Saturn is undoubtedly the most interesting member of the planetary system, not only from its being accompanied by 8 satellites, but especially on account of the system of rings by which it is surrounded. Belts are also occasionally noticed, but they are far more indistinct than those of Jupiter, though doubtless due to the same physical cause, whatever that may be. Spots are rare. Sir W. Herschel considered this planet to be surrounded by a very dense atmosphere; an idea that has been fully confirmed by subsequent observers.

When this planet was first telescopically examined by Galileo, he noticed that it presented a very oval outline, which he conjectured was owing to a larger planet having on each side of it two smaller ones. He added, that with telescopes of superior power, the planet did not appear triple, but exhibited an oblong form, somewhat like the shape of an olive.

Continuing his observations, the illustrious astronomer was not long in noticing that the two (supposed) bodies gradually decreased in size, though still in the same position as regards their primary, until they finally disappeared altogether.

The form of the Earth is not strictly spherical, the polar diameter being less than the equatorial by about 26½ miles; it is, in fact, like many, probably all, the planets, an oblate spheroid. The great circle of the heavens apparently described by the Sun every year, owing to our revolution round that body, is called the ecliptic, and is usually employed by astronomers as a fixed plane of reference. The Earth's equator prolonged in the direction of the fixed stars, differs from the equator of the heavens, which is inclined to the plane of the ecliptic at an angle which in January 1, 1860, was equal to 23° 27′ 33″ and which angle is known as the obliquity of the ecliptic. It is this inclination which gives rise to the vicissitudes of the seasons during our annual revolution round the Sun. The two points where the celestial equator is intersected by the ecliptic, are called the equinoxes; the points exactly midway between these being the solstices. It is from the vernal (or spring) equinox, that right ascensions are measured along the equator and longitudes along the ecliptic.

The class of bodies which will now come under our notice are among the most interesting with which the astronomer has to deal. Appearing suddenly in the nocturnal sky, and often dragging after them tails of immense size and brilliancy, they were well calculated, in the earlier ages of the world, to attract the attention of all, and still more to excite the fear of many. It is the unanimous testimony of history, during a period of upwards of zooo years, that comets were always considered to be peculiarly “ ominous of the wrath of heaven, and as harbingers of wars and famines, of the dethronement of monarchs, and the dissolution of empires.” We shall hereafter examine this question at greater length. Suffice it for us, here, to quote the words of the Poet, who speaks of

However little attention might have been paid by the ancients to the more ordinary phenomena of nature (which, however, were pretty well looked after), yet certain it is, that comets and total eclipses of the Sun were not easily forgotten or lightly passed over; hence the aspect of remarkable comets that have appeared at various times have been handed down to us, often with circumstantial minuteness.

Every inhabitant of a maritime country like Great Britain is more or less familiar with the phenomena now under our consideration, but beyond knowing the general fact, that the Moon has something to do with the tides, their physical history is not so well understood as it ought to be.

The phenomena of the tides are very frequently attributed to the attraction of the Moon, whereby the waters of the ocean are drawn towards that side of the Earth on which our satellite happens to be situated; in fact, that it is high water when the Moon is on or near the meridian of the place of observation.

This, though to a certain extent true, by no means adequately represents the facts of the case, for high water is not only produced on that side of the Earth immediately under the Moon, but also on the opposite side at the same time. The two tides are therefore separated from each other by 180°, or by a space equal to half the circumference of the globe. The diurnal rotation of the Earth, causing every portion of its surface to pass successively under the tidal waves, in about 24h., it follows that there are everywhere 2 tides daily, with an interval of about 12 hours between each; whereas, if the common supposition were correct, there would be only.

Of the total eclipses which have of late years been systematically observed, that of July 18, 1860, is by far the most interesting and important: it owes its interest to the agreeable circumstances connected with it, hereafter to be more fully spoken of, and its importance, to the very extensive and refined observations which were made by so many astronomers in America, Europe, and Africa.

