646 Messrs. K. Honoja and S. Shimizu on the Vibration of 



of the make or break of the current. The thickness of the 

 bar had no effect on the pitch of the sound. Non-magnetic 

 bodies gave no sound under similar conditions. He then 

 concluded that the vibration of the wire was produced by the 

 magnetic change of length. Beatson* noticed a sound 

 produced in a stretched iron or steel wire carrying an inter- 

 mittent current. De la Rive t tried, not only bars of iron 

 and steel, but also those of lead, zinc, bismuth, tin, antimony, 

 platinum, gold, and silver. He placed these bars between 

 the poles of an electromagnet and passed an intermittent 

 current through them. They all sounded, the ferromagnetic 

 metals producing sound with only the intermittent current 

 through them, although there was no magnetizing field 

 acting. The experiments with fine powders of several metals 

 and powdered coke gave similar results. He ascribed the 

 phenomenon to some molecular transposition. Ferguson % 

 and Ader § noticed similar phenomena with intermittent as 

 well as alternate currents. Trowbridge || found that nickel 

 and cobalt also produced sound under similar conditions. 

 In studying the effect of tension and compression on the 

 intensity of sound produced in iron and nickel bars, Bach- 

 metjew^f found that the effect was parallel to that of tension 

 on the magnetic change of length. He thus concluded that 

 the intensity of the sound is a function of the change of 

 length by magnetization. 



A short consideration of these results leads us to distinguish 

 three kinds of the sound. The first is the combined effect of 

 the magnetic force and the electric current. The sounds 

 noticed by Page, Delezenne, and De la Rive belong to this 

 category ; they do not depend upon the magnetic property 

 of the substance, but on the mechanical action produced by 

 the magnetic force and the current. 



The second kind of sounds accompanies the magnetization 

 or demagnetization of a magnetic substance in making or 

 breaking a magnetizing current. The sounds noticed by 

 Marrian and others belong to this category. The cause of 



* Beatson, Electr. Mag. April 1846 ; Arch, de Geneve, vol. ii. p. 113. 



f De la Rive, Phil. Trans, i. p: 39 (1847) ; Pogg. Ann. vol. lxxvi. 

 p. 270 ; Arch, des Sc. phys. et nat. vol. xxv. p. 3] 1 (1866) ; Pogg. Ann. 

 vol. cxxviii. p. 452 ; Ann. de chim. et de phys. [4] vol. viii. p. 305 (1866). 



X Ferguson, Proc. Roy. Soc. Edinb. March 6, 1878 ; Beibl. vol. iii. 

 p. 205. 



§ Ader, Compt. Rend. vol. lxxxviii. p. 641 (1879)'; Beibl. vol. iii. p. 642. 



|| Trowbridge, Beibl. vol. iii. p. 289 (1879) ; Proc. Amer. Acad. vol. xi. 

 p. 114 (Dec. 1878). 



U" Bachmetjew, Exner's Rep. vol. xxvi. p. 137 (1890) ; Beibl. vol. xiv. 

 p. 537. 



