^j'g TOOLS OF STONE WARE. 



X)f my own discovery, or at most giving away a few specimens 

 8s files for ladies nails of peculiar delicacy : but having since 

 reflected, that in glass grnidiug (the stones for which come 

 from the North, and are very expensive) in flatting metallic 

 mirrors, laying mezzotinto grovmds, and -a number of ope- 

 rations that require unexpensive friction, these stone-ware 

 graters, if I may so call them, as not being of the exact 

 shape of files, may ultimately become very useful. I take 

 a pleasure in furnishing you. with a description. of,-sm,y; .me- 

 thod of applying this substance, accompanied with a speci- 

 men or two of a portable size, that you may the better- be 

 Sow* of their able to judge of their value to the arts, which to me, the 

 adYajitages. jj^^y^ J reflect on them seem the more important; as in all 

 operations of grinding a great deal of manual labour must 

 first be bestowed on the tool, whereas here we may mould 

 ours in an instant, if we use a press, as in pipe making, and 

 the expense is infinitely inferior to that incurred in construct- 

 ing even the cheapest file or logrator. 

 I am. Sir, 

 Your most obedient humble servant, 

 Bristol, Feb. lOihy 1S09' G. CUMBEIII.AND. 



Perhaps they P. S. I have not yet tried it, not having the means just 



might be use- ^^^ ^^ hand, but if a good parabolic reflector wereto beim- 



ed for%iecu- pressed with a mass of stone-ware clay covered with muslin, 



la»s. g0 as to.»make several casts of different degrees , of . fineness, 



we might this way acquire tools, that would greatly lessen 



the expense of the operation of grinding; but much wotild 



depend on care in baking. Our stone ware warps but little 



ever. 



ANNOTATION. 



This ingenious invention promises to be of considerable 

 use in the arts. The abraaion of surfaces is performed 

 either by a toothed tool, as in filing, rasping, &g. ; or by a 

 grinder, in which cutting or hard 'particles are bedded with , 

 , considerable firmness in a bofter mass; or by scowering, | 



polishi 



'i 



