would be near subduple of the second, or subqua. duple of the first: the months of the greatest would be about 254. A year of Jupiter has a great number of days; but of the four sorts of months, the least contains only four days and a quarter; the greatest something more than forty. Mr. Cassini has observed a couple of spots in the body of Jupiter, which make a revolution on the centre of this planet, from east to west, in about 9 hours and 56 minutes. Others have lately confirmed it by better observations. This proves, that the planet moves about upon its own centre. Behold the shortest period that is made in the firmament! the days and the nights, each of them five hours apiece.

Campani observed, with a more than ordinary telescope, certain protuberances and inequalities in the surface of this planet.

We may here insert a remark upon the periodical motions of the planets; both the primary and their secondaries. One thing very considerable in the periodical motion of the secondary planets, is, that it is mixed with a kind of cochleous direction towards one or other pole of its primary planet; by which means every satellite, by gentle degrees, changes its latitude, and makes its visits towards each pole of its primary.

We will here break off with the words of Mr. Molynex. "From hence may we justly fall into the deepest admiration, that one and the same law of motion should be observed in bodies so vastly distant from each other, and which seem to have no dependence or correspondence with each other. This doth most evidently demonstrate, that they were all at first put into motion by one and the

same unerring hand, even the infinite power and wisdom of God, who hath fixed this order among them all, and hath established a law which they cannot transgress.

Chance, or dull matter, could never produce such harmonious regularity in the motion of bodies so vastly distant: this shews a design and intention in the first Mover.

ESSAY VII. Of MARS.

MARS borrows his light from the Sun, as well as the rest of his planetary brethren. He has his increase and his decrease of light, like the Moon; may be seen almost bisected, when in his quadra ture with the Sun, or in his perigæon; though never corniculated or forked, like his inferiors.

Dr. Hook discovered several spots in Mars, and particularly a triangular one, which has a motion. Mr. Cassini afterwards discovered four spots, the two first on one face of Mars, afterwards two more that were larger, on the other face. Upon further observation it was found, that the spots of these two faces turned by little and little from east to west, and returned at the space of twenty four hours and forty minutes. In such a term therefore, there is a revolution of Mars upon his own axis.

The year of Mars is near twice as long as ours; his natural day a little greater than ours: his artificial day is almost every where equal to his night, besides what belongs to twilight. Mars as well as Jupiter has a perpetual equinox. Hence there can be but little variety of seasons in any one particular place of these planets.

Whence the fascice, or fillets observed in Mars?

There appear certain swathes, as we may call them, which are placed parallel to his equator. Are they owing to the heat and cold there, like our clouds and snows?

It is thought that Mars has an atmosphere, because fixed stars are obscured, and as it were extinct, when they are seen just by his body.

ESSAY VIII. Of VENUS.

VENUS has various appearances; round some. times; anon half round; by and by like a cres

cent.

Mr. Cassini discovered certain spots on this planet, by the motion whereof it appeared that it moved upon its own centre, and upon an axis, which carries it from north to south; a motion wholly unknown any where else in the heavens. Two spots it has, which are very thin, long, uncertainly terminated; and a shining part belongs to one of them).

He discovered also, as he judges, a satellite attending this planet; which Dr. Gregory assents to, as more than probable. This is not usually seen, perhaps because it may not have a fit surface to reflect the light of the Sun; which is the case of the spots in the Moon.

Herigone, and Keplerus, and Rhætensis, conclude, that Venus moves about its axis in fourteen hours. Dr. Cheyne says in twenty

three.

ESSAY IX. Of MERCURY.

THE great Hevelius hath observed, that Mercury changes his face, like Venus, and like our moon; appearing sometimes round, sometimes half round, sometimes like a crescent.

This planet has his abode so near the Sun, that as yet there has been little discovered of him.

It appears not yet, whether he revolves upon his own axis, and so what may be the length of his days. But it is probable he may have such a motion, as well as the other planets. However, his year is hardly equal to a quarter of ours.

Sir Isaac Newton has terrible apprehensions of the heat in this planet, as being seven times as much as the heat of the summer sun in England; which according to his experiments made by the thermoscope, would be enough to make water boil. If the bodies in this planet be not enkindled by this heat, they must be of a peculiar density. But Mr. Azout pretends to prove, that though this planet be so near the Sun, yet the light there is not capable of burning any objects.

ASTRONOMICAL SYNOPSIS.

Adapted to modern improvements in this science.

Saturn

79,042

901,668,908

29

164 7 21

50

83 294 8 39

Herschel 35,112 1,803,534,392

"Great God, thou hast lifted me up to heaven; Oh! let me not after all be cast down to hell. The philosopher, who gazing on the stars with his attentive observation, tumbled into a pit that he observed not, was not so unhappy as he that has visited heaven on the noble intentions of astronomy, but by an ungodly life, procures to him

self a condemnation to that hell, which is a state and place of utter darkness. Wretched astronomers! who are among the wandering stars, to whom is reserved the blackness of darkness for ever."

We will conclude what we collect about the stars, with transcribing a passage out of the Miscellanea Curiosa. "The honourable Mr. Roberts computes the distances of the fixed stars; which he supposes to be so many suns of a different magnitude. He thinks, that it seems hardly within the reach of any of our methods to determine it. The diameter of the earth's orb, which is at least one hundred and sixty millions of miles, is but a point in comparison of it. At least nine parts in ten, of the space between us and the fixed stars, can receive no greater light from the Sun, or any of the stars, than what we have from the Sun in a clear night. Light takes up more time in travelling from the stars to us, than we in making a West India voyage, which is ordinarily performed in six weeks. A sound would not arrive to us from thence in fifty thousand years, nor a cannon bullet in a much longer time. This is easily computed, by allowing ten minutes for the journey of light from the Sun hither; and that sound moves about thirteen hundred feet in a second."

ESSAY X. Of COMETS.

I is an admirable work of our God, that the many globes in the universe are placed at such distances, as to avoid all violent shocks upon one another. Even comets too, move so as to serve the holy ends of their Creator! Comets, which