THEORY OF THE STEAM ENGINE, CXLVII, 
400° 500° Fah. 
a 
200° 300° 
106° 
| 
~~ 100 
WALA ALAA By 
WAAL 80 gj 
YWBBAALGAAGAAE 70 6 
NA 60 ms 
vid 
40 S A 
30 
20 By 
10 
0 
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| 
WSS: 
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aSSsesazrsag An 
BOILER PRESSURE POUNDS PER SQ. IN, 
A—Percentage of heat available for useful work. 
B—Temperature of steam. 
that can possibly be utilised, supposing the engine considered as 
a heat engine to be a perfect engine, the temperature of the con- 
denser being taken as 100° Fah. 
It will be noticed that with steam of 285 ibs. pressure, and 
assuming that we are dealing with a perfect heat engine, it is 
impossible to turn more than 35 per cent of the heat supplied into 
useful work. There is much to be done in the future to increase 
the economy of the steam engine, and researches like those des- 
cribed by the author are the only means to attain that end. 
Mr. Barraciovau in reply said he was greatly obliged to Mr. 
Houghton for the diagrams he had prepared. He however, could 
not agree with him that there was very little debateable matter 
in the paper. One object which he had in view in writing the 
paper was to show the marked divergence in the opinions of those 
who are in a position to write with authority on the subject. The 
