( 432 ) 
_ •+ — ^-— = 0 . (20) 
Q* Q* [Qt 92^2) 
From (17) and (19) we obtain 
— — ^\ + Ct= 0,. (21) 
q i 
from (18) and (20) 
b 6, 
- 4- <7 = 0. . (22) 
So 
b = b^ — Cg,* ±= b, — Cqs . (23) 
The equation (17) becomes 
a =-|;-^(|- 2 ). <*» 
and the equation (18) becomes 
. w 
From (24; and (25) we obtain 
b _ c RlQ * ~ ^2^1 ( 2R 1—Qi) ( 06 ) 
R r -R 2 
and 
a — C Pi ( 2iZ i—Pi) ~ g 2 g a ) (27) 
12 , - 12 2 
Substituling these values in (16) we find 
_z, \9x( 2 Ri-Qi)—Q,( 2 R 3 —Q2) , 
C i“ -+ 
■ Q*Ri(%R* ffa)— QiR*(%Ri —pi) _ j j (28) 
In the peculiar case in which q 1 and p 3 differ very little from 
one another we may put 
Q* = Q j 
Pl = 9 +* . < 29 > 
r = 9 + * 1 
d and n being infinitely small. In this case we have 
c= EL . (3») 
