floors, which is ingenious. Those floors are made of tiles, a foot
square and two inches thick, their corners being supported by bricks
set on end, that are a foot long and four inches square; the tiles,
too, join into each other, by ridges and hollows along their sides.
This forms a hollow under the whole floor, which on one side of the
house has an opening into the air, where a fire is made, and it has a
funnel rising from the other side to carry off the smoke. The fuel is
a sulphurous pitcoal, the smell of which in the room is thus avoided,
while the floor, and of course the room, is well warmed. But as the
underside of the floor must grow foul with soot, and a thick coat of
soot prevents much of the direct application of the hot air to the
tiles, I conceive that burning the smoke, by obliging it to descend
through red coals, would in this construction be very advantageous,
as more heat would be given by the flame than by the smoke, and the
floor being thereby kept free from soot would be more heated with
less fire. For this purpose I would propose erecting the funnel close
to the grate, so as to have only an iron plate between the fire and
the funnel, through which plate, the air in the funnel being heated,
it will be sure to draw well, and force the smoke to descend, as in
the figure (Plate, Figure 9.) where A is the funnel or chimney, B the
grate on which the fire is placed, C one of the apertures through
which the descending smoke is drawn into the channel D of figure
10, along which channel it is conveyed by a circuitous route, as
designated by the arrows, until it arrives at the small aperture E,
figure 10, through which it enters the funnel F. G in both figures is
the iron plate against which the fire is made, which, being heated
thereby, will rarefy the air in that part of the funnel, and cause
the smoke to ascend rapidly. The flame thus dividing from the grate
to the right and left, and turning in passages, disposed, as in
figure 10, so as that every part of the floor may be visited by it
before it enters the funnel F, by the two passages E E, very little
of the heat will be lost, and a winter room thus rendered very
comfortable.
No. IV.
Page 265. _Few can imagine_, &c. It is said the Icelanders have very
little fuel, chiefly drift wood that comes upon their coast. To
receive more advantage from its heat, they make their doors low, and
have a stage round the room above the door, like a gallery, wherein
the women can sit and work, the men read or write, &c. The roof being
tight, the warm air is confined by it and kept from rising higher and
escaping; and the cold air, which enters the house when the door is
opened, cannot rise above the level of the top of the door, because
it is heavier than the warm air above the door, and so those in the
gallery are not incommoded by it. Some of our too lofty rooms might
have a stage so constructed as to make a temporary gallery above, for
the winter, to be taken away in summer. Sedentary people would find
much comfort there in cold weather.
No. V.
Page 285. _Where they have the art of managing it_, &c. In some
houses of the lower people among the northern nations of Europe, and
among the poorer sort of Germans in Pensylvania, I have observed this
construction, which appears very advantageous. (Plate Figure 11.) A
is the kitchen with its chimney; B an iron stove in the stove-room.
In a corner of the chimney is a hole through the back into the stove,
to put in fuel, and another hole above it to let the smoke of the
stove come back into the chimney. As soon as the cooking is over,
the brands in the kitchen chimney are put through the hole to supply
the stove, so that there is seldom more than one fire burning at a
time. In the floor over the stove-room, is a small trap door, to
let the warm air rise occasionally into the chamber. Thus the whole
house is warmed at little expence of wood, and the stove-room kept
constantly warm; so that in the coldest winter nights, they can work
late, and find the room still comfortable when they rise to work
early. An English farmer in America, who makes great fires in large
open chimneys, needs the constant employment of one man to cut and
haul wood for supplying them; and the draft of cold air to them is
so strong, that the heels of his family are frozen while they are
scorching their faces, and the room is never warm, so that little
sedentary work can be done by them in winter. The difference in
this article alone of economy shall, in a course of years, enable
the German to buy out the Englishman, and take possession of his
plantation.
_Miscellaneous Observations._
Chimneys, whose funnels go up in the north wall of a house and are
exposed to the north winds, are not so apt to draw well as those in
a south wall; because, when rendered cold by those winds, they draw
downwards.
Chimneys, enclosed in the body of a house, are better than those
whose funnels are exposed in cold walls.
Chimneys in stacks are apt to draw better than separate funnels,
because the funnels, that have constant fires in them, warm the
others, in some degree, that have none.
One of the funnels, in a house I once occupied, had a particular
funnel joined to the south side of the stack, so that three of its
sides were exposed to the sun in the course of the day, viz. (Plate,
Figure 12.) the east side E during the morning, the south side S in
the middle part of the day, and the west side W during the afternoon,
while its north side was sheltered by the stack from the cold winds.
