24 LETTER CONCERNING 
made there, and found it as he faid. I opened the door, 
and perceived it was not want of air. I made a temporary 
contraction of the opening of the chimney, and found that 
it was not its being too large that caufed the fmoke to iffue. 
I went out and looked up at the top of the chimney: Its 
funnel was joined in the fame ftack with others, fome of 
them fhorter,, that drew very well, and I faw nothing to 
prevent its doing the fame. In fine, after every other ex- 
amination I could think of, I was obliged to own the in- 
fufficiency of my {fkill. But my friend, who made no 
' pretenfion to fuch kind of knowledge, afterwards difco- 
vered the caufe himfelf. He got to the top of the funnel 
by a ladder, and looking down, found it filled with twiggs 
and ftraw cemented by earth, and lined with feathers. 
It feems the houfe, after being built, had ftood empty fome 
years betore he occupied it ; and he concluded that fome 
large birds had taken the advantage of its retired fituation 
to make their neft there. The rubbifh, confiderable in 
quantity, being removed, and the funnel cleared, the 
chimney drew well, and gave fatisfaction. 
In general, f{moke is a very traCtable thing, ‘eafily go- 
verned and directed when one knows the principles, and 
is well informed of the circumftances. You know I made 
it de/cend in my Pennfylvania ftove. I formerly had a 
more fimple conftruction, in which the fame effect was 
produced, but vilible to the eye. It was compof- 
poe Fed of two plates A B and CD, placed as in the 
4 figure. The lower plate A B refted with its edge 
in the angle made by the hearth with the back of the 
chimney. The upper. plate was fixed to the breaft, and 
lapt over the lower about fix inches, leaving a fpace of 
four inches wide and the length of the plates (near two 
feet) between them. Every other paflage of air into the 
funnel was well ftopped. When therefore a fire was made 
at E, for the firft time with charcoal, till the air in the 
funnel was a little heated through the plates, and then 
wood 
