A Talk About Chimneys 
The Principle of Building Flues 
I am one of the trustees of a country church, and we 
have been greatly troubled with the draught of the 
furnace. Some advocate a new furnace. I think it 
may be the chimney that is at fault. The furnace is 
one that is admitted to need a good draft, as the flue 
in the furnace is not as direct to the chimney as some, 
I have a smaller furnace of the same make in my house. 
The chimney is about the same height, 40 feet or more 
above the grate, as the church chimney. I have about 
20 feet of horizontal pipe to the chimney and have no 
trouble with the draught, while the church has about 
20 feet of lO-inch pipe which has. a rise of three feeet 
in that length. The church chimney is 18 inches wide 
outside and contains two flues lined with tile. Origin- 
allly the "furnace only connected with one flue, but the 
gas was so bad sometimes with a south or southwest 
wind that an effort was made to improve the draught 
by knocking the tw'O flues into one at the bottom. The 
trouble is as bad as ever. How large a flue should a 
chimney have for a furnace of which the fire pot is 
about ,30 inches in diameter at the top (door)? Could 
two flues be expected to work well even if the united 
area was sufficient? The chimney stands on the south¬ 
west side of the building and is about as high as the 
roof. J. E. J, 
Canada. 
P LANNING FOR DRAFT.—Trouble from smoke 
or gas is quite frequently blamed on a furnace 
or stove, when in practically every case the trouble 
is with the chimney. No furnace has a draft of 
itself; it must be connected with an upright pipe, 
the chimney, to secure this. The purpose of the 
chimney is to create ithis draft and by so doing pro¬ 
vide a means for removing the gaseous products of 
combustion from the building, and 
at the same time provide a supply of 
fresh air containing oxygen to sup¬ 
port combustion in the fire-pot. 
PRINCIPLE OF COMBUSTION. 
—When a fire is built out of doors 
the air immediately over the fire be¬ 
comes heated, and is warmer than 
that surrounding it at a little dis¬ 
tance. As air becomes heated it 
expands and of course in expanding 
becomes lighter than the colder, 
denser air not directly over the fire. 
Being lighter, this Avarm air is dis¬ 
placed and forced upward by the 
cooler and heavier air siirrounding 
it, in the same way that a cork is 
forced to the top of a pail of water. 
As this fiesli air rushes in toward 
the fire the flame is supplied Avith 
oxygen from it, and in this AA’ay com¬ 
bustion is supported. By the time 
that the oxygen content of the air 
has been exhausted it has in turn 
become heated, and so is displaced 
Avith more fresh, cool air from the 
outside. This process is continuous 
and keeps up until the material 
burning is consumed, warm air be¬ 
ing forced upward from the center 
of the fire because of its lighter 
Aveight, and colder and heavier air 
rushing in from all sides to take 
its place. Observance of smoke col¬ 
umns on a calm day Avill verify this. 
NECESSITIES OF CONSTRUC¬ 
TION.—The action of the chimney 
is exactly the same, only perfected 
and refined. The bonfire used prac¬ 
tically all of its heat in creating 
the draught aboA-e it, Avhile the effort in chimney¬ 
building is to secure a good draft Avith the use of as 
little heat as possible. It has been found by experi¬ 
ments that heated air travels in spirals up the chim¬ 
ney, its path being similar fo the shape of a cork¬ 
screw. Consequently the round-lined chimneys are the 
best, as there is no AA’aste space in them, they have a 
small Avail surface to cool the ascending gase-s and 
if lined Avith tile they are smooth and offer little re¬ 
sistance to the upAvard fioAA’ of the Avarm air. In a 
chimney built Avith a square interior the corners are 
not used. This is shoAA'ii in Fig. G52, 1, the effective 
portion being represented by shading. The chimney 
having the oblong cross section. Fig. G52, 2, the usual 
construction, is the AA'oi'st of the lot, and should not 
be used unless its smallest dimension -is as great as 
the diameter of the pipe leading into it. The corners 
of this type of chimney, not having heated air floAV- 
ing upAAmrd in them, frequently permit of doAvn 
currents of cold aii", AA’hich still further reduce 
their efficiency. This may be one of the faults 
of the chimney mentioned by J. R. J .; cold air may 
be fioAving doAvn one of the fines, passing through 
the opening made betAveen them as in Fig. G52, 4, and 
mingling Avith the hot gases in the other and thus 
resulting in less air being forced through the fire 
and the consequent production of more coal gas— 
this being a product formed by burning coal Avith 
too small a supply of oxygen. Being combustible. 
