Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 1.djvu/341

 to the times, and an orbit more approaching to the form of an ellipis having its focus in that centre, than it can decribe round the innermot and greatet body T by radii drawn to that body.

For the attractions of the bodies S (Pl. 21. Fig. 3.) towards T and P compoe its abolute attraction. which is more directed towards O the common centre of gravity of the bodies T and P, than it is to the greatet body T; and which is more in a reciprocal proportion to the quare of the ditance SO, than it is to the quare of the ditance ST; as will eaily appear by a little conideration.

The ame laws of attraction uppoed, I ay that the exterior body S will, by radii drawn to O the common centre of gravity of the interior bodies P and T, decbribe round that centre, area's more proportional to the times, and an orbit more approaching to the form of an ellipis having its focus in that centre, if the innermot and greatet body be agitated by thee attractions as well as the ret, than it would do if that body were either