we expect every moment that they are to be torn from their base, and that the process of destructive separation which we had only contemplated in its effects, is about to be exhibited before us in tremendous reality. The mountains called the Appennines, which traverse a portion of the Moon's disc from north-east to south-west, rise with a precipitous and craggy front from the level of the Mare Imbrum. In some places their perpendicular elevation is above, four miles; and though they often descend to a much lower level, they present an inaccessible barrier to the north-east, while on the southwest they sink in gentle declivity to the plains."

The caverns which are observed on the Moon's surface, are no less remarkable than the rocks and mountains, some of them being three or four miles deep, and forty in diameter. A high angular ridge of rocks marked with lofty peaks and little cavities, generally encircles them, an insulated mountain frequently rises in their centre, and sometimes they contain smaller cavities of the same nature with themselves. These hollows are most numerous in the south-west part of the Moon, and it is from this cause that this part of the Moon is more brilliant than any other part of her disc. The mountainous ridges which encircle the cavities, reflect the greatest quantity of light; and from their lying in every possible direction, they appear, near the time of full Moon, like a number of brilliant radiations issuing from the small spot called Tycho.

It is difficult to explain, with any degree of probability, the formation of these immense cavities; it is highly probable, that the earth would assume the same figure, if all the seas and lakes were removed; and that the lunar cavities are either intended for the reception of water, or that they are the beds of lakes and seas which have formerly existed in the Moon.

The circumstance of there being no water in the Moon, affords a strong proof of the truth of this theory."

OF THE CONSTELLATIONS, OR ASTERISMS.

A spectator who observes the heavens with a tolerable degree of attention, will soon perceive that by far the greater number of the stars never change their situation with respect to each other. Such stars as always appear to occupy the same situation in the heavens, or the same relative distance from one another, have been called fixed stars; to distinguish them from the planets, whose situations are constantly changing. The fixed stars constitute by far the most numerous class of celestial bodies; for on casting the eye quickly to the heavens in a clear winter evening, they appear to be innumerable.

A planet may be known from a fixed star, by the steadiness of its light; for a fixed star appears to emit a twinkling light, but a planet gives a mild steady light.

The grandeur of such a scene with the perpetual and regular change, which the whole appears to undergo by the daily revolution of the earth on its axis, must have attracted the attention of mankind at a very early period. But previous to attempting to make either regular or accurate observations, on the motions and relative situations of the various bodies which compose this splendid scene, it was necessary to invent some method by which the one might be distinguished from the other. To give a particular name to every star which was visible to the naked eye, was impossible.

It therefore became necessary to adopt a more general method of distinguishing them. This was accomplished by portioning out the heavens into imaginary figures, of men, birds, fishes, &c. called Constellations or Asterisms. After this, the situation of a star could be known by mentioning its place in the Constellation in which it was situated; as the bull's eye, the lion's heart, the dog's nose, &c. In what age of the world this arrangement of the stars into constellations took place is not known, but it was certainly antecedent to any authentic record; so that whether the shepherd or the sage, was employed in their formation, cannot now be ascertained. Homer and Hesiod who lived at least 800 years before the Christian era, mention several of the constellations.

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The Pleids, Hyads, with the northern team,
And great Orion's more refulgent beam;
To which, around the axle of the sky,
The bear revolving points his golden eye,
Still shines exalted in th' ethereal plain,
Nor bathes his blazing forehead in the main.

POPE'S HOMER.

In the book of Job, Arcturus, Orion, and the Pleiades, are twice mentioned.

Canst thou the sky's benevolence restrain,
And cause the Pleiads to shine in vain?
Or, when Orion sparkles from his sphere,
Thaw the cold season, and unbind the year?
Bid Mazzaroth his destin'd station know,

And teach the bright Arcturus where to glow?

The writer of the book of Amos has also mentioned Orion and the seven stars; which plainly shews that the constellations must not only have been invented before his time, but that they must have been of some standing at that period.

These signs, which now seem so whimsical and uncouth, were not however the offspring of unsystematic fancy; they appear to have been intended to signify the state of the earth at the different seasons of the year, particularly the figures of the constellations in the Zodiac, which are supposed by some astronomers to be Egyptian hieroglyphics. Among these there are some that have as it were a common relation to every portion of the globe, while others seem to relate to circumstances or events merely local. Aries, is said to signify that the lambs begin to follow the sheep about the time of the

vernal equinox, when the sun enters this sign; and that the cows bring forth their young about the time he approaches the second constellation, Taurus, or the Bull. The third sign now called Gemini, was originally two kids, and signified the time of the goats bringing forth their young, which are usually two at a time, while the former (the sheep and the cow) commonly produce only one..

The fourth sign, Cancer the Crab, an animal that goes sideways and backwards, was placed at the northern tropic, or that point of the ecliptic, where the sun begins to return back again from the north to the southward. The fifth sign, Leo, the Lion, as being a furious animal, was thought to denote the heat and fury of the burning sun after he had left Cancer, and entered the next sign Leo.

