r 344 3 
larly in the Vertical} and the Time being given, the 
Gravity may be meafured by the Space which is the 
Subtenfc of the Angle of Contad. In other Cafes, 
when the Gravity varies, or its Diredion changes, it 
may be meafured at any Point by the Subtenfe of the 
Angle of Contad, that would have been generated 
in a given Time, if the Gravity had continued to ad 
uniformly in parallel Lines from that Term, that is, 
by the Subtenfe of the Angle of Contad in the Para- 
bola that has its Diameter in the Diredion of the 
Force, and has the ciofeft Contad with the Curve} 
which leads us to the fame Theorem as before. 
In general, let the Gravity (that refults from the 
Compofition of any Number of centripetal Forces, 
which are fuppofed to ad on the Body in one Plane) 
be refolved into a Force parallel to the Bafe ; then the 
former fhali be meafured by the Second Fluxion of 
the Ordinate, and the latter by the Second Fluxion 
of the Bafe, the Time being fuppofed to flow uni- 
formly, fo that the Velocity of the Body may be 
meafured by the Fluxion of the Curve. When the 
Trajedory is not in one Plane, the Force is refolved 
in a fimilar manner into Three Forces, which are 
meafured by Three Second Fluxions analogous to 
them. 
Whether the Body move in a Void, or in a Me- 
dium that refills its Motion j the Gravity that refults 
from the Compofition of the centripetal Forces which 
ad upon the Body, is always as the Square of its 
Velocity diredly, and the Chord of the Circle of 
Curvature that is in the Diredion of the Gravity iar 
vetfely. 
When 
