'257 
) 
O \ QXÙ 
ponendo pro dt fuum valorem inventum , & dzdx 
dx ddy 
pro ädy^ ex æquatione dy , h 
ddt 
ddt 
dy 
dt 
depre- 
henditur valor ipfÎLis , qui pro ipfo in fuperio- 
x'*'dz^ 
ri æquatione fubditutus dat 0.- r — — 
P 2f7rx^ dz 
2dx^ Ttx'^dzdx 
xdz' — ddx > m qua æ- 
X ‘ ’ /^ -f- dz 
, quatione ponendo x~ ~ invenitur per debitam rc- 
ndv 
0 
dz'^ '^dzy 
du8:ionem vdz^ + 
gi ^2 -y2 
^1 + 2/- 
Trdz 
g^h 
= 0 , Æquatio hæc conincidit cum ilia a Dom d’A- 
lembert exhibita in fua Lunæ Theoria. Eadem 
hæc æquatio facile etiam deducitur fequenti modo 
ab æquationibus 0dt^ — xdz'^ ■ — ddx 8c 7rdt^ =: 
2 dzdx -f- xddZ) quarum pofterior dat dt 
x^ dz 
—JT . & quæ æquationes obtinent 
-h 2 Jttx'^ dz 
dum ddt = 0 . Ponatur namque — — , nec non 
'U 
valor ipfîus dt pro ipfo in priori æquatione & fiet 
0dz^ dz^ ddv 2 dv^ 
J — [ ydum 
^7C dz \ V v'^ 
f» (s’Â’ + î/-— - ) 
ve- 
t 
