142 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



some deep freezing shafts. Here contracts frequently 

 stipulate a survey capable of registering a deviation of 1 

 in 200 or 1 off the vertical in every 200 deep. The normal 

 range of this device is about 2 deg. from the vertical. 



It makes and maintains claims to simplicity, cheapness, 

 lightness, rapidity and ability to survey narrow deep holes, 

 giving a continuous record of amount and direction of dip. 

 It was successfully employed at Seaham Colliery Sinkings. 

 We are indebted to Professor Briggs for the following details 

 and personal notes. 



The Transmitter and Receiver. — The transmitter is hung 

 in the hole on the rods and the receiver is situated near the 

 mouth of the hole, the two electrically connected with a 

 flexible five-strand cable. 



Fig. 84. — Clinophone receiver. 



The transmitter^ has a plumb B (Plate IX) hung on a 

 "G" violin string A connected to needle H through the 

 wire wrapping of the string. The needle dips into a solu- 

 tion (NaS04) F in the vulcanite cup E which has four 

 platinum foil electrodes eNes, es and ew, 90 deg. apart (Fig. 

 8, Plate IX) each reaching to the cup base. These connect 

 respectively to the rods Dn,De,Ds and Dw insulated from 



1 See also Brydon, A. D., Trans. Inst. Min. Engr., Vol. 71, p. 431; Briggs, 

 H., Proc. Roy. Soc, Vol. 46, p. 223, Edinburgh, 1926. 



