al 
> 
OF COAL AND RATE OF EVAPORATION. p 4) | 
Fire-places each 3 feet by 6 feet, giving 18 square feet 
of fire surface. 
Internal flue 3 feet 9 inches in diameter. 
Fire-bars half inch thick with half inch spaces. 
The boiler plate 3**s of an inch in thickness. 
The experiments made with this boiler were continued 
under difierent circumstances and at various times of the 
year, and the average result obtained, working under the 
best conditions I could command, was 5.90 lbs. of water 
evaporated from the temperature of 84° by oue pound of 
coal consumed. 
Or if we add one-sixth to this result as equivalent to the 
heating of the feed water, the ultimate result will stand 
thus : 
In the breeches boiler 6.88 lbs. of water are evaporated 
from 212° by one pound of coal. 
In all the experiments made with this boiler, though my 
results were affected more or less by what was considered 
to be a slightly deficient draught, still each fire evaporated 
24.429 Ibs. of water from 60° in the course of twelve suc- 
cessive working hours, and generally throughout the series 
it was found that this boiler was more affected by disturb- 
ing causes than the boilers of other shapes, possibly in 
consequence of the comparatively small size of the fire- 
places. 
The smallness of the yield from this boiler is a matter 
of surprise. I have, however, uo reasonable grounds for 
suspecting the accuracy of my experiments, since they 
were so often repeated and under such varied circum- 
stances. 
VI, Series or EXPERIMENTS. 
I may add that in a short series of experiments made 
on two other boilers of an analogous construction, namely, 
with two fire-places and two internal flues passing from 
