Closing Years of the Nineteenth Century. 435 



By direct transformation from the original to the new 

 variables it is found that, when quantities of order iv*/c* and 

 wv/c* are neglected, these equations take the form 



divj d! = 4?rc 2 p, curl a di = - Sh^B^, 



div t H! = 0, curl, hi = (1/c 2 ) ddj/fy 



F = d! + [v lt hj, 

 where div, d, stands for 



Since these have the same form as the original equations, 

 it follows that when terms depending on the square of the 

 constant of aberration are neglected, all electrical phenomena 

 may be expressed with reference to axes moving with the earth 

 by the same equations as if the axes were at rest relative to the 

 aether. 



In the last chapter of the Versuch Lorentz discussed those 

 experimental results which were as yet unexplained by the 

 theory of the motionless aether. That the terrestrial motion 

 exerts no influence on the rotation of the plane of polariza- 

 tion in quartz* might be explained by supposing that two 

 independent effects, which are both due to the earth's motion, 

 cancel each other; but Lorentz left the question undecided. 

 Five years later Larmorf criticized this investigation, and 

 arrived at the conclusion that there should be no first-order 

 effect ; but LorentzJ afterwards maintained his position against 

 Larmor's criticism. 



Although the physical conceptions of Lorentz had from 

 the beginning included that of atomic electric charges, the 

 analytical equations had hitherto involved p, the volume-density 

 of electric charge; that is, they had been conformed to the 

 hypothesis of a continuous distribution of electricity in space. 

 It might hastily be supposed that in order to obtain an 



* Cf. p. 416. t Larmor, Aether and Matter, 1900. 



J Proc. Amsterdam Acad. (English ed.), iv (1902), p. 669. 

 2 F 2 



