CHIMNEYS. 5 
difcharges a part of it into the room, offending the eyes 
and damaging the furniture ? 
The caufes of this effeét, which have fallen under my 
obfervation, amount to zie, differing from each other, 
and therefore requiring different remedies. 
1. Smoky chimneys in a new houfe, are fuch, frequently 
from mere want of air. The workmanfhip of the rooms 
being all good, and juft out of the workman’s hand, the 
joints of the boards of the flooring, and of the pannels of 
wainfcotting are all true and tight, the more fo as the 
walls, perhaps not yet thoroughly dry, preferve a damp- 
nefs in the.air of the room which keeps the wood-work 
{welled and clofe. The doors and the fafhes too, being 
worked with truth, fhut with exadtnefs, fo that the room 
is as tight as a fnuff-box, no paflage being left open for 
air to enter, except the key-hole, and even that is fome- 
times covered by a little dropping fhutter. Now if {moke 
cannot rife but as connected with rarefied air, and a column 
of fuch air, fuppofe it filling the funnel, cannot rife, unlefs. 
other air be admitted to fupply its place; and if, therefore, 
no current of air enter the opening of the chimney, there 
is nothing to prevent the f{moke coming out into the room. 
If the motion upwards of the air in a chimney that is 
freely fupplied, be obferved by the rifing of the fmoke or 
a feather in it, and it be confidered that in the time fuch 
feather takes in rifing from the fire to the top of the 
chimney, a column of air equal to the content of the fun- 
nel muft be difcharzed, and an equal quantity fupplied 
from the room below, it will appear abfolutely impoffible 
that this operation fhould go on if the tight room is kept 
fhut ; for were there any force capable of drawing con- 
ftantly fo much air out of it, it muft foon be exhaufted 
like the receiver of an air pump, and no animal could live 
in it. ‘Thofe therefore who ftop every crevice in a room 
to prevent the admiffion of freth air, and yet would have 
their chimney carry up the fmoke, require inconfiftencies, 
and 
