was constructed. These moons, and also those which accompany Jupiter, are estimated to be not less than the earth in magnitude, and are found, like our moon, to revolve round their axes in the same time in which they revolve about their respective primaries. RINGS OF SATURN.-The most extraordinary circumstance connected with this planet, is, the phenomenon of a double ring, which surrounds its body, but nowhere touches it, being thirty thousand miles distant from any part of the planet, and is carried along with the planet in its circuit round the sun. This is the most singular and astonishing object in the whole range of the planetary system; no other planet being found environed with so wonderful an appendage; and the planets which may belong to other systems, being placed beyond the reach of our observations, no idea can be formed of the peculiar apparatus with which any of them may be furnished. This double ring consists of two concentric rings, detached from each other; the innermost of which is nearly three times as broad as the outermost. The outside diameter of the exterior ring is 204,000 miles; and, consequently, its circumference will measure six hundred and forty thousand miles, or eighty times the diameter of our globe. Its breadth is 7,200 miles, or nearly the diameter of the earth. Were four hundred and fifty globes, of the size of the earth, placed close to one another, on a plane, this immense ring would enclose the whole of them, together with all the interstices, or open spaces between the different globes. The outside diameter of the innermost ring is 184,000 miles, and its breadth twenty thousand miles, or about 2 times broader than the diameter of the earth. The dark space, or interval between the two rings, is 2,800 miles. The breadth of both the rings, including the dark space between them, is thirty thousand miles, which is equal to the distance of the innermost ring from the body of Saturn. The following figure represents a view of Saturn and his rings, as they would appear, were our eye perpendicular to one of the planes of those rings; but our eye is never so much elevated above either plane, as to have the visual ray standing at right angles to it: it is never elevated more than 30 degrees above the planes of the rings. When we view Saturn through a telescope, we always see the ring at an oblique angle, so that it appears of an oval 00 form, the outward cireular rim being projected into an ellipsis more or less oblong, according to the different degrees of obliquity with which it is viewed, as will be seen in the figure of Saturn in the copperplate engraving. These rings cast a deep shadow upon the planet, which proves that they are not shining fluids, but composed of solid matter. They appear to be possessed of a higher reflective power than the surface of Saturn; as the light reflected by them is more brilliant than that of the planet. One obvious use of this double ring is, to reflect light upon the planet, in the absence of the sun : what other purposes it may be intended to subserve, in the system of Saturn, is, at present, to us unknown. The sun illuminates one side of it during fifteen years, or one-half of the period of the planet's revolution; and, during the next fifteen years, the other side is enlightened in its turn. Twice in the course of thirty years, there is a short period, during which neither side is enlightened, and when, of course, it ceases to be visible ;-namely, at the time when the sun ceases to shine on one side, and is about to shine on the other. It revolves round its axis, and, consequently, around Saturn, in ten hours and a half, which is at the rate of a thousand miles in a minute, or fifty-eight times swifter than the earth's equator. When viewed from the middle zone of the planet, in the absence of the sun, the rings will appear like vast luminous arches, extending along the canopy of heaven, from the eastern to the western horizon; having an apparent breadth equal to a hundred times the apparent diameter of our moon, and will be seen darkened about the middle, by the shadow of Saturn.* There is no other planet in the solar system, whose firmament will present such a variety of splendid and magnificent objects, as that of Saturn. The various aspects of his seven moons, one rising above the horizon, while another. is setting, and a third approaching to the meridian; one. entering into an eclipse, and another emerging from it; one appearing as a crescent, and another with a gibbous phase; and sometimes the whole of them shining in the same hemisphere, in one bright assemblage ;-the majestic motions of the rings,-at one time illuminating the sky with their splendor, and eclipsing the stars; at another, casting a deep shade over certain regions of the planet, and unveiling to view the wonders of the starry firmament-are scenes worthy of the majesty of the Divine Being to unfold, and of rational creatures to contemplate. Such magnificent displays of Wisdom and Omnipotence, lead us to