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LI. Oti the Vibratory Movements which Magnetic and Non- 

 magnetic Bodies experience under the influence of' external 

 and transmitted Electric Currents, By Professor De la 

 Rive*. 



MWERTHEIM has published in the Annates de 

 • Chimie et de Physique, 3rd series, vol. xxiii. p. 302, 

 some further researches on the sounds produced by the electric 

 current. He directs attention to the fact that these sounds 

 are of two kinds ; those proceeding from the action of an ex- 

 ternal current which magnetizes an iron bar or wire, and 

 those produced by a current transmitted either through an iron 

 bar or wire. The sounds of the first kind were discovered as 

 early as 1837 by Mr. Page, and afterwards investigated by MM. 

 Marian, Matteucci, Wartmannf and myself I was the first who 

 indicated the existence of the sounds of the second kind, which 

 Mr. Beatson discovered nearly at the same time as myself, and 

 which have also been the object of the researches of the physi- 

 cists named above, and likewise of some others. M.Wertheim, 

 in 1844, demonstrated that the electric current and magnetiza- 

 tion produce a diminution of the coefficient of elasticity (m the 

 bodies which are submitted to their influence ; but he thought 

 that he perceived in the sounds produced by these two causes 

 rather a mechanical effect than a molecular phaenomenon J, 

 attributing the sounds which the magnetization determines to 

 the attractive action of the helix on the wire or on the bar of 

 iron, and those caused by the transmitted current to a kind 

 of shock which that transmission effected upon the conducting 

 metal. Admitting, in the case of magnetization, in part the 

 cause pointed out by M. Wertheim, I showed that the mole- 

 cular action has its own, and that, in the case of the trans- 

 mitted current, it alone is active. An experiment by M.Guiller- 

 min, and the researches of M. Wartmann, confirmed this view, 

 if not on all points, at least on the greatest number. Lastly, in 

 a more recent memoir, I succeeded in showing that, under the 

 influence of a magnet or a helix traversed by a continuous 

 current, all conducting bodies are capable of producing a 

 sound when they transmit a discontinuous current. 



Li a memoir just published, M. Wertheim, resuming the 

 subject, establishes first, by numerous experiments made with 

 great care, that in magnetization there is a mechanical trac- 

 tion due to a longitudinal and to a transversal component; 

 that the latter becomes null when the iron bar is in the centre 



* From die Annates de Chimie et de Physique for June 1849. 



t Phil. Mag. vol. xxviii. p. 544. 



X Comptes Rendus des Seances det'Academie des Sciences, vol. xxiii. p. 336. 



