Preface and Acknowledgments (First Edition) 



The chief object of this book is to describe the fundamental theories, 

 equipment and field techniques of the recognized exploratory geophysical 

 methods, and to illustrate their application to problems of economic 

 geology. The wide-spread use of geophysics has resulted in a voluminous 

 quantity of domestic and foreign literature, in addition to some three 

 thousand patents on geophysical methods, apparatus and allied equipment. 

 The dynamic condition of the art has necessitated continual revision of 

 the manuscript during the period of its preparation. As new and better 

 techniques became accepted by the profession, their inclusion in the text 

 relegated previously written material to a position of less importance. 

 Constant revision of the manuscript has been necessary to keep abreast 

 of developments. 



A careful attempt has been made throughout the text to give full 

 credit to the proper investigators for all original ideas and applications. 

 It often is difficult to differentiate between original developments of one 

 individual and developments that occur over a period of time, and which 

 are due to the collaboration of many workers. Especially is this true 

 in the field technique governing the application of the various exploratory 

 methods and the development of the practical equipment. 



An effort has been made to cite patent references whenever possible 

 as well as literature references, because, due to the highly competitive 

 nature of modern exploration geophysics, patent specifications oftentimes 

 tend to be more authoritative than the reports in contemporary literature. 



During final compilation of the manuscript, each chapter was sub- 

 mitted to reviewers who had extensive experience in the particular phases 

 of geophysics treated in that chapter. In practically all cases, the re- 

 viewers reworked portions of the chapter or added new material. The 

 present form of the book has been determined in large measure by the 

 criticisms and additions supplied by these collaborators. In many cases 

 where controversial views were held, all the reviewers naturally did not 

 agree as to the relative advantage or disadvantage of certain methods 

 or equipment and therefore did not subscribe to all statements of the 

 text. In such cases, the author has attempted to present both views, and 

 he must necessarily assume full responsibility for errors of omission, or 

 over emphasis, of this controversial material. 



Grateful acknowledgment is given to the various consulting geophysi- 

 cists and officials of oil companies who so generously supplied certain 

 material and assisted in the revision of the manuscript. The excellent 

 cooperation of these collaborators and critics is one of the pleasant 

 memories associated with the compilation of the text. 



