650 Messrs. K. Honda and S. Shimizu on the Vibration of 



thin rotating cylinder carrying a reflecting mirror was placed 

 horizontally, and came in contact with the vertical wire at a 

 suitable pressure. The working of the arrangement was the 

 same as in the case above referred to. 



The magnetizing coil was wound in 4 layers, and gave a 

 field of 26*0 c.G.s. units due to a current of one ampere. 

 The coefficient of self-induction of the whole circuit was 

 1*66 x 10 7 c.G.s. units and its resistance 18"2 12, so that the 

 time of relaxation was 0*00091 second. 



With the above arrangement, we also found two marked 

 maxima in the amplitude of vibration for iron as well as for 

 nickel. The amplitude of vibration is plotted against the 

 frequency of the current in figs. 2 and 3. In both cases, the 



Fig. 2. — Iron Wire. 



,. n -6 ...... _.. 



Length 59"6 cm. ; Piam. ( 



>0405 cm. 









\ ^7/ / 









r^-^^sr — ' 







60 100 1*0 (wrot/SAty/ 



Fig. 3.— Nickel Wire. Length 60-3 cm.; Diam. 0-0396. 



100 



140 (i*0£QU£A/CY) 



maximum field during one complete period of vibration was 

 28*5 c.G.s. units, and the weight attached to the lower end of 

 the wire was reduced to the tension per square millimetre. 



As will be seen from the figures, the amplitude of vibration 

 and the frequency corresponding to the maximum amplitude 



