ART OF SHAVINC?. 4-9 



in the edge ,• 2. That the edge fliould be tried upon the haridf 

 after every two or more ftrokes, in order to afcertain the in- 

 ftant at which it ftiall have become very uniformly rough. This 

 roughnefs, if the hone be good, and the prefiure light, will 

 conftitute a very fine edge, though in general lefs fmooth than 

 is left by a good (trap; and 3. The edge will therefore be 

 completed by a ftroke or two upon fuch a furface. But I will 

 fuppofe that a longer continuance of whetting has been ne- 

 cefTary, fb as to produce what is called a wire/ confl fling of a Wire upon the 

 very thin film of fteel adhering along the edge. If this fliould edge » 

 break off upon the hone during the whetting, the edge will 

 become notched in paffing over it ; for which reafon it muft. 

 be taken off by a direct operation ; namely, by paffing the Taken off.- 

 edge of the razor once along the hone, holding the back ra- 

 ther more upright than half way between the flat and the per- 

 pendicular polition, and then paffing it once back again, in- 

 clining the razor the contrary way. Thefe two ftrokes wiH 

 detach the wire, and produce a very perfect, though very ob- 

 tufe edge ; which muft then be brought up to the requiftte 

 keennefs by two or more light ftrokes in the firft mentioned 

 method, taking care not to go too far. In both the proceffes 

 of (trapping and whetting, we have iuppoled the razor to be 

 laid flat ; but where a ftrong edge is required, the whetting, 

 but not the ftrapping, may be performed with the back of the 

 razor elevated fomewhat lefs above the face of the hone, than 

 half the breadth of the blade. 



Our cutting inftrument being now in order, there remains Enquiry now fa 



but one more obfervation before we proceed to the fubject of , heat,n B a rzzoi 



i • i • i • mi t r i o ^iii »n Water is ad- 



operation ; which is, that it will be lound to act coimderably vantageoua. 



better after immerfion in hot water. While I admit the fact, 

 I muft confefs that I am far from being fatisfied with any of 

 the explanations. It has been faid, that the expanfion by heat By improving 

 enlarges the fine notches of the edge, and probably developes tne &*& > 

 or opens others ; but this effect can hardly be thought of any 

 confequence, when it is confidered that the whole expanfion 

 produced by boiling water does not exceed one part in ten 

 thoufand. Others have remarked, that as heat foftens horn, Or by foftening 

 hair, and other fimilar fubftances, the hot edge may pafs tnenair 3 

 through a hair more eafily than if cold ; but here we may re- 

 mark, that the heat feems too little, and its application to the 

 hair too momentary, to be productive of lb confiderable a 

 V$L*iL — January. E difference; 



