(5 ART. 10.— K, HONDA AND S. SHIMIZU: 



make and break. If Uns view be true, the pitch of the sound due to 

 an alternate current must be double thiit of the sound due to an 

 intermittent current for the same number of vibrations of the string 

 alternator, becau.se the magnetic change of length is independent of 

 the direction of the field. By an actual experiment analogous to 

 that of Lissajous, we found this inference to be verified. The above 

 results also .show that the magnetic change of length occurs so 

 quickly as to follow rapid changes of magnetization of as much as 

 150 reversals per .second. 



If the frequency be kept constant, the relation between the 

 amplitude of vibration and the maximum field during one complete 

 period of vibration is similar to the relation of the change of length to 

 a steady field. The maximum field u.sed in most of our experiments 

 was o0.7 C.G.S. units. 



It is also to be observed that if an intermittent or alternate 

 current is pas.sed through a spiral of nonmagnetic metal, an 

 audible .sound is produced. This is perhaps due to the periodic 

 attraction of the currents flowing through the spiral in the same 

 direction, and is of a quite different nature from the sound above 

 referred to. 



5. Gradually varying the frequency of the intermittent or 

 alternate current, while the range of the field was kept constant, we 

 observed the singular phenomenon that the amplitude of vibration 

 passed through several maxima and minima. Two marked maxima 

 and minima were observed in the case (^f nickel wire. The 

 maxima occurred at the frequencies of 80 and 150 per .second, while 

 the minima at the frequencies of 68 and I-IO per second. The 

 phenomenon which was chiefly due to the longitudinal vibration of 

 the wire, was, to a certain extent, modified by the resonance of the 

 system, consisting of a reflecting mirror and two springs attached to it, 



