Electromagnetic Mass of a Moving Electron. 543 



IdW if m w 



~ 5 acW I c 2 + e z / 



5 ac 2 /3 3 

 dv ' 



(ii.) Surface Distribution. 



n 2 e 2 v 

 3 ac 4 p 



dG 2 £ 2 





rfr 3 ac 2 /3 3 

 1 tfW 



In this case the integral ^p x(F x ) o dr o becomes \o-Q%(F x ) d$ , 

 taken over the surface of the sphere of radius a, and 

 F x = 2ttgq cos 6. 



Thus 



I (7 ^(F x ) ^S =:47rV O - 2 ( "cos 2 6 sin 6 cW 



8 „ „ 1 e 2 



and 



1 ^ W x f nrv,re 



"Ga^i c 2 i+ c- 2 J 



z e 



3 ac 2 /3 3 



20 2 



