27^ IMPROTED MUFFLES. 



Description of farthest side are only shown, and in which frame the tin 

 the method of i i /• , • t i • i . . i i •■ • 



jnakiee the - "lould, ng. 1, is placed, simply constructed by jommg two 



muffles, pieces of wood, the one as broad as the bottom of the mutile 



mould, and having two narrow grooves (e e), cut in it, so that 



the edges of the tin mould may be confined therein. Th« 



•«' other board, being joined to this at its edge, should come up 



»o high asjust to be under the edge of the mould. 



The sixth is the tool for cutting the muffles of different 

 lengths (fig. 7)> find is made of a piece of wood, to the end of 

 which is fixed a thin piece of brass {f), which, extending 

 about one inch and a quarter beyond the top of the wood, is 

 bent at right angles, and made thinner at the end, that it may 

 the more conveniently cut the muffle. Under this piece of 

 wood is used another straight piece (^), with two steady pins, 

 ■which, being shifted at the will of the workman, will cut them 

 of any length. 



The seventh ia the mould for formiijg the bottom of th» 

 close muffle (fig. 8), which is made of a mahogany or oak 

 plank, about sixteen inches long, ten wide, and about three 

 eighths of an inch thick; upon tliis is fixed a ledge on each 

 side, one inch broad, and nearly half an inch tliick, and at 

 each end a ledge of the same kind is placed, at such a distance 

 as is best suited to the length of the bottom required. Fig. 9 

 and 10, are circular moulds for muffle bottoms of dial plates. 

 Fig. 11, a complete muffle standing on its bottom. Fig. 12, a 

 roller for rolling the composition in the first mould. Fig. J 3, 

 a tool for making small holes in the muffle. 



The usual composition for making muffles is as follows: viz. 

 two parts pipe clay and one part sand, such as is used by th« 

 bjicklaycrs, sifted, and mixed together to a proper consist- 

 ence; this is very expensive, on account of I he high price of 

 pipe clay, which is about-ten shillings the hundred weight, 

 whereas ! employ in my improved mode of making them the 

 coarser kind of Stourbridge clay, which can be had at the 

 glass-houses, in the ground state, for six shillings the hundred 

 weight; and this I sift also, to separate the finer part, which f 

 fmploy for making other smaller articles necessary in my bu- 

 siness; using o-hly the grosser or coarser part for miiffles, to 

 which I add one eighth part only of pipe clay, mixing thein 



well 



