150 DEEP BOREHOLE SURVEYS AND PROBLEMS 



Timing 

 'Waich 



can be plotted for maximum, «m, Im and minimum a, 

 L values of angular devia- 

 tions and lengths. 



In Fig. 90 we have an 

 easy way of getting the 

 borehole inclination i at the 

 depth concerned. Con- 

 struct the triangle xyz in 

 which the angle xyz and 

 the side xy are known from 

 construction and the side xz 

 is also known, being equal to 

 the maximum length hi 

 above (previously obtained 

 by raising and lowering h 

 and plotting; to this add the 

 length of the plumb bob). 

 The angle sought is zxy = 90 

 deg. — i. Repeat this pro- 

 cedure from place to place to 

 get the amount and direction 

 of dip, the latter being more 

 satisfactorily obtained by 

 taking three such readings at 

 120 deg. apart in azimuth at 



-BaHery 

 Case 



Shell 



':jk-V.Ba fiery 

 ^^ '^(10 Used) 



Flexible 

 Bctffery Wire 



,, Refracting 

 Spring 



Universal 

 /Bearing 



Elecfromagnef 



.-Plurnb Bob 



Plunger 

 ^yConfrolled 

 hy Magne-f 



^ Pa per Disk 

 '-Cork Disk 



I ^-Tapered 

 Sfeel Nose 



YiG. 90. Fig. 91. — The driftmeter. 



each given spot and making a graphic or tabular check. 



