566 



Similarly, 



Mr. Lubbock on the Heat of Vapours, S^c. 

 1 



ISK 



K 



av {I' + c) fjJ ' 



ISK 



K 



a V [l + c) [t. 



1 IS 



[jj av {r + c) 



p y — E p = — 



1 _ IS 



[X. av {I + c) 



p a {I + c) — p' ac 



44^ Nap, log ^ ' - ^^'T 

 vE{l—y) ^ ^1 7-1 



11 -Ep "^ 

 pa {I + c) — p' ac— {p" +f) a I 



y-n 



aRl 



- [4-64U966]— log*<; 



r 



log 



Ep' 'y 



I — Ev' "^ I 

 [l-Ep^ ] 



> = log { 



/ + c 



TT~c 



log 



7 ° 



ii)- 



y-i 



If the machine work without expansion, 



y-i 



1 - ^y ^ 



1 + 8 



The data upon questions relating to the steam-engine are the 

 quantities a, I, I', S, and z^, and it is evident that from these quan- 

 tities the quantities ]«. and ju,' may at once be found by an easy arith- 

 metical operation; from these the following table will give the 

 corresponding pressures p and p', and these pressures being in- 

 troduced into equation A^ the value of « r may be easily found. 



* Log. of Briggs, the pressure being reckoned in atmospheres, the log. of the con- 

 stant is [7*9670537], the pressure being reckoned in lbs. per square foot. 



