564 Proceedings of the Royal Irish Academy, 



dv ^^ C dR 



Integrating, r^ -j- = K- \^' dt, 



dt J dv 



dv _H I [dR 



dt r^ r'^\ dv 



Assume r = » + S« + 8r, 



dt (t^ \ CD 



^H ^r 1 CdR ^^ 

 a- a a- ] dv 



Since the last line contains only periodic termsj, 



JT 



w = -[l -2 

 a- \ a 



whence, very nearly, 



dv h- 1 CdE ^^ 



— =^n - In : —r- dt. 



dt a a^] dv 



