Page:The American Cyclopædia (1879) Volume I.djvu/164

 AEROLITE not of volcanic origin, and astronomers proved that their velocity in approaching the earth is far too great to be accounted for by terrestrial attraction. Mechanical science indeed proves that a body falling from an infinite distance will arrive at the earth with a velocity of only 6 to 7 miles per second, while a&rolites pass tangentially through our atmosphere with more than double or triple that rate, in fact, with a planetary velocity ; some of them even overtake the earth in its course, as is the case with those falling about sunset. By the com- bined rotation and revolution of the terrestrial globe, that portion of the earth where it is sunset moves from its zenith, while that por- tion where it is sunrise moves toward its zenith, or at least toward that portion of the zodiac nearest to its zenith, and thus has more chance of coming in contact with isolated flying masses ; this accounts for the fact that the greatest number of aerolites fall in the forenoon. Of the cases recorded in history, the most re- markable are as follows : An aerolite is men- tioned by Pliny, which fell in 467 B. C. in Thrace, and was still extant in his time ; he states that it had the size of a wagon. The Chinese chronicle a large aerolite which fell during a thunderstorm long before our era. The Annales Fuldewes report a great shower of aerolites in Saxony in 823, by which men and cattle were killed and 35 villages were set on fire. Among the other cases, the most remarkable are the falls of aerolites in 921, 1010, 1164, and 1304, all in Europe. In Alsace there fell in 1492 un aerolite of 260 Ibs., which is still pre- served in the church of Ensisheim. In Crema a shower of many hundreds of stones took place Sept. 14, 1511 ; 1,200 pieces were collected, of which one weighed 260 Ibs., and another 120 Ibs. Records of later date become more and more complete and authentic, and all doubts in regard to the accuracy of their statements, existing till the end of the last century, were removed when, on April 26, 1803, at Aigle in France, a small immovable cloud was seen, out of which, during explosions lasting five to six minutes, a number of stones fell on a surface two miles long. The largest weighed 20 Ibs., the smallest ounce. On March 13, 1807, an aerolite of 140 Ibs. fell in Smolensk, Russia ; and on May 22, 1808, at Stannern in Moravia, between 200 and 300 stones fell, from half an ounce to 11 Ibs. in weight. An Amer- ican vessel 240 miles S. of Java experienced on Nov. 14, 1856, a shower of stones of the size of shot, which were afterward proved not to be the product of the eruption of a distant volcano, carried along with the winds, as ft first suggested, but of true cosmical origin a question easily settled by the microscope and chemical analysis, as will be seen later. Klein published in his Sonnensystem (Brunswick, 1869) a record of more than 300 well authen- ticated cases, of which 3 were in the loth cen- tury, 15 in the 16th, 23 in the 17th, 40 in the 18th, and 216 in the first 69 years of the 19th century. It is certain that such falls were just as frequent in former centuries as they are now, only the records are lacking. In regard to the ancient geological eras, there is no doubt that the falls of meteoric masses were even more frequent ; it is highly probable even that a portion of the earth's and moon's mass is largely made up of such aerolites, which are not now found in the lower strata of the earth for the simple reason that they are very oxid- izable, and have been disintegrated by air and water and mixed with the original terrestrial matter, by the immense changes through which our earth's crust has passed ; they may there- fore exist in a better state of preservation on the moon's surface. Olbers supposes that the earth has during countless ages hollowed out for itself a kind of comparatively empty nit among those flying aerolites, attracting all within the reach of its gravitation, and that now, by the periodical inequalities and pertur- bations of its orbit, it occasionally appropriates some masses which had before escaped its attractive power, or that the earth occasionally comes in the neighborhood of masses having an orbit which intersects its own. (See MKTEOB.) In regard to the sizes, the largest masses on record were heard of by Capt. Ross in 1818, when the Esquimaux of Baffin bay informed him of their existence on the W. coast of Green- land. They were found in 1870 by the Swe- dish Arctic expedition, which brought some of them to Stockholm, where they excited so much interest that in 1871 20 more specimens were collected, now in the royal academy of Stockholm, the largest weighing 25 tons, with a maximum sectional area of 42 square feet. The next in size weighs 10 tons, and has been presented to the museum of Copenhagen. In Mexico and Brazil similar masses have been found. The British museum possesses one of more than five tons. In the museum in St. Petersburg is a mass of 1,680 Ibs. found in Si- beria in 1772. Yale college, New Haven, pos- sesses, among more than 100 specimens, one aerolite of 1,635 Ibs., which fell in Texas in 1808. The Smithsonian institution possesses a very remarkable annular specimen discovered about 1700 in Mexico, which, according to an Indian tradition, fell there about 200 years be- fore during a shower of stones ; its weight is 1,400 Ibs. Aerolites of a weight of 200 to 400 Ibs. are not uncommon in collections, and those of 100 Ibs. and less are very common. In re- gard to the chemical composition of these stones, it must be observed that in passing through our atmosphere they undergo some change, as they always take fire in the upper regions, and arrive at the ground quite hot, * sometimes making a deep hole. Combustible substances in their composition, and perhaps an atmosphere of combustible gases surrounding them, combined with the immense velocity with which they enter our atmosphere, cause on the sudden diminution of that motion a most intense rise of temperature, ignition,