Polar Sea, there are some scientific observations on the phenomena of the Aurora, which throw considerable light on this curious and interesting subject. The meteor is usually conceived to have its place very high above the earth; but exceedingly different elevations have been assigned to it by different philosophers. Euler supposed it to be some thousands of miles distant, others have fixed its place at a few hundred miles, and others again much lower. The diffused nature of the appearance in this country, renders it difficult to make any accurate observation on the subject; but if the Aurora should continue occasionally to assume the form of a movable luminous arch, gliding slowly in a well-defined continuous body towards the zenith, as it has lately done in several instances and in different seasons, observations taken from various stations might settle the point. Be this as it may, and however high the northern lights may actually rise in this comparatively southern latitude, it seems to be ascertained by Captain Franklin and his companions, that, in the higher latitudes of North America, and still nearer the Pole, the region of the Aurora is not many miles above the earth. They discovered, by actual observation, that, in several instances, it did not rise higher than six or seven miles; and both there and in Siberia, it would seem to be often much lower even than this. The same kind of appearances, as are described by Gmelin, above quoted, appear sometimes to occur on the other side of the Atlantic. These, however, are not frequent; and the more usual phenomena partake much of the nature of the following, which I quote from Mr. Richardson's interesting observations on this meteor :

"When the Aurora had exhibited itself in this form for a considerable space of time, the whole mass of light suddenly appeared in motion, and, sweeping round on each side, was gathered together to the southward of the zenith. Immediately thereafter, a large portion of it was seen in the southeast, assuming an exact resemblance to a curtain suspended in a circular form in the air, and hanging perpendicularly to the earth's surface. The lower edge

of this curtain was very luminous, and had a waving motion; and the illusion was farther heightened by the momentary appearance of perpendicular dark lines or breaks in the light, in rapid succession round the circle, exactly as the waving of a curtain would cause the dark shades of its folds to move along it. This beautiful curtain of light was about forty degrees high, and of a pale yellowish color, and sent forth on the one side a process which approached the southeast-by-east point of the horizon, and the other was connected with a long regular arch, terminating in the northwest horizon, similarly constructed, and having the same waving motion with the curtain itself. All this time the sky was perfectly clear, except in the southern quarter, which, to the height of four or five degrees, was occupied by dark clouds, apparently intermediate between stratus and cirro-stratus.

"Half an hour after its first appearance, this curtainformed Aurora was resolved into a number of detached irregular portions, which sometimes increased rapidly in every direction, until they met with other masses, either before existing, or appearing at the instant, and formed a uniform sheet of light, which covered the whole sky. The formation of this great sheet of light was so rapid, that the eye could only trace its progress partially, and its dissolution and reappearance were equally sudden."*

SECOND WEEK-WEDNESDAY.

METEORIC SHOWERS.

I HAVE now to mention another celestial phenomenon of a very singular nature, connected with two days in the present week, which has lately attracted the attention of the scientific world. The following account of

* Franklin's Narrative, p.621.

it I extract from Mrs. Somerville's Connexion of the Physical Sciences.'

"On the morning of the 12th of November, 1799, thousands of shooting stars, mixed with large meteors, illuminated the heavens for many hours, over the whole continent of America, from Brazil to Labrador; they extended to Greenland, and even Germany. Meteoric showers were seen off the coast of Spain, and in the Ohio country, on the morning of 13th November, 1831; and during many hours on the morning of 13th November, 1832, prodigious multitudes of shooting stars and meteors fell at Mocha, on the Red Sea, in the Atlantic, in Switzerland, and at many places in England. But by much the most splendid meteoric shower on record, began at 9 o'clock in the evening of 12th November, 1833, and lasted till sunrise next morning.* It extended from Niagara and the northern lakes of America, to the south of Jamaica, and from sixty-one degrees of longitude in the Atlantic, to one hundred degrees of longitude in Central Mexico. Shooting stars and meteors, of the apparent size of Jupiter, Venus, and even the full moon, darted in myriads toward the horizon, as if all the stars in the heavens had started from their spheres. They are described as having been as frequent as flakes of snow in a snow-storm, and to have been seen with equal brilliancy over the greater part of the continent of North America.

