Part 35

“Whatever may be the origin of these luminous meteors, it is difficult to conceive any instantaneous inflammation taking place in a region where there is less air than in the vacuum of our air-pumps; and where (twenty-five thousand toises high) the mercury in the barometer would not rise to twelve-thousandths of a line. We have ascertained the uniform mixture of atmospheric air to three-thousandths nearly, only to an elevation of three thousand toises: consequently, not beyond the last stratum of fleecy clouds. It might be admitted, that, in the first revolutions of the globe, gaseous substances which yet remain unknown to us, may have risen toward that region, through which the falling stars pass: but accurate experiments, made upon mixtures of gases which have not the same specific gravity, prove that we can not admit a superior stratum of the atmosphere entirely different from the inferior strata. Gaseous substances mix and penetrate each other with the least motion; and a uniformity of their mixture would have taken place in the lapse of ages, unless we suppose in them the effects of a repulsive action unexampled in those substances which we can subject to our observations. Further, if we admit the existence of a particular aerial fluid in the inaccessible region of luminous meteors, falling stars, bolides, and the =aurora borealis=, how can we conceive why the whole stratum of those fluids does not at once take fire, but that the gaseous emanations, like the clouds, occupy only limited spaces? How can we suppose an electrical explosion without some vapors collected together, capable of containing unequal charges of electricity, in air, the mean temperature of which is, perhaps, twenty-five degrees below the freezing-point of the centigrade thermometer, and the rarefaction of which is so considerable, that the compression of the electrical shock could scarcely disengage any heat? These difficulties would in great part, be removed, if the direction of the motion of falling stars allowed us to consider them as bodies with a solid nucleus, as cosmic phenomena (belonging to space beyond the limits of our atmosphere) and not as telluric phenomena (belonging to our planet only.)

“Supposing that the meteors of Cumana were only at the usual hight at which falling stars in general move, the same meteors were seen above the horizon in places more than three hundred and ten leagues distant from each other. Now, what an extraordinary disposition to incandescence must have reigned on the twelfth of November, in the higher regions of the atmosphere, to have furnished, during four hours, myriads of bolides and falling stars, visible at the equator, in Greenland, and in Germany.

“Mr. Benzenberg judiciously observes, that the same cause, which renders the phenomenon more frequent, has also an influence on the largeness of the meteors, and the intensity of their light. In Europe, the nights when there are the greatest number of falling stars, are those in which very bright ones are mixed with very small ones. The periodicalness of the phenomenon augments the interest which it excites. There are months, in which M. Brandes has reckoned in our temperate zone, only sixty or eighty falling stars in one night; and in other months their number has risen to two thousand. Whenever one is observed, which has the diameter of Sirius or of Jupiter, we are sure of seeing so brilliant a meteor succeeded by a great number of smaller meteors. If the falling stars be very frequent during one night, it is very probable that this frequency will continue during several weeks. It would seem that, in the higher regions of the atmosphere, near that extreme limit where the centrifugal force is balanced by gravity, there exists, at regular periods, a

## particular disposition for the production of bolides, falling stars, and

the =aurora borealis=. Does the periodicalness of this great phenomenon depend upon the state of the atmosphere? or upon something which the atmosphere receives from without, while the earth advances in the ecliptic? Of all this we are still as ignorant as men were in the days of Anaxagoras.

“With respect to the falling stars themselves, it appears to me, from my own experience, that they are more frequent in the equinoctial regions than in the temperate zone; more frequent over the continents, and near certain coasts, than in the middle of the ocean. Do the radiation of the surface of the globe, and the electrical charge of the lower regions of the atmosphere, which varies according to the nature of the soil, and the positions of the continents and seas, exert their influence as far as those hights, where eternal winter reigns? The total absence even of the smallest clouds, at certain seasons, or above some barren plains destitute of vegetation, seems to prove, that this influence can be felt at least as far as five or six thousand toises high. A phenomenon analogous to that of the twelfth of November, was observed thirty years before, on the table-land of the Andes, in a country studded with volcanoes. At the city of Quito, there was seen, in one part of the sky, above the volcano of Gayambo, so great a number of falling stars, that the mountain was thought to be in flames. This singular sight lasted more than an hour. The people assembled in the plain of Exico, where a magnificent view presents itself of the highest summit of the Cordilleras. A procession was already on the point of setting out from the convent of St. Francis, when it was perceived that the blaze of the horizon was caused by fiery meteors, which ran along the skies in all directions, at the altitude of twelve or thirteen degrees.”

