CORE ORIENTATION 



77 



tional planes. In each of these, under the pressure of a 

 spring, is a movable piston g on rods h carrying on their 

 exterior ends hinged movable porcelain heads k. If the 

 rod is moved outward by internal pressure these heads 

 take a mold of the borehole walls. A compass n whose 

 needle m is arrestable by the lever o actuated by the spring 

 p is used for taking the strata strike. There is a piston con- 

 nected to which, as a result of the pressure of spring p, can 



■^ 



Fig. 41. — Rapoport's device. 



close a duct leading to the channel h. The piston is pressed 

 up when a means of pressure appears in 6 and the needle is 

 freed to take up its position. If before raising the appa- 

 ratus out of the hole the pressure channel is closed, the 

 piston g goes in first and then q is brought by the spring 

 p to the original position, thus again locking the needle. 



Obviously very hard strata, and very friable strata too, 

 make the application of the device, in its present form, 

 useless ; but, as said, we present the apparatus for its possi- 

 ble use under suitable modifications. 



Florin's Method. — This ingenious apparatus was in- 

 vented by a chemist, Jean Florin, of Brussels in 1908^ and 



1 Florin, J., Enregistrer rorientation des strates au fond des trous de 

 sondage, Annates des mines de Belgique, Tome 13, p. 781, 1908. 