This funnel, which came from the ground-floor, and had a considerable
height above the roof, was constantly in a strong drawing state day
and night, winter and summer.
Blacking of funnels, exposed to the sun, would probably make them
draw still stronger.
In Paris I saw a fire-place so ingeniously contrived as to serve
conveniently two rooms, a bedchamber and a study. The funnel over the
fire was round. The fire-place was of cast iron (Plate, Figure 13.)
having an upright back A, and two horizontal semicircular plates B C,
the whole so ordered as to turn on the pivots D E. The plate B always
stopped that part of the round funnel that was next to the room
without fire, while the other half of the funnel over the fire was
always open. By this means a servant in the morning could make a fire
on the hearth C, then in the study, without disturbing the master by
going into his chamber; and the master, when he rose, could, with a
touch of his foot, turn the chimney on its pivots, and bring the fire
into his chamber, keep it there as long as he wanted it, and turn it
again, when he went out, into his study. The room which had no fire
in it was also warmed by the heat coming through the back plate, and
spreading in the room, as it could not go up the chimney.
FOOTNOTES:
[51] This letter, which has been published in a separate pamphlet,
both in this country and America, first appeared in the Transactions
of the American Philosophical Society, in which it was read Oct. 21,
1785. _Editor._
[52] See Notes at the end of the Letter, No. I.
[53] See Notes at the end of the Letter, No. II.
[54] See Notes at the end of the letter, No. II.
[55] See Notes at the end of the letter, No. II.
[56] See Notes at the end of the letter, No. III.
[57] See Notes at the end of the Letter, No. II.
[58] "It may be just remarked here, that upon comparing these
proportions with those arising from the common divisions of the
monochord, it happens that the first answers to unisons, and although
the second is a discord, the third answers to the third minor, the
fourth to the third major, the fifth to the fourth, the sixth to the
fifth, and the seventh to the octave." NUTSHELLS, page 85.
[59] Badoin. _Editor._
[Illustration:
_Plate X._ _Vol. II. page 297._
STOVE FOR BURNING PIT-COAL.
_Published as the Act directs, April 1, 1806, by Longman, Hurst, Rees
& Orme, Paternoster Row._]
_Description of a new Stove for burning of Pitcoal, and consuming
all its smoke._[60] _By Dr. B._ FRANKLIN.
Towards the end of the last century an ingenious French philosopher,
whose name I am sorry I cannot recollect, exhibited an experiment
to show, that very offensive things might be burnt in the middle of
a chamber, such as woollen rags, feathers, &c. without creating the
least smoke or smell. The machine in which it was made, if I remember
right, was of this form, (Plate X. Figure 1.) made of plate iron.
Some clear burning charcoals were put into the opening of the short
tube A, and supported there by the grate B. The air, as soon as the
tubes grew warm, would ascend in the longer leg C and go out at D,
consequently air must enter at A descending to B. In this course it
must be heated by the burning coals through which it passed, and
rise more forcibly in the longer tube, in proportion to its degree
of heat or rarefaction, and length of that tube. For such a machine
is a kind of inverted syphon; and as the greater weight of water in
the longer leg of a common syphon in descending is accompanied by an
ascent of the same fluid in the shorter; so, in this inverted syphon,
the greater quantity of levity of air in the longer leg, in rising
is accompanied by the descent of air in the shorter. The things to
be burned being laid on the hot coals at A, the smoke must descend
through those coals, be converted into flame, which, after destroying
the offensive smell, came out at the end of the longer tube as mere
heated air.
Whoever would repeat this experiment with success must take care that
the part A, B, of the short tube, be quite full of burning coals,
so that no part of the smoke may descend and pass by them without
going through them, and being converted into flame; and that the
longer tube be so heated as that the current of ascending hot air
is established in it before the things to be burnt are laid on the
coals; otherwise there will be a disappointment.
It does not appear either in the Memoirs of the Academy of Sciences,
or Philosophical Transactions of the English Royal Society, that any
improvement was ever made of this ingenious experiment, by applying
it to useful purposes. But there is a German book, entitled _Vulcanus
Famulans_, by Joh. George Leutmann, P. D. printed at Wirtemberg in
1723, which describes, among a great variety of other stoves for
warming rooms, one, which seems to have been formed on the same
principle, and probably from the hint thereby given, though the
French experiment is not mentioned. This book being scarce, I have
translated the chapter describing the stove, viz.
"_Vulcanus Famulans, by John George Leutmann, P. D._
"_Wirtemberg, 1723._
"CHAP. VII.
