From it's characteristic ruddiness, and from other phænomena, it has been fuppofed that it's atmofphere is nearly of the fame denfity with our's. Dr. Herschel has obferved two white luminous circles furrounding the poles of this planet; these are supposed to arife from the fnow ly-" ing about those parts,

The appearance of Jupiter through a telescope, opens a vast field for speculative inquiry. The furface is not equally bright, but is diftinguished by certain bands, or belts, of a dufkier colour than the rest of the furface, running parallel to each other, and to the plane of it's orbit. They are not regular or constant in their appearance; fometimes only one is feen, at other times eight have been feen; fometimes one or more spots are formed between the belts, which increase till the whole is united in one large dufky band. There are also bright spots to be discovered on Jupiter's furface; thefe are rather more permanent than the belts, and re-appear after unequal intervals of time. The remarkable fpot, by whofe motion the rotation of Jupiter on his axis was ascertained, difappeared in 1694, and was not seen again till 1708, when it re-appeared exa&ly in the fame place, and has been occafionally feen ever fince. The disappearance and re-appearing

of the spots is not fo wonderful as the changes that have been obferved in the belts; the elder Caffini faw one evening five belts upon the planet, but while he was viewing them, they underwent the most surprizing change. In an hour from their fullest appearance there remained only three out of five, and one of thefe fcarce perceptible.

Though the great diftance of the planet Saturn, and the tenuity of it's light, do not permit us to diftinguish the varieties of it's furface; yet some of the first discoveries made by the telescope were on this planet, and the ring is ftill one of the most curious phænomena we are acquainted with. There is not, indeed, any thing in the whole fyftem of nature more wonderful than this ring, which appears nearly as bright as any part of the furface of the planet; by what means it is fufpended, or by what law fupported; whether it is only a bright but permanent cloud, or whether it is a vast number of fatellites difpofed in the fame plane, whofe blended light gives it to us the form of one continual body, we can only form crude conjecture. M. Meffier has observed on the anses of this ring, feveral luminous white twinkling points, differing in vivacity from each. other.

OF

OF COMETS.

Comets are a kind of ftars, appearing at unexpected times in the heavens, and of fingular and various figures, defcending from far distant parts of the fyftem, with great rapidity, furprizing us with the fingular appearance of a train, or tail; and after a short stay, are carried off to diftant regions, and difappear.

They were imagined in ancient times to be prodigies hung out by the immediate hand of God in the heavens, and intended to alarm the world. Their nature being now better underflood, they are no longer terrible. But as there are ftill many who think them to be heavenly warnings, portents of future events, it may not be improper for the tutor to inform his pupil, that the Architect of the univerfe has framed every part according to divine order, and fubjected all things to laws and regulations that he does not hurl at random ftars and worlds, and diforder the fyftem of the whole glorious frame, to produce falfe apprehenfions of diftant events, fears without foundation, and without ufe. Religion glories in the test of reafon, of knowledge, and of true wisdom; it is every way connected with, and is always elucidated by them. From philosophy

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philofophy we may learn, that the more the works of the Lord are underflood, the more he must be adored; and that his fuperintendency over every portion is more clearly evinced, and more fully expreffed by their unvaried course, than by ten thousand deviations,

The existence of an univerfal connection between all the parts of nature is now generally allowed. Comets undoubtedly form a part of this great chain; but of the part they occupy, and of the ufes for which they exift, we are equally ignorant. It is a portion of science whofe perfection is reserved for fome diftant day, when thefe bodies and their vaft orbits may, by long and accurate obfervation, be added to the known parts of the folar system.

The aftronomy of comets is very imperfect; for but little can be known with certainty, where but little can be seen. Comets afford few obfer

vations on which to ground conjecture, and are for the greatest part of their courfe beyond the reach of human vifion.

It is, however, now generally supposed, that they are planetary bodies, making part of our fyftem, revolving round the fun in extremely long elliptic

elliptic curves. That as the orbit of a comet is more or less excentric, the distance to which they recede from the fun will be greater or lefs. Very great difference has been found by obfervation in this respect, even so great, that the fides of the elliptic orbit in fome cafes degenerate almost into right lines.

That those comets which go to the greatest diftance from the fun, approach the nearest to him at their return.

Their motions in the heavens are not all direct, or according to the order of the figns, like thofe of the other planets. The number of those which move in a retrograde manner, is nearly equal to those whose motion is direct.

The orbits of most of them are inclined in large angles to the plane of the ecliptic.

very

in

The velocity with which they move is variable every part of their orbit; when they are near the fun, they move with incredible swiftnefs; when very remote from him, their motion is inconceivably flow.

They