Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 1.djvu/52

8 the centre of the Magnetim, or the Earth in the centre of the gravitating force), or any thing ele that does not yet appear. For I here deign only to give a Mathematical notion of those forces, without conidering their Phyical caues and eats.

Wherefore the accelerative force will tand in the same relation to the motive, as celerity does to motion. For the quantity of motion aries from the celerity, drawn into the quantity of matter; and the motive force arises from the accelerative force multiplied by the ame quantity of matter. For the um of the actions of the accelerative force, upon the everal particles of the body, is the motive force of the whole. Hence it is, that near the uffice of the earth, where the accelerative gravity, or force productive of gravity in all bodies is the ame, the motive gravity or the weight is as the body; but if we hould ascend to higher regions, where the accelerative gravity is les, the weight would be equally diminihed, and would always be as the product of the Body, by the Accelerative gravity. So in those regions, where the accelerative gravity is diminihed into one-half, the weight of a body two or three times les, will be four or ix times les.

I likewie call Attractions and Impules, in the ame ene, Accelerative, and Motive; and ue the words Attraction, Impule, or Propenity of any ort towards a centre, promicuouly, and indifferently, one for another; conidering thoe forces not Phyically, but Mathematically: wherefore the reader is not to imagine, that by thoe words I anywhere take upon me to define the kind, or the manner of any Action, the caues or the physical reason thereof, or that I attribute Forces, in a true and Phyical ene, to certain centres (which are only Mathematical points); when Rh