[Footnote 1: Read by Wm. C. Conant before the Polytechnic Association
of the American Institute, New York, May 10, 1883.]
I suppose that we all consider ourselves to be sufficiently impressed
with the importance of ventilation. If I should stop here to declaim
against foul exhalations, or to dwell upon the virtues of fresh air,
you might feel inclined to interrupt me by saying, "Oh, we know all
about that! If you have anything practical to advance, come to the
point." Gentlemen, I beg your pardon, but I must say that the great
fact concerning ventilation, as yet, is that its strongest advocates
are not conscious of one-half the seriousness of the subject; and the
second fact is that the supposed means of ventilation prescribed by
science _fail to secure it_.
This, then, is my point to-night--the supreme necessity, still urgent,
and _universally_ urgent, for a reformation of the breath of life. I
believe in a promised time when the days of a man's life shall again
be as the days of a tree. And next to the abolition of vice and sin, I
believe that the very grandest factor of such result must be an entire
disuse of obstructed air for the lungs. I propose to bring forward
some evidence of the necessity, and likewise of the possibility, of a
reform so radical and sweeping as this. The subject is too wide for
the occasion. I shall be able to read only extracts from what I have
prepared, in the few minutes that you can give with patience to my
unpracticed lecturing.
The best prescription that doctors have to give (when we are not too
far gone to take it) is to live out of doors. Why is this? Why is life
out of doors proverbially synonymous with robust health? Why is it
that a superior vitality, and a singular exemption from disease,
notoriously distinguish dwellers in the open air, by land or sea?
Without disparaging the virtues of exercise or of bracing temperature,
indispensable as these are for the recuperation of enfeebled
constitutions, we must admit that among the native and settled
inhabitants of the open air high health is the rule in warm climates
as well as in cold, and with the very laziest mortals that bask in the
sun, or loaf in the woods. The fact is that simple vegetative health
seems to be nearly independent of all other external conditions but
that of a pure natural diet for the lungs. Man in nature seems to
thrive as spontaneously as plants, by the free grace of air, earth,
and sun. On the other hand, the very diseases from which houses are
supposed to defend us--that most numerous class resulting from
colds--are the special scourge of the lives that are most carefully
shielded from their commonly supposed cause--exposure to the open air.
Those diseases diminish, and entirely disappear, just so far as
exposure in the pure and freely moving air becomes complete and
habitual. Soldiers, inured to camp life, catch cold if they once sleep
in a house; and, generally speaking, the inhabitants of the free air
contract colds _only_ by exposure to confined exhalations from their
own or other bodies, within the walls of houses. The explanation of
this is plain and simple: Carbonic acid detained within four walls
accumulates in place of the breath of life--oxygen--and narcotizes the
excretory function of the skin. The moment that this great and
continual vent of waste and impurity from the system is obstructed,
internal derangement ensues in every direction. All hands, so to
speak, are strained to extra duty to discharge the noxious
accumulation. The lungs labor to discharge the load thrown back upon
them, with hastened respiration, increased combustion, and feverish
heat. The pores of the mucous membrane in the nose, throat, alimentary
canal, or bronchial passages, are forced by an aggravated discharge
(or catarrh), and this congestive and inflammatory pressure is a fever
also. There is nothing of "cold" about it except as an auxiliary and
antecedent, in cases where an external chill has struck upon nerves
already half paralyzed by the universal narcotic--carbonic acid--which
house dwellers may be said to "smoke" perpetually.
So much for nerve-poison; but blood-poisoning is a still more terrible
characteristic of house-protected existence. It is now the almost
universal opinion of the medical profession that the whole class of
malarial and zymotic diseases that make such frightful progress and
havoc in the most civilized communities, are due to living germs with
which the exhalations of organic waste and decay are everywhere loaded
in inconceivable numbers. They are known to multiply themselves many
times over, every two or three hours. They swarm into the blood by
millions, through all the absorbents, especially those of the lungs,
that drink the atmosphere in which they are suffered to linger and
propagate. Mr. Dancer, the eminent microscopist, counted in a sample
from such an atmosphere a number of organized germs equivalent to
3,700,000 in the volume of air hourly inhaled by one person. That is
over 60,000 germs per minute, and about 2,000 in every breath. In the
blood, they still propagate, and feed, and grow, consuming its oxygen,
thus defeating its purification, and turning that stream of otherwise
healthful and invigorating nutrition into a stream of effete and
corrupt matter--a sewer rather than a river of life--or at best an
impoverished and impure supply for the support of existence.
