METEORITES OF NORTH AMERICA. 463 



through the efforts of Irwin and the brothers Ainsa. Irwin 12 , who had come into posses- 

 sion of the mass in 1857, while it lay uncovered in a street of Tucson, gave as the place of 

 discovery, in accordance with the statement of the natives, the Santa Catarina Mountains. It 

 was asserted that about 200 years before a fall of meteorites had taken place there and large 

 masses of iron had been left by it. According to a brief notice by Santiago Ainsa, 12 the iron 

 was long known to the Jesuits. He stated that in 1735 his great grandfather, Juan Baptista 

 Ainsa, had visited the place of its discovery, Los Muchadios, in the Sierra de la Madera, with 

 the view of transporting it to Spain. The mass was then brought to the garrison in the neigh- 

 borhood of Tucson, and later into the city itself, where, for lack of means of transportation, it 

 remained. 



Henry, 13 the Secretary of the Smithsonian Institution, collected these reports in 1863, 

 whereby he, in consequence of an error, changed the locality to Los Muchachos, in the Sierra 

 Madre Mountains. He designated the block as the Ainsa meteorite; but in 1865 16 he stated 

 that in future it should bear the label, "Irwin-Ainsa Meteorite." 



The kidney-shaped mass was taken possession of and sent to San Francisco in the year 1862 

 by Gen. James H. Carleton, who was in command of the column from California. He presented 

 the mass to the city of San Francisco as a memento of the march of his column, and asked that 

 it might be "placed upon the plaza, there to remain for the inspection of the people and for 

 examination by the youth of the city forever." It was, however, deemed advisable to keep the 

 specimen in a safer and drier place and it was, accordingly, removed to the museum of the Society 

 of California Pioneers. This building was destroyed by the earthquake of 1906 and the meteorite 

 found in the ruins. It was then removed to the Museum of the State Mining Bureau. 



The shape and dimensions of this mass as given by Whitney " were as follows : 



Shape irregular, but in general that of a flattened elongated slab; length, 49 inches; average breadth, 18 inches; 

 thickness varying from 2 to 5 inches. Weight, 632 pounds. 



The dimensions of the ring-shaped mass were given by Whitney " as follows: 



Greatest exterior diameter 49 inches 



Least exterior diameter 38 inches 



Greatest width of central opening 26. 5 inches 



Least width of central opening 23 inches 



Greatest thickness at right angles to plane of ring 10 inches 



Width of thickest part of ring 17. 5 inches 



Width of narrowest part 2. 75 inches 



Weight estimated by Ainsa as 1, 600 pounds 



An inscription on the specimen now gives the weight as 1, 400 pounds. 



Whitney u indicated the Sierra de la Santa Catarina as the locality of the Tucson-Iron and 

 left it undetermined whether this was the same mountain range which Velasco had called the 

 Sierra de la Madera. 



The statements regarding Tucson, made at different times by Meunier 17, 24 have very little 

 agreement one with another. In 1869 17 he gave the specific gravity of the olivine as 3.35 and 

 classed the iron among those which yield distinct Widmannstatten figures; in 1873 19 he pro- 

 nounced Tucson a mixture of tsenite and nickel-free iron; in 1884 20 he repeated the statement 

 with regard to the action of etching, in one place, while in another place he declares that no figures 

 are produced by the acid; in 1S93 2i he stated that Tucson consists of a distinct alloy of nickel- 

 iron, Tucsonine, with more than 10 per cent of nickel; the structure he said was octahedral, but 

 the iron yielded no figures with acid. 



In 1870 Haidinger 18 assumed a vein-origin formation for the Carleton-Tucson meteorite. 

 For the ring-shaped Ainsa-Tucson he assumed the perforation of a flat iron mass rotating in the 

 direction of its greatest breadth by the action of atmospheric resistance. Through stability of 

 rotation, he thought a ring would form; if this continued longer a disruption would occur and 

 fragments somewhat of the form of Hraschina would result. 



Wads worth 21 included Tucson among the pallasites. According to him the silicates are 

 arranged in the ring-shaped mass approximately in regular rows, whereby a certain similarity 