"On a Stove, which draws downwards.
"Here follows the description of a sort of stove, which can easily
be removed and again replaced at pleasure. This drives the fire down
under itself, and gives no smoke, but however a very unwholesome
vapour.
"In the figure, A is an iron vessel like a funnel, (Plate X. Figure
20.) in diameter at the top about twelve inches, at the bottom near
the grate about five inches; its height twelve inches. This is set on
the barrel C, which is ten inches diameter and two feet long, closed
at each end E E. From one end rises a pipe or flue about four inches
diameter, on which other pieces of pipe are set, which are gradually
contracted to D, where the opening is but about two inches. Those
pipes must together be at least four feet high. B is an iron grate.
F F are iron handles guarded with wood, by which the stove is to be
lifted and moved. It stands on three legs. Care must be taken to stop
well all the joints, that no smoke may leak through.
"When this stove is to be used, it must first be carried into the
kitchen and placed in the chimney near the fire. There burning wood
must be laid and left upon its grate till the barrel C is warm, and
the smoke no longer rises at A, but descends towards C. Then it is to
be carried into the room which it is to warm. When once the barrel C
is warm, fresh wood may be thrown into the vessel A as often as one
pleases, the flame descends and without smoke, which is so consumed
that only a vapour passes out at D.
"As this vapour is unwholesome, and affects the head, one may be
freed from it, by fixing in the wall of the room an inverted funnel,
such as people use to hang over lamps, through which their smoke goes
out as through a chimney. This funnel carries out all the vapour
cleverly, so that one finds no inconvenience from it, even though the
opening D be placed a span below the mouth of the said funnel G. The
neck of the funnel is better when made gradually bending, than if
turned in a right angle.
"The cause of the draft downwards in the stove is the pressure of the
outward air, which, falling into the vessel A in a column of twelve
inches diameter, finds only a resisting passage at the grate B, of
five inches, and one at D, of two inches, which are much too weak
to drive it back again; besides, A stands much higher than B, and
so the pressure on it is greater and more forcible, and beats down
the frame to that part where it finds the least resistance. Carrying
the machine first to the kitchen fire for preparation, is on this
account, that in the beginning the fire and smoke naturally ascend,
till the air in the close barrel C is made thinner by the warmth.
When that vessel is heated, the air in it is rarefied, and then all
the smoke and fire descends under it.
"The wood should be thoroughly dry, and cut into pieces five or six
inches long, to fit it for being thrown into the funnel A." Thus far
the German book.
It appears to me, by Mr. Leutmann's explanation of the operation of
this machine, that he did not understand the principles of it, whence
I conclude he was not the inventor of it; and by the description of
it, wherein the opening at A is made so large, and the pipe E, D,
so short, I am persuaded he never made nor saw the experiment, for
the first ought to be much smaller and the last much higher, or it
hardly will succeed. The carrying it in the kitchen, too, every time
the fire should happen to be out, must be so troublesome, that it is
not likely ever to have been in practice, and probably has never been
shown but as a philosophical experiment. The funnel for conveying
the vapour out of the room would besides have been uncertain in its
operation, as a wind blowing against its mouth would drive the vapour
back.
The stove I am about to describe was also formed on the idea given by
the French experiment, and completely carried into execution before
I had any knowledge of the German invention; which I wonder should
remain so many years in a country, where men are so ingenious in the
management of fire, without receiving long since the improvements I
have given it.
_Description of the Parts._
A, the bottom plate which lies flat upon the hearth, with its
partitions, 1, 2, 3, 4, 5, 6, (Plate X. Figure 2.) that are cast with
it, and a groove Z Z, in which are to slide, the bottom edges of the
small plates Y, Y, figure 12; which plates meeting at X close the
front.
B 1, figure 3, is the cover plate showing its under side, with the
grooves 1, 2, 3, 4, 5, 6, to receive the top edges of the partitions
that are fixed to the bottom plate. It shows also the grate W W, the
bars of which are cast in the plate, and a groove V V, which comes
right over the groove Z Z, figure 2, receiving the upper edges of the
small sliding plates Y Y, figure 12.
B 2, figure 4, shows the upper side of the same plate, with a square
impression or groove for receiving the bottom mouldings T T T T of
the three-sided box C, figure 5, which is cast in one piece.
D, figure 6, its cover, showing its under side with grooves to
receive the upper edges S S S of the sides of C, figure 5, also a
groove R, R, which when the cover is put on comes right over another
Q Q in C, figure 5, between which it is to slide.
