ae LET TER -concerninc 
tight houfe, I have known a kitchen chimney on the low- 
eft floor, when it had a great fire in it, overpower any 
other chimney in the houfe, and draw air and {moke into 
its room, as often as the door was opened communicating 
with the ftaircafe. 
Remedy. Take care that every room have the means 
of fupplying itfelf from without, with the air its chimney 
may require, fo that no one of them may be obliged to 
borrow from another, nor under the neceffity of lending. 
A variety of thefe means have been already defcribed. 
5. Another caufe of {moking is, when the tops of chim- 
neys are commanded by higher buildings, or by a hill, fo that 
the wind blowing over fuch eminences falls like water over 
a dam, fometimes almoft perpendicularly on the tops of 
the chimneys that lie in its way, and beats down the fmoke 
contained in them. 
Remedy. That commonly applied to this cafe, is a 
turncap made of tin or plate iron, covering the chimney 
above and on three fides, open on one fide, turning on a 
f{pindle, and which being guided or governed by a vane, 
always prefents its back tothe current. This I believe may 
be generally effeGtual, though not certain, as there may be 
cafes in which it will not fucceed. Raifing your funnels 
if practicable, fo as their tops may be higher, or at leaft 
equal with the commanding eminence, is more to be de-= 
pended on. But the turning cap, being eafier and cheaper, 
fhould firft be tried. If obliged to build in fuch a fituation, 
I would chufe to place my doors on the fide next the hill, 
and the backs of my chimneys on the furtheft fide; for 
then the column of air falling over the eminence, and of 
courfe preffing on that below and forcing it to enter the 
doors, or Was-z/?-dases on that fide, would tend to balance 
the preflure down the chimneys, and leave the funnels 
more free in the exercife of their fun@tions. 
6. There is another cafe of command, the reverfe of 
that laft mentioned. It is where the commanding emi- 
nence 
