THEORY OF ELECTRO DYNAMICAL ACTION. 101 



from their first appearance, gave a clear promise of 

 some new and wide generalization ; and held out a 

 prize of honour and fame to him who should be 

 first in giving the right interpretation of the riddle. 

 In France, the emulation for such reputation is 

 perhaps more vigilant and anxious than it is else- 

 where; and we see, on this as on other occasions, 

 the scientific host of Paris springing upon a new 

 subject with an impetuosity which, in a short time, 

 runs into controversies for priority or for victory. 

 In this case, M. Biot, as well as Ampere, endea- 

 voured to reduce the electro-magnetic phenomena 

 to general laws. The discussion between him and 

 Ampere turned on some points which are curious. 

 M. Biot was disposed to consider as an elementary 

 action, the force which an element of a voltaic wire 

 exerts upon a magnetic particle, and which is, as 

 we have seen, at right angles to their mutual dis- 

 tance; and he conceived that the equal reaction 

 which necessarily accompanies this action acts oppo- 

 sitely to the action, not in the same line, but in a 

 parallel line, at the other extremity of the distance; 

 thus forming a primitive couple, to use a technical 

 expression borrowed from mechanics. To this Ampere 

 objected 4 , that the direct opposition of all ele- 

 mentary action and reaction was a universal and 

 necessary mechanical law. He showed too that 

 such a couple as had been assumed, would follow 

 as a derivative result from his theory. And in 



4 Ampere, Theorie, p. 154. 



