496 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vol. 50 



meteoric showers, and, in addition, no gradation in size along the 

 supposed line of flight, nor evidence of atmospheric friction upon 

 their surfaces — favors the idea that all were thrown out, and it is 

 not impossible that practically the entire mass not dissipated by 

 volatilization was thus ejected. It should be remarked, in this con- 

 nection, that a most liberal estimate of the material carried away 

 by collectors or still remaining as shale on the plain would scarcely 

 account for a thousandth part of a mass sufficient to form the crater. 



The failure thus far to find a large intact mass within the crater 

 might be further explained on the ground that a considerable portion 

 of it was volatilized by the intense heat generated at the moment of 

 striking the surface, and the comparatively small residual remaining 

 has largely succumbed to oxidation. It must be remembered, how- 

 ever, that the method of borings, whereby the materials are brought 

 to the surface by a stream of water forced downward through the 

 drill-pipe is such as to practically preclude the securing of particles 

 of metallic iron of any but the smallest sizes. Even if permitted 

 by the dimensions of the hole, their high specific gravity would cause 

 them to be left behind, and only the lighter sand grains and more 

 minute particles would be brought to the surface. 



The work thus far done does not, therefore, disprove the presence 

 of a large quantity of fragmental iron, although tending to show that 

 no large mass lies there buried. It is possible, too, that the esti- 

 mated size of the body making the crater is an exaggeration, since 

 if, as seems probable, volatilization of a considerable portion fol- 

 lowed immediately upon striking the ground, the outrush of vapor 

 due to the enormous expansion in passing from the solid to the 

 gaseous condition would certainly have served to tear away the rock 

 and increase the diameter to an extent that we have no means of 

 estimating. 



Acknowledgments 



This investigation detailed above has been rendered possible only 

 through the generous and hearty cooperation of Messrs. Barringer 

 and Tilghman, to whom reference has been made so repeatedly 

 that further allusion seems almost superfluous. To Mr. G. K. 

 Gilbert the writer is also indebted for notes, maps, and other materials 

 collected at the time of his studies. To the U. S. Geological Survey 

 he is indebted for prints from Mr. Gilbert's negatives, for a re- 

 drawing of the contour map, and for the photomicrographs repro- 

 duced in plate lxx. Mr. Holsinger, manager at the crater, has 

 kindly forwarded material as requested and furnished photographs 



