PREFACE 



The amount of trouble, litigation and random specula- 

 tion that could be avoided by a correct knowledge of the 

 course of deep boreholes is immeasurably great. It is 

 generally agreed among those most concerned that the 

 deep borehole which does not deviate from its intended 

 direction has yet to be bored. Bearing these significant 

 facts in mind I have attempted in the following pages to 

 trace the evolution of modern borehole-surveying devices 

 and add various problems relevant to strata location and 

 orientation. 



Since most of the world's deep borehole projects are 

 outside the British Empire I have supplemented my 

 experience and observations by information from many 

 and varied sources. In this respect I have been most 

 generously aided by many workers in America, Germany, 

 Russia and elsewhere, and I hope these are all sufficiently 

 acknowledged where the respective transcriptions appear 

 in the text. In particular I am indebted to the several 

 acute and vigorous bodies of oil-field investigators centered 

 about Oklahoma and the Gulf Coast in America and the 

 Rumanian societies on this side. Some methods of bore- 

 hole exploration have not been dealt with here either 

 because they are shrouded in commercial secrecy or because 

 they do not appear to add very materially to the advance- 

 ment of the art. 



Generally speaking the present geological engineer does 

 not seem to be enamored of the highly ingenious and exact 

 suite of post-war instruments, being in many cases content 

 to sacrifice precision to rapidity, ease and cheapness. For 

 these reasons the old and tried acid-bottle and similar fluid 

 methods still hold the field in point of numbers, though 

 the gyrocompass and multiple photographic methods 



