about the greateſt; I ſay that the interior of the two revolving bodies will, by radii drawn to the innermoſt and greateſt, deſcribe round that body, area's more proportional to the times, and a figure more approaching to that of an ellipſſis having its focus in the point of concourſe of the radii, if that great body be agitated by thoſe attraction, than it would do if that great body were not attracted at all by the leſſer, but remained at reſt; or than it would if that great body were very much more much leſs attracted, or very much more or very much leſs agitated by the attractions.
This appears plainly enough from the demonſtration of the ſecond corollary of the foregoing propoſition; but it may be made out after this manner by a way of reaſoning more diſtinct and more univerſally convincing.
Case 1. Let the leſſer bodies P and S (Pl. 21. Fig. 2.) revolve in the ſame plane about the greateſt body T, the body P deſcribing the interior orbit PAB, and S the exterior orbit ESE, Let SK be the mean diſtance of the bodies P and S; and let the accelerative attraction of the body P towards S, at that mean diſtance, be expreſſed by that line SK. Make SL to SK as the ſquare of SK to the ſquare of SP, and SL
