372 THE POPULAR SCIENCE MONTHLY. 



fragment of rock on top of the snow, which is supposed to be part 

 of the meteorite. 



All meteorites appear to be fragments broken off from larger 

 bodies. Sometimes numerous fragments reach the earth, and at 

 other times only single masses. Thus, in the fall at L/Aigle, 

 already mentioned, about three thousand pieces were picked up, 

 scattered over an ellipse more than six miles long. An equally 

 large number fell at Knyahinya, June 9, 1866. Still more at 

 Pultusk in 1868. Several thousand were also picked up after a 

 fall at Estherville, Emmett County, Iowa, May 10, 1879. In such 

 a rain of meteorites the fragments vary greatly in size, some 

 weighing less than a grain, while the largest may weigh a hun- 

 dred pounds or more. In most cases the peculiar characters or 

 composition of the various specimens make it easy to recognize 

 them as fragments of the same mass. In the case of the Esther- 

 ville meteorite most of the pieces were coated with a fused crust, 

 owing to the explosion having taken place before they had lost 

 their great velocity. 



In the case of a stone which fell at Butsura in 1861, fragments 

 found three or four miles apart could be fitted together, and some 

 of the pieces, though fitting perfectly, had been coated on the faces 

 of juncture with a thin crust, showing that they had been blown 

 apart when the meteorite was still very high in the air. 



Meteorites, when not seen to fall, are easily recognized, not only 

 by the characteristic fused crust and pittings already referred to, 

 but by certain very marked peculiarities of structure. There are 

 three large groups : those consisting of metallic iron ; those con- 

 sisting of earthy minerals containing only grains of metallic iron ; 

 and those like the Pallas, made up of a continuous network of 

 iron inclosing stony matter. The stony meteorites are usually 

 made up of little rounded grains imbedded in a ground-mass of 

 fragments of the same material, a type of structure called chon- 

 dritic, which in its details is so characteristic that pieces of the 

 same mass can usually be easily identified, even though found at 

 places or times remote from each other. The iron meteorites are 

 still more easily recognized, although only about nine at most 

 have been seen to fall; for, since iron has not been found in 

 masses of any size in terrestrial rocks, unless in Greenland, these 

 large meteoric fragments are at once noticed wherever found. 

 Stony ones, on the contrary, are not only apt to be overlooked, 

 but the falls of past ages must have been altered and broken up 

 by weathering. Meteoric iron can be easily identified, because 

 it is usually extremely malleable, but at the same time very 

 tough, owing to its being made up of a network of crystalline 

 plates, the plates consisting of pure iron, bounded by layers of 

 an iron-nickel alloy and other impurities, which have separated 



