68 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



is pushed aside, so that the rod h turns and with it the ring 

 g to arrest the needle /. 



The descent of the pin I cannot be directly effected by 

 the rinsing water, but when the lead ball n is dropped 

 in the rods it deflects the current and its surface is sufficient 

 to considerably hinder its momentum. When ball n meets 

 the pin I the obstructed current throws a back pressure 



Fig. 34. — Heine's stratameter (origi- Fig. 35. — Heine's stratameter (modi- 

 nalform). fied form). 



on the rinsing pump manometer. Thus the ball with the 

 water presses down pin I through its friction socket to 

 actuate eccentric k on rod h and so arrest the needle. 

 This instant of arrest can be read on the pump manometer 

 by a visible back kick of the indicator, because then the 

 water gets a freer passage through the channel o to the floor 

 of the borehole. The whole process lasts only a few 

 minutes. Now the rods including the stratameter, core 

 barrel and core are lifted out and the north direction 

 of the needle transferred to the core. 



The above apparatus has a whole series of structural 

 modifications, as for instance in Fig. 35. Here the arresting 