"Those who witnessed this grand spectacle, were surprised to see that every one of the luminous bodies, without exception, moved in lines, which converged in one point in the heavens; none of them started from that point; but their paths, when traced backwards, met in it, like rays in a focus, and the measure of their fall showed that they descended from it in nearly parallel straight lines towards the earth.

*The French Academy of Sciences have taken an interest in the discussion to which this phenomenon has given rise, and it appears, from the recent communication of M. L. Ekberte, that the meteoric shower of 13th November, 1832, extended even to the Mauritius, where it is said to have been seen at the same period, and with the same appearances, as in other parts of the world.

"By far the most extraordinary part of the whole phenomenon is, that this radiant point was observed to remain stationary near the star y Leonis,* for more than two hours and a half, which proved the source of the meteoric shower to be altogether independent of the earth's rotation, and its parallax showed it to be far above the atmosphere.

"As a body could not be actually at rest in that position, the group must either have been moving round the earth or the sun. Had it been moving round the earth, the course of the meteors would have been tangential to its surface, whereas they fell almost perpendicularly, so that the earth, in its annual revolution, must have met with the group. The bodies that were nearest, must have been attracted towards the earth by its gravity; and as they were estimated to move at the rate of fourteen miles in a second, they must have taken fire on entering our atmosphere, and have been consumed in their passage through it.

"As all the circumstances of the phenomenon were similar, on the same day, and during the same hours, in 1832, and as extraordinary flights of shooting stars were seen at many places, both in Europe and America, on 13th November, 1834, tending also from a fixed point in the constellation Leo, it has been conjectured, with much apparent probability, that this group of bodies performs its revolution round the sun in a period of about 182 days, in an elliptical orbit, whose major axis is 119,000, 000 of miles; and that its aphelion distance, where it comes in contact with the earth's atmosphere, is about 95,000,000 of miles, or nearly the same with the mean distance of the earth from the sun."

These views correspond with those of the most celebrated living astronomers. M. Arago, from the facts mentioned, concludes that "a new planetary world is about to be revealed to us ;" and, at all events, there does seem

*[That is, the star designated by the letter Gamma in the constellation Leo. Gamma is the third letter of the Greek alphabet, and is used by astronomers to denote those stars which are third in magnitude in their respective constellations. AM. ED.]

to be a stream of innumerable bodies, comparatively small, but of various dimensions, moving constantly round the sun, whose orbit cuts that of our earth, at the point which it occupies on the 12th or 13th of November, every year.* For any thing that we can tell, indeed, there may be vast numbers of bodies circling round the sun, and even round the earth itself, which, on account of their minuteness and opacity, escape human observation. Such a supposition serves to explain the meteoric appearances which are constantly occurring in the clear nights of winter, and which might, perhaps, be not less common in summer, were the operations in the upper regions equally visible at that season.

Falling stars would seem to be nothing else than bodies of this description, rendered visible from being ignited by the rapidity of their passage through our atmosphere, or by some chemical cause; and meteoric stones, the fall of which is much more frequent than is commonly supposed, may be accounted for in the same way. Some of the latter are of great magnitude, exceeding, in certain instances, seventy miles in diameter. Mrs. Somerville mentions one which passed within twenty-five miles of us, and was estimated to weigh about 600,000 tons, and to move with a velocity of about twenty miles in a second. This huge mass was providentially prevented from striking the earth, a detached fragment of it alone having yielded to the force of our planet's gravitation. It is remarkable, that the chemical composition of these meteoric stones, while it materially differs from that of the

*[ This conclusion must be regarded as much too hasty, considering the great deficiency of successive accurate observations, and our yet imperfect knowledge of meteoric phenomena. It seems to be now conceded, that since the famous meteoric shower of November 13, 1833, there has been no larger number of meteors noted at that season, than on many other nights of the year. But the whole subject is an exceedingly interesting one, and we may hope will receive farther elucidation. It is proper to add, that the best account of the great "shower" of November, 1833, was given by Professor Olmsted of New Haven, and published in Silliman's American Journal of Science and the Arts ;' in which work there have since appeared several other papers on the same subject. AM. ED.]