E, figure 7, the front plate of the box.
P, a hole three inches diameter through the cover D, figure 6, over
which hole stands the vase F, figure 8, which has a corresponding
hole two inches diameter through its bottom.
The top of the vase opens at O, O, O, figure 8, and turns back
upon a hinge behind when coals are to be put in; the vase has a
grate within at N N of cast iron H, figure 9, and a hole in the top,
one and a half inches diameter, to admit air, and to receive the
ornamental brass guilt flame M, figure 10, which stands in that hole,
and, being itself hollow and open, suffers air to pass through it to
the fire.
G, figure 11, is a drawer of plate iron, that slips in between in
the partitions 2 and 3, figure 2, to receive the falling ashes. It
is concealed when the small sliding plates Y Y, figure 12, are shut
together.
I, I, I, I, figure 8, is a niche built of brick in the chimney and
plastered. It closes the chimney over the vase, but leaves two
funnels, one in each corner, communicating with the bottom box K K,
figure 2.
_Dimensions of the Parts._
_Feet._ _In._
Front of the bottom box, 2 0
Height of its partitions, 0 4¼
Length of No. 1, 2, 3 and 4, each, 1 3
Length of No. 5 and 6, each, 0 8¼
Breadth of the passage between No. 2 and 3, 0 6
Breadth of the other passages each, 0 3½
Breadth of the grate, 0 6½
Length of ditto, 0 8
Bottom moulding of box C, square, 1 0
Height of the sides of ditto, 0 4
Length of the back side, 0 10
Length of the right and left sides, each, 0 9½
Length of the front plate E, where longest, 0 11
The cover D, square, 0 12
Hole in ditto, diameter, 0 3
Sliding plates Y Y, their length, each, 1 0
----- ----- ----- their breadth, each, 0 4½
Drawer G, its length, 1 0
----- ----- breadth, 0 5¾
----- ----- depth, 0 4
----- ----- depth of its further end, only, 0 1
Grate H in the vase, its diameter to the
extremity of its knobs, 0 5¾
Thickness of the bars at top, 0 0¼
----- ----- ----- at bottom, less, 0 0
Depth of the bars at the top, 0 0¾
Height of the vase, 1 6
Diameter of the opening O, O, in the clear, 0 8
Diameter of the air-hole at top, 0 1½
----- of the flame hole at bottom, 0 2
_To fix this Machine._
Spread mortar on the hearth to bed the bottom plate A, then lay that
plate level, equally distant from each jamb, and projecting out
as far as you think proper. Then putting some Windsor loam in the
grooves of the cover B, lay that on: trying the sliding plates Y Y,
to see if they move freely in the grooves Z Z, V V, designed for them.
Then begin to build the niche, observing to leave the square corners
of the chimney unfilled; for they are to be funnels. And observe also
to leave a free open communication between the passages at K K, and
the bottom of those funnels, and mind to close the chimney above the
top of the niche, that no air may pass up that way. The concave back
of the niche will rest on the circular iron partition 1 A 4, figure
2, then, with a little loam, put on the box C over the grate, the
open side of the box in front.
Then, with loam in three of its grooves, the groove R R being left
clean, and brought directly over the groove Q Q in the box, put on
the cover D, trying the front plate E, to see if it slides freely in
those grooves.
Lastly, set on the vase, which has small holes in the moulding of its
bottom to receive two iron pins that rise out of the plate D at I I,
for the better keeping it steady.
Then putting in the grate H, which rests on its three knobs h h h
against the inside of the vase, and slipping the drawer into its
place; the machine is fit for use.
_To use it._
Let the first fire be made after eight in the evening or before
eight in the morning, for at those times and between those hours all
night, there is usually a draft up a chimney, though it has long been
without fire; but between those hours in the day there is often, in
a cold chimney, a draft downwards, when, if you attempt to kindle a
fire, the smoke will come into the room.
But to be certain of your proper time, hold a flame over the air-hole
at the top. If the flame is drawn strongly down for a continuance,
without whiffling, you may begin to kindle a fire.
First put in a few charcoals on the grate H.
Lay some small sticks on the charcoals,
Lay some pieces of paper on the sticks,
Kindle the paper with a candle,
Then shut down the top, and the air will pass down through the
air-hole, blow the flame of the paper down through the sticks, kindle
them, and their flame passing lower kindles the charcoal.
When the charcoal is well kindled, lay on it the sea-coals, observing
not to choak the fire by putting on too much at first.
