lU 



THE ART OF MAKING MICROSCOPE SLIDES 



Cutting 



discover whether or not the edges are 

 parallel by lowering the V)lock until it does 

 not quite touch the edge of the knife, ad- 

 justing it until the lower edge is parallel, 

 then lowering the block again and com- 

 paring the relation of the upper edge with 

 the edge of the knife. 



Cutting Paraffin Ribbons 



Tlie first step in cutting sections on this 

 type of microtome is to make sure that 



causes the two movable holding arms to 

 hold the knife near its edge. The knife is 

 now held in a pair of hemicyhnders which 

 may be moved so as to adjust the knife 

 angle (see Fig. 61). The knife should be 

 set at that angle which experience has 

 shown to be desirable — no guide other 

 than experience can be used — and the two 

 setscrews which lock these inclinable hemi- 

 cyhnders in place then tightened. The two 

 original setscrews, which hold the knife in 



Fig. 65. Starting the paraffin ribbon. 



every one of the setscrews seen in Fig. 65 

 is fully tight. The setscrews holding the 

 block holder may be tightened in any or- 

 der, provided that the result leaves the 

 block correctly orientated, l)ut those con- 

 nected with the knife must be done in the 

 correct order. First the knife is inserted 

 into the holder and fixed firmly, but not 

 tightly, in place by the two bearings at 

 each end. The tightening of these screws 



place, are now screwed up as tightly as 

 the thumb can bear. This leaves two set- 

 screws which come through the inclinable 

 hemicyhnders and bear on the bottom 

 edge of the knife. These two setscrews 

 should then be tightened simultaneously 

 and uniformly. The effect of this is to force 

 the knife upward and thus wedge it with 

 extreme firmness in the knife holder. 

 Now that everything is tight the handle 



