PREFACE 



A systematic treatment of the metallography of meteoric iron 

 was prompted by the author's experience in describing an iron mete- 

 orite by metallographic methods somewhat more than a decade 

 ago. He was then unable to find that any new meteorite had been 

 so described, and the literature bearing upon the subject was scanty. 

 It consisted chiefly of the writings of iron and steel technicians in 

 the books ind periodicals of that trade and a few contributions in 

 the proceedings of scientific bodies. The work done by such inves- 

 tigators upon meteoric iron being incidental to their studies of arti- 

 ficial iron and other metals, they naturally passed over many matters 

 of interest to students of meteorites as such. Also, in their inves- 

 tigation of meteoric iron they did not utilize fully the methods of 

 research that were in common use in the study of artificial metals. 



The present work aims to apply metallography, both theoretically 

 and practically, to the study of iron meteorites. To that end the 

 author has attempted to give a sufficient outline of the metallography 

 of artificial iron and its alloys to enable the reader to interpret mete- 

 oritic structures; the principal types and structural features are 

 described and illustrated; methods of research are explained; and 

 finally a somewhat comprehensive bibliography is presented. 



The illustrations have been selected from about 1,300 photomi- 

 crographs, covering more than a hundred meteoric irons. All these 

 may be consulted at the United States National Museum. The 

 author also has deposited all the negative plates in the Museum, 

 where prints from any of them may be obtained. They were made 

 mostly by graduate students in the engineering department of the 

 University of Michigan, skilled in photomicrography of artificial 

 irons, who from time to time acted as assistants in the author's 

 laboratory work. Especially noteworthy was the work of A. W. 

 Herbenar, his assistant for 2 years, not only in producing a large 

 part of the photographs but also in working out details in the tech- 

 nique of etching and in finding numerous features of interest in the 

 specimens examined. 



The author's grateful acknowledgments are due to Dr. W. F. 

 Foshag, of the United States National Museum, and to his associate, 

 E. P. Henderson, for many courtesies and the loan of numerous 

 specimens; to Dr. F. H. Pough, of the American Museum of Natural 

 History, Dr. H. W. Nichols, of the Field Museum of Natural His- 