The bolides, or fire-balls, and falling stars, so striking an example of which is given above, are of all sizes, from a small shooting-star of the fifth magnitude, to a cone or cylinder of two or three miles in diameter. They differ in consistency as much as in dimensions, and in color as much as in either. Occasionally, they are a subtile, luminous and pellucid vapor; and sometimes a compact ball, or globe, as though the materials of which they are formed, were more condensed and concentrated. Not unfrequently they have been found to consist of both, and consequently to assume a comet-like appearance, with a nucleus or compact substance in the center, or toward the center, and a long, thin, pellucid or luminous main, or tail, sweeping on each side. They are sometimes of a pale white light; at others, of a deep igneous crimson; and, occasionally iridescent and vibratory. The rarer meteors appear frequently to vanish on a sudden, as though abruptly dissolved or extinguished in the atmospheric medium, their flight being accompanied by a hissing sound, and their disappearance by an explosion. The most compact of them, or the nuclei of those which are rarer, have often descended to the surface of the earth, and with a force sufficient to bury them many feet under the soil; generally exhibiting marks of imperfect fusion and considerable heat. The substance is, in these cases, for the greater part metallic; but the ore of which they consist is not anywhere to be found, in the same constituent proportions, in the bowels of the earth. Under this form the projected masses are denominated aerolites, or meteoric stones.

It may not be uninteresting to preface a succinct account of the most surprising of these meteors, by a notice of the hypotheses which have been imagined concerning them; however justly the learned Humboldt may have concluded, in the words of the extracts given above, that we are still “as ignorant on this subject as men were in the days of Anaxagoras.” Sir J. Pringle contended, with other philosophers, that they are revolving bodies, or a kind of terrestrial planets. Doctor Halley conjectured them to consist of combustible vapors, accumulated and formed into concrete bodies on the outskirts, or extreme regions of the atmosphere, and to be suddenly set on fire by some unknown cause; an opinion which, with little difference, has been since entertained by Sir W. Hamilton and Dr. King. Dr. Blagdon regarded them altogether as electrical phenomena. M. Izarn believed them to consist of volcanic materials, propelled into the atmosphere in the course of explosions of great violence. M. Chladni supposed them to be formed of substances existing exteriorly to the atmosphere of the earth and other planets, which have never incorporated with them, and are found loose in the vast ocean of space, being there combined and inflamed by causes unknown to us. Lastly, another and rather wild hypothesis is, that the whole, or at least the more compact division of these meteors, are made up of materials thrown from immense volcanoes in the moon. This hypothesis, which was started by M. Olbers, in 1795, has been since very plausibly supported by the celebrated Laplace, but does not apply to the smaller and less substantial meteors, named shooting-stars. Hence these philosophers derive the latter phenomena from some other cause, as electricity, or terrestrial exhalations; and observe, in support of the distinction they find it necessary to make, that shooting-stars must be of a different nature from fire-balls, since they sometimes appear to ascend as well as to fall. This observation has been especially dwelt on by Messrs. Chladni and Benzenberg, both of them favorably noticed, as accurate observers, by Humboldt.

By far the most plausible and satisfactory theory, however, is one somewhat like that of Dr. Halley, which may be illustrated thus. If a stick of wood, after being covered over night in the hot ashes, so as to become in part or wholly charred, be taken out in the morning, and waved back and forth in the air, every one has noticed that it will send forth sparks by hundreds and thousands. Now the more modern theory as to these aerolites, or falling-stars, is, that they are thrown off from small, opaque, planetary bodies, revolving in space, which when they come within the atmosphere of the earth, are heated from their rapid motion through it, and throw off small heated portions, like the sparks from the waving brand. And this theory is confirmed by the fact, that, of late years, these meteoric showers have been annual, and always at about the same period of the year, as if the earth was then passing in that part of her orbit where she meets with the planetary bodies spoken of, and they come in contact with her atmosphere. In the volumes of the “American Journal of Science,” may be found abundant facts on this subject, and also the various theories started to account for the facts.

