210 MR W. J. M. RANKINE ON EXPANSIVE MACHINES. 
accounted for by the fact, that the steam for each stroke, which is produced in 
the boiler in about seven or eight seconds, escapes suddenly into the cylinder in 
a fraction of a second. 
Thirdly, The expansive working of the steam, tstead of being continued 
down to 30° centigrade, the temperature of the condenser, stops at a much higher 
temperature, 74°66. This is the most important cause of loss of power. 
If we now take for r, and 7, the absolute temperatures at the beginning and 
end of the expansive working, and calculate the maximum duty of one pound 
of steam by Carnor’s Law between those temperatures, we find,— 
7, =107°-26 + 274°-6 =381°-86 
T,= 74°66 + 274°6 =349°:26 
0:08542 
ae 
H,=564°5; 2. = 5 : i 48°22 
To this es to be added ie day. at full pressure, of aint at T,, dimi- 
nished by one-third for back-pressure and friction, and by one-fifteenth 
for liquefaction in the cylinder, = . 5 z : : ; ; 237-14 

The whole amounting to 71°36 
Which agrees very nearly with 73°-23, the observed duty, and almost exactly 
with 71°-2, the duty as calculated by the formule and tables of Section Fourth. 
These examples shew clearly the nature and causes of the waste of heat in 
the steam-engine. 

