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is intercepted, by the dead embers at the outside of the fire, 
the wall against which it burns will be red hot, and that heat 
is constantly conducted away, unless it is intercepted by 
some such means as I have described. Grates may there¬ 
fore be constructed in this manner with peculiar profit and 
advantage. 
The principle, however, on which the fire-places I have 
described are constructed, is by no means new ; nor is the 
practical application of it to the warming of rooms original. 
I find that Doctor Franklin put it in practice sixty-five years 
ago. Yesterday for the first time I had the pleasure of 
reading the description of his Pennsylvania fire-place, pub¬ 
lished in 1745. To the back of the Franklin stove now in 
use, there was attached what he calls an air box, into which 
the cold air was received from without, and discharged 
warm into the room. The flame and smoke passed over 
this air box, descended behind it down to the hearth, and 
then ascended the chimney. He conjectured that ten bar¬ 
rels of heated air were by these means brought into his room 
every hour. If he was correct in this, no doubt his contriv¬ 
ance was successful; and I can only account for its not com¬ 
ing into general use, from the circumstance of its being too 
complicated in its structure, to be managed or understood, 
by the common class of people. If these difficulties were 
the true cause of Doctor Franklin’s original Pennsylvania 
fire-place being laid aside, I think they are obviated in a 
great measure by the simplicity of my method of putting up 
his open stove. It is attended with no more trouble, expense 
or difficulty, than any other common method ; and the ben¬ 
efits derived from it are incalculably greater. 
In 1783, Doctor Franklin, in his letter to Doctor Ingen- 
hausz, adverts to this principle as applicable to common 
fire-places, in the following words : a M. Gauger, a very 
ingenious and intelligent French writer, proposes with 
judgment to admit the air above the opening of the chim¬ 
ney ; and to prevent inconvenience from its coldness, he di- 
