remarkable, their chemical analysis develops the same substances in nearly the same proportions, though one may have reached the earth in India and another in England. Their specific gravities are about the same; considering 1000 as the proportionate number for the specific gravity of water, that of some of the aërolites has been found to be,
Ensisheim stone3233
Benares3352
Sienna3418
Gassendi’s3456
Yorkshire3508
Bachelay’s3535
Bohemia4281
The greater specific gravity of the Bohemian stone arose from its containing a greater proportion of iron. An analysis of one of the stones that fell at L’Aigle gives:
Silica46 per cent
Magnesia10 ”
Iron45 ”
Nickel 2 ”
Sulphur 5 ”
Zinc 1 ”
Iron is found in all these bodies, and in a considerable quantity, with the rare metal nickel. It is a singular fact, that though a chemical examination of their composition has not discovered any substance with which we were not previously acquainted, yet no other bodies have yet been found, native to the earth, which contain the same ingredients combined. Neither products of the volcanoes, whether extinct or in action, nor the stratified or unstratified rocks, have exhibited a sample of that combination of metallic and earthy substances which the meteoric stones present. During the era that science has admitted their path to the earth as a physical truth, scarcely amounting to half a century, few years have elapsed without a known instance of descent occurring in some region of the globe. To Izarn’s list, previously given, upward of seventy cases might be added, which have transpired during the last forty years. A report relating to one of the most recent, which fell in a valley near the Cape of Good Hope, with the affidavits of the witnesses, was communicated to the Royal Society, by Sir John Herschel, in March, 1840. Previously to the descent of the aërolites, the usual sound of explosion was heard, and some of the fragments falling upon grass, caused it instantly to smoke, and were too hot to admit of being touched. When, however, we consider the wide range of the ocean, and the vast unoccupied regions of the globe, its mountains, deserts, and forests, we can hardly fail to admit that the observed cases of descent must form but a small proportion of the actual number; and obviously in countries upon which the human race are thickly planted many may escape notice through descending in the night, and will lie imbedded in the soil till some accidental circumstance exposes their existence. Some, too, are no doubt completely fused and dissipated in the atmosphere, while others move by us horizontally, as brilliant lights, and pass into the depths of space. The volume of some of these passing bodies is very great. One which traveled within twenty-five miles of the surface, and cast down a fragment, was suppose to weigh upward of half a million of tons. But for its great velocity, the whole mass would have been precipitated to the earth. Two aërolites fell at Braunau, in Bohemia, July 14, 1847.
In addition to aërolites, properly so called, or bodies known to have come to us from outlying space, large metallic masses exist in various parts of the world, lying in insulated situations, far remote from the abodes of civilization, whose chemical composition is closely analogous to that of the substances the descent of which has been witnessed. These circumstances leave no doubt as to their common origin. Pallas discovered an immense mass of malleable iron, mixed with nickel, at a considerable elevation on a mountain of slate in Siberia, a site plainly irreconcilable with the supposition of art having been there with its forges, even had it possessed the character of the common iron. In one of the rooms of the British Museum there is a specimen of a large mass which was found, and still remains, on the plain of Otumba, in the district of Buenos Ayres. The specimen alone weighs 1400 lbs., and the weight of the whole mass, which lies half buried in the ground, is computed to be thirteen tons. In the province of Bahia, in Brazil, another block has been discovered weighing upward of six tons. Considering the situation of these masses, with the details of their chemical analysis, the presumption is clearly warranted that they owe their origin to the same causes that have formed and projected the aërolites to the surface. With reference to the Siberian iron a general tradition prevails among the Tartars that it formerly descended from the heavens. A curious extract, translated from the Emperor Tchangire’s memoirs of his own reign is given in a paper communicated to the Royal Society, which speaks of the fall of a metallic mass in India. The prince relates, that in the year 1620 (of our era) a violent explosion was heard at a village in the Punjaub, and at the same time a luminous body fell through the air on the earth. The officer of the district immediately repaired to the spot where it was said the body fell, and having found the place to be still hot, he caused it to be dug. He found that the heat kept increasing till they reached a lump of iron violently hot. This was afterward sent to court, where the emperor had it weighed in his presence, and ordered it to be forged into a sabre, a knife, and a dagger. After a trial the workmen reported that it was not malleable, but shivered under the hammer; and it required to be mixed with one third part of common iron, after which the mass was found to make excellent blades. The royal historian adds, that on the incident of this iron of lightning being manufactured, a poet presented him with a distich that, “during his reign the earth attained order and regularity; that raw iron fell from lightning, which was, by his world-subduing authority, converted into a dagger, a knife, and two sabres.”
A multitude of theories have been devised to account for the origin of these remarkable bodies. The idea is completely inadmissible that they are concretions formed within the limits of the atmosphere. The ingredients that enter into their composition have never been discovered in it, and the air has been analyzed at the sea level and on the tops of high mountains. Even supposing that to have been the case, the enormous volume of atmospheric air so charged required to furnish the particles of a mass of several tons, not to say many masses, is, alone, sufficient to refute the notion. They can not, either, be projectiles from terrestrial volcanoes, because coincident volcanic activity has not been observed, and aërolites descend thousands of miles apart from the nearest volcano, and their substances are discordant with any known volcanic product. Laplace suggested their projection from lunar volcanoes. It has been calculated that a projectile leaving the lunar surface, where there is no atmospheric resistance, with a velocity of 7771 feet in the first second, would be carried beyond the point where the forces of the earth and the moon are equal, would be detached, therefore, from the satellite, and come so far within the sphere of the earth’s attraction as necessarily to fall to it. But the enormous number of ignited bodies that have been visible, the shooting stars of all ages, and the periodical meteoric showers that have astonished the moderns, render this hypothesis untenable, for the moon, ere this, would have undergone such a waste as must have sensibly diminished her orb, and almost blotted her from the heavens. Olbers, was the first to prove the possibility of a projectile reaching us from the moon, but at the same he deemed the event highly improbable, regarding the satellite as a very peaceable neighbor, not capable now of strong explosions from the want of water and an atmosphere. The theory of Chladni will account generally for all the phenomena, be attended with the fewest difficulties, and, with some modifications to meet circumstances not known in his day, it is now widely embraced. He conceived the system to include an immense number of small bodies, either the scattered fragments of a larger mass, or original accumulations of matter, which, circulating round the sun, encounter the earth in its orbit, and are drawn toward it by attraction, become ignited upon entering the atmosphere, in consequence of their velocity, and constitute the shooting stars, aërolites, and meteoric appearances that are observed. Sir Humphry Davy, in a paper which contains his researches on flame, strongly expresses an opinion that the meteorites are solid bodies moving in space, and that the heat produced by the compression of the most rarefied air from the velocity of their motion must be sufficient to ignite their mass so that they are fused on entering the atmosphere. It is estimated that a body moving through our atmosphere with the velocity of one mile in a second, would extricate heat equal to 30,000° of Fahrenheit – a heat more intense than that of the fiercest artificial furnace that ever glowed. The chief modification given to the Chladnian theory has arisen from the observed periodical occurrence of meteoric showers – a brilliant and astonishing exhibition – to some notices of which we proceed.
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