Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 1.djvu/252

 equal to it XCy, the angle ICk, and the place k, in which the body will then be found. Q. E. I.

We uppoe in thee propoitions the centripetal force to vary in its reces from the centre according to ome law, which any one may imagine at pleaure; but at equal ditances from the centre to be every where the ame.

I have hitherto conidered the motions of bodies in immovable orbits. It remains now to add omething concerning their motions in orbits which revolve round the centres of force.