l64 PHILOSOPHICAL TRANSACTIONS. [aNNO 1777. 



ofF every quarter of a minute with a great deal of water. By a repetition of 

 this 2 or 3 times, the hones (being of a very soft and friable substance) will be 

 cut down to the figure, without wearing or altering the bruiser at all. Though 

 this business may be quickly done, and can be continued but for a few strokes at 

 a time, I need not say that it is necessary that those strokes be carried in the 

 same direction, and with the same care, which was observed in grinding the 

 former tools together. As soon as the hones have received the general figure of 

 the bruiser, and all the turning strokes are worn out from them, the emery 

 must be carefully washed off; in order to which, it will be necessary to clear it 

 from the joints with a brush under a stream of water. The bruiser and metal 

 must also be cleared in the same manner, and with equal care, from any lurk- 

 ing particles of emery. 



The hones being fixed down to the block, you now begin to work the bruiser 

 on them with very cautious, regular, short strokes, forward and backward, to 

 the right and left, turning the axis of the bruiser in the hand while you move 

 round the hones, by shifting your position, and walking round the block. 

 Indeed the whole now depends on a knack in working, which should be conducted 

 nearly in the following manner. Having placed the bruiser on the centre of the 

 hones, slide it in an equable manner forward and backward, with a stroke or two 

 directly across the diameter, a little on one side, and so on the other; then 

 shifting your position an 8th part round the block, and having turned the bruiser 

 in your hand about as much, give it a stroke or two round and round, but not 

 far over the edges of the hones, and then repeat the cross strokes as before: 

 those round strokes (which ought not to be above 2 or 3 at most) are given every 

 time you shift your own position and that of the metals, previous to the cross 

 ones, in order to take out any stripes either in the hones or bruiser, which may 

 be supposed to be occasioned, by the straight cross strokes. During the time 

 of working, no mud must be suffered to collect on the hone, so as to destroy 

 the perfect contact between the two tools; and therefore they must every now 

 and then be washed clean by throwing some water on them. When by working 

 in this manner all the emery strokes are ground ofl' from the bruiser, and it 

 has acquired a good figure and clean surface, you may then begin with the metal 

 on the hones, in the same cautious manner, washing off the mud as fast as it 

 collects, though that will be much less now than when the bruiser was ground 

 on them. Every now and then however the bruiser irmst be rubbed gently and 

 lightly on the hones, which will as it were, by sharpening them and preventing 

 too great smoothness, occasion them to cut the metal much faster. 



When, after having some time cautiously wrought in the manner before 

 described, the hone-pavement has uniformly taken out all the emery strokes, 

 and given a fine face and true figure to the metal, which will be pretty welj 



