Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 2.djvu/436

388 Bodies, projected in our air, ſuffer no reſiſtance but from the air. Withdraw the air, as is done in Mr. Boyle's vacuum, and the reſiſtance ceaſes. For in this void a bit of fine down and a piece of ſolid gold deſcend with equal velocity. And the parity of reaſon muſt take place in the celeſtial ſpaces above the Earth's atmoſphere; in which ſpaces, where there is no air to reſiſt their motions, all bodies will move with the greateſt freedom; and the Planets and Comets will conſtantly purſue their revolutions in orbits given in kind and poſition, according to the laws above explain'd. But though theſe bodies may indeed perſevere in their orbits by the mere laws of gravity, yet they could by no means have at ſirſt deriv'd the regular poſition of the orbits themſelves from thoſe laws.

The ſix primary Planets are revolv'd about the Sun, in circles concentric with the Sun, and with motions directed towards the ſame parts and almoſt in the ſame plane. Ten Moons are revolv'd about the Earth, Jupiter and Saturn, in circles concentric with them, with the ſame direction of motion, and nearly in the planes of the orbits of thoſe Planets. But it is not to be conceived that mere mechanical cauſes could give birth to ſo many regular motions: ſince the Comets range over all parts of the heavens, in very eccentric orbits. For by that kind of motion they paſs eaſily through the orbs of the Planets, and with great rapidity; and in their aphelions, where they move the ſloweſt, and are detain'd the longeſt, they recede to the greateſt diſtances from each other, and thence ſuffer the leaſt diſturbance from their mutual attractions. This most beautiful Syſtem of the Sun, Planets and Comets, could only proceed from the counſel and dominion of an intelligent and powerful being. And if the fixed Stars are the centers of other like ſyſtems, theſe being form'd by the like wiſe counſel, muſt be all ſubject to the dominion