RURAL NEW-YORKER 
when the supply of oxygen is increased the gas is 
burned, and instead of being a nuisance furnishes 
heat to the building. 
TIGHT WALLS NEEDED,—It, of course, goes 
without saying that a chimney should be built tight 
—every bit of air that gets into it Avithout first 
passing through the grates is dead loss. Strange as 
it may seem at first thought, it should also be built 
thick and AA'arm, and AA’here possible a protected 
position should be chosen for it. Where badly ex¬ 
posed for the whole length a double wall as indi¬ 
cated by the sketch Fig, G52, 3, is a help in keeping 
the interior warm. The draft is created in a chim¬ 
ney b.v the heated and therefore' lighter air column 
contained in it being forced upward by colder and 
heavier air entering through the grates and di.splac- 
ihg it. If the walls are so thin and cold that this heat 
is lost, the air column loses its buoyancy in propor¬ 
tion, and ceases to rise unless warmed by further 
heat from the fire, and this heat Ave Avish to use as 
fully as possible in AV'arming the rooms beloAA% in¬ 
stead of heating air in and around the chimney. 
HINDRANCES TO DRAFT.—Not only should a 
chimney be tight and Avarm, but it should be straight 
and smooth inside as Avell, extending from a good 
foundation in the ground to a point at least tAvo 
feet above the highest point of the roof near it. 
Straight because offsets and bends are very likely 
to clog with soot and fine a.shes carried up by the 
draught, smooth to lessen the resistance to the fioAV 
1393 
of cleaning aAvay soot or other obstructions to draft. 
SIZE OF CHIMNEY.—As to proper size of chim¬ 
ney flue. King tells us in “Progressive Furnace Heat¬ 
ing” that it .should be large enough to pass 300 feet 
of air for each pound of coal burned, a furnace 
burning IG pounds of coal per hour requiring 4800 
cubic feet of air in the same length of time for 
complete combustion of the coal. In general it is 
.safe to rely on the manufacturer.s’ judgment, as 
they have AA'orked things out quite closely, and a 
round tile-lined chimney, haA’ing the same diameter 
of the pipe connection on the furnace or a square 
chimney someAA-hat larger Avill usually be of suf¬ 
ficient size if the conditions above noted are cared 
for. The following table taken from the .same source 
is also helpful in determining proper flue sizes. 
It refers to chimneys of a height sufficient for the 
ordinary tAVo to three-story building. 
Equivalent cubic ft. 
Round Tile 
Rectangular 
Brick in¬ 
of space to be 
standard 
tile stand¬ 
side di¬ 
heated 
sizes 
ard sizes 
mensions 
inches 
inches 
inches 
10,000 
to 
15,000 
8 
SVjXSVi 
8X8 
15,000 
to 
25,000 
10 
81 / 2 x 13 
8X12 
25,000 
to 
40,000 
12 
1.3 X13 
12X12 
40,000 
to 
75,000 
IG 
13X18 
12x16 
75,000 
to 
125,000 
20 
18X18 
IG X16 
125,000 
to 
200,000 
24 
18X201/^ 
16X20 
Destruction of Roadside Trees in France by Retreating Germans, Fig. 654 
The column headed “Equivalent cubic feet of 
space to be heated” Avould be affected someAvhat 
by the amount of glass .surface, outside doors, etc., 
and if soft coal is to be used the author state.s 
that about 25% should be added 
to the flue ai*ea. The question of 
a successful chimney resolves it¬ 
self into one of providing every 
facility for the escape of the heated 
gases before their heat is lost, so 
that as little as po.ssible of the 
available heat of the fire is used in 
maintaining a draft, and at the 
same time preventing the entrance 
of cold air at any point except 
through the grates of the fire-pot, 
Avhere it is used to support combu.s- 
tion. Dampers should of course be 
provided, so that this draft can be 
controlled and lessened AA'heii it is 
desired to do so, but the chimney 
should be such that its full effect 
ma3' be had Avhen necessary. 
