88 DEEP BOREHOLE SURVEYS AND PROBLEMS 



are controlled by the inertia of a heavy rotating mass the 

 rotational speed of which does not coincide with that of 

 the rods, the resulting momentum difference being har- 

 nessed. Figure 1 (Plate VI) shows ^ the position of the 

 apparatus capsule 7 relative to the boring bit 2 the core 6 

 and the rod string 4. It is filled with a non-corrosive liquid 

 like petroleum to counteract pressure. Figure 2 is an 

 enlarged view of the mechanism with Figs. 3 and 4 cross- 

 sectional views of the same on lines 3, 3 and 4, 4, respectively. 



The compass needle is automatically locked at a pre- 

 determined time after drilling ceases, and before breaking 

 off the core, as also is the plumb bob, thus giving direction 

 and amount of dip. 



The capsule 7 (Fig. 1) is made of non-magnetic material 

 as also is the portion of rod string near it, and it is supported 

 by fasteners 8 (Fig. 2) to the inner surface of the rod string. 

 It has a removable cap 9, for access and inspection, and an 

 eye suspension ring 10. The compass 11 may be either 

 of the magnetic type (as here) or gyroscopic, and from it 

 hangs the plumb bob 12. The compass needle 14 is held 

 by a locking rod 15 passing through the compass case 

 16 while the plumb bob can be locked by the reticulated disc 

 or wire screen 17 engaging its pointed end 13. 



The locking mechanism for compass and bob is a spring 

 motor 18 on frame 19 inside the capsule. The spring-driven 

 shaft 20 of this motor is connected to a train of gears 22 

 (Fig. 3) with a fan-type governor 23, and a double-cam 

 24 provides the vertical reciprocation of the compass 

 locking rod 15. The plumb bob locking member 17 is also 

 mounted on compass-locking rod 15 by set screws 28 and 

 both locking devices are arranged so as only to move freely 

 vertically. The ratchet wheel 31 and its pawl 32 on shaft 

 20 are the starting and stopping mechanism operating 

 through the arm 34 and spring 35. The most ingenious 

 part of the apparatus is the means for automatically 

 starting and stopping the spring motor at the proper time 

 with relation to the drilling operation. For this purpose 



1 U. S. Patent No. 1,665,058, Apr. 3, 1928. 



