54^ Account of the Duration of Wood •woriitig agahijl Iran^ 



V. 



On the Glajs Trundles of Gtizett RenAUT ; and the Duration of the Teeth of Jlliil-work. 



By C. B. 



I 



To Mr. NICHOLSON. 

 SIR, 



OBSERVE in your Journal for January laft, an account of Citizen Molard's having fubfti- 

 tuted glafs in the place of iron for the trundles of lantern pinions, which he ftates to be much 

 preferable to the latter ; as he fays, caft-iron wears out the wooden teeth they a£t againft in 

 about four months ; whereas, the glafs, in the experiment he made, wore tlie wooden 

 teeth about one-twelfth of an inch only in eighteen months. 



The ufe of glafs, in the trundles of lantern pinions, is liable to many objeftions ; 

 experience, however, may point out methods of obviating many of thefe : but I think 

 it right to mention, that Citizen Molard is extremely wrong, when he fays, caft-iron 

 wears out the wooden teeth in four months ; if it does fo in France, it is otherwife ia 

 this country: I have had a mill of my own at work for thefe four years, in which 

 wooden teeth aft againft iron, and I have never been obliged to get fo much as a 

 new tooth. Some months fince I favr a fteam engine, at Meff. Fifli and Yates', in 

 St. John-ftreet, which turns machinery for his grinding of fnufF and cutting tobacco. 

 This machine was ereded by Mr. Rennie, engineer of this city, in the year 1786, 

 4nd has been conftantly at work for about fifteen hours per day ever fmce; yet the 

 wooden teeth, in the firft motion, which a£t on caft-iron, had not worn above one-fixth of 

 an inch; and the iron teeth did not feem to be worn y, part of an inch: and from 

 every appearance, they will work without repair for ten or twelve years to come ; as 

 the workmen told me, that they had not, apparently, worn any thing for thefe fix years 

 paft. They appeared to be very well executed; but not better than Mr. Rennie ge- 

 nerally does fuch work. 



By publifhing the above, you may, perhaps, prevent an ill-founded prejudice from 

 being taken againft the ufe of caft-iron, in mill-work; which, from experience, I can 

 fay, is the beft material I have known to be ufed. 



I am, Sir, 



Your moft humble fen-ant, 

 Fd). 4th, 1799. C. B. 



I have vifited the manufaflory of Meff. Fi(h and Yates', and find that the ftatement 

 given above is perfeftly correal. It may be prefumed, that the iron trundles, men- 

 tuned by Citizen Renaut, at page 522, were either ill finiflied, or rough from the forge; 

 and, at all events, it appears, that they ought not to afford ground for any prejudice. 



againft good work in the ufual materials. 



W.N. 

 nO 



