CORE ORIENTATION 67 



to be specially marked thus using up more time, while in 

 Gothan's method the apparatus is actually a part of the rods 

 so does not use up the time. Furthermore, it gives direction 

 and amount of deviation. 



The demerits of Gothan's apparatus lie in the uncertainty 

 of the measuring device and 



1. We do not know whether at the moment of arrest 

 the needle maintains its correct relation to the strata. 



2. We cannot guarantee no twisting of the core on 

 extraction, a tendency which increases with depth. 



3. Kicking of the core on wrenching cannot be avoided 

 and this minimizes the reliability of the result. 



4. We do not know the state of the core, whether fast or 

 loose, when the needle was arrested. 



5. Blunted core catchers cause faulty results. (For 

 success a sharply defined core is required; also the core 

 must be jerked off sharp and its lower face must be clean 

 fractured without traces of friction markings.) 



Meine's Stratameter. — Dr. Meine of Berlin invented his 

 well-known apparatus about 1902.^ He utilized a messen- 

 ger ball dropped down the drill rods instead of a clock to 

 trip a clamp for locking a compass needle on a core barrel. 



The apparatus (Fig. 34) consists of a lower part a, which 

 can be unscrewed from an upper part b, the former having 

 a bored-out portion holding a needle and arresting lever. 

 The short arm of the lever / can be depressed by a ring g 

 lifting the needle against the plate p and arresting it. In 

 the hollowed part of the lower portion the internal part c 

 of the apparatus rests on a ring of wood fiber or like 

 tightening material, and it can be screwed up tight by a 

 screw nut d. Through the center plate c goes the rod h 

 rotatable about its long axis through a stuffing box. This 

 rod has top and bottom lugs, the lower one engaging 

 with a flange of the ring g causing it to turn, while the upper 

 or eccentric lug k stands tight under the conical point of the 

 pin I. When the latter pin descends vertically the lug k 



1 British Patent No. 16,514 and German Patent No. 154,496. 



