C 439 ] 
Problem XVIII. 
44. To find, the motion of the moons node during the 
time that the fun is pafling from the node of the 
moon' s orbit 'with the ecliptic , to its point of flat ion \ 
that is, in three months , wanting a few days. 
Here we are to make ufe of the formula of Art. 13. 
becaufe the motion of the moon’s nodes is very fen- 
iible in refpedt of the motion of the fan. 
To- T 
Wefhallhavey4 /$x — x-x( 1 — Ah x x |) ; and 
2r 4 2 irr 
employing the values of Prob. XI. except that here 
t — 27 \ days, which is the time of the moon’s re- 
volution about the earth, and that - = to the fine of 
r 
85 deg. divided by the radius; the axe of the lunar 
orbit being inclined in an angle of about 87 degrees to 
the ecliptic. Therefore - == —9ft- 1 947 , Laftly, by 
r 10000000 
Art. 2 c. we muff take = 1, and the 
i — 2a 
^ X ^ 7 x 
formula will be changed into this, ■ ■ ■■■■■ x 
3 6 5t 
x il2 de S- x (1 3 x 2 7l y 99^ 1 94-7 y 1 
8 365^ 10000000 2 x b 
9661947 
— ■ ■ ■ am 
icooocoo 
redudtion) 4 0 . 36'. 33". 
This is the motion of the moon’s node during the 
time that the fun is palling from the node of the 
moon’s orbit with the ecliptic to its point of flation ; 
that is, during the time the fun is moving 90 < — 4 de- 
grees 
