THEORY OF ELECTRODYXAMICAL ACTION. 27 



ral phenomena above stated would be accounted for. And the choice 

 between the two modes of conception, appeared at first sight a matter 

 of indifference. The majority of philosophers at first adopted, or at 

 least employed, the former method, as Oersted in Germany, Berzelius 

 in Sweden, Wollaston in England. 



Ampere adopted the other view, according to which the magnet is 

 made up of conducting-wires in a transverse position. But he did for 

 his hypothesis what no one did or could do for the other : he showed 

 that it was the only one which would account, without additional 

 and arbitrary suppositions, for the facts of continued motion in electro- 

 magnetic cases. And he further elevated his theory to a higher rank 

 of generality, by showing that it explained, not only the action of 

 a conducting-wire upon a magnet, but also two other classes of facts, 

 already spoken of in this history, the action of magnets upon each 

 other, and the action of conducting-wires upon each other. 



The deduction of such particular cases from the theory, required, 

 as may easily be imagined, some complex calculations : but the deduc- 

 tion being satisfactory, it will be seen that Ampere's theory conformed 

 to that description which we have repeatedly had to point out as the 

 usual character of a true and stable theory ; namely, that besides ac- 

 counting for the class of phenomena which suggested it, it supplies an 

 unforeseen explanation of other known facts. For the mutual action 

 of magnets, which was supposed to be already reduced to a satisfactory 

 theoretical form by Coulomb, was not contemplated by Ampere in the 

 formation of his hypothesis ; and the mutual action of voltaic currents, 

 thouo-h tried only in consequence of the suggestion of the theory, WUN 

 clearly a fact distinct from electromagnetic action ; yet all these facts 

 flowed alike from the theory. And thus Ampere brought into view a 

 class of forces for Avhich the term " electromagnetic " was too limited, 

 and which he designated 1 by the appropriate term clectrodynamic ; 

 distinguishing them by this expression, as the forces of an electric 

 current, from the statical effects of electricity which we had formerly 

 to treat of. This term has passed into common use among scientific 

 writers, and remains the record and stamp of the success of the Am- 

 perian induction. 



The first promulgation of Ampere's views was by a communication 

 to the French Academy of Sciences, September the 18th, 1820; Oer- 

 sted's discoveries having reached Paris only in the preceding July 



1 Ann. de Chim., torn. xx. p. 60 (1822). 