On the twenty-first of March, 1676, two hours after sunset, an extraordinary meteor was seen to pass over Italy. At Bononia, its greatest altitude in the south-south-east, was thirty-eight degrees; and at Sienna, fifty-eight degrees toward the north-north-east. In its course, which was from east-north-east to west-south-west, it passed over the Adriatic sea, as if coming from Dalmatia. It crossed all Italy, being nearly vertical to Rimini and Savigniano, on the one side, and to Leghorn on the other: its perpendicular altitude was at least thirty-eight miles. At all the places near its course it was heard to make a hissing noise as it passed, like that of artificial fireworks. In passing over Leghorn, it gave a very loud report, like that of a cannon; immediately after which another sort of sound was heard, like the rattling of a deeply loaded wagon passing over the stones, which continued for several seconds. The professor of mathematics at Bononia, calculated the apparent velocity of this surprising meteor at not less than one hundred and sixty miles in a minute of time, which is above ten times as swift as the diurnal rotation of the earth under the equinoctial, and not many times less than that with which the annual motion of the earth about the sun is performed. It there appeared larger than the moon in one diameter, and above half as large again in the other; which, with the given distance of the eye, made its real smaller diameter above half a mile, and the larger one in proportion. It is, therefore, not surprising, that so great a body, passing with such an amazing velocity through the air, however rarefied it may be in its upper regions, should occasion so loud a hissing noise as to be heard at such a distance. It finally went off to sea toward Corsica.

Two luminous meteors of great magnitude were noted at Leipsic within the space of six years. On the twenty-second of May, 1680, about three in the morning, the first of these was seen, to the great terror of the spectators, descending in the north, and leaving behind it a long white streak where it had passed. As the same phenomena was witnessed in the north-north-east at Haarburg, and also at Hamburg, Lubeck and Stralsund, all of which places are about a hundred and fifty English miles from Leipsic, it was concluded that this meteor was exceedingly high above the earth. The second meteor was still more terrific. On the ninth of July, 1686, at half past one in the morning, a fire-ball with a tail was observed in eight and a half degrees of Aquarius, and four degrees north, which continued nearly stationary for seven or eight minutes, with a diameter nearly equal to half the moon’s diameter. At first, its light was so great that the spectators could see to read by it; after which it gradually disappeared. This phenomenon was observed at the same time in several other places, more especially at Schlaitza, a town distant from Dantzic forty English miles toward the south, its altitude being about six degrees above the southern horizon. At Leipsic it was estimated to be distant not more than sixty English miles, and to be about twenty-four miles perpendicular above the horizon, so that it was at least thirty miles high in the air.

A very extraordinary meteor, which the common people called a flaming sword, was first seen at Leeds, in Yorkshire, on the eighteenth of May, 1710, at a quarter after ten at night. Its direction was from south to north: it was broad at one end, and small at the other; and was described by the spectators as resembling a trumpet, moving, with the broad end foremost. The light was so sudden and intense, that they were startled at seeing their own shadows, when neither sun nor moon shone upon them. This meteor was, in its course, seen not only in Yorkshire and Lancashire, but also in the counties of Nottingham and Derby, notwithstanding which, each of those who observed it, although so many miles distant from each other, fancied it fell within a few yards of him. In disappearing, it presented bright sparklings at the small end.

A blazing meteor was, on the nineteenth of March, 1719, seen in every part of England. In the metropolis, about a quarter after eight at night, a sudden powerful light was perceived in the west, far exceeding that of the moon, which then shone very bright. The long stream it gave out appeared to be branched about the middle; and the meteor, in its course, turned pear-fashioned, or tapering upward. At the lower end it came at length to be larger and spherical, although not so large as the full moon. Its color was whitish, with an eye of blue of a most vivid, dazzling luster, which seemed in brightness very nearly to resemble, if not to surpass, that of the body of the sun in a clear day. This brightness obliged the spectator to turn his eyes several times from it, as well when it was a stream, as when it was pear-fashioned and a globe. It seemed to move, in about half a minute or less, about the length of twenty degrees, and to disappear about as much above the horizon. Where it had passed, it left behind a track of a cloudy or faint reddish-yellow color, such as red-hot iron or glowing coals have: this continued more than a minute, seemed to sparkle, and kept its place without falling. This track was interrupted, or had a chasm toward its upper end, at about two-thirds of its length. No explosion was heard; but the place where the globe of light had been, continued for some time after it was extinct, of the same reddish-yellow color with the stream, and at first sparks seemed to issue from it, such as proceed from red-hot iron beaten out on an anvil.

It was agreed by all the spectators in the capital, that the splendor of this meteor was little inferior to that of the sun. Within doors the candles did not give out any light; and in the streets, not only all the stars disappeared, but the moon, then nine days old, and high near the meridian, the sky being very clear, was so far effaced as scarcely to be seen: it did not even cast a shade, where the beams of the meteor were intercepted by the houses; so that, for a few seconds of time, there was in every respect, a resemblance of perfect day.

