OF STEAM-ENGINES. 



found, by actual experiment, fetting out from the boiling 

 point of water, or 212*, at which degree fteam of water is 

 only equal to the preflure of the almofphere, that in order 

 to give it an increafed elaftic force equal to five pounds the 

 fquare inch, the temperature muft be raifed to about 2271", 

 xvhen it will have acquired a power to expand itfelf to five 

 times its volume, {iill being equal to the afmofphere, and capa- 

 ble of being applied as fuch in the working of fteam-engines, 

 according to his invention: and with regard to various other 

 prefTures, temperatures, and expanfive forces of fleam, the 

 fame are fliown in the following table : 



Table of the relative preffuref per fquare inch, teinperatiires and 

 expanfibHily of fleu77i at degrees of heat above the boiling point 

 of tcater, btginnintr with the temperature of Jieam of an elafiic 

 force equal to five pounh per fquare inch, and extending to 

 Jieam able to fujlainfortj/ pouudi on the fquare inch. 



^^6% 



Pounds per 

 fquare Inch. 



Steam ot f 5'] 

 an elaftic 



torce pre- 

 dominat- 

 ing over 

 'he pref- 



ure of 



lie atmo- 

 fphere 

 apon a 

 lafety- 

 valve, 



6 



7 



8 



9 

 10 

 15 

 20 

 25 

 30 

 35 



UoJ 



requires 

 to be 

 maintain 

 ^ed by a 

 tempera- 

 ture equal 

 to about 



Degrees 

 of Hcdt. 



r227n 



230i 

 23 2| 

 23 5 1 

 237 



and at 

 ihefe re- 

 fpective 



Expan- 

 fibility. 



r n 



6 I 



times its 

 volume, 

 and con 

 tinue 



QiQi . degrees of ' equal in 



2.5.91 I ^"^'"f" 

 9fi7 expand 



1282 J 



20 

 2.5 

 30 

 35 



to the 

 preflure 

 -of the 

 atmo- 

 (phere. 



Table of 

 pre (Tires, 

 temperatures 

 and expan- 

 fions of fteatn 

 equal in force 

 to the atmof- 

 phere. 



And fo in like manner, by fmall additions of temperature, 

 an expanfive power may be given to fleam to enable it to ex- 

 pand to 50, 60, 70, 80, 90^ 100, 200, 300, or more times 

 its volume, without any limitation but what is impofed.by 

 the frangible nature of every material of which boilers ant^ 

 the other parts of ftearn-engines have been or can be made; 

 and prudence dictates that the expanfive force fliould never 

 be carried to the utmoft the niateria's can bear, but rather be 

 kept confiderably within that limit. 



Upon this difcovery, Mr. WooU has obtained a patent foi: 

 various improvements in the lleam-engine, from the fpecifica- 

 . ' tioa 



