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ON THE MEANS OF GIVING A FINE EDGE TO RAZORS, 

 LANCETS, AND OTHER CUTTING INSTRUMENTS. 



BY THOMAS ANDREW KNIGHT, ESQ., F.R.S., 

 President of the Horticultural Society, &c. 



TN the preparation of steel, and in the art of subsequently 

 forming it into cutting instruments, the British manufac- 

 turers are, I believe, unrivalled ; and they have probably 

 approximated, if they have not attained, perfection : but in 

 the art of giving the finest possible edge to their instruments, 

 when formed, I think that they have generally still some- 

 thing to learn ; for I hear surgeons often complaining, that 

 they rarely find themselves in possession of a perfectly well set 

 instrument ; and I have never yet, in any instance, seen a 

 razor come from a cutler so set that I could use it with any 

 degree of comfort, though I have obtained razors from many 

 of the most eminent manufacturers of the metropolis. The 

 machinery which they employ has long appeared to me to be 

 imperfect and uncertain in its mode of operating, and in many 

 respects inferior to that which I have been some years in the 

 habit of using, and which I shall proceed to describe. 



This consists of a cylindrical bar of cast steel, three inches 

 long without its handle, and about one-third of an inch in 

 diameter. It is rendered as smooth as it can readily be made 

 with sand, or, more properly, glass-paper, applied longitudi- 

 nally ; and it is then made perfectly hard. Before it is used, 

 it must be well cleaned, but not brightly polished, and its sur- 

 face must be smeared over with a mixture of oil and the char- 

 coal of wheat straw, which necessarily contains much siliceous 

 earth in a very finely reduced state. I have sometimes used 

 the charcoal of the leaves of the Elymus arenarius and other 

 marsh grasses ; and some of these may probably afford a more 

 active and (for some purposes) a better material ; but upon 

 this point I do not feel myself prepared to speak with decision. 



In setting a razor, it is my practice to bring its edge (which 

 must not have been previously rounded by the operation of a 

 strop) into contact with the surface of the bar at a greater or 



