112 THE WATEll HaM. 



It is prolBibie P. 105. the pipe IZ^Ofeet foyig.] This column of water uhicti 

 ram woni'/iiot ^"^^^'^^^ ^o more than 40 atmospheres, would, I apprehend, 

 he duraWr un- greatly excecd what in actual practice could be trusted 

 sores/ " either to the wafer ram or any other hydraulic engine. Bra- 



mah's pressure engine, described in our first volume of the quar- 

 to series, supports between two and three hundred atmospheres 

 by piston work : but a sudden stroke with this action would' 

 ?oon destroy the apparatus. By suddenly checking the escape 

 of the water in one of the small pressure engines which acted. 

 by a power of upwards of one hundred atmospheres, 1 found 

 that the cylinder, which was one inch diameter and half an 

 inch thick in metal, was soon hammered out so as to exhibit 

 external marks of the violence, and no longer to fit its piston. 

 The author's lu order to form a more correct notion of the actual effect 



c'stiaiateof its ^£ ^j^^ author's engines compared with other hydraulic* 



power defec- ° ' '' 



tivc. machines, it may be observed that tlie author seems fo have 



supposed, in p. 102, that the effect of an engine falls short of 



the measure of power applied to it only because of friction ami 



impediments. I have inserted the words generate velocity 



between brackets in thetext, because the case in question relates 



to preponderance and not equilibrium. This indispensable 



deduction from the power in the best and simplest engines is 



at least one-fourth, in order to work at a proper rate. The 



He underrates author greatly undervalues the engines which raise water 



casr!nt/ '*" ''^ ^^ whecl work ; and by referring to the machine at Marly he 



has taken perhaps the least productive which could have been 



any where found. (Sec the description, with large plates, in 



Besaguliers' Lectures.) As an under-shot wheel engine, it has 



only half the power of an over-shot ; and from the prodigious 



weight and complication of its parts, it is not in the least 



adapted to be taken as the representation of works of the kind, 



Thp water iam - ThoUgtf the water ram is deserving of notice for its simplicity 



hasflot mure i ,-,■ \ • ■. ^- " r i • i i • . 



power thaw ^^" ctlect in many situations, some of which the inventor has 



other engines,, mentioned, it does not from his facts appear to have more 



power than other engines. This statement, of bctv.een three- 



— as it naay fourths and one-half of the power (page 102) being obtained in 

 raise three- , ,,. • . i- /• , ■ • 



fourth»of what the effect, is very much to the credit of the engine, as it comes 



^"^'■s- near the water pressure engine of Trcvithick(Phil. Jour. v. i. p. 



1,6 1.) and other good machines which arc not loaded with 



needless parts. Jh'rom goncrul reasoning, I should not hu>e 



oxpectcd so much* 



The 



