enough to take in the apparent Paths of all the Planets.

COROLLAR Y.

The fuperior Planets appearing direct, Stationary, and retrograde, is a proof of the Earth's annual Motion round the Sun; for if it had no fuch Motion, they never could appear otherwise than direct.

That all the Planets, both primary and fecondary, may be habitable Worlds, is a Notion, (however laughed at by the Vulgar, yet) not without a reasonable Probability. For who that has feen any Engine, a Windmill for Inftance, in his own Country, and knows the Use of it is to grind Corn; if he travels into another Country, and there fees an Engine of the fame fort, will not reasonably conclude that it is defigned for the fame Purpofe? So when we know that the Use of this Planet, the Earth, is for an Habitation of various Sorts of Animals; and we fee other Planets at a Distance from us, fome bigger, and some less than the Earth, all of them folid Bodies, much of the fame Shape with the Earth one, at least, encompaffed with an Atmofphere as the Earth is; all moving periodically round the Sun; moft, if not all, of them revolving on their own Axis, just as the Earth does; and fome of them attended

4

;

tended with Moons, to enlighten them in the Night is it not highly reasonable to conclude, that they are all defigned for the fame Use that the Earth is, and that they are habitable Worlds, like this in which we live?

What Use can we conceive of Jupiter's and Saturn's Moons, which are not visible to us without the Help of Telescopes, unless they are to enlighten those Planets in the Night? And of what Ufe can their Light be to those Planets, if there be no Inhabitants to enjoy the Benefit of it? Nay, of how little Ufe are any even of the primary Planets to our World? How little is the Light which they afford us? And as for any Influence upon us and our World, which the Aftrologers afcribe to them, which they conceit to be different, according to their different Afpects *, and by which they pretend to foretel future Events;

it

Afpes of the heavenly Bodies, fignify their Situa tion in the Zodiac, with respect to one another; or their Distance from one another in Longitude. The Names and Characters of the Different Aspects are,

1. Sextile, when they are two Signs, or 60 Degrees from one another.

2. Quartile, when they are three Signs, or go Degrees diftant.

3. A Trine, when they are four Signs, or 120 Degrees diftant.

4.8 Oppofition, when they are fix Signs, or 180 Degrees diftant.

it is most certainly all a groundless and foolish Conceit. Whoever confiders the vaft Digance of the Planets from us, and that their Afpects are according to natural laws, will not eafily believe they can have fuch Influence at all.

any

C

С НА Р. VIII.

Of COMETS.

OMETS, or Blazing-Stars, were anciently supposed to be Meteors, or Exhalations, fet on Fire in the highest Region of the Air; but the Modern Aftronomers have found that they are above the Orbit of the Moon. Moft probably they are a Sort of excentrical Planets, which move periodically round the Sun.

5. 8 Conjuntion, when they are in the fame Sign and Degree.

N. B. Two Bodies are faid to be in Conjunction when both are upon the fame Line of Longitude, tho' they may not be in the fame Point of the Heavens; but feveral Degrees Diftant from each other in refpect of Latitude. Thus Mercury and the Moon may be in Conjunction, when yet they are 12 Degrees afunder; that is, when the former has near 7 Degrees of Latitude on one Side of the Ecliptic, and the latter above 5 Degrees Latitude on the other Side.

their

Their Orbits are very long Ellipfes, havthe Sun in one Focus *.

The proper Motion of Comets is not the fame in all, but each has its peculiar Courfe. Some go from Weft to Eaft, others from Eaft to Weft; fome from North to South, others again from South to North, in all Planes and Directions: fo that they are not, as the Planets are, contained within the Zodiac.

Not many more than twenty Comets have yet been observed been obferved; at leaft fo as that their Paths in the Heavens have been traced and defcribed. The Time in which they complete their Revolution is not yet known, except perhaps of two or three of them.

When the Comets defcend near to the Sun, they become vifible, and continue fo for fome time while they are ascending again from him: but as they remove further off, we lofe Sight of them by Degrees; 'till at length they run out into får diftant Regions, where they are quite invifible to us, in by far the greater Part of their Orbits.

* Mr. Azout, a French Gentleman, was the first, that I can find, who pretended to predict the future Motion of a Comet; which he did upon obferving the Path of one that appeared Jan. 1664, and of another that appeared the Year following. But our great and famous Sir Isaac Newton has fince cleared up the Doctrine, and the Phænomena of the Comets, far beyond all that went before him, in his excellent Princ. Philof. Mathem. Lib. 3. Prop. 39. c.

When a Comet descends near to the Sun it is fet on Fire; and its Tail feems to be nothing else but a long and very thin Smoke, or Train of Vapours ftreaming from it, which always points to the Region oppofite to the Sun.

The popular Divifion of Comets into three Kinds, viz. Cauduti or tailed, Barbati or bearded, and Criniti or hairy, arifes not from any real Difference of Comets from one another, but from different Circumftances of the fame Comet. For instance,

When a Comet is moving towards the Sun, the Train of Vapours follows it, like a Tail.

When it is moving from the Sun, after its Perihelion, the luminous Vapour marches before it, in the Manner of a Beard.

When the Vapour is projected directly behind the Comet from us, it is then hid from our View, excepting that we see a little of it appearing round the Comet, like a Border of Hair. This Appearance may be accounted for, partly, from the Train of Vapours widening as it recedes from the Head, (as it always does) fo that we see a little of the remoter Part round the Body of the Comet; and partly, because the Vapour is raised, by the Heat of the Sun, chiefly from the Side or Hemisphere which