The wonders of the world

by John Loraine Abbott

“The scientific men who have lately made such laborious researches on falling stars and their parallaxes, consider them as meteors belonging to the furthest limits of our atmosphere, between the region of the aurora borealis and that of the lightest clouds. Some have been seen, which had not more than fourteen thousand toises, or about five leagues of elevation. The highest do not appear to exceed thirty leagues. They are often more than a hundred feet in diameter; and their swiftness is such, that they dart, in a few seconds, over a space of two leagues. Some of these have been measured, the direction of which was almost perpendicularly upward, or forming an angle of fifty degrees with the vertical line. This extremely remarkable circumstance has led to the conclusion, that falling stars are aerolites, which, after having hovered about a long time in space, take fire on entering accidentally into our atmosphere, and fall toward the earth.

“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.