Green-Mountain freeman. [volume] (Montpelier, Vt.) 1844-1884, 1855-12-13
THE PHILOSOPHY OF CHIMNEYs.

A recent number of the London Quarterly
RerieU contains readable and instructive arti-
ticle upon chimneys and other belongings. The
writer is apparently decided admirer Of the
open fireplace, as u general enhancer of home
joys, and while he admits its defects, and its an
nnal chapter of accidents or annoyances, still
thinks the enjoyment of the open fire to be too
deeply seated (among Englishmen especially,)
to be disturbed by these causes But leaving
the social aspect of the open Fireplace, which
the weather just now would rob of all it's charms
the writer gives much that is new in relation to
chimneys, and the philosophy of their action,
some portions of which We condense for our col
umns.
The chimney has been in use five centuries
Existing remains prove that perpendicular aues
were constructed in England as far back as the
18th century. In the drawings of the time of
Henry ILL.,, chimneys of cylindrical form, are
represented as considerably higher than the roof,
and orders to raise the chimneys of the kings
houses were frequent in that reign. Neverthe-
less, it was still the general custom, even il the
18th century, to retain the hearth in the middle
of the room. When the wood was fairly igni-
ted, the smoke would not be great, and the GEN.
trail position of the fire was favorable to the rad
iation of heat. This method of warming the
hall was confined long after the fire places with
chimneys h id been erected in smaller apartments
By the reign of Elizabeth the advantages of the
new system were SO well appreciated, that la
dies in their visits to their friends, if they could
not be Accommodated with rooms with chimncys,
were frequently sent out to other houses, where
they could enjoy the luxury.
But Notwithstanding the chimney is 80 ven-
erable an institution, it has been employed with
very imperfect appreciation of the physical laws
on which it depends. Probably, says the wri-
ter from whom we quote, even at the present
day, few of those who erect chimneys would be
able to explain the conditions of their successful
action; while tho learned chimney-doctor often
fails in his diagnosis, and rashy prcscribes for
!, malady from which the patient may be free,
: while neglecting that which would be evident
to the eve of the man of science
1t is often supposed either that smoke asccnds
> the chimney because it is lighter than the sur
rounding air, Or that some mysterious power
o exists in the chimney by which the smoke is
drawn up and discharged That smoke is moi
lighter than air, the following experiment, de-
u yised by DR., Franklin, will show If pipe o
i tobacco be lighted, the stem plunged to the bot
tom of a decanter half full of cold water, AM
:, the bowl covered with piece Of linen SO tina
ID it could be blown through without burning th
d. lips, the smoke will descend the stem Of tn
pipe and bubble up through the liquid, ant
10 thus becoming cooled, it will not rise out of tn
~ decanter, but spread over the surface of the Wa
y ter. This shows that smoke is in reality hea,
Ter than air. But the murky cloud, which cor
sists of carbon, hydrogen, carconic acid carbon
: ic oxide. vapor of water, and other products,
y mixed with "a large proportion of the air whc
~ enters the fire. 1t is this Invisible column
10 heated air, that by its expansive force carrie
ne with it the visible and less heated smoke, unit
nc it emerges from the top of the chimney, whel
it encounters the cold of the external atmo
leu phcre, loses its accessive power and unless son
es' kindly breeze carries it away hangs likes clor
over the crowded city, or falls in minute part
re- cles of carbon, be- rimming everything below.
aid Air. then, being essential to the draft
old chimneys, the quantity needed and the bt
all mode of supplying it is an important inqui
her in connection with the subject. DR.. Franklin
method of ascertaining in rough way HI
self much air is required to be admitted per minu
be was to set the door aIjar until the fire burn
rve properly, and gradually close it again until
y a smoke began to appear he then opened it
ual tie wider, and if the width of the crevice v
ess half an inch in door eight feet high, the 70
ling would need an aperture equal to forty-eit
wen square inches, or hole six inches by eight
this Six inches square would probably be sufici
all for the wants Of most chimneys, but where
let form the aperture is difficult question.
hal made in the door, it admits cold current
nv the back and feet Of persons sitting near
fire, and also interferes with the privacy of
INV room if made in the window, it brings do
out cataract Of untsmpsred air npon the be