The flame descending through the hole in the bottom of the vase,
and that in plate D into the box C, passes down farther through the
grate W W in plate B 1, then passes horizontally towards the back of
the chimney; there dividing, and turning to the right and left, one
part of it passes round the far end of the partition 2, then coming
forward it turns round the near end of partition 1, then moving
backward it arrives at the opening into the bottom of one of the
upright corner funnels behind the niche, through which it ascends
into the chimney, thus heating that half of the box and that side of
the niche. The other part of the divided flame passes round the far
end of partition 3, round the near end of partition 4, and so into
and up the other corner funnel, thus heating the other half of the
box, and the other side of the niche. The vase itself, and the box C
will also be very hot, and the air surrounding them being heated, and
rising, as it cannot get into the chimney, it spreads in the room,
colder air succeeding is warmed in its turn, rises and spreads, till
by the continual circulation the whole is warmed.
If you should have occasion to make your first fire at hours not
so convenient as those above mentioned, and when the chimney does
not draw, do not begin it in the vase, but in one or more of the
passages of the lower plate, first covering the mouth of the vase.
After the chimney has drawn a while with the fire thus low, and
begins to be a little warm, you may close those passages and kindle
another fire in the box C, leaving its sliding shutter a little open;
and when you find after some time that the chimney being warmed draws
forcibly, you may shut that passage, open your vase, and kindle your
fire there, as above directed. The chimney well warmed by the first
day's fire will continue to draw constantly all winter, if fires are
made daily.
You will, in the management of your fire, have need of the following
implements:
A pair of small light tongs, twelve or fifteen inches long, plate,
figure 13.
A light poker about the same length with a flat broad point, figure
14.
A rake to draw ashes out of the passages of the lower plate, where
the lighter kind escaping the ash-box will gather by degrees, and
perhaps once in a week or ten days require being removed, figure 15.
And a fork with its prongs wide enough to slip on the neck of the
vase cover, in order to raise and open it when hot, to put in fresh
coals, figure 16.
In the management of this stove there are certain precautions to
be observed, at first with attention, till they become habitual.
To avoid the inconvenience of smoke, see that the grate H be clear
before you begin to light a fresh fire. If you find it clogged with
cinders and ashes, turn it up with your tongs and let them fall upon
the grate below; the ashes will go through it, and the cinders may be
raked off and returned into the vase when you would burn them. Then
see that all the sliding plates are in their places and close shut,
that no air may enter the stove but through the round opening at the
top of the vase. And to avoid the inconvenience of dust from the
ashes, let the ash-drawer be taken out of the room to be emptied; and
when you rake the passages, do it when the draft of the air is strong
inwards, and put the ashes carefully into the ash-box, that remaining
in its place.
If, being about to go abroad, you would prevent your fire burning in
your absence, you may do it by taking the brass flame from the top
of the vase, and covering the passage with a round tin plate, which
will prevent the entry of more air than barely sufficient to keep a
few of the coals alive. When you return, though some hours absent, by
taking off the tin plate and admitting the air, your fire will soon
be recovered.
The effect of this machine, well managed, is to burn not only the
coals, but all the smoke of the coals, so that while the fire is
burning, if you go out and observe the top of your chimney, you will
see no smoke issuing, nor any thing but clear warm air, which as
usual makes the bodies seen through it appear waving.
But let none imagine from this, that it may be a cure for bad or
smoky chimneys, much less, that as it burns the smoke it may be used
in a room that has no chimney. It is by the help of a good chimney,
the higher the better, that it produces its effect; and though a
flue of plate iron sufficiently high might be raised in a very lofty
room, the management to prevent all disagreeable vapour would be too
nice for common practice, and small errors would have unpleasing
consequences.
It is certain that clean iron yields no offensive smell when heated.
Whatever of that kind you perceive, where there are iron stoves,
proceeds therefore from some foulness burning or fuming on their
surface. They should therefore never be spit upon, or greased, nor
should any dust be suffered to lie upon them. But as the greatest
care will not always prevent these things, it is well once a week
to wash the stove with soap lees and a brush, rinsing it with clean
water.
_The Advantages of this Stove._
1. The chimney does not grow foul, nor ever need sweeping; for as no
smoke enters it, no soot can form in it.
2. The air heated over common fires instantly quits the room and
goes up the chimney with the smoke; but in the stove, it is obliged
to descend in flame and pass through the long winding horizontal
passages, communicating its heat to a body of iron plate, which,
having thus time to receive the heat, communicates the same to the
air of the room, and thereby warms it to a greater degree.