90 Prof. E. Wartmann's Fifth Memoir on Induction. 



governed by such similar laws, that M. Melloni* and other 

 philosophers admit the identity of their nature. The same 

 has been the case, since Ampere, with electricity and mag- 

 netism, the analogous properties of which are comprised in 

 phaenomenaof attraction, repulsion, and induction. The only 

 manifestations common to the four fluids are their impondera- 

 bility, their property of mutually engendering themselves in 

 matter, and of reacting in various cases upon one another, 

 their incapacity of passing freely through certain bodies, 

 (opake, athermanous, isolating) ; lastly, their extreme velo- 

 city of propagation, But these resemblances do not admit of 

 our deciding whether electricity is transmitted by radiation, 

 as might be conjectured from its more rapid motion than that 

 of light, or by conductibility, in the manner of the caloric of 

 contact, as has been supposed by a sort of universal conven- 

 tion, to which scientific language gives faith. The expressions 

 of conducting bodies and isolating bodies have only acquired a 

 * theoretical importance from the remarkable works of Ampere 

 on the propagation of electricity t> and of Mr. Faraday on the 

 induction of contiguous particles J. 



148. In his Recherches sur quelques points de V Electricitc 

 voltatque, M. Vorsselman de Heer has given his opinion that 

 the velocity of the current depends only on the matter of the 

 conductor, just as the rapidity of sound is modified only by 

 the nature of the medium in which it is transmitted §. If 

 this was the case, the proposed hypotheses on the mode of 

 propagation and on the nature of the electric fluid would be 

 very much simplified. But the phenomenon is probably more 

 complicated ; and M. PoggendorfFhas recently shown that the 

 rapidity of transmission of the current of the battery seems to 

 be proportioned to the product of the conductibility of the 

 medium by its section ||. 



149. The object of this memoir is to establish the fact ex- 

 perimentally, that rectilinear propagation, a fundamental con- 

 dition of all radiation, is not verified for dynamic electricity, 

 which consequently does not possess the property of being 



* On the Identity of the various luminous, calorific and chemical radia- 

 tions, vibrated by the Sun and the terrestrial sources. Bill. Univ., vol. xxxix. 

 p. 168. 



f On the mode of transmission of Electric currents, and on the Electro- 

 chemical theory. This memoir, which had remained inedited, has been 

 published in the Scientific Review of Quesneville, vol. xxxi. p. 171, Nov. 



1847. 



I Experimental Researches in Electricity, §§ 18 and 19, Phil. Trans. 1 838. 



§ Bulletin des Sciences Physiques et Naturelles en Neerlande, 1839, vol. i. 

 p. 319. 



|| Annalen der Physik und Cltemie (1848, No. 3), vol. lxxiii. p. 355. 



