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THE AMERICAN MUSEUM JOURNAL 



is surrounded by an upcast ridge from 

 one hundred and fifty to two hundred 

 feet above the surrounding plain, and 

 fragments of meteoric iron are numer- 

 ous in the slopes of this ridge and on 

 the plain outside. At some time in the 

 past a huge meteoric mass fell and ex- 

 cavated this enormous hole. 



The similarity of form and propor- 

 tions between the Arizona Meteor 

 Crater and lunar craters is very strik- 

 ing and is strongly suggestive of the 



idea that the craters on the moon are 

 the unobliterated records of innumera- 

 ble giant impacts of meteoric masses; 

 unobliterated because, though formed 

 millions, if not billions, of years ago, 

 the moon's surface is not subject to ero- 

 sion, as the moon has no atmosphere — 

 it never had an atmosphere, being too 

 small to retain one. Consequently it 

 preserves a record of all that has hap- 

 pened to scar it during countless ages 

 of past time. 



COLLECTIONS OF METEORITES IX THE AMERICAN MUSEUM 



The collection of meteorites in the Amer- 

 ican Museum is large and varied, and exhib- 

 its in a considerable number of specimens 

 various features of which Dr. Thomson 

 speaks in his paper. 



In one of the alcove windows on the east 

 side of the hall of geology and invertebrate 

 paliEontology of the Museum, there are a 

 number of transparencies taken from photo- 

 graphs of meteors in flight. These were 

 made by Dr. E. E. Barnard at the Yerkes 

 Observatory, Williams Bay, Wisconsin. 

 The meteors are represented by long white 



streaks of light. In looking at these par- 

 ticular photographs one should not lose 

 sight of the fact that the meteor trail is 

 within our atmosphere .and that the multi- 

 tudes of stars which are also in evidence are 

 millions upon millions of miles away. It is 

 also interesting to note that the light 

 streaks are not of a uniform width through- 

 out. Instead of being spindle-shaped in 

 outline as we might at first suppose, they are 

 more like a series of elongated spindles or 

 darts joined by attenuated bands of light. 

 Does this imply that the elements of the air 



The iron meteorite has a very thin black crust, of metallic luster. The texture within remains un- 

 altered by the fiery journey through the sky. On some iron meteorites peculiar crosslines, "Widman- 

 statten lines," may be etched with a weak solution of nitric acid 



