Case 6. And if there be compoſed a new ſphere out of innumerable corpuſcles ſuch as p, ſituate within the firſt ſphere AEBF; it may be proved as before that the attraction whether, ſingle of one ſphere towards the other, or mutual of both towards each other, will be as the diſtance pS of the centres. Q. E. D.
Proposition LXXVIII. Theorem XXVIII.
If ſpheres in the progreſſion from the centre to the circumference be however diſſimimar and unequable, but ſimilar on every ſide round about at all given diſŧances from the centre; and the attractive force of every point be as the diſŧance of the attracted body; I ſay that the entire force with which two ſpheres of this kind attract each other mutually is proportional to the centres of the ſpheres.
This is demonſtrated from the foregoing propoſition in the ſame manner as the 76th propoſition was demonſtrated from the 75th
Cor. Thoſe things that were above demonſtrated in prop. 10. and 64. of the motion of bodies round the centres of conic ſections, take place when all the attractions are made by the force of ſphærical bodies of the condition above
