воок IV.

O F THE

MOTIONS

OF THE

HEAVEN S.

CHA P. I.

THAT THE BARE MOTION OF THE HEAVENS AND EARTH ARE A DEMONSTRATION OF A GOD.

́N treating concerning the motion of the hea

IN

venly bodies, it will be neceffary to take in that of the earth too, it being not easy to speak of one without the other. And here there are two things that are manifeft demonstrations of the prefence and management of God, namely, that fuch bodies fhould move at all, and that their motion is fo regular.

1. That all thofe vaft globes of the universe fhould have a motion, muft of neceffity be from fome

R 3

1

concluded of all, from the conftant fimilitude and confent that the works of nature have with one another. But in what manner thefe motions are performed, whether by the motion of the heavenly bodies round the Earth, or by the Earth round its own axis, or any other way, it matters not much how to enquire.

2. It is manifeft that the Earth is fet at such a due diftance from the heavenly bodies, and the heavenly bodies, at fuch a due distance from one another, as to interfere,clash with, or diforder one another; nay, fo great is their diftance, fo convenient their fituation, that they do not fo much as eclifpe one another, except fuch planets as are called secondary.

3. It is farther manifeft alfo, that thofe vaft bodies are fo far off, as to appear extremely small to our eye, confidering their prodigious magnitudes.

Now for the effecting of this, or any of the other matters, it is neceffary that there be a fufficient space. And that there is fuch, and what that space is, we may make a judgment of, by confidering particulars according to the best obfervations we have of these things.

And

And to begin nearest home; the nearest of the heavenly bodies to us is the Moon, whofe orb is the leaft of any of the celeftial globes, but yet The takes up a space of near 480 thousand English miles in breadth to perform her monthly revolution in. And as for the Earth, if with the moderns we fuppofe it, together with its fatellite the Moon, to revolve round the Sun; or, which amounts to the fame thing, if the Sun revolves round the Earth, this Magnus Orbis, as it is ufually called, is a space of above 540 millions of miles in circumference, or 172 millions of miles breadth. And if to that we add the increment caused by the sweep of the Moon, or the excurfion

of

The Moon's mean distance from the Earth, according to Sir Ifaac Newton's Princip. p. 430, is 604 femidiameters of the Earth, according to which the diameter of the Moon's orbit is 479905 English Miles.

* Concerning the distance between the Sun and the Earth, there is a great difagreement between the former and the latter aftronomers, occafioned by the difagreement between their obfervations of the Sun's horizontal parallax (which is equal to the Earth's femidiameter viewed at the Sun). Tycho making it three minutes, Kepler but one, Bullialdus 2 minutes 21 feconds, and Riccioli bur 28 feconds. Confequently the distances arifing from hence are less than those of the latter aftronomers. The very ingenious and accurate Monf. de La Hire, in his Tabul. Aftron. thinks the Sun's horizontal parallax

Jupiter by the motion and vectorial power of those planets; and all the primary planets to be turned round about the fun by the power of the fun, yet at laft we must find out a mover of the fun itself, and those other primaries; a cause of fufficient power to wheel about those prodigious maffes, of fuch vaft bulks, as have before been affigned to them, and which, befides their own weight, are, according to their former hypothefes, clogged and encumbered with the vis inertia of all thofe planets whether primary or fecondary, or both, which they drive round. And if this was the cafe, what power can be found fufficient for this work, but that of the fame infinite hand that at first gave them being?

And fo for all the reft of the moving bodies of the univerfe, fuch as comets, the new ftars before fpoken of P, and the flow motion of the firmament, or fixt ftars in 25920 years. This latter I fhall fay no more of, because it may not

arife

Book II. chap. 3.

But

• Ptolemy made this motion to be one degree in 100 years. others fince make it to be more. Mr. Street, in his Caroline Tables, make it 1 gr. 20: Hevelius 1 gr. 24′. 46′′. 50′′: but Mr. Flamfteed agrees Riccioli's number to come nearest the truth, viz. gr. 23'. 20′′. in 100 years, or 50′′. in a year. According to which rate the motion (called the Platonic year) is accomplished in 25920 years,

arife from any motion of the firmament itfelf, but from fome other caufe. But for comets, what power but that of the Almighty could give them fuch prodigious projections as their trajec tories or orbs are found to have? orbs that run into fuch amazingly long ellipfes as approach to parabolas, that 'tis wonderful how their projectile force fhould carry them to fuch immense diftances, and their gravity at the fame time bring them back, and incomparably retain them in their orbs.

And fo for the new stars, which I have faid are fo many fignals of planetary fyftems difperfed here and there all over the univerfe, they are all of them fo many manifeftations and demonstrations of an infinite Being that hath imparted motion unto them: and they are a fign also that there are other globes, befides the fun and its planets, which are moving bodies, even that all the globes in the univerfe are fuch, and confequently fo many proofs of an Almighty first

mover.

Thus

Sir Ifaac Newton demonftrates how this may arife from the fphæroidal figure of the Earth. Princip. 1. iii. Prop. 21. & l. i. Prop. 66. Corol. 20. See the matter alfo more eafily demonstrated in Dr. Gregory's Aftron. l. i. Prop. 64.