day, 21 hours, 18 minutes and 26 seconds, at the distance of 193 thousand; the fourth in two days, 17 hours 44 minutes and 51 seconds, at the distance of 247 thousand; the fifth in 4 days, 12 hours, 25 minutes and 11 seconds, at 346 thousand; the 6th in 15 days, 22 hours, 41 minutes and 13 seconds, at the distance of 802 thousand; and the 7th or outermost in 49 days, 7 hours, 53 minutes and 43 seconds, at the distance of two millions, 337 thousand miles from the centre of Saturn-their primary. When we look with a good telescope, at the body of Saturn, he appears like most of the other planets, in the form of an oblate spheroid, arising from the rapid rotation about his axis. He however appears more flattened at the poles, than any of the others, and although his motion on his axis is not equal to that of Jupiter, yet he does not appear to be in form, so near that of a globe as that planet. When we consider that the ring by which Saturn is encompassed, lies in the same plane of his equator, and, that it is at least equal if not more dense than the planet, we shall find no difficulty in accounting for the great accumulation of matter, at the the equator of Saturn. The ring acts more powerfully upon the equatorial regions of Saturn; than upon any part of his disk; and by diminishing the gravity of these parts, it aids the centrifugal force in flattening the poles of the planet. Had Saturn indeed never revolved upon his axis, the action of the ring would of itself have been sufficient, to have given it the form of a spheroid. 7,200 Breadth of the exterior ring, ON HERSCHEL, OR URANUS. M. S. 7.25 From inequalities in the motion of Jupiter and Saturn, for which no rational account could be given, and from the mutual action of these planets, it was inferred by some Astronomers, that another planet existed beyond the orbits of Jupiter and Saturn; by whose action these. irregularities were produced. This conjecture was confirmed on the 13th of March, 1781; when Dr. Herschel discovered a new planet, which in compliment to his Royal Patron, he called Georgium Sidus, although it is more generally known by the name of Herschel, or Uranus. This new planet, (which had been formerly observed as a small star by Flamstead, and likewise by Tobias Mayer, and introduced into their catalogue of fixed stars,) is situated, one thousand, eight hundred millions of miles, from the centre of the System, and performs its revolution round the Sun in 83 years, 150 days, and 18 hours. Its diameter is computed at 35,112 miles. When seen from the earth, its mean apparent diameter is three and seconds, and as seen from the Sun, 4 seconds of a degree. As the distance of this planet from the Sun is twice as great as that of Saturn, it can scarcely be distinguished without the aid of instruments. When the sky however is serene it appears like a fixed star of the sixth magnitude, with -a bluish white light, and a brilliancy between that of Venus and the Moon; but seen with a power of two or three hundred, its disk is visible and well defined.-The want of light arising from the distance of this planet from the Sun, is supplied by six satellites, all of which were discovered by Dr. Herschel. The first of those satellites is twenty five and half seconds from its primary, and revolves round it in 5 days, 21 hours and 25 minutes; the second is nearly 34 seconds distant from the planet, and performs its revolution in 8 days, 17 hours, 1 minute and 19 seconds. The distance of the third satellite is 38,57 seconds, and the time of its periodical revolution is ten days, 23 hours, and four minutes. The distance of the fourth satellite is 44,22 seconds, and the time of its periodical revolution is 13 days, 11 hours, 5 minutes and 30 seconds. The distance of the fifth is one minute and 28 seconds, and its revolution is completed in 38 days, 1 hour, and 49 minutes. The sixth satellite, or the furthest from the centre of its primary, at the distance of nutes, and nearly 57 seconds, and therefore requires 107 days, 16 hours, and 40 minutes to complete E one revolution. The second and fourth of these were discovered on the 11th of January, 1787, the other four were discovered in 1790, and 1794; but their distantances, and times of periodical revolution, have not been so accurately ascertained as the other two. It is however, a remarkable circumstance, that the whole of these satellites move in a retrogade direction, and in orbits lying in the same plane, and almost perpendicular to the ecliptic. When the Earth is in its perihelion, and Herschel in its aphelion, the latter becomes stationary, as seen from the Earth, when his elongation, or distance from the Sun is 8 signs, 17 degrees, and 37 minutes, his retrogradations continue 151 days, and 12 hours. When the Earth is in its aphelion, and Herschel in its perihelion, it becomes stationary, at an elongation of 8 signs, 16 degrees, and 27 minutes, and its retrogadations continue 149 days and 18 hours. ON COMETS. Comets are a class of celestial bodies, which occasionly appear in the Heavens. They exhibit no visible or defined disk, but shine with a pale and cloudy light, accompanied with a tail or train, turned from the Sun. They traverse every part of the Heavens, and move in every possible direction. When examined through a good telescope, a Comet resembles a mass of aquious vapors, encircling an opaque nucleus, of different degrees of darknes in dif ferent Comets; though sometimes, as in the case of several discovered by Dr. Herschel, no nucleus can be seen. As the Comet advances towards the Sun, its faint and nebulous light becomes more brilliant, and its luminous train gradually increases in length. When it reaches its perihelion, the intensity of its light, and the length of its tail reaches their maximum, and then it sometimes shines with all the splendor of Venus. During its retreat from the perihelion,it is shorn of its splendor, and it gradually resumes its nebulous appearance; and its train decreases in magnitude, until it reaches such a distance from the Earth, that the attenuated light of the Sun, which it reflects, ceases to make an impression on the organ of sight. Traversing unseen the remote portion of its orbit, the Comet wheels its etherial course far beyond the limits of the Solar System. What region it there visits, or upon what destination it is sent, the limited powers of man are unable to discover. After the lapse of years, we perceive it again returning to our System, and tracing a portion of the same orbit round the Sun, which it had formerly described. Various opinions have been entertained by Astronomers respecting the tails of Comets. These tails or trains, sometimes occupy an immense space in the Heavens. The Comet of 1681, stretched its tail across an arch of 104 degrees; and the tail of the Comet of 1769 subtended an angle of 60 degrees at Paris, 70 at Bologna, 97 at the Isle of Bourbon, and 90 degrees at |