HEAT IN EXPANSIVE MACHINES. 209 
from those formule, that the proportion of the total heat converted into power in 
any possible steam-engine is less than that indicated by Equation (66.) 
The annexed Table illustrates this :— 

| | Heat trans- | | 
| Total heat | formed into | 
; 5 expended in| expansive | Proportion 
Absolute temperature in the Absolute temperature in the | centigrade | power, in | of heat ren- 
Maximum 
proportion 
CASE. 
boiler =7; centigrade. condenser =, centigrade. | degrees ap-| centigrade | dered effec- ere re 
| plied to | degrees ap- tive. | Fae ° 
| | liquid water.| plied to i 
| liquid water. 




First Ideal Example in | On EE 0. DA BYo Pee DOr oe| Om | 0.6 ; ; 
Section 4, Art. 82, f 144°] + 274°°6 = 4187 | 81°°'7 +274°-6 = 356°3| 568°7 | 83°2 071463 | 0-1490 
Second Ideal Example, |170°9+ 274°°6 =445°°5| 100°4+274°6=374°6| 558°6 86°3 | 071545 | 0°1592 

gine, Experiment F,, 
Mr Wicxsreev’s En- 
by calculation, . . } 
135°2 + 274°°6 =409°8| 30°+274°6 = 304°6| 617°°-7 T1°"2 | 071153 | 0°2567 

Do., by observation, . . Ditto. Ditto. Ditto. 73°23 | 0°1185 | Ditto. 




(1) (2) (3) | BAKO) Cea) 

The heat transformed into power, as given in the fifth column, has been reduced 
to centigrade degrees in liquid water, by dividing the duty of a pound of steam by 
Mr Joue’s equivalent, 1389-6 feet per centigrade degree. Hence the first two 
numbers in that column are less than those given in Art. 32, which were com- 
puted from too small an equivalent. 
The first two cases fulfil the conditions required by Carnor’s law in every respect 
except one, viz.:—that the steam remaining at the end of the stroke, instead of 
beine*partially liquefied by refrigeration, and then reduced to water at the tem- 
perature of the boiler by compression, is supposed to be entirely liquefied by 
refrigeration. This occasions the loss of the heat necessary to raise the water 
from the temperature of the condenser to that of the boiler; but at the same time, 
there is a gain of the power which would be required to liquefy part of the steam 
by compression, and those two quantities partially compensate for each other’s 
effects on the ratio of the power to the heat expended, so that although it is below 
the maximum, the difference is small. 
In the third and fourth examples, founded on the calculated and observed 
duty of Mr WicksTEED’s engine during experiment F, the actual ratio is less than 
half the maximum. This waste of heat is to be ascribed to the following causes. 
First, The mode of liquefaction, which has already been referred to. 
Secondly, The initial pressure in the cylinder is but 18-93 lb. on the square inch, 
while that in the boiler is 45°7; so that although the steam is produced at 135°:2 
centigrade, it only begins to work at 107°:26. This great fall of pressure is 
VOL. XX. PART II. 3K 







