AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 27 



principle of recording the progress of the borehole is here 

 again dependent on the sinking of the rods and time. 

 The paper is turned by clockwork and the recording pen is 

 driven by the feed device. The paper roll is chosen of 

 such diameter that the clockwork rotates it on its axis once 

 in 12 hr. and 1 mm. of paper corresponds to 1 min. of time. 

 Therefore millimeter paper is chosen for the graph. The 



Fig. 6. — Foraky stratigraph. 



recording contrivance is driven from a screw spindle on 

 the rod feed in such a way that a sinking of the rods of 10 

 cm. corresponds to a progressive motion of the pen of 1 

 cm. 



The inked pen C (Fig. 6) moves ^ proportionally with the 

 descent of the rods. It is connected to the rods by the screw 

 spindle d from the feed device and by a cone- wheel trans- 

 mission gear e actuating the screw spindle /. This carries a 

 positive nut g holding the pen c. The axis of the clockwork 

 b gives the true reading and the whole is encased in the 

 casing h for protection. The apparatus is placed on a frame 

 in the boring tower but not in contact with it. It has been 

 successfully applied to depths of over 4,000 ft. 



^Gluckauf, p. 417, Mar. 18, 1911. 