The same pestilential but invisible hosts of bacteria, mustered and
bred in the close filthiness of Oriental cities, and jungles, swarm
out as Asiatic cholera on the wings of the wind, sweeping the wide
world with havoc. Settled on the tropical shores of the Eastern
Atlantic, they lie in wait for their victims in the sluggish and
terrible coast fever. On the western coast of the same ocean, perhaps
from some cause connected with oceanic or atmospheric currents, they
make devastating irruptions inland, as yellow fever, in every
direction where the walls of their enclosure are low enough to be
freely passed. These, let us remember, are all essentially the same
organic poison that is engendered _wherever_ life and death are plying
their perpetual game; and this, like Cleopatra's "worm, will do its
kind" in the veins of man, wherever obstructions, natural or
artificial, temporary or permanent, interfere with its prompt
diffusion in the vastness of the general atmosphere. Our "house of
life" stands generously open, for every "inmate bad" to come and go
through the absorbent, unquestioned, except in the stomach, where the
tangible poisons have to go by the act of swallowing and where they
are often challenged and ejected. It seems at first thought very
strange that we are not so well protected by natural instinct or
sensibility from the subtle poisons of the atmosphere as from those
that can affect us only by the voluntary act of swallowing. The
obvious explanation, however, of this apparent neglect is that Nature
protects us in general from gaseous poisons by her own system of
ventilation; and if, when we devise houses, necessarily excluding that
system, we fail to devise also a sufficient substitute for it, the
consequences of such negligence are as fairly due as when we swallow
tangible poison.
I have hitherto referred only to the _dispersion_ of poisonous
exhalations, as if the best and most necessary thing the atmosphere
can do for us were to dilute the dose to a comparatively harmless
potency. But this is now known to be not the true remedial process
with respect to the zymotic germs. The most wonderful achievement of
recent investigation reveals a philosophy of both bane and antidote
that astonishes us with its simplicity as much as with its efficiency.
At the moment when humanity stands aghast at the announcement that
germs are not destroyed by disinfectants, comes the counter discovery
that they are rendered harmless by oxygen. It seems that it makes no
difference, really, of what sort or from what source are the bacteria
that we take into the blood. The only material difference to us
depends on _the sort of atmosphere_ in which their hourly generations
are bred. For example, the bacteria _developed in confined air_, from
a simple infusion of hay, are found by experiment to be as capable of
generating that most terrible of blood poisoners, the malignant
pustule, as are the bacteria taken from the pustule itself.
On the other hand, the bacteria from the malignant pustule itself,
after propagating for a few hours in pure and free air, become a
perfectly harmless race, and are actually injected into the blood
with impunity. The explanation of the strange discovery is this--note
its extreme simplicity--bacteria bred in copious oxygen perish for
want of it as soon as they enter the blood vessels; whereas those
inured to an unventilated atmosphere for a few generations, which
means only a few hours, are prepared to thrive and propagate
infinitely within our veins; and that is the whole mystery of blood
poisoning and zymotic diseases. Taken in connection with the narcotic
or _nerve-poisoning_ power of carbonic acid (to which all the classes
of diseases resulting from colds are due), we have also in this simple
but grand discovery the whole mystery of the question with which we
set out--why free air is health, and why sickness is a purely domestic
product. The restitution of natural health to mankind demands only,
but demands absolutely, the constant diffusion in copious and
continuous floods of atmospheric oxygen, of the nerve-poisoning
carbonic acid of combustion (organic and inorganic), and of the
blood-poisoning bacteria of organic decomposition.
We find, then, as a matter both of experience and of philosophy, that
life or death, in the main and in the long run, turns on the single
pivot of atmospheric movement or obstruction. The resistance of mere
rising ground or dense vegetation to a free movement of the air from
low-lying levels performs an obstructive office similar to that of the
walls and roofs of houses, and with like effect. The invariable
condition of unhealthy _seasons_ and _days_ is a state of rarefaction
and stagnation of the atmosphere, when the poison-freighted vapor
cannot be lifted and dispersed, and every one complains of the sultry,
close, "muggy" (meaning _murky_) feeling of the air. Few reflect, when
fretted by the boisterous winds of March, upon the vital office they
perform in dispersing and sanitating the bacteria-laden exhalations
let loose by the first warmth from the soaked soil and the macerated
deposits of the former year.
