428 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



and lends itself to the economical treatment of valuable material. 

 The machine (fig. 64) is driven by a motor of about ^-^ h.p. at 2000 

 revolutions per minute. The vertical cutting disk is made of soft sheet 



CD 



6 



iron and is attached to a horizontal axis journalled in a small mclmed 

 shaft. The diameter of this disk is about 70 mm. ; its thickness about ' 3 

 The compound holder for receiving the rock specimen is fitted 



mm. 



on to a spindle which is parallel to the cutter-shaft, and is held up to 