Our limits wholly forbid our entering into any very lengthened statement: we shall therefore select from the published accounts of the observations, such portions as we deem most fitted to be placed on record in a work like the present, prefacing them by a brief epitome of the general circumstances attending “ the Himalaya Expedition.”

On Nov. 15, 1859, the Astronomer Royal, in an interview with the Duke of Somerset, First Lord of the Admiralty, drew his Grace's attention to the then approaching eclipse, at the same time suggesting the desirability of a ship being appropriated for the conveyance of observers to and from the coast of Spain. After the request was duly considered, Her Majesty's Government volunteered to place at the disposal of the Astronomer Royal and his friends, H.M.S. “ Himalaya”; the offer was of course gratefully accepted, and in due course of time the expedition set forth.

This planet was discovered by Sir W. Herschel on March 13, 1781, whilst he was engaged in scrutinising some small stars in Gemini. He observed one of them which seemed to have a more sensible diameter than the others, and to be less luminous. The application of high magnifying powers rendered these peculiarities more perceptible: he therefore made some very careful observations, and found that it was moving at the rate of 2¼″ per hour. He then announced to the Royal Society the discovery of a new comet, so little was a planet expected. Maskelyne found it, and soon suspected its true nature. On proper inquiries being made, it was found that Flamsteed had seen it 3 times, Mayer, once, and Le Monnier, 11 times previously to the epoch of Herschel's discovery; all of whom had been ignorant of its real nature.

A brisk discussion took place on the name the new planet was to have. Herschel himself desired to call it the Georgium Sidus in compliment to his friend and patron, our most excellent Sovereign King George III.; some of the foreign astronomers, amongst whom was Laplace, insisted that it ought to bear the name of its discoverer; Bode proposed Uranus as the mythological father of Saturn; and this name finally triumphed, though for a long course of years it was frequently known as the Georgian Planet.

The class of phenomena we are about to describe are those produced by the interposition of celestial objects; for we know well that inasmuch as many of the heavenly bodies are constantly in motion, it follows that the direction of lines drawn from one to another will vary from time to time; and it must occasionally happen that three will come into the same line. “ When one of the extremes of the series of 3 bodies, which thus assume a common direction, is the Sun, the intermediate body deprives the other body, either wholly or partially, of the light which it habitually receives. ”When one of the extremes is the Earth, the intermediate body intercepts, wholly or partially, the other extreme body from the view of observers situate at places on the Earth which are in the common line of direction, and the intermediate body is seen to pass over the other extreme body, as it enters upon or leaves the common line of direction, and the intermediate body is seen to pass over the other extreme body, as it enters upon or leaves the common line of direction. The phenomena resulting from such contingencies of position and direction are variously denominated ‘Eclipses’ ‘Transits’ and ‘Occultations’ according to the relative apparent magnitudes of the interposing and obscured bodies, and according to the circumstances which attend them.“ We shall proceed to consider the several phenomena in detail, beginning with Eclipses.

Variation in the Obliquity of the Ecliptic. — Although it is sufficiently near for all general purposes to consider the inclination of the plane of the ecliptic as invariable; yet this is not strictly the case, inasmuch as it is subject to a small but appreciable change of about 48″ per century. This phenomenon has long been known to astronomers, on account of the increase it gives rise to, in the latitude of all stars in some situations, and corresponding decrease in the opposite regions. Its effect at the present time is to diminish the inclination of the two planes of the equator and the ecliptic to each other; but this dimimition will not go on beyond certain very moderate limits, after which it will again increase, and thus oscillate backwards and forwards through an arc of 1 ° 21 ′: the time occupied in one oscillation being about 10,000 years. One effect of this variation of the plane of the ecliptic—that which causes its nodes on a fixed plane to change—is associated with the phenomena of the precession of the equinoxes, and undistinguishable from it, except in theory.

Precession.—The precession of the equinoxes is a slow but continual shifting of the equinoctial points from East to West.