75-77] Solution in Powers of a Parameter 



77 



I have not succeeded in obtaining a general direct proof of this formula, 

 but it is easy to verify it a posteriori for all the cases in which it is used in 

 the present book. 



It may be noticed that if 



P-F( X y z 



r < 'la*' F 2 ' 

 then the value of P is 



It appears that a term of degree n in P gives rise to 

 first order terms of degrees n, n 2, n 4, . . . , 

 second 2n - 2, 2n - 4, 2n - 6, . . . , 

 third 3n-4,3w-6, 3tt-8,... 



and so on. 



