GRIST AND SAW-MILLS. ^^7 



1. It is fubjefi: to little or no friflion. 



2. It may be erefted at a fniall expence when compared with 

 any other fort of fleam-engine. 



3. It has every advantage which may be attributed to Bolton 

 and Watt's engines, by condenfing out of the receiver, either 

 in the penftock or at tlie level of the v/ater. 



4. Another very great advantage is, that the water in the 

 upper part of the pipe adjoining the receiver, acquires a heat 

 by its being in frequent contaifi: with the fteam, very nearly equal 

 to that of boiling water ; hence the receiver is always kept uni- 

 formly hot as in the cafe of Bolton and Watt's engines. 



5. A very fmall flream of water is fufficient to fupply this 

 engine, (even where there is no fall) for all the water raifed by 

 it is returned into the refervoir HHH. 



From the foregoing reafons it manifeflly appears that no kind 

 of fteam-engine is fo well adapted to give rotatory motion to 

 machinery of every kind as this. Its form is fimple, and the 

 materials of which it is compofed are cheap ; the power is more 

 than equal to any other machine of the kind, becaufe there is 

 no deduftion to be made for friftion, except on account of 

 turning the cocks which is but trifling. 



Its great utility is therefore evident in fupplying water for every 

 kind of work performed by a water-wheel, fuch as griil-mills, 

 faw-mills, blafl-furnaces, forges, &c. 



Dimensions of the Stcam-Engine for working an overfloot 'wheels 

 accompanied with fuch calculations as are necejjary for afcer- 

 taining the ffz.cs of its different parts, when applied to various 

 purpofes. 



The quantity of water which this machine is intended to 

 raife into the receiver in a given time, cannot be afcertained 

 until fome llandard be fixed on for the height of the furface of 

 the water in the receiver above that in the refervoir HHH, which 

 when known, we fliall be enabled to calculate the diameters of 

 the receiver and pipes with certainty. 



Writers on the lubjeft of hydraulics generally allow that a 

 column of water 34 feet high is equal to the prefliire of the at- 

 mofphere when the mercury in the barometer ftands at 29.5 inches. 

 Now if we admit that the water wiJI afcend into an exhaufled 



