C 4*5 3 
of Incidence, it is only at the Equator that the cen- 
trifugal Force can be changed into a centripetal Force. 
^ E, 
Corollary L 
Therefore the modern Cartejians are ftrangely 
miftaken, when they pretend to account for Gravity 
by the Reverfe of the central centrifugal Force. 
Corollary II. 
And they can never, a fortiori.^ in their Principles, 
explain the Figure of the Earth and of Jupiter-^ which 
are flatted Spheroids made by the Converfion of an 
Ellipfis upon itsfmall Axis. 
Lemma I. 
If the centrifugal Force reprefented by IC (fee p. 
420.) be decompofed on the fpherical Tangent into 
a Force, that for its Direflion has the Centre of the 
Sphere} the central Force, which refults from this 
Decompofition, will be to the centrifugal Force, as 
the Radius I C to the Radius O C. 
For the centrifugal Force IC, being decompofed 
into C on the Tangent of the Sphere, will flrike this 
Tangent with a Force that will be reprefented by 
I E. But on account of the fimular Triangles I EC, 
IOC} IE. IC : ;IC. OC. 
Lemma IL 
A Body which deferibes a Curve, firikes this Curve 
every time it pafles from one Side to the other, with 
an infinitely fmall Force of the firft kind with regard 
to its Velocity'. . 
To 
