90 DEEP BOREHOLE SURVEYS AND PROBLEMS 



is caused to move up and down. The vertical travel of 

 rod 42 is controlled by a light compression spring 43 and a 

 collar 44 engaging lug 41. The attached setting rod 45 

 with a V kink 46 and angle bend stopper 47 moves also 

 vertically upward or downward, and when the V bend 46 

 encounters the detent arm it moves it out, disengaging 

 governor 23. Thus the inertia motor and associated 

 mechanism provide for starting and stopping the spring 

 motor. 



For operating the device the capsule is sunk into the hole 

 to the position shown by 7 (Fig. 1) with respect to the core 

 and when coring commences both compass and bob are 

 locked and the mechanism is in the position shown in Fig. 

 2. Owing to the inherent inertia of the motor it does 

 not turn until the rods have rotated several turns. Thus 

 lug 41 gets a planetary movement about the worm, moving 

 downward on it before the rotor starts to turn. In this 

 way rod 42 moves down the V kink 46, engages and moves 

 out detent arm 34 clear of governor 23 and the spring motor 

 operates shaft 20 through a quarter clockwise turn. Then 

 by the attached mechanism described the compass is freed 

 and the plumb bob and their locking bars held clear. 



When drilling ceases the rotation of the worm gear rela- 

 tive to the tooth 41 takes place, for then the momentum 

 of the inertia rotor 36 is such that it continues to rotate 

 after the drilling action ceases when the worm gear moves 

 tooth 41 and rod 42 upward. The mechanism may be 

 timed for 20 to 30 sec. after the drill stops, when the V 

 part of rod 45 will have moved up engaging the detent arm 

 34, allowing the spring motor to act. This action of the 

 spring motor now moves the stud 25 upward, compressing 

 spring 26 and locking the compass needle 14, and at the 

 same time the grid disc 17 locks the now quiescent plumb 

 bob in position. Thus we get the direction and amount 

 of core dip. Cover 9 is removed at the surface and the 

 inner mechanism taken out after noting the compass 

 orientation marks on the case. The spring shown dotted 

 at 48 is then rewound because it operates shaft 20. 



