The momentum of even light bodies of such size, and in such numbers, trav ersing the atmosphere with such astonishing velocity, must have produced extensive derangements in the atmospheric equilibrium. Cold air from the upper regions would be brought down to the earth; the portions of air incumbent over districts of country remote from each other, being mutually displaced, would exchange places, the air of the warm latitudes be transferred to colder, and that of cold latitudes, to warmer regions.

Various hypotheses have been proposed to account for this wonderful phenomena. The agent which most readily suggests itself in this, and in many other unexplained natural appearances, is electricity. But no known properties of electricity are adequate to account for the production of the meteors, for the motions, or for the trains which they, in many instances, left behind them. Others, again, have referred their proximate cause to magnetism, and to phosphoretted hydrogen; both of which, however, seem to be utterly insufficient, so far as their properties are known, to account for so unusual a phe

nomenon.

Professor Olmsted, of Yale College, who has taken much pains to collect facts, and to establish a permanent theory for the periodical recurrence of such phenomena, came to the conclusion, that

The meteors of November 13th, 1833, emanated from a nebulous body, which was then pursuing its way along with the earth around the sun; that this body continues to revolve around the sun, in an elliptical orbit—but little inclined to the plane of the ecliptic, and having its aphelion near the orbit of the earth; and finally, that the body has a period of nearly six months, and that its perihelion is a little below the orbit of Mercury.

This theory, at least accommodates itself to the remarkable fact, that almost all the phenomena of this description, which are known to have happened, have occurred in the two opposite months of April and November. A similar exhibition of meteors to that of November, 1833, was observed on the same day of the week, April 20th, 1803, at Richmond, in Virginia, Stockbridge, Massachusetts, and at Halifax, in British America. Another was witnessed in the autumn of 1818, in the North sea, when, in the language of the observers, "all the surrounding atmosphere was enveloped in one expansive sea of fire, exhibiting the appearance of another Moscow in flames."

Exactly one year previous to the great phenomenon of 1833, namely, on the 12th of November, 1832, a similar me

What effect must the momentum of even light bodies of such size, moving with such velocity, have had upon the atmosphere? Mention some hypotheses which have been proposed to account for these meteors. To what conclusion did Professor Olmsted, after a long investigation, come, in regard to them? To what remarkable facts in such phenomena, is this theory adapted? At what other corresponding periods have similar phenomena been observed?

teoric display was seen near Mocha, on the Red sea, by Capt. Hammond and crew, of the ship Restitution.

A gentleman in South Carolina, thus describes the effect of the phenomenon of 1833, upon his ignorant blacks:-"I was suddenly awakened by the most distressing cries that ever fell on my ears. Shrieks of horrour, and cries of mercy, I could hear from most of the negroes of three plantations, amounting in all to about six or eight hundred. While earnestly listening for the cause, I heard a faint voice near the door calling my name; I arose, and taking my sword, stood at the door. At this moment, I heard the same voice still beseeching me to rise, and saying, 'O! my God, the world is on fire!' I then opened the door, and it is difficult to say which excited me most-the awfulness of the scene, or the distressed cries of the negroes; upwards of one hundred lay prostrate on the ground-some speechless, and some with the bitterest cries, but most with their hands raised, imploring God to save the world and them. The scene was truly awful; for never did rain fall much thicker, than the meteors fell towards the earth; east, west, north, and south, it was the same!"

Since the preceding went to press, the Author has been politely furnished, by Professor Olmsted, with the accompanying communication.

"I am happy to hear that you propose to stereotype your 'Geography of the Heavens.' It has done much, I believe, to diffuse a popular knowledge of astronomy, and I am pleased that your efforts are rewarded by an extended patronage.

"Were I now to express my views on the subject (Meteoric Showers) in as condensed a form as possible, I should state them in some such terms as the following: The meteoric showers which have occurred for several years past on or about the 13th of November, are characterized by four peculiarities, which distinguished them from ordinary shooting stars. First, they are far more numerous than common, and are larger and brighter. Secondly, they are in much greater proportion than usual, accompanied by luminous trains. Thirdly, they mostly appear to radiate from a common centre,-that is, were their paths in the heavens traced backwards, they would meet in the same part of the heavens: this point has for three years past, at least, been situated in the constellation Leo. Fourthly, the greatest display is every where at,nearly the same time of night, namely, from three to four o'clock—a time

