MR. HORNBIOWER ON HORSE POWERS, QS 



{which may be done injiistlf an hour) and where water rannot Oefcriptlon of 



be had for condenfa|ion, this engine may be worked by the ^j^^j^^^ 



preffare of (Irong fleam alone, as the internal cylinder is kept 



as hotaf> the (ieam in the boiler.* This dangerous plan never / 



oii^ht to be reforted to but in cafes of neceflity, as it is no fav- 



iiifT of coah, and as there can be no certain ru^e when to dif- 



coiilinue tlie ufe of the boiler, (he weaknefs of which is not 



prevented by putting the fire in a tube in the in fide of it. This 



engine requires no framing nor milUwright work in the fixing, 



but merely bohing down to the floor it flands upon. It takes 



up very little room, and all its parts are within reach, without 



the necetlity of upper floors or ftages, which would be the cafe 



if the beam was above; but by being fixed below and alone, 



it has no tendency to move from its (ituation. 



VI. 



Ixiier from Mr. J. C. Horn blower, Engineer, on the Mea- 

 Jure of Force by Horfe F oners. 



To Mr. NICHOLSON. 



Dear Sir, 



Jl am Induced to trouble you on account of the prefent un- Unceiftainty of 

 fettled ftate of things refpeding what is ufually called the poioer "^^^^ '^""of 

 of a horfe, I cfo not know why a matter of this fort (hould a horfe. 

 remain fo difregarded, efpecially as it has fo long become one 

 of our data, comprehending the unities of weight, fpace and , 

 time, by whicli we are to be underflood in our communica- 

 tions on the fuijeft, and by which we are to afcertain the pre- 



* Many engines are at prefent worked in London and elfewhere 

 %y the mere force of fteam, without condtnfation, under Trevithick's 

 itent. The force is from 45 to 60 lb. on the round inch ; a pre£- 

 ire equal to about 25 fathoms of water at the mod:. Various af- 

 '^fcrtions and reports concerning the fafety, the economy, and the 

 "Other effefts of thefc engines have pafled under my notice; but the 

 interred fituation of fome of the narrators on both fides, and the 

 (hort time of trial, have induced me to wait for more fafts before I 

 iQiould give any account of the engine in this J»urnaL 4 hope to 

 do this a few months hence. — W. N. 



cife 



