A fine grained kind of stone, used for sharpening razors, penknives, and other cutting instruments. The exquisite edge given by cutlers to razors, lancets, etc. can rarely be produced by those persons who are not in the habit of using them. This arises partly from ignorance of the properties in which consists the difference between a good and a bad hone, and partly from a want of that skill and slight of hand in the use of a hone, which long and constant practice only can give in perfection. Mr. Fayrer, of Pentonville, has, however, constructed a novel kind of hone, by the use of which the unskilled and inexperienced operator may, without difficulty, produce a good edge. This hone consists of a plate of brass a about an inch wide, and of any convenient length, ground to a perfectly smooth surface on both sides, one of which is marked R and the other S; part of each end is cut or filed away, leaving only two pins or pivots, on which the hone turns or swings. In the frame c c are two uprights d d, with notches to receive the pivots; e e are two boxes, one to hold a coarser and the other a finer powder, made of oil-stone ground down and washed over: for the latter, finely pulverized water-of-Ayr stone may be substituted.
To use this hone, first place the side marked R uppermost, and put on it a few drops of oil and a little of the coarser powder, then draw along it in the usual manner the edge of the instrument to be sharpened. As the hone swings on two pivots, the surface necessarily applies itself quite evenly along the edge of the blade, in whatever direction the pressure of the hand is made that holds the tool; and the particles of the powder, as the operation proceeds, are continually becoming smaller and smaller, and therefore giving a finer and finer edge. To finish the setting, turn uppermost the surface of the hone marked S, apply to it oil and the finer powder, and proceed as before.