THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



OCrOBRR 1847. 



XL. Fourth Memoir on Induction. By M. Elie Wart- 

 MANN, Professor of Natural Philosophy in the Academy of 

 Geneva *. 



[With a Plate.] 



[Continued from vol. xxx. p. 272.] 



§ XIV. On the Commutators employed to render noltaic cur' 



rents discontinuous.^ and to separate currents of induction, 



116. TT is exactly a century since a remedy for various ail- 

 Jl ments was first sought in the electric fluid. The first 

 experiments were made at Geneva by Prof. Jallabert in IT^Tt* 

 At a later period, when the voltaic battery was invented, its 

 physiological effects were studied, and they are now employed 

 for the cure of various affections, such as obstinate ulcers J, 

 dumbness§, deafness II, blindness^, tic-doIoureux**,paralysisff, 

 &c. Lastly, since the discovery of magnetic and electric in- 

 duction in 1831 by Mr. Faraday, it has been found that the 

 induced currents, as well as the electrical discharges of the 

 Leyden jar, have an extremely short duration, and produce 

 greater shocks than batteries of a large number of elements. 

 The idea therefore has occurred of rendering the current of 

 the electromotor apparatus discontinuous, to approximate it 



* Communicated by the Author. 



\ Experiences sur I' Electricite, p. 127. 8vo. Geneva, 1748. 



J Becquerel, Traiie de P/ii/sique,vo].'n. p. 638. Paris, 1844. 



§ Namias, De alctini effetti delV elettnco sopra I Animate Economia, &c., 

 p. 27. Venice, 1841. 



11 Giornale per servire ai progressi delta Patologia et delta Terapeutica. 

 Gennajo, 1843, p. 108. Giornale delle Scienze Mediche di Torino, vol. iv. 

 p. 430. 



^ Giornale per servire, &c.,'DecQmh&t 1841, p. 658. Biblioteca Italiana, 

 fascicolo 25, p. 12, &c. 



** Zantedeschi, Trattaio delta Elettricitd, vol. ii. p. 525. 



tt Giornale di Fisica, S^c. di Pavia, decade II. vol. vii. p. 284 ; and 

 vol. viii. p. 219. Annali delle Scienze del Regno Lombardo-Veneto, January 

 and February 1833, &c. 



PhiL Mag. S. 8. Vol. 3L No. 208. Oct. 1 847. R 



