CORE ORIENTATION 



61 



III). In Fig. 1 (Plate III) note that the cross-guided heavy 

 rod a is connected to the straight bit chisel ai by means of a 

 conical joint. The bit has a small recess X on one side. 

 Over the heavy rod the gun-metal body K is fixed by a 

 conical Oynhausen joint hh' (Fig. 2). The bored-out non- 

 magnetic box K encloses a watertight ground-in stopper 



r "'oi 1 



F16.6 



F10.3 



F10.5 



Plate III. — Koebrich's core orientation apparatus. 



V. Inside the cap are a clock and compass and the compass 

 is arrested by the wing F of the clock U (Figs. 3, 4) moving 

 clockwise, taking with it the lever arm h of the double- 

 armed lever 1, 2, 3, (Fig. 5). In this way end 3 of the lever 

 which is bent round engages the arresting spring / and frees 

 it. This latter springs up and clamps the needle against 

 the cover plate of the compass. A circular graduation 

 about the axis of F is arranged so that the interval between 



