110 



THE ART OF MAKING MICROSCOPE SLIDES 



Knives 



CUTTING >i 



FACET 



BLADE 



Fig. 58 



Fig. 59 



CUTTING TIP 



CLEARANCE 

 ANGLE 



KNIFE 

 ANGLE 



BLOCK 



Fig. 61 

 Fig. 58. Knife ground as simple wedge without cutting facet. 

 Fig. 59. Flat ground knife showing cutting facet. 

 Fig. 60. Hollow ground knife showing cutting facet. 

 Fig. 61. Cutting action of knife on wax block. 



shows it at the beginning of the stroke) the 

 cutting facet is produced as the angle 

 between the cutting edge lying on the 

 stone and the enlarged temporarj' back 

 which has been placed on the knife. Since 

 a much blunter cutting facet is required 

 for hard materials than for soft, it is 

 strongly to be recommended that either 



two knives, or at least two sharpening 

 backs, be secured. It does not matter what 

 kind of stone is used for sharpening pro- 

 vided that it is of the finest obtainable 

 grit, that it is dead fiat, and that under no 

 circumstancs wliatever is it used for any 

 purpose except the sharpening of micro- 

 tome knives. It does not matter whether 



