28 MR. JOHN GRAHAM ON CONSUMPTION 
It had been thus fitted to meet theoretical considera- 
tions in connection with smoke burning. When altered 
to the condition as seen in figures 12 and 13, a saving ac- 
crued of at least 30 per cent. on the consumption of coal, 
as practically estimated. 
The evaporating power of the present boiler, which is of 
the same class as the last, but greater in diameter and 
longer, may be considered as 6.46 lbs. of water at 60° 
evaporated by one pound of coal. 
Or adding one-sixth for the heating of the feed water 
from 60° to 212°, the power will be 7.54 lbs. of water eva- 
porated by one pound of coal. 
X. Serres oF ExpeRIMEnNts. 
Fig. 15. 
Scale of feet 
42.5074 INS FOS : Fiyet 15 Feet 
Fig. 16. Fig. 17. 
The next boiler was, as shown in the drawing, of the 
shape usually called the “Butterly,” or, “Fishmouthed 
boiler.” Its dimensions were as follows : 
Length 25 feet by 7 feet in diameter. 
