8 MR. JOHN GRAHAM ON CONSUMPTION 
Il.— On the Consumption of Coal in Furnaces, and the 
Rate of Evaporation from Engine Boilers. By Joun 
GRAHAM, Esa. 
Read February 23rd, 1858. 
Tue experiments to be detailed in the present paper were 
originally undertaken with a view to beneficial applica- 
tion, and were conducted, as they are now described, in as 
simple a manner as I was capable of doing. I have been 
desirous to avoid all entanglements arising from the use of 
formule and the introduction of theoretical speculations ; 
the great and important field of practical knowledge to 
which the enquiry belongs being as yet, in my humble 
opinion, too little explored to admit of much generalizing ; 
and I have aspired only to lay down a road into the region, 
hard and dry, on the basis of sure experiment. 
I, Series or EXPERIMENTS. 
The experiments which I shall first describe were made 
with the view to ascertain the comparative evaporative 
power of equal but differently placed areas of heating sur- 
face, for the purpose of deciding whether we should look 
most, as regards the saving of coals, to the improvement of 
the fire-place, or the extension of evaporating flue surface. 
The results obtained were in accordance with general 
observation. Four open tin pans, each twelve inches 
square, were carefully fitted up in brickwork, and ar- 
ranged together side by side, as seen in Fig. 1, the flame- 
j 
ee 
