Rock Section Cattivg Apparatus. 



the top of tlie clainp support, so as to be reino.ved and replaced at 

 will without altering its relation to the index pointer. The rod 

 is also provided with a lock nut so that perfect rif(idity can be 

 maintained during the operation of grinding. The graduation of 

 the disc is such that the rod may lie i-aised or lowered the j-^jj 

 of an inch, or any greater fraction or value up to about 2 inches. 

 One can thus successively grind away definite amounts from a 

 fossil or thick section, and reproduce, by drawings or photo 

 graphs, the varying features revealed during the operation, and 

 this without disturbing or detaching the specimen from the 

 clamp. 



