It is the popular idea, that because the body, and consequently the breath, is warmer than the ordinary temperature of a room, it rises and acc.u.mulates at the ceiling.
Upon this theory most of our buildings have been ventilated whenever any attention whatever has been given to the subject; but that theory is incorrect; consequently, all practice based thereon is also wrong.
This subject of the direction taken by the breath upon leaving the body, has been warmly discussed within a few years. It has been a very difficult matter to prove conclusively and satisfactorily, but I think we have devised some very simple experiments that will prove to you very clearly what we have stated.
I have here a simple gla.s.s tube two feet long and one and a half inch interior diameter; one end is closed with a rubber diaphragm, through which is pa.s.sed a small rubber tube--the other end is all open. We will rest this about horizontal, and taking a little smoke in the mouth, it will be discharged with the breath into the gla.s.s tube; it is first thrown towards the top, but it soon falls, and now see it flowing along the bottom of the tube like water--watch it as it reaches the far end--there, see it fall almost like water.
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Now, by raising the closed end of the pipe, you see we can pour it all out, and by filling it again and raising the other end, it falls back.
Thus you see that, notwithstanding the extra warmth in the breath, it is heavier than the atmosphere, and falls to the floor of an ordinary room like this, say, when the temperature is from 60 to 70. This is owing to the carbonic acid and moisture contained in it.
I have varied this experiment in a number of ways, by pa.s.sing it through smaller tubes and discharging it into the air in one or two seconds after leaving the lungs, and by pa.s.sing it through water of various temperatures, and discharging it into rooms of different temperatures, with the same general results. As the temperature of the air diminishes, the tendency