IMPROVEMENTS IN HYDRAULIC ENGINES. 5 



two in addition to the Schemnitz might coft Iefs, than boring 

 the cylinder of the pifton engine perfect, and its additional 

 machinery : for merely raifing water the powers of each are 

 nearly equal, depending all on the height of the original fall 

 of water. 



The great advantage of the pifton prefliire engine is, not The preffiure en- 

 as a cheap engine for raifing water, but as that in which a fall g1 "® vv ° » f 

 of water can be applied without any wafte to work mills or water, 

 machinery for any purpofe ; which is of very great confequence 

 when the fall of water is of confiderable height, and the ftream, 

 or fupply, fmall. 



Conceiving it of very great importance to have it deter- Great Import- 

 mined in what fltuations each of the principal engines, worked a . nce of com P a - 

 by water preilure, is to be preferred, I have commenced this rent methods of 

 comparifon, and if this fliall be acceptable, will fend another a PP ] ying water 

 paper on a fimilar fubject ; that is, on the comparifon of the Wheel work 

 common mill water wheel, with another mode of applying &c. 

 the water to turn mill work, which, I think, I can demon- 

 ftrate to be much preferable. I hope what I have thus began 

 will excite fome others to the fame enquiry ; and that by this 

 means the multiplicity of water preifure engines will be at laft 

 arranged, and their comparative utility afcertained, fo that in 

 every different cafe of fall or fupply of water, an engineer may 

 know at once which he mould ufe. 



I beg leave to add here fome remarks on the pifton prefliire Mr. Trevl- 

 engine in your Journal for March: Mr. Trevithack will, I tha ? k ' s P refl * ur e 

 hope, excufe my taking from him the honour of his being the C uted in 1731 

 firfl inventor of this mode of applying a fall of water, to give b y Denifard and. 

 it back to MefTrs. Denifard and Deuille of France, when I im^ineTby Mr. 

 confcfs that for a long time I was in the fame error with him, Bofwellin 1796* 

 and thought it had firft occurred to me, and propofed it with 

 that idea to Mr. Carnac in Nov. 1796, to draw the water 

 from his copper mine, (by which he would have faved the 

 daily labour of twenty men, as he had a fall of water very 

 proper for this engine — a fact which I have Mr. Carnac's 

 fignature to prove;) but I fince found out that in Belidor's Defcribed In 

 Hydraulic Architecture, publithed at Paris 1739, in the fourth Belidor * 

 book and firft chapter, there is a method defcribed at large, 

 with very well executed plates, by which a fall of water ope- 

 rating in a cylinder on a pifton may work a pump to force 

 water to a greater height j and what is remarkable, Belidor 

 2 propofes 



