370 M. B. Riemann on Electrodynamics, 



masses, if p denote their density at the point (x, y, z), is defined 

 by the condition 



d*U d*XJ d*U . 



and by the condition that U is continuous and is constant at an 

 infinite distance from acting masses. A particular integral of 

 the equation 



dHJ d*V d*\J 



dz 2 + dif + dz* ' 



which remains continuous everywhere outside the point (a?, y' } z f ) f 

 is 



r ' 



and this function forms the potential function produced from 

 the point (x f , y ! , z } ), if at the time t the mass —f{t) is there. 



Instead of this, I assume that the potential function U is de- 

 fined by the condition 



d*TJ /d*\J d*U d*U\ 



^-"A^ + w^^r p ' 



so that the potential function from the point (at, y', z'), if the 

 mass — f(t) is there at the time t } becomes 



/(<-.-) 



If the coordinates of the mass e at the time t are denoted by 

 00 u Vt> z u an d those of the mass e' at the time t ( by %\<, y 1 ?, z\<, 

 and putting for shortness* sake 



((#,-*V)*+ (y t -y\f+ (*«--*V5*)*'* =s ^75 =nt> i')> 



on this assumption the potential of e upon e' at the time t 

 becomes 



= -ee f F 



(<-7'> 



The potential of the forces exercised by all the masses e of the 

 conductor S upon the masses e f of the conductor S' from the 

 time to the time i becomes therefore 



?-M'-H 



h 



