254 Modern Microscopy 



used when the bevel forming the edge of the knife becomes 

 rounded from continual stropping, or when the edge is 

 notched or turned. A little experience will quickly teach 

 the microtomist when to bring the hone into use. The 

 utmost care should be taken of the hone ; none but the 

 microtome knives should ever be applied to it. After use 

 it should be carefully cleaned and dried, wrapped up, and 

 put away in a box. If oil is used as a lubricant, it should 

 never be allowed to remain on the hone after use, as it has 

 a hardening effect, and in course of time will render the 

 stone too hard for our special purpose. 



These minutise may appear superfluous to the uninitiated, 

 but it is only by adherence to them that success will attend 

 their efforts. Should the knife be notched, it will require 

 a considerable expenditure of time to restore its edge ; but 

 in the ordinary course of setting the bevel, which forms the 

 edge, the process is not lengthy. 



Having the knife-guide adjusted upon the back of the 

 blade, it may be mentioned that a notch made at one 

 end of the knife-guide will enable it to be always put 

 on the knife one way, thus maintaining its relationship to 

 the bevel of the knife-edge. Having also the hone pre- 

 pared with its lubricant, lay the knife, concave side down- 

 wards, diagonally upon the left-hand side of the hone, and 

 draw it edge forwards and from heel to point along the 

 hone to the right-hand side. Do not draw the knife along 

 the hone in such a manner that its point inscribes an arc, 

 but in such a way that its point will inscribe a straight 

 line. Do not turn the knife as in razor honing, but repeat 

 the above process continuously i.e., continue to draw the 

 knife from left to right upon the hone, not allowing it 

 to touch the hone from right to left. After a number of 

 strokes in this manner, say fifty to one hundred for re- 

 setting, but several hundred if a notch is to be removed, 

 carefully dry the knife and examine its edge with a micro- 

 scope magnifying about 70 diameters, when a slight fringe 

 or jaggedness will be observed projecting from the edge of 



