We require in our houses an artificial temperate climate which shall
be uniform throughout, and at the same time we need a gentle movement
of air that shall supply the requirements of respiration without any
gusts, or draughts, or alternations of temperature. Everybody will
admit that these are fundamental _desiderata_, but whoever does so
becomes thereby a denouncer of open-grate fireplaces, and of every
system of heating which is dependent on any kind of stoves with
fuel burning in the rooms that are to be inhabited. All such devices
concentrate the heat in one part of each room, and demand the admission
of cold air from some other part or parts, thereby violating the
primary condition of uniform temperature. The usual proceeding effects
a specially outrageous violation of this, as I showed in the last
chapter.
I might have added domestic cleanliness among the _desiderata_;
but in the matter of fireplaces, the true-born Briton, in spite of
his fastidiousness in respect to shirt-collars, etc., is a devoted
worshiper of dirt. No matter how elegant his drawing-room, he must
defile it with a coal-scuttle, with dirty coals, poker, shovel, and
tongs, dirty ash-pit, dirty cinders, ashes, and dust, and he must amuse
himself by doing the dirty work of a stoker towards his “cheerful,
companionable, pokeable” open fire.
It is evident that, in order to completely fulfil the first-named
requirements, we must, in winter, supply our model residence with
fresh artificially-warmed air, and in summer with fresh cool air. How
is this to be done? An approach to a practical solution is afforded
by examining what is actually done under circumstances where the
ventilation problem presents the greatest possible difficulties, and
where, nevertheless, these difficulties have been effectually overcome.
Such a case is presented by a deep coal mine. Here we have a little
working world, inhabited by men and horses, deep in the bowels of
the earth, far away from the air that must be supplied in sufficient
quantities, not only to overcome the vitiation due to their own
breathing, but also to sweep out the deadly gaseous emanations from the
coal itself.
Imagine your dwelling-house buried a quarter of a mile of perpendicular
depth below the surface of the earth, and its walls giving off
suffocating and explosive gases in such quantities that steady and
abundant ventilation shall be a matter of life or death, and that in
spite of this it is made so far habitable that men who spend half their
days there retain robust health and live to green old age, and that
horses after remaining there day and night for many months actually
improve in condition. Imagine, further, that the house thus ventilated
has some hundreds of small, very low-roofed rooms, and a system of
passages or corridors with an united length of many miles, and that its
inhabitants count by hundreds.
Such dwellings being thus ventilated and rendered habitable for man and
beast, it is idle to dispute the practical possibility of supplying
fresh air of any given temperature to a mere box of brick or stone,
standing in the midst of the atmosphere, and containing but a few
passages and apartments.
The problem is solved in the coal-pit by simply and skilfully
controlling and directing the natural movements of unequally-heated
volumes of air. Complex mechanical devices for forcing the ventilation
by means of gigantic fan-wheels, etc., or by steam-jets, have been
tried, and are now generally abandoned. An inlet and an outlet are
provided, _and no air is allowed to pass inwards or outwards by any
other course than that which has been pre-arranged for the purposes of
efficient ventilation_. I place especial emphasis on this condition,
believing that its systematic violation is the primary cause of the
bungling muddle of our domestic ventilation.
Let us suppose that we are going to open a coal-pit to mine the coal
on a certain estate. We first ascertain the “dip” of the seam, or its
deviation from horizontality, and then start at the _lowest_ part,
not, as some suppose, at that part nearest to the surface. The reason
for this is obvious on a little reflection, for if we began at the
shallowest part of an ordinary water-bearing stratum we should have
to drive down under water; but, by beginning at the lowest part and
driving upwards, we can at once form a “sumpf,” or bottom receptacle,
to receive the drainage, and from which the accumulated water may be
pumped. This, however, is only by the way, and not directly connected
with our main subject, the ventilation.
In order to secure this, the modern practice is to sink two pits, “a
pair,” as they are called, side by side, at any convenient distance
from each other. If they are deep, it becomes necessary to commence
ventilation of the mere shafts themselves in the course of sinking.
