MERRILL — SCHUCHERT 627 



nized as of petronrraphic rather than mineralopjical interest and 

 given an entity of their own.'' In 1S80 the Museum had about 10 

 falls and finds, among which were the large irons of Tucson and 

 Casas Grandes. In 1888 the number had increased to 128 specimens 

 due to the active interest of F. W. Chirke, with I'jG aihlitiunal ones 

 in the Shepard collection, which was placed on deposit in 1887 

 and became the property of the Museum in 1917. Most of the speci- 

 mens in both collections were small. In 1902 there were, all told, 

 348 falls of which 143 were irons, and in 1916, 412 distinct falls and 

 finds. Merrill alone has described 40 new falls. From Canyon 

 Diablo the collection had 400 complete individuals weighing 2,200 

 pounds; and of the Holbrook, Ariz., find, over 600 complete indi- 

 viduals. (MS. 1929.) As Farrington has well said (1930), "In 

 this as in all of his undertakings Merrill achieved remarkable suc- 

 cess." Certainly he built for the National Museum one of the great 

 meteorite collections of the world, probably the sixth one in numbers 

 of falls and finds. 



Meteorites, as defined by Merrill, are those " masses of metal and 

 mineral matter which come to the earth from space in the form 

 of falling bodies and which are commonly considered identical in 

 nature with the meteors, or so-called ' shooting stars,' which on 

 clear nights may often be seen darting rocket-like across the sky." 

 (191Ga: 1.) They are from regions outside our earth. "The most 

 satisfactory theory would seem to be that they are fragments of 

 comets which have gone to pieces." (1925c: 457.) A meteorite 

 " furnishes tangii)Ie testimony of the nature of materials existing 

 outside of our solar system, and affords, aside from the spectroscope, 

 the only clue to the matter of which celestial bodies are composed." 

 Truly they are chips of other worlds (Weltspiine), as the German 

 Chladni said in 1794 — " the remains of worlds gone to pieces." 

 (1916a: 13.) 



It is estimated that upward of 20,000,000 shooting stars strike 

 the earth's atmosphere daily and are burnt into gas and dust, and 

 the total weight of meteoric matter annually added to our earth 

 has been e>timated at 100,000 tons. Meteors are all small, " perhaps 

 scarcely more than a grain in weight." Even iron meteorites up to 

 20 pounds may be wholly consumed in their flight through our at- 

 mosphere. The surface of the stony meteorites, as they fall on 

 earth, consists of a black crust that is rarely more than a few milli- 

 meters thick. This crust is formed while the stone is falling through 

 the atmosphere, burning at white to blue heat, and is eroded away 

 about as fast as it is made. This black crust, according to Merrill, 

 is " a more or less perfect glass." In iron meteorites the crust is 

 thinnest, being an oxide of iron. (191Ga : 21.) 



