96 



MR. rtORNfiLOWKR ON HORSE POWERS, 



for horfes. 



Defagullers 



confiders it as 



550 lb. raifcd 50, ^ ' 



feet per minute ""'"'^ ^'^ 



clfe value or efled of any mill or engine in and about London-. 

 Indeed I do not know why it was adopted for the piirpofes in- 

 tended, ii being (b indettnite. 

 This unity pro- I can eafily conceive it probable that fomcbody who has em- 

 bab.y arofe trom ployed horfes for forae time in mill-work, may have applied to 

 fteam engines . , ,- . , t , • . 1 11 



beirgfubftituted^" engineer, and laid ** I have a mmd to have my work done 



by a fleam engine inflead of horfes for I am to a point that I 

 Ihal! fave money by it, and pleafe to give me an eftimate of the 

 coll of an engine that will do the work of my horfes;'" and 

 the;n.the engineer fets about getting information as to what 

 may be deemed the effect a horfe can produce, and calls it the 

 hor/l pnvjer; and perhaps having Deiagnlier*.-. Experimental 

 Philofophy at hand, sipplies to him, and there he finds that a 

 ill raife a hogdiead of water 50 feet high in a minute; 

 ihen what is the weight of a hogfliead of water, and lie finds 

 from fome prvriiculars related by him» 2nd voL page 505, that 

 a hogfhead of water is equal to 550 lb. but of what meafure 

 is uncertain, for the ale hogfliead, 51 gallons, is 540 lb. and 

 the wine hogfliead, (JJ gallons, is 504- lb. reckoning the cubic 

 foot at 1000 ounces avoirdupois. 



Some engineers who have very unceremonlouny taken the 

 lead in this afl'air, have adopted I do not know what for a da-- 

 turn, but the refuU is this: An engine by calculating 10 lb. on 

 the fquare inch, making the whole preffure = 1000, moving 

 through 200 feet per minute, h caWed a four-horfe engine.— 

 Let us fee then what will be the effed of one horfe according 

 to this faa. 



It r. '. . , ^ ^ , 200000 

 1000*^' X 200^^' = 200000 = the whole effe^, then - 



4 



= the effefi of one horfe. Now compare this with the eflimato 

 of Dr. Defaguliers, which is a hogfliead of water at 550 lb. 

 50feet higli in a minute; 550lb.x50ft. =27500and ; 50000 

 — 27500 = 22.500 = the difference between one of Mr. 

 Watt's horfes and one of the dolor's, on the former of which 

 I make no comment. 



Mr. Smeaton, whom I hold as having fuperior claim to pre- 

 cedency on fubjecls of this nature, has utterly diiapproved of^ 

 DefaguUer's experiment by th« rnoH powerfiU convi6tion of 

 its fallibility, formed by conclufions drawn from fterling ex- 

 perience in the accgmplifVyment of works on a large fcale; and 

 he ftate« the greateft effect to be 40 f«et high in a minute; bat 



9^m 



Another efti- 

 mate; nearly 

 double that of 

 D&faguliers. 



Snseaton's efti- 

 mate one- fifth 

 tefs than De- 

 faguliers. 