This is done by driving an air-way—a horizontal tunnel from one to
the other, and then establishing an “upcast” in one of them by simply
lighting a fire there. This destroys the balance between the two
communicating columns of air; the cooler column in the shaft without a
fire, being heavier, falls against the lighter column, and pushes it up
just as the air is pushed up one leg of an =U= tube when we pour water
down the other. Even in this preliminary work, if the pits are so deep
that more than one air-way is driven, it is necessary to stop the upper
ways and leave only the lowest open, in order that the ventilation
shall not take a short and useless cut, as it does up our fireplace
openings.
Let us now suppose that the pair of pits are sunk down to the seam,
with a further extension below to form the water sumpf. There are two
chief modes of working a coal-seam: the “pillar and stall” and the
“long wall,” or more modern system. For present illustration, I select
the latter as the simplest in respect to ventilation. This method, as
ordinarily worked, consists essentially in first driving roads through
the coal, from the pits to the outer boundary of the area to be worked,
then cutting a cross road that shall connect these, thereby exposing a
“long wall” of coal, which, in working, is gradually cut away towards
the pits, the roof remaining behind being allowed to fall in.
Let us begin to do this by driving, first of all, two main roads, one
from each pit. It is evident that as we proceed in such burrowing, we
shall presently find ourselves in a _cul de sac_ so far away from the
outer air that suffocation is threatened. This will be equally the case
with both roads. Let us now drive a cross-cut from the end of each
main road, and thus establish a communication from the downcast shaft
through its road, then through the drift to the upcast road and pit.
But in order that the air shall take this roundabout course, we must
close the direct drift that we previously made between the two shafts,
or it will proceed by that shorter and easier course. Now we shall have
air throughout both our main roads, and we may drive on further, until
we are again stopped by approximate suffocation. When this occurs,
we make another cross-cut, but in order that it may act we must stop
the first one. So we go on until we reach the working, and then the
long wall itself becomes the cross communication, and through this
working-gallery the air sweeps freely and effectually.
In the above I have only considered the simplest possible elements of
the problem. The practical coal-pit in full working has a multitude
of intervening passages and “splits,” where the main current from the
downcast is divided, in order to proceed through the various streets
and lanes of the subterranean town as may be required, and these
divided currents are finally reunited ere they reach the upcast shaft
which casts them all out into the upper air.
In a colliery worked on the pillar and stall system—_i.e._, by taking
out the coal so as to leave a series of square chambers with pillars of
coal in the middle to support the roof—the windings of the air between
the multitude of passages is curiously complex, and its absolute
obedience to the commands of the mining engineer proves how completely
the most difficult problems of ventilation may be solved when ignorance
and prejudice are not permitted to bar the progress of the practical
applications of simple scientific principles.
Here the necessity of closing all false outlets is strikingly
demonstrated by the mechanism and working of the “stoppings” or
partitions that close all unrequired openings. The air in many pits has
to travel several miles in order to get from the downcast to the upcast
shaft, though they may be but a dozen yards apart. (Formerly the same
shaft served both for up and down cast, by making a wooden division
(a _brattice_) down the middle. This is now prohibited, on account
of serious accidents that have been caused by the fracture of the
_brattice_.)
But it would not do to carry the coal from the workings to the pit
by these sinuous air-courses. What, then, is done? A direct road is
made for the coal, but if it were left open, the air would choose
it: this is prevented by an arrangement similar to that of canal
locks. Valve-doors or “stoppings” are arranged in pairs, and when
the “hurrier” arrives with his _corve_, or pit carriage, one door is
opened, the other remaining shut; then the _corve_ is hurried into
the space between the doors, and the entry-door is closed; now the
exit-door is opened, and thus no continuous opening is ever permitted.
Only one such opening would derange the ventilation of the whole pit,
or of that portion fed by the split thus allowed to escape. It would,
in fact, correspond to the action of our open fireplaces in rendering
effective ventilation impossible.
