CORE ORIENTATION 



81 



tions. It consists essentially of a tube which can be 

 fitted over the core stub, the tube containing a hemispheri- 

 cal pendulum and clockwork arresting device adjustable to 

 a predetermined instant.^ 



In Fig. 43 the hollow cylinder h is shown in the borehole 

 a, its prolonged lower part being capable of fitting over the 

 core stub with a scratching tooth of steel or diamond for 



Fig. 43. — Goodman's apparatus. 



scribing the same. The hollow pendulum c bearing on 

 pivot d on the circular base e is graduated externally on its 

 rim Ci and has an agate bearing i for the pivot. The cone 

 ends in a short screwed stem g, and a magnet h rests on it. 

 The hemispherical screwed cap nut k holds stem g, securing 

 the needle h to the top of the cone c. The base plate e is 

 borne on a flange of cylinder h and is framed to the upper 

 clockwork base plate I by pillars m. On top of nut k a small 

 plunger n is provided axially central passing through the 



1 See also British Patent No. 23,003, Apr. 29, 1909. 