The perpendicular hight of this surprising meteor was estimated at sixty-four geometrical miles; and it was computed to have run about three hundred of these miles in a minute. It was seen, not only in every part of Great Britain and Ireland, but likewise in Holland, in the western parts of Germany, in France and in Spain, nearly at the same instant of time. The accounts from Devonshire, Cornwall, and the neighboring counties, were unanimous in describing the wonderful noise which followed its explosion. It resembled the report of a large cannon, or rather of a broadside at some distance, which was soon followed by a rattling noise, as if many small arms had been promiscuously discharged. This tremendous sound was attended by an uncommon tremor of the air; and everywhere in those counties, not only the windows and doors of the houses were sensibly shaken, but, according to several of the reports, even the houses themselves, beyond the usual effect of cannon, however near.

On the eleventh of December, 1741, at seven minutes past one in the afternoon, a globe of fire, somewhat larger than the horizontal full moon, and as bright as the moon appears at any time when the sun is above the horizon, was seen at Peckham, in Surrey, in a south-south-east direction, moving toward the east with a continued equable motion, and leaving behind it a narrow streak of light, whiter than the globe itself, throughout its whole course. Toward the end it appeared less than at the beginning of its motion; and within three or four seconds suddenly vanished. Its apparent velocity was nearly equal to half the medium velocity of the ordinary meteors called falling or shooting stars; and its elevation, throughout the whole of its course, about twenty degrees above the horizon.

On the eighteenth of August, 1783, an uncommon meteor was seen in several parts of Great Britain, as well as on the continent. Its general appearance was that of a luminous ball, which, rising in the north-north-east, nearly of a globular form, became elliptical, and gradually assumed a tail as it ascended. In a certain part of its course it underwent a remarkable change, which might be compared to bursting, and which, it ought to be observed, has been since frequently noticed in the passage of the aerolites, or meteoric stones, particular mention of which will be made hereafter. After this it no longer proceeded as an entire mass, but was apparently divided into a great number, or cluster of balls, some larger than others, and all carrying a tail, or leaving a train behind. Under this form, it continued its course with a nearly equable motion, dropping or casting off sparks, and yielding a prodigious light, which illumined all objects to a surprising degree; until, having passed the east, and verging considerably to the southward, it gradually distended, and was at length lost to the sight. The time of its appearance was sixteen minutes past nine in the evening, mean time of the meridian of London, and it continued visible about half a minute.

This beautiful meteor having been seen in Shetland, and in the northern parts of Scotland, ascending from the north, and rising like the planet Mars, little doubt was entertained of its course having commenced beyond the furthest extremity of Great Britain, somewhere over the northern ocean. Having passed over Essex and the straits of Dover, it probably entered the continent not far from Dunkirk, where, as well as at Calais and Ostend, it was thought to be vertical. Still holding on its course to the southward, it was seen at Brussels, at Paris, and at Nuits in Burgundy; insomuch that there was sufficient proof of its having traversed thirteen or fourteen degrees of latitude, describing a track of at least one thousand miles over the surface of the earth; a length of course far exceeding the extent of what had been then ascertained of any similar phenomenon.

During the passage of this meteor over Brussels, the moon appeared quite red, but soon recovered its natural light. The results of several observations give it an elevation of more than fifty miles above the surface of the earth, in a region where the air is at least thirty thousand times rarer than here below. Notwithstanding this great elevation, the fact of a report having been heard some time after it disappeared, rests on the testimony of too many witnesses to be controverted. It was compared to the falling of some heavy body in a room above stairs, or to the discharge of one or more large cannon at a distance: this report was loudest in Lincolnshire and the adjacent counties, and also in the eastern parts of Kent.

Supposing the transverse diameter of this meteor to have subtended an angle of thirty minutes when it passed over the zenith, and that it was fifty miles high, it must have been almost half a mile across. The tail sometimes appeared ten or twelve times longer than the body; but most of this was train, and the real elongation behind seems seldom to have exceeded twice or thrice its transverse diameter; it consequently was between one and two miles in length. Now if the cubical contents be considered, for it appeared equally round and full in all directions, such an enormous mass must afford just matter of astonishment, when the extreme velocity with which it moved is considered. This velocity, agreeably to the observations of Sir William Herschel and several other astronomers, could not have been less than twenty miles in a second, exceeding that of sound above ninety times, and approaching toward that of the earth in her annual orbit. At such a rate it must have passed over the whole island of Great Britain in less than half a minute, and would, in the space of less than seven minutes, have traversed the whole diameter of the earth!