ACKNOWLEDGMENTS 



It IS A PLEASURE to acknowledge the assistance of a number of individuals 

 and organizations. Professor Perry Byeriy reviewed the entire manu- 

 script; Doctor M. M. Slotnick and Mr. H. Guyod read several chapters 

 and made valuable suggestions. Dr. R. F. Aldredge contributed diagrams 

 on curved-ray interpretation; Mr. Charles Erdmann supplied values of 

 rock resistivities for Colorado, Wyoming, and Montana; and Mr. Dart 

 Wantland supervised compilations of densities, and magnetic and elastic 

 rock properties by students of the Colorado School of Mines. Permission 

 to use material from their publications was granted by the American 

 Institute of Mining- and Metallurgical Engineers, the Akademische Ver- 

 lagsgesellschaft, the American Petroleum Institute, the American Asso- 

 ciation of Petroleum Geologists, the Society of Exploration Geophysicists, 

 and a number of other institutions and publishing houses. Specific 

 reference to source for such illustrations will be found in footnote references 

 in the text. 



A number of illustrations are reproduced by courtesy of the following 

 companies and institutions : 



American Askania Corporation 



Cambridge Instrument Company 



Colorado School of Mines 



Geo. E. Failing Supply Company 



Heiland Research Corporation 



Harvey Radio Laboratories, Inc. 



James G. Biddle Company 



Seismos Company 



Texas Body and Trailer Company 



U. S. Bureau of Mines 



U. S. Bureau of Standards 



U. S. Coast and Geodetic Survey 



U. S. Geological Survey 

 Messrs. M. P. Capp and A. N. McDowell made most of the line drawings, 

 and Miss Johanna Lyon assisted in the preparation and indexing of the 

 manuscript. 



C. A. H. 



