THEORY OF CHEMISTRY. 09 



itrucled with or without arches. This, with little variation, is 

 the invention of a Dutch gentleman, and was applied to the 

 load of a .52 inch cylinder (an atmofphcrical engine) fet up 

 with advantages, which in point of workmanihip at that time 

 was perhaps not equalled, and therefore may be faid to have 

 been fairly tried. 



This engine was calculated to raife 60,000 gallons per mi- Dimenfions and 

 nute, and the fcantles were 1 8 by 12, and 12 by 8, and where load * 

 lurch timber can be had, it is hardly to be expected to have a 

 lever with greater advantages than this for a fingle ftroke, 

 and where a double flroke is required, it may be doubled for Double con- 

 that purpofe, retaining all its principles and properties as in lon * 

 Fig. 3. which I fuppofe needs no explanation. 



Fig. 4. is a lever constructed by an eminent engineer in Strong framed 

 Hungary fome years lince, which potFeilesa very great degree gar „ 

 of fupport by the king poft and iron braces, but does not, in 

 my opinion, difcover fo much fcience as the two preceding 

 ones. I forgot to obferve, that inner arches may be attached 

 to Fig. 1. without materially affecting its principle, if they 

 are well let on the whole framing, and bolted to each other 

 without palling through the fcantles, 

 I am, SIR, 



Your molt obedient Servant,, 



J. C. HORNBLOWER. 

 Eaft Row, City Road, Taefday, May 11, 1802. 



III. 



On the Theory of Chemiftry. In a Letter from the Rev. 

 J.Priestley, L.L.D. F. R. S. #c, 



To Wm, NICHOLSON, Esq, 

 Dear Sir, 



IN October laft I fent you a reply to Mr. Cruickftiank's ob- Reference to 

 fervations on one of my arguments in fupport of the doctrine for ™r letter, 

 of phlogifton, in which I think I clearly ihewed that he fup- . ' P * ] 

 pofed fixed air to be formed in circumftances in which it is 

 impoflible that it mould be formed, and that it is decompofed 

 jbv a fubfiauce which has no fuch power. Having juft re- 

 ceived 



