( 624 ) 
R = - «, |/«,«» 4«i (ft-ft). 
Consequently system (6) takes this form: 
ftJl 2iVm 1 « I «,i 
1 1 * 
„ ! » 
dt 1 * 
— = im. a, a-lmsy,-, 
where JV is written for n 2 = ; further: 
mi ~~ N* ’ 
tp = 2 
As t does not appear explicitly in It we get according to what 
has been said at the close of § 4 as an integral: 
«, j/a 2 cos <p = constant. . . ... (10) 
Furthermore it appears at once from (9) that: 
da. . da, 
' i* + n = *■ 
Therefore: 
«i -f- « 2 —: constant .(11) 
is another integral. 
The latter gives us reason to introduce a new variable £, in such 
a way that: 
«> = X i V Ar ’ i ’ 5 ’ *»'=-j- R t h ' (1—£>; 
5 is then always situated between 0 and 1, R, is of moderate greatness. 
By this (10) obtains the form: 
.(12) 
in which K represents a constant. 
The first equation of (9) becomes : 
til ~ ~jf~ S V 1— g m (f . h . 
By elimination of <p between (12) and (13) we arrive at: 
(13) 