The passing air, then, that we breathe so lightly, is on other
business, and carries a load we little think of, and that is not to be
trifled with. This grand carrier of nature, on business of life or
death, must not be detained, must not be hindered! or they who
interfere with the business by restraining walls and roofs will take
the consequences. It is a good deal like stopping a bullet, except as
to consciousness and suddenness of effect.
That men live at all in their obstructed and therefore poison-loaded
atmosphere, is a proof of the wonderful efficiency of the protective
economy of Nature within us; so wonderful, indeed, that few can
believe the fact of living to be consistent with the real existence of
such a deadly environment as science pretends to reveal. It is a
common impression, therefore, that actual results fail to justify the
alarm sounded by sanitarians. Hence the necessity for calling
attention at the outset to an ample and manifest equivalent for the
deadly dose of confined exhalations taken daily by all civilized men.
We perceive that that dose is not lost, like the Humboldt River, in a
"sink," but reappears, like the wide-sown grass, in a perennial and
universal crop of diseases, almost numberless and ever increasing in
number, peculiar to house-dwellers. The trail of these plagues stops
nowhere else; it leads straight to the imprisoned atmosphere in our
artificial inclosures, and there it ends. That marvelous protective
economy of Nature within us, to which we have referred, is no
perpetual guaranty against the consequences of our negligence; it is
only a limited reprieve, to afford space for repentance; and unless we
hasten to improve the day of grace, the suspended sentence comes down,
upon us at last with force the more accumulated by delay.
Now, therefore, the grand problem of sanitary science (almost
untouched, almost unrecognized) proves to be no other and no less than
this:
What can be done to remedy the obstructive nature of an inclosure, so
that its gaseous contents shall _move off_, and be replaced by pure
air, as freely, as rapidly, and as incessantly, as in the open
atmosphere?
It happens to be the most necessary preliminary in approaching this
problem, to show how _not_ to do it, for that, respectfully be it
spoken, is what we have hitherto practiced, as results abundantly
prove. Fallacies, both vulgar and scientific, obstruct our way. A
fundamental fallacy respects the very nature of the work, which is
supposed to be _to get in fresh air_. In point of fact, this care is
both unnecessary and comparatively useless. Take care of the bad air,
and the fresh air will take care of itself. Only make room for it, and
you cannot keep it out. On the other hand, unless you first make room
for it, you cannot keep it _in_; pump it in and blow it in as you may,
you only blow it _through_, as the Jordan flows comparatively
uncontaminated through the Dead Sea. This is a law of fluids that must
be kept in view. The pure air is quite as ready to get out as to get
in; while the air loaded with poisonous vapors is as sluggish as a
gorged serpent, and will not budge but on compulsion. Such compulsion
the grand system of wind _suction_, actuated by the sun, supplies on
the scale of the universe; and this we must imitate and adapt for our
more limited purposes.
It would seem as if we need not pause to notice so shallow though
common a notion as that which usually comes in right here, namely,
that confined air will move off somehow of itself, if you give it
liberty; being supposed to be much like a cat in a bag, wanting only a
hole to make its escape. Air is ponderable matter--as much so as
lead--and equally requires force of some kind to set it or keep it in
motion. But applied philosophy itself relies on a fallacious, or, at
best, inadequate source of motive power for ventilation. It gravely
prescribes ventilating flues and even holes, and promises us that the
warmed air within the house will rise through these flues and holes,
carrying its impurities away with it, from the pressure of the cooler
and denser air without. But we very well know that the best of flues
and chimneys will draw only by favor of lively fires or clear weather.
They fail us utterly when most needed, in warm and murky weather, when
the barometer is low, and the thin atmosphere drops, down its damp and
dirty contents, burying us to the chimney tops in a pestilent
congregation of vapors.
Nevertheless, so far as I can discover, these holes and flues, at best
a little fire at the bottom of the latter, are the sole and
all-sufficient expedients of science and architecture for ventilation
to this _day_, in spite of their total failure in experience. I can
find nothing in standard treatises or examples from philosophers or
architects, beyond a theoretical calculation on so much expansion of
air from so many units of heat, and hence so much ascensional force
_inferred_ in the ventilating flue--a result which never comes to
pass, yet none the less continues to be cheerfully relied on.
