176 M. E. Ecilund on the Nature of Electricity. 



circuit is not determined exclusively by the direct action exerted 

 by the inducing current upon it, but also by the modification of 

 the state of equilibrium in the aether of the surrounding insulating 

 medium. As soon as the inducing current ceases, the sether 

 molecules return to their primitive position of equilibrium, and 

 consequently we have in the closed circuit an induced current 

 equal in intensit}', but opposite in direction, to the former. 

 "When an inducing current is brought near or removed from a 

 closed circuit, the effect is evidently the same as when a current 

 commences or ceases in a circuit at rest. Although no induced 

 current properly so called is observed in the insulating medium, 

 since the great resistance to conduction impedes the origination 

 of such a current, we have nevertheless no reason to suppose that 

 the sether molecules therein remain in a state of perfect repose : 

 the positions of equilibrium are modified there also, since expe- 

 riment has demonstrated that no substance can be considered 

 absolutely nonconducting. 



If two molecules of aether, m and m^, are at rest at the distance 

 r one from the other — according to what has been said before, 



their mutual repulsion is ^-. For the unit of measure of 



T' 



aether masses we have obviously taken here the mass of aether 

 which is capable of giving to another mass of equal amount the 

 acceleration 1 in the time 1, the distance between the masses 

 being 1. If, on the contrary, m' only is at rest while m moves 

 with the constant velocity A in a direction making the angle 6 

 with the line of junction between the two molecules, we have, for 

 the case in which ??i approaches m' (in which we designate the 

 acute angle by 6), 



-'^\^l + ct^{-hco,e)+frj [l-cos^^])] 



as the expression of the repulsion according to equation (1) of 

 the first part of this memoir. 



For the case in which m recedes from ?n', and designating the 

 obtuse angle by 6, we obtain the same formula, except only that 

 h cos 6 (which is equal to the projection of the velocity along the 

 line of junction) has the opposite sign. 



From equations (7) and (10) we have : — 



^ (7 [1 - cos^ ^])= I ^^'U - cos^ 0), 

 and 



(jy{-h cos 0) = -ah cos 6>- 1 h'- cos^ 0. 



Introducing these values of '^p and 6 into the above expression 



