486 DR & PLARR ON THE DETERMINATION OF 



Secondly, in S.^i the first term of ^i disappears, because &-<**-* 

 -x^i. We get r 



Taking the fr 1 of the expression of & 



In the coefficient of a; we have 



= ?»„ 



This gives 





Summing together S«*+W* we have the factor W, affecting all the 

 terms, and the equation * 



in which for abbreviating we put 

 becomes 



If, instead of eliminating S, we had eliminated 2i from Sfc*(«, we would 

 have got v 



W r~ W 

 But as we have 



- [Wx + S/afa-it] = - [S.(Vi<j>i + Vj<pj)<f> - > 