conclude that the numerous splendid objects connected with this planet, were not created merely to shed their lustre on naked *See the Engraving, fig. 7. which represents a view of the appearance which the rings and moons of Saturn will exhibit, in certain cases, about midnight, when beheld from a point 20 or 30 degrees north from his equator. The shade on the upper part of the rings represents the shadow of the body of Saturn. This shadow will appear to move gradually to the west as the morning approaches. rocks and barren sands; but that an immense population of intelligent beings is placed in those regions, to enjoy the bounty, and to adore the perfections of their great Creator. -The double ring of Saturn, when viewed through a good telescope, generally appears like a luminous handle on each side of the planet, with a dark interval between the interior edge of the ring, and the convex body of Saturn; which is owing to its oblique position with respect to our line of vision. When its outer edge is turned directly towards the earth, it becomes invisible, or appears like a dark stripe across the disk of the planet. This phenomenon happens once every fifteen years. THE PLANET HERSCHEL.-This planet, which is also known by the names of the Georgium Sidus, and Uranus, was discovered by Dr. Herschel on the 13th March, 1781, It is the most distant planet from the sun, that has yet been discovered; being removed at no less than 1800 millions of miles from that luminary, which is nineteen times farther than the earth is from the sun-a distance so great, that a cannon ball, flying at the rate of 480 miles an hour, would not reach it in 400 years. Its diameter is about 35,000 miles; and, of course, it is about eighty times larger than the earth. It appears like a star of the sixth magnitude; but can seldom be distinguished by the naked eye. It takes about 83 years and a half to complete its revolution round the sun; and, though it is the slowest moving body in the system, it moves at the rate of 15,000 miles an hour. As the degree of sensible heat in any planet does not appear to depend altogether on its nearness to the sun, the temperature of this planet may be as mild as that which obtains in the most genial climate of our globe.* The diameter of the sun, as seen from Herschel, is little more than the apparent diameter of Venus, as seen by the naked eye; and the light which it receives from that luminary, is 360 times less than what we experience; yet this proportion is found by calcu lation to be equal to the effect which would be produced by 248 of our full moons; and, in the absence of the sun, there are six moons which reflect light upon this distant planet, all of which were discovered likewise by Dr. Herschel. See Note, page 199. Small as the proportion of light is, which this planet receives from the sun, it is easy to conceive, that being similar to man, placed on the surface of this globe, with a slight modification of their organs of vision, might be made to perceive objects with a clearness and distinctness even superior to what we can do. We have only to suppose, that the Creator has formed their eyes with pupils capable of a much larger expansion than ours; and has endued their retina with a much greater degree of nervous sensibility. At all events, we may rest assured, that He who has placed sentient beings in any region, has, by laws with which we are partly unacquainted, adapted the constitution of the inha bitant to the nature of the habitation. "Strange and amazing must the difference be, Where Providence, all-wise, has fixed their lot." BAKER'S UNIVERSE. The celestial globes which I have now described, are allthe planets which are at present known to belong to the solar system. It is probable that other planetary bodies may yet be discovered between the orbits of Saturn and Herschel, and even far beyond the orbit of the latter; and it is also not improbable that planets may exist in the immense interval of 37 millions of miles between Mercury and the Sun.* These (if any exist) can be detected only by a series of day observations, made with equatorial telescopes; as they could not be supposed to be seen, after sunset, on account of their proximity to the sun. Five primary† planets, and eight secondaries, have been discovered with *The Author, some years ago, described a method by which the planets (if any) within the orbit of Mercury, may be discovered in the day-time, by means of a simple contrivance for intercepting the solar rays, and by the frequent application, by a number of observers, of powerful telescopes, to a certain portion of the sky, in the vicinity of the sun. The details of this plan have not yet been published; but the reader will see them alluded to, in No. V. of the Edinburgh Philo. sophical Journal, for July, 1820, p. 191. A primary planet is that which revolves round the sun as a centre; as Mars, Jupiter, and Saturn. A secondary planet is one which revolves round a primary planet as its centre; as the Moon, and the |