COMPASS AND PLUMB-BOB METHODS 



135 



compass housing are completely filled with warmed gela- 

 tine and then adjusted into tube A which is filled with hot 

 water to keep the gelatine fluid. Before reading, the latter 

 is again taken out. The protection tube A' is screwed over 

 tube A and the apparatus sent into the hole. The counter- 

 balance sectors always permit a rotation of the internal 



Figs. 81 and 82. — Bawden's apparatus. 



tube in such a manner that the pendulum can always play 

 free. On the gelatine solidifying the pendulum and the 

 needle are fixed in their positions of rest and these are read 

 aboveground. 



The apparatus of Bawden utilizes the principle of Mac- 

 George's device as also does that of Cross, ^ which latter 

 therefore need not be mentioned here. The Bawden 



1 Denny, C, "Diamond Drilling," pp. 76 et seq., Crosby Lockwood. 



