Knives 



PARAFFIN SECTIONS 



111 



it be a water stone, to be lubricated witli 

 soap and water like the yellow Belf^ian 

 stones commonly emjjloyed in l']uro[)e, or 

 an oilstone, to he lubricated with mineral 

 oil like the pike stones so commonly eni- 

 ployed in the United States. It does mat- 

 ter, however, that it should be flooded 

 with lubricant before staitinj;-, and that 

 the knife should be drawn with a lij;lit 

 pressure (notice that tlie fiii,<;er is behind 

 and t}ot on top of the knife in the illustra- 

 tion) the entire length of the stone at each 



itself. If the knife-edge is nicked to a 

 deeper extent than about a quarter of a 

 millimeter, the only thing to do is either 

 to return the knife to the maiuifacturer 

 to l)e reground, or try to avoid that por- 

 tion of the blade containing the nick when 

 cutting sections. It must be emphasized 

 that the only {purpose of setting is to pro- 

 duce a cutting facet, and that grinding, 

 which cannot be done in the ordinary 

 laboratory, is required for the removal of 

 knife impeifections. 



Fig. 62. Setting the cutting facet. 



operation. If onlj- the central portion of 

 the stone is used, it soon becomes hol- 

 lowed out and it thus becomes impossible 

 to maintain a uniform angle. About three 

 strokes on each side of the knife are quite 

 enough to produce a perfectly sharp cut- 

 ting facet; to continue beyond three 

 strokes will have no effect other than to 

 diminish the length of life of the knife. 



This direction for the use of three 

 strokes in setting applies, of course, only 

 to knives which have been reasonably 

 treated and not to those which through 

 carelessness have acquired a nick in their 

 edge. Where the nick is large it is almost 

 impossible to remove it in setting, for the 

 continual repetition of setting merely 

 grinds away the edge of the knife and 

 ultimately alters the thickness of the blade 



The next question to arise is that of 

 stropping the blade of the knife by pulhng 

 it backward across a leather surface in the 

 manner shown in Fig. 63. If the knife has 

 been set properly, stropping (the only pur- 

 pose of which is to poUsh the facet) is quite 

 unnecessary. The nature of the leather 

 surface which is used for stropping makes 

 it obviously impossible to pull the knife 

 blade forward and thei-e is a grave risk in 

 pulhng it backward, lest the facet, instead 

 of becoming polished on its flat surfaces, 

 will become rounded on its edges, and thus 

 the work of setting be undone. Certainly 

 no beginner should be permitted to use a 

 strop until he has demonstrated his ability 

 to set a knife-edge to tiie point where it 

 will cut an excellent section without strop- 

 ping. It is also strongly recommended to 



