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Transactions of the Society. 



be done afc once after the knife has been shifted. The knife F 

 (fig. 3) itself is longer than the distance between the two clamps 

 H, Hi, and can be shifted lengthwise in the clamps, again increas- 

 ing the proportion of the cutting edge of the knife that can be 

 used. The knife holder can be moved so as to place the object as 

 near the knife as desired before the cutting begins. The knife can 

 also be adjusted in the knife holder. To do this the knife is 



Fig. 3. 



rotated about a line parallel to tlie cutting edge and then clamped 

 in that position. The movement is given by a double wedge 

 (fig. 4), which lifts the back of the blade at the two places where 

 it is clamped. The wedge is moved by a screw with a divided 

 head F, indicating the amount of the angular movement. The 

 best clearance angle for cutting depends on the material to be cut 

 and on the form of the cutting edge of the knife ; when this angle 