Unfortunately for the facts, they contradict the philosophy, and are
only to be ignored with silent contempt. A French Academician's report
on the ventilation of a large public building, lately reprinted by the
Smithsonian Institution, states with absolute assurance and exactness
the cubic feet of air changed per minute, with the precise volume and
velocity of its ascension, by burning a peck of coal at the bottom of
the trunk flue. No mention is made of the anemometer or any other
gauge of the result asserted, and we are left to the suspicion that it
is merely a matter of theoretical inference, as usual; for every one
who has had any acquaintance with practical tests in these matters
knows that no such movement of air ever takes place under such
conditions, unless by exceptional favor of the weather.
I have seen a tall steam boiler chimney induce through a four inch
pipe a suction strong enough to exhaust the air from a large room as
fast as perfect ventilation would require. But this, it is well known,
requires four hundred or five hundred degrees of heat in the chimney.
I never saw an ordinary domestic fire of coals produce any noticeable
ventilating suction, without the use of a blower, urging the
combustion to fury, and I presume nobody else ever did.
But, while nobody ever saw an active suction of air produced by the
mere heat of a still or unexcited fire--unless the _quantity_ of heat
were on a very large scale--everybody has seen a roaring current
sucked through the narrowed throat of a chimney or a stove by a
blazing handful of shavings, paper, or straw. It is very remarkable,
when you come to think of it, that the burning of an insignificant
piece of paper, with less heat in it, perhaps, than a pea of
anthracite, will cause a rush of air that a bushel of anthracite
cannot in the least degree imitate. It is not only a curious but a
most important fact. In short, it is _the cardinal_ fact on which
ventilation practically turns. But what is the nature of it? There are
three factors in the phenomenon. In the first place, the mechanical
peculiarity of flame, or gas in the moment of combustion, as compared
with a gas like air merely heated, is _an almost explosive velocity of
ascent._ The physical peculiarity from which this results is the
intensity of its heat--commonly stated at 2,000 degrees, as to our
common illuminating gas--acting instantaneously throughout its mass,
just as in gunpowder. The gas goes up the flue in its own flash, like
the ignited charge in the barrel of a gun: the burning coals can only
_send_, and by a leisurely messenger, namely, the moderately heated
gases, and contiguous air, that rise only by the gravitation or
pressure of the surrounding atmosphere.
And yet it is not the small flame itself that roars in the chimney but
the rush of air induced by it. The semi-explosion of flame is but for
an instant, though constantly renewed, and its explosive impulse
cannot carry its light products of combustion very far through
stationary and resistant air. It is _the induction of air_ carried
with it by such semi-explosive impulse (under proper mechanical
conditions) that is strange to our observation and understanding, and
is the second factor in the phenomenon we are accounting for and
preparing to utilize.
The process, as it actually is, may be clearly exhibited by a very
simple means. Let anyone take a tube, say an inch in diameter--a roll
of paper will do as well as anything--and, applying it closely to his
mouth, try the whole force of his lungs through it upon any light
object. The amount of effect will be found surprisingly small; and
unless the tube is a short one, it will be so far absorbed by friction
and atmospheric resistance as to be almost imperceptible. Then let him
hold the same tube near to the mouth, but not in contact, and repeat
the experiment. With the best adjustment, the effect may be described
as tenfold or fifty-fold, or almost any fold--the effect of the simple
blowing being merely nominal as compared with the induced current
added by blowing _into_ the tube instead of _in_ it. The blast enters
the free and open orifice with all the contiguous air which its
surface friction and the vacuum of its movement can involve in its
rolling vortex. While the entrance is thus crowded with pressure, the
exit is free; and the result at the exit is a blast of well sustained
velocity and _magnified volume;_ ready itself to repeat the miracle on
a still larger scale if provided with the apparatus for doing so. To
test this, now place a second and larger tube in such position as to
prolong the first in a straight line, but with a slight interval
between the meeting ends; so that the blast, as magnified in volume in
entering the first tube, may enter in like manner the second tube and
be magnified again. With correct adjustments this experiment will
prove more surprising than the first. Put on a third and still larger
tube in the same way, and still larger surprise will meet a still
larger volume and force of blast, like a stiff breeze set in motion by
the puny effort of a single expiration. Of course, the prime impulse
must bear a certain proportion to the result; and the inductive or
tractional friction of the initial blast, of flame or breath, will be
used up at length unless re-enforced. In ventilating practice, there
_is_ such re-enforcement, from an excess of gravity in the cooler
atmosphere outside the flue in which the flame is operating with its
heat as well as its ascensional traction; so that there has been found
no limit to the extensions and fresh inductions that may be added to
the first or trunk flue, with increase rather than diminution of power
at every point. But the terms on which such extensions must be made
have been referred to in our illustration, and must be accurately
ascertained and observed. They constitute what is, in effect, the
third factor in the phenomenon of a roaring draught, and also,
therefore, ineffective ventilation. That is, the entering or induced
current of air must always find its channel of progress and exit
certain correct degrees larger than the opening by which it entered.
