262 Prof. R. Clausius on the Determination of the 



pression which according to my fundamental law represents 

 the force-component in question ; we can therefore use for 

 this term the developments already carried out in the prece- 

 ding section, and need only carry out the developments for the 

 second term. 



To determine the force exerted by a current-element dsf. upon 

 a moved unit of electricity, let us consider in the element first, 

 again, the positive electricity N dsf , which flows with the velo- 

 city c f . In order to express for this electricity the portion of 

 the force-component which corresponds to the second term of 

 the preceding expression, we have to substitute in it 1 and 

 h' ds f for e and e 7 , whereby we obtain 



*H$*[(#+(3Dl**4(Ja)}- 



In this we put, in accordance with (1) and (2), 



dx' __ ~§x' f ~dx r 

 ~dt~"dt w 



d 



dt 



/l^\_b_/l^\ , ,d /I d%\ 

 \r dt)-"dt\r dt) + C W\r dtp 



by which the expression is changed into 



+4£t) + ^Mf)J- 



The corresponding expression for the negative electricity 

 — h f ds') which flows with the velocity — c'i, is 



By addition of these two expressions we get 

 kdS \ l dx Lj»«^' + 2 {■d S i)J +l -ds'\rdt)f' 



