which it will afterwards purſue its courſe. For by compounding the proper motion of the body with that motion, which the impulſe alone would rate, you'll have the motion with which the body will go off from a given place of impulſe, in the direction of a right line given in poſition.
Cor. 4. And if that body is continually diſturbed by the action of ſame foreign force, we may nearly know its courſe, by collecting the changes which that force introduces in ſome points, and elminating the continual changes it will undergo in the intermediate places, from the analogy that appears in the progreſs of the ſeries.
Scholium.
If a body P (Pl. 6. Fig. 4.) by means of a centripetal force tending to any given point R move in the perimeter of any given conic ſection, whoſe centre is C; and the law of the centripetal force is required: Draw C G parallel to the radius RP, and meeting the tangent PG of the orbit in G; and the force required (by cor. 1. & ſchol. prop, 10. & cor. 3. prop. 7.) will be as .
