66 A NEW METHOD OF DETERMINING 
we have 
where, as before, 
In a similar manner all the other expressions for the forces have been derived. 
When we compute only perturbations of the first order with respect to the mass 
we need the perturbing function 
CO SS (4) — fH 
and the forces 
dQ 4 Ee "|-3 ON . 
are, = eS) Lam oa] — eG) — 
qe — — pa2(“)" ae 2 sin (f+ Il’) + (1). 
The other forces are only needed when we take into the account terms of the sec- 
ond order also with respect to the mass. 
An inspection of the expressions for the forces shows that besides the functions 
(> wal(G) » wai) 
we need expressions for the magnitudes 
r!\? i 7 git I 7 6 , , sti JT Rs a 
G)o gm a gin F 41), = 7 ain (f+ ID; 
(BD), (i, GBe, Gay”. 