The following, from the report of the Lords’ Committee on Accidents
in Coal Mines, 1849, illustrates the magnitude of the ventilation
arrangements then at work. In the Hetton Colliery there were two
downcast shafts and one upcast, the former about 12 feet and the latter
14 feet diameter. There were three furnaces at the bottom of the
upcast, each about 9 feet wide with about 4 feet length of grate-bars;
the depth of the upcast and one downcast 900 feet, and of the other
downcast 1056 feet. The quantity of air introduced by the action of
these furnaces was 168,560 cubic feet per minute, at a cost of about
eight tons of coal per day. The rate of motion of the air was 1097 feet
per minute (above 12 miles per hour). This whole current was divided by
splitting into 16 currents of about 11,000 cubic feet each per minute,
having, on an average, a course of 4¼ miles each. This distance was,
however, very irregular—the greatest length of course being 9-1/10
miles; total length 70 miles. Thus 168,560 cubic feet of air were
driven through these great distances at the rate of 12 miles per hour,
and at a cost of 8 tons of coal per day.
All these magnitudes are greatly increased in coal-mines of the present
time. As much as 250,000 cubic feet of air per minute are now passed
through the shafts of one mine.
The problem of domestic ventilation as compared with coal-pit
ventilation involves an additional requirement, that of warming, but
this does not at all increase the difficulty, and I even go so far as
to believe that cooling in summer may be added to warming in winter by
one and the same ventilating arrangement. As I am not a builder, and
claim no patent rights, the following must be regarded as a general
indication, not as a working specification, of my scheme for domestic
ventilation and the regulation of home climate.
The model house must have an upcast shaft, placed as nearly in the
middle of the building as possible, with which every room must
communicate either by a direct opening or through a lateral shaft. An
ordinary chimney built in the usual manner is all that is required to
form such a main shaft.
There must be no stoves nor any fireplaces in any room excepting the
kitchen, of which anon. All the windows must be made to fit closely,
as nearly air-tight as possible. No downcast shaft is required, the
pressure of the surrounding outer atmosphere being sufficient. Outside
of the house, or on the ground floor (on the north side, if possible),
should be a chamber heated by flues, hot air, steam, a suitable stove,
or water-pipes, and with one adjustable opening communicating with the
outer fresh air, and another on the opposite side connected by a shaft
or air-way with the hall of the ground floor and the general staircase.
Each room to have an opening at its upper part communicating with
the chimney, like an Arnott’s ventilator, and capable of adjustment
as regards area of aperture, and other openings of corresponding or
excessive combined area leading from the hall or staircase to the lower
part of the room. These may be covered with perforated zinc or wire
gauze, so that the air may enter in a gentle, broken stream.
All the outer house-doors must be double, _i.e._, with a porch or
vestibule, and only one of each pair of doors opened at once. These
should be well fitted, and the staircase air-tight. The kitchen to
communicate with the rest of the house by similar double doors, and the
kitchen fire to communicate directly with the upcast shaft or chimney
by as small a stove-pipe as practicable. The kitchen fire will thus
start the upcast and commence the draught of air from the warm chamber
through the house towards the several openings into the shaft. In cold
weather, this upcast action will be greatly reinforced and maintained
by the general warmth of all the air in the house, which itself will
bodily become an upcast shaft immediately the inner temperature exceeds
that of the air outside.
But the upcast of warm air can only take place by the admission of
fresh air through the heating chamber, thence to hall and staircase,
and thence onward through the rooms into the final shaft or chimney.
The openings into and out of the rooms being adjustable, they may be so
regulated that each shall receive an equal share of fresh warm air; or,
if desired, the bedroom chimney valves may be closed in the daytime,
and thus the heat economized by being used only for the day rooms; or,
_vice versâ_, the communication between the upcast shaft and the lower
rooms may be closed in the evening, and thus all the warm air be turned
into the bedrooms at bedtime.
If the area of the entrance apertures of the rooms exceeds that of the
outlet, only the latter need be adjusted; the room doors may, in fact,
be left wide open without any possibility of “draught,” beyond the
ventilation current, which is limited by the dimension of the opening
from the room into the shaft or chimney.
So far, for winter time, when the ventilation problem is the easiest,
because then the excess of inner warmth converts the whole house into
an upcast shaft, and the whole outer atmosphere becomes a downcast. In
the summer time, the kitchen fire would probably be insufficient to
secure a sufficiently active upcast.