The sixth sign received the sun at the time of the ripening of corn, and the approach of harvest; which was aptly expressed by one of the female reapers, with an ear of corn in her hand, namely Virgo, or the Virgin.

The next sign, Libra, or the Balance, evidently denotes the equality of days and nights, which take place at that season; and Scorpio, the next sign in order, denotes the time of gathering in the fruits of the earth, which being generally an unhealthly season, is represented by this venomous animal, extending his long claws, threatening the mischief which is to follow. The fall of the leaf was the season of the ancient hunting; and for this reason the constellation Sagittarius represents a huntsman with his arrows and his club; the weapons of destruction employed by huntsmen at that time. The reason of the Goat being chosen to mark the farthest south point of the ecliptic, is obvious enough, for when the sun has attained his extreme limit in that direction, he begins to return, and mounts again to the northward, which is very well represented by the goat, an animal that is always found climbing and ascending some mountain as it browses. As the winter has always been considered a wet and uncomfortable season, this was expressed by Aquarius, the figure of a man pouring out water from an urn. The last of the zodiacal constellations was Pisces, a couple of fishes tied together, which had been caught, which signified that the severe season was over, and though the flocks did not yet yield their store, yet the seas and rivers were open, and fish might be caught in abundance. These ideas have been beautifully expressed by Chatterton, in the following lines:

Ou the earth's orbit see the various signs,-
Mark where the sun our year completing, shines :
First the bright Ram his languid ray improves ;
Next glaring wat'ry thro' the Bull he moves:
The am'rous Twins admit his genial ray;
Now burning, thro' the Crab he takes his way;
The Lion, flaming, bears the solar power;
The Virgin faints beneath the sultry shower.
Now the just Balance weighs his equal foroe,
The slimy Serpent swelters in his course;
The sable Archer clouds his languid face;
The Goat with tempests urges on his race;
Now in the Water his faint beams appear,
And the cold Fishes end the circling year.

Although these signs might have served to distinguish the seasons of the year when they were first formed, or employed for that purpose, yet this is not altogether the case at the present day. For owing to the retrograde motion of the equinoctial points, the constellations of the Zodiac have now so far changed their positions, as to be found more than a sign advanced.* The constellation Aries, for example, is now three or four degrees within the sign Taurus, or the first point of Aries, which used to coincide with the equinoctial point, is now about thirty-four degrees farther advanced; however, the first point of the sign Aries still continues to be reckoned from the equinoctial point. The signs of the Zodiac must therefore now be distinguished from the constellations, the signs merely being ideal, and serving only to designate the course of the sun in the ecliptic, while the constellations continue to signify a group or cluster of stars, designated by some particular name.

Besides the constellations in the Zodiac, the catalogue of Ptolomy, (which is the first or earliest on record) enumerate 21 to the north, and 15 to the south of it, making in all 48, but these included only the visible part of the heavens, or such as came under their notice. The number of constellations, however, increased, as the knowledge of the stars became more extensive; and at the same time more stars were introduced into each constellation, as their positions became known.

Such stars as were not included in any of these constellations, were called by the ancients informs or sporades stars; but modern astronomers have now reduced these informs, or unformed stars into new constellations, which have now swelled the number to 95. Of these 12 are in the zodiac, the names of which have already been mentioned; 37 to the north of it, and 46 to the south of it. The northern constellations are

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Though the division of the heavens into the constellations above enumerated, be entirely fanciful, yet it is of great advantage in describing the position of particular stars. The judicious and practical astronomer has therefore always resisted every attempt, either to change their names, or to lay them aside, because better could not be substituted in their place; and because they keep up the greater correspondence and uniformity between the old astronomy and the

new.

ON THE POSITION OF The constelLATIONS, AND PRINCIPAL STARS IN THE NORTHERN HEMISPHERE.

As there is no particular constellation, or star, in the heavens, so singular in its appearance, or so singularly situated with respect to the rest, as to entitle it to the distinction of being first described, but as the constellation Ursa Major, or the Great Bear, never goes below the horizon of places of considerable northern latitude; and as it is one of the most conspicuous constellations in the northern hemisphere, we shall not only begin to describe it first, but endeavour to trace out the others by means of it..

In the Great Bear there are seven very conspicuous stars, four of which form a trapezium in the body, and the other three are in the tail of that animal. The two former stars in the trapezium are called the guards, or pointers, because a straight line passing through them points out the pole. The pointer which is nearest the pole star is called Dubhe; the first in the tail next the body, Alioth; and the last in the tail, Benetnach.‡

Nearly in the direction of the pointers, and about five times the interval between them, reckoning from Dubhe, is Alruccabah, or the Pole Star, situated in the tip of the tail of the constellation Uursa Minor, in which there are also seven stars, forming a figure

The new constellations are those marked thus (*).

These seven stars form a figure somewhat resembling a plough: hence it is often called Charles' Wain, or the Plough.