﻿450 Prof. R. Clausius on the new Conception of 



and e', moving in the two conductors. The distance from each 

 other he calls r; but from the first he makes the distiuction that 

 in determining r he considers the two quantities of electricity at 

 different times. The distance between the position of e at the 

 time t and the position of e' at the time /' he denotes by r(t, t'). 

 If thus we wish to determine the potential emitted from e at the 

 time t—At, and which arrives at e' at the time t, we have, as 

 before, to denote by r(t—At, t) the value of r which then comes 

 into play. Thus the potential of e upon e' (if, with Riemann, 

 we use the minus sign, since similar electricities repel each 

 other) is 



r{t—At,t) 



In calculating with this expression, he distinguishes between the 

 differentiations which refer to the motion of e from those which 

 refer to the motion of e', by denoting the first by d and the 

 latter by d ! . 



For the sake of greater convenience, he introduces the func- 

 tional sign F with the meaning 



by which the expression for the potential passes into 



-eeT(/-Af, t). 



Using this functional sign, he distinguishes between the deduc- 

 tions which refer to e and those referring to e l by affixing to F 

 either an accent or an index, that is, either by F ; or by F 2 . 



So far nothing can be urged against Niemann's expressions ; 

 but in the further treatment points occur with which I cannot 

 agree. 



First of all, in determining A^ he proceeds just like Neumann. 

 Denoting the velocity of propagation of the potential by a, he 

 puts 



a 



in which r is the distance of the quantities of electricity e and e' 

 at the time t. His expression for the potential accordingly 

 becomes 



ee'F 



(<-;•<)• 



But to carry out logically his own distinction of the various dis- 

 tances, he ought to put 



