[ 421 3 
b ' 
fince — exprefifes here the fine of the angle of in- 
clination of the earth’s axe to the plane of the lunar 
orbit, and -is its cofine ; we fhall have then 1° K =*; 
r 
cic 
; C K 
b c 
= C<P — <PK 
a 
g 
r a 
““—gg+gz _ fj + g z ff — g Z 
a 
xg—z — 
a 
, or — , when the 
a 
point 1° is on the other fide with refped: to l 1 j 
RM 
PR 
f 
NK a 
i° K 
— x^— ^ 
/ ■ 
a 
%g-\-z 
or 
of Pi 
a c 
r 
PM Nl° 
a c 
r 
for the other fide 
FR~t°K 
\/x.x — zz: Laftly, the differ- 
ac 
r 
xdz 
2 7T 5C 
Tr 
ence of the arc V 1° = d u — — 
V/jc 
x dt, calling ?i T the time which the pole of the lu- 
nar orbit employs in performing its revolution in the 
circumference 2 7 r x, whence we get d t — 
2 7 r 
d z 
x. jc — ZZ 
The fpace run through in an infiant dt by the pole 
P of the earth parallel to the plane of the lunar orbit 
being 