about half way from midnight to sunrise. The meteors are inferred to consist of combustible matter, because they are seen to take fire and burn in the atmosphere. They are known to be very light, because, although they fall towards the earth with immense velocity, few, if any, ever reach the earth, but are arrested by the air, like a wad fired from a piece of artillery. Some of them are inferred to be bodies of comparatively great size, amounting in diameter to several hundred feet, at least, because they are seen under so large an angle, while they are at a great distance from the spectator. Innumerable small bodies thus, consisting of extremely light, thin, combustible matter, existing together in space far beyond the limits of the atmosphere, are believed to compose a body of immense extent, which has been called 'the nebulour body.' Only the skirts or extreme portions of this are brought down to the earth, while the entire extent occupies many thousand, and perhaps several millions of miles. This nebulous body is inferred to have a revolution around the sun, as well as the earth, and to come very near to the latter about the 13th of November each year. This annual meeting every year, for several years in succession, could not take place unless the periodic time of the nebulous body is either nearly a year, or half a year. Various reasons have induced the belief that half a year is the true period; but this point is considered as somewhat doubtful. The zodiacal light, a faint light that appears at different seasons of the year, either immediately preceding the morning or following the evening twilight, ascending from the sun in a triangular form, is with some degree of probability thought to be the nebulour body itself, although the existence of such a body, revolving in the solar system, was inferred to be the cause of the meteoric showers, before any connexion of it with the zodiacal light was even thought of."

OUR attention has hitherto been directed to those bodies which we see scattered every where throughout the whole celestial concave. These bodies, as has been shown, twinkle with a reddish and variable light, and appear to have always the same position with regard to each other. We know

that their number is very great, and that their distance from us is immeasurable. We are also acquainted with their comparative brightness and their situation. In a word, we have before us their few visible appearances, to which our knowledge of them is well nigh limited; almost all our reasonings in regard to them being founded on comparatively few and uncertain analogies. Accordingly our chief business, thus far, has been to detail their number, to describe their brightness and positions, and to give the names by which they have been designated.

There now remain to be considered certain other celestial bodies, all of which, from their remarkable appearance and changes, and some of them from their intimate connection with the comfort, convenience, and even existence of man, must have always attracted especial observation, and been objects of the most intense contemplation and the deepest interest. Most of these bodies are situated within the limits of the Zodiac. The most important of them are, the Sun, so superior to all the heavenly bodies for its apparent magnitude, for the light and heat which it imparts, for the marked effects of its changes of position with regard to the Earth; and the Moon, so conspicuous among the bodies which give light by night, and from her soft and silvery brightness, so pleasing to behold; re

To what particulars is our knowledge of the fixed stars, those heavenly bodies which we have heretofore been considering, well nigh confined? Where are the bodies which now remain to be considered, situated? Which of them are the most important?

markable not only for changes of position; but for the varied phases or appearances which she presents, as she waxes from her crescent form through all her different stages of increase to a full orb, and wanes back again to her former diminished figure.

The partial or total obscuration of these two bodies, which sometimes occurs, darkness taking place even at mid-day, and the face of night, before lighted up by the Moon's beams, being suddenly shaded by their absence, have always been among the most striking astronomical phenomena, and so powerful in their influence upon the beholders, as to fill them with perplexity and fear. If we observe these two bodies, we shall find, that, besides their apparent diurnal motion across the heavens, they exhibit other phenomena, which must be the effect of motion. The Sun during one part of the year, will be seen to rise every day farther and farther towards the north, to continue longer and longer above the horizon, to be more and more elevated at mid-day, until he arrives at a certain limit; and then, during the other part, the order is entirely reversed. The Moon sometimes is not seen at all; and then, when she first becomes visible, appears in the west, not far from the setting Sun, with a slender crescent form; every night she appears at a greater distance from the setting Sun, increasing in size, until at length she is found in the east, just as the Sun is sinking below the horizon in the west.

The Sun, if his motions be attentively observed, will be found to have another motion, opposite to his apparent diurnal motion from east to west. This may be perceived distinctly, if we notice, on any clear evening, any bright star, which is first visible after sunset, near the place where he sunk below the horizon. The following evening, the star will not be visible on account of the approach of the Sun, and all the stars on the east of it will be successively eclipsed by his rays, until he shall have made a complete apparent revolution in the heavens. These are the most obvious phenomena exhibited by these two bodies.

There are, also, situated within the limits of the Zodiac, certain other bodies, which, at first view, and on a superficial examination, are scarcely distinguishable from the fixed stars. But observed more attentively, they will be seen to shine with a milder and steadier light, and besides being carried round with the stars, in the apparent revolution of the great celestial concave, they will seem to change their

Describe the most obvious phenomena of the Sun and Moon. Describe the most obvious phenomena of the planets.