64 DEEP BOREHOLE SURVEYS AND PROBLEMS 



Gothan's Stratameter. — This device was invented in 

 Goslar (Hartz) Germany in 1899 and is the first kind of 

 orientating apparatus in which a recording contrivance 

 is directly fitted to a rotary core barrel during coring. It 

 has been used to great depths in Germany and is attached 

 to a single-barrel core drill. It consists of an instrument 

 case attached to the top end of the barrel, the case holding 

 a magnetic compass (and in the Otto-Gothan device also a 

 plumb bob), a soft sheet and a clockwork mechanism. 

 The clock previous to lowering is set to trip at a chosen 

 time. The core is drilled and stays until the clock trips, 

 when the compass is clamped and the plumb bob dropped 

 into the soft sheet, providing an indentation on it. The 

 barrel is then withdrawn and the orientation deduced from 

 the clamped compass and position of the indentation. 

 Gothan also provided a swivel stand so that the position 

 and inclination of the core may be reproduced to visualize 

 the orientation. It has been frequently described.^ We 

 shall describe the Otto-Gothan device later on. 



In Fig. 1 (Plate IV) note that the clockwork and compass 

 are placed in a delta-metal box G which is fixed and guided 

 by a second housing Gi. The first housing is fixed to the 

 ring e screwed into the boring cylinder a. The fixing device 

 for the magnetic needle I consists of a spring n fixed in the 

 upper part of the clockwork and actuated from below 

 by the conical rod o. While the needle is free rod o bears 

 against a lug of lever p and holds its end pi away from the 

 balance q. If the pointer r is set to any chosen number, 

 on reaching this time number, spring n acts by a lug s 

 engaging in the corresponding notch so that the small 

 wheel Si connected to arm disc s raises up arm Vi. Thus 



iRedmayne, R. a. S., "Modern Practice in Mining," Vol. 1, 1925. 



Macready, S. a., Bull. Amer. Assoc. Petroleum Geol., Vol. 14, No. 5, p. 

 565, 1930. 



Freise, F., "Stratameter und Bohrlochneigungsmesse," 1906. 



Ullrich H. and Werneke, H., Mitt. Markscheiderwesen, Heft 4, p. 38, 

 1902. 



British Patent Nos. 2220, Jan. 31, 1899, and 21,183, 1901. 



U. S. Patent No. 649.636. 