EOBKRT H. SMITH. 
Western Lambs Turned Into a Field of Corn and Soy Beans in Carroll Co., Ind. Fig. 655 
of the air current, and extending above the roof to 
prevent eddy currents from blOAving dOAvn it as 
indicated by the arroAvs in Fig. G52, 6. A stove or 
furnace connected to such a chimney is likely to 
belch out puffs of smoke and gases as gusts of Avind 
strike the chimnej' tops. Also, a chimney in such 
a position is quite likelj’ to be Avorse Avhen the Avind 
comes from a certain quarter. Tall trees near a 
chimney will frequently give the same effect; this is 
particularlj' true of evergreens. From the mention 
of the fact bj' J. B. ,T. that gas is verj' bad Avheu 
south or southAvest Avinds are bloAving, I am led to 
think that this maj’ be, at least, one .source of his 
trouble. Increased height might help, or the addi¬ 
tion of a top that alAA’ays SAving aAvay from the Avind, 
provided that the opening is large. Do not, Iioaa'- 
ever, attempt to use one of tliese tops AA’ith a re¬ 
stricted opening. 
REMOVING OBSTRUCTIONS.-During the use 
of chimneys through the Winter incrustations Avill 
gather on the inner surface that throxigh the Sum¬ 
mer .scale off and drop, sometimes partially or eu- 
tirel.y clo.sing the flue. Birds also frequently nest 
in them Avith the same effect. Stove pipes project¬ 
ing too far into the flue often re.sult in ixoor di'aught. 
Fig. 652, 5. When a chimney is straight enough to 
permit, a feAv pieces of brick or stones tied up in 
a burlap sack and pulled up and doAvn inside of 
the chimney bj’" means of a rope makes a good w^ay 
Another Fight with 
Trespassers 
T he story of the Noaa' England 
farmer and the Greek tres- 
pa.ssers on page 13.33 is matched. 
IMy oldest son lies in a local 
hospital Avith a 10 or 12-inch 
Avoxind and broken arm from 
a gunshot fired by an Italian 
pot-hunter Avhom he Avent to 
arrest for aiming the gun at his 
3 'ouuger brother a fexA' minutes be¬ 
fore. Avlio also AA’arned the repeate«I 
offender to leave the farm. The 
man's trial is postponed pending 
my .son's sufficient recovery to per¬ 
mit him to appear in court. The 
trial Avill be considerably delayed 
since the local able surgeon Avill take his patient 
to New York surgeons as soon as he ma.v be safelj' 
moved. 
An instant before the shot aatis fired the gun 
muzzle Avas at m 3 ' son's body. He SAA'ept the gun 
aside Avith his left hand and smashed the shooter 
to the ground Avith his right. The left arm Avas 
terribly torn from Avrist to elboAA', much flesh and 
skin being shot clean aAvay from the bone. The 
arteries flooded forth their tide until the boy's uncle 
tAvisted the patient's belt about the arm, Avhen he 
just made tlie trip home unaided, a third of a mile. 
When the shooter AA'ent doAA’n the 3 'ounger brother, 
15 years old and never in a fight before, tackled 
the miscreant Avith his left hand, raining bloAvs upon 
the face and head. The Avretch all but got up and 
to his gun again Avhen the uncle Avas free to help 
subdue him, Avhich he could not do until he had 
tAvisted the shoulder strap of his game bag tightly 
about his neck. The surgeons, the ambulance, the 
police, came quickly. It Avas a red afternoon. 
Our farm lies close to the toAvn, some of it Avithin 
the city line. For a half century Ave haA'e endured 
many depredations, not a little abuse, With some 
fortitude, if not alAvays AV'ith a SAveet spirit. No 
person ever asked hunting privilege but he had 
it. IMany assumed it Avithout asking. The shooting- 
up quite changed the programme. I promise all 
sensible and careful persons safety if they obtain 
