeated with successively increasing currents. 