Every one knows that a stove or chimney wide open admits of but little
suction in connection with even the blaze of paper or shavings.
The mobility of air seems almost preternatural, when the proper
conditions for setting a current in motion are supplied. But without a
current established, it is surprising in turn to find how obstinately
and elusively immovable it can be. It is like tossing a feather; or
trying to drive a swarm of flies; dodging and evading every impulse
applied. But, given a flue, to define and conduct a stream; an upright
flue, to take advantage of the slighter gravity of the warmed air
within it; and a flue contracted at the inlet and expanded as it
rises, so as to free, diffuse, and lighten the column of air, toward
the exit; _then_, initiate an induced current of air at the inlet, by
the injection of a jet of gas in the state of semi-explosive action
called flame; the pressure pushing upward from the crowded entrance
finds easier way and less resistance the farther it goes in the
expanding flue; the warmth and reduced gravity of the stream comes in
as an auxiliary in overcoming friction and any exceptional obstruction
in the state of the atmosphere; and now, as the ball is once set
rolling, with a little _aid_ instead of resistance from gravitation,
its initial impulse all the while sustained by the gas jet, and
friction reduced to a very small incident--there is nothing to prevent
the current rolling on with accelerated velocity (within the
limitations imposed by increasing friction) and rolling on forever. I
might, if I had time, add a curious consideration of the law of
_vortex motion_ in elastic fluids, demonstrated by Helmholtz, which
relieves the motion of such fluids from friction, as wheels facilitate
the movement of a solid; and which also sucks into the rolling vortex
the contiguous air, thus entraining it, as we have seen, so much more
effectively than could be done by a direct and rigid current, like a
jet of water, for instance. A wheel set in motion on an almost
frictionless bearing of metalline, runs without perceptible abatement
of velocity, until one begins to involuntarily question whether it
will ever stop. In the all but free winds that roll with minimized
friction in the higher atmosphere, there seems to be a self-moving
force; so persistent is simple momentum in a mass so infinitesimally
obstructed and so infinitely wheeled. An active current of air in a
ventilating flue is only less perfect in the same conditions; and so
it is quite conceivable, and not incredible, that such a current may
be gradually established and thenceforward permanently maintained by a
small motor flame barely more than enough to overbalance the minimized
friction. This is not a supposed or theoretically inferred fact, like
the facts of ventilation sometimes alleged by theorists. On the
contrary, the theory I have offered is merely an attempt to explain
facts that I have witnessed and that anyone can verify with the
anemometer. But the _theory_ by no means covers the art and mystery of
ventilation; for ventilation is truly an _art_ as well as a mystery.
The art lies in a consummate experience of the sizes, proportions, and
forms of flues, their inlets, expansions, and exits, with many other
incidental adaptations necessary, in order to insure under _all_
circumstances the regular exhaustion of any specific volume of air
required, per minute. And this art has by one man been achieved. It
would be a double injustice if I should neglect from any motive to
inform my audience to whom I am indebted for what I know about
ventilation practically, and even for the knowledge that there is any
such fact as a practicable ventilation of houses; one who is no
theorist, but who has felt his way experimentally with his own hands,
for a lifetime, to a practical mastery of the art to which I have
attempted to fit a theory; every one present who is well informed on
this subject must have anticipated already in mind the name of Henry
A. Gouge.
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