To help this there should be in one of the upper rooms—say an
attic—an opening into the chimney secured by a small well-fitting
door; and altogether enclosed within the chimney a small automatic
slow-combustion stove (of which many were exhibited in South
Kensington, that require feeding but once in twenty-four hours), or a
large gas-burner. The heating-chamber below must now be converted into
a cooling chamber by an arrangement of wet cloths, presently to be
described, so that all the air entering the house shall be reduced in
temperature.
Or the winter course of ventilation may be reversed by building a
special shaft connected with the kitchen fire, which, in this case,
must not communicate with the house shaft. This special shaft may thus
be made an upcast, and the rooms supplied with air from above down the
house shaft, through the rooms, and out of the kitchen _viâ_ the winter
heating-chamber, which now has its communication with the outside air
closed.
Reverting to the first-named method, which I think is better than the
second, besides being less expensive, I must say a few concluding words
on an important supplementary advantage which is obtainable wherever
all the air entering the house passes through one opening, completely
under control, like that of our heating-chamber. The great evil of our
town atmosphere is its dirtiness. In the winter it is polluted with
soot particles; in the dry summer weather, the traffic and the wind
stir up and mix with it particles of dust, having a composition that
is better ignored, when we consider the quantity of horse-dung that is
dried and pulverized on our roadways. All the dust that falls on our
books and furniture was first suspended in the air we breathe inside
our rooms. Can we get rid of any practically important portion of this?
I am able to answer this question, not merely on theoretical grounds,
but as a result of practical experiments described in the following
chapter, in which is reprinted a paper I read at the Society of Arts,
March 19, 1879, recommending the enclosure of London back yards with
a roofing of “wall canvas,” or “paperhanger’s canvas,” so as to form
cheap conservatories. This canvas, which costs about threepence per
square yard, is a kind of coarse, strong, fluffy gauze, admitting light
and air, but acting very effectively as an air filter, by catching and
stopping the particles of soot and dust that are so fatal to urban
vegetation.
I propose, therefore, that this well-tried device should be applied at
the entrance aperture of our heating chamber, that the screens shall
be well wetted in the summer, in order to obtain the cooling effect of
evaporation, and in the winter shall be either wet or dry, as may be
found desirable. The Parliament House experiments prove that they are
good filters when wetted, and mine that they act similarly when dry.
By thus applying the principles of colliery ventilation to a
specially-constructed house, we may, I believe, obtain a perfectly
controllable indoor climate, with a range of variation not exceeding
four or five degrees between the warmest and the coldest part of the
house, or eight or nine degrees between summer and winter, and this
may be combined with an abundant supply of fresh air everywhere, all
filtered from the grosser portions of its irritant dust, which is
positively poisonous to delicate lungs, and damaging to all. The cost
of fuel would be far less than with existing arrangements, and the
labor of attending to the one or two fires and the valves would also
be less than that now required in the carrying of coal-scuttles, the
removal of ashes, the cleaning of fireplaces, and the curtains and
furniture they befoul by their escaping dust and smoke.
It is obvious that such a system of ventilation may even be applied
to existing houses by mending the ill-fitting windows, shutting up
the existing fire-holes, and using the chimneys as upcast shafts in
the manner above described. This may be done in the winter, when the
problem is easiest, and the demand for artificial climate the most
urgent; but I question the possibility of summer ventilation and
tempering of climate in anything short of a specially-built house
or a materially altered existing dwelling. There are doubtless some
exceptions to this, where the house happens to be specially suitable
and easily adapted, but in ordinary houses we must be content with the
ordinary devices of summer ventilation by doors and windows, plus the
upper openings of the rooms into the chimneys expanded to their full
capacity, and thus doing, even in summer, far better ventilating work
than the existing fire-holes opening in the wrong place.
I thus expound my own scheme, not because I believe it to be perfect,
but, on the contrary, as a suggestive project to be practically amended
and adapted by others better able than myself to carry out the details.
The feature that I think is novel and important is that of consciously
and avowedly applying to domestic ventilation the principles that have
been so successfully carried out in the far more difficult problem of
subterranean ventilation.
The dishonesty of the majority of the modern builders of suburban
“villa residences” is favorable to this and other similar radical
household reforms, as thousands of these wretched tenements must sooner
or later be pulled down, or will all come down together without any
pulling the next time we experience one of those earthquake tremors
which visit England about once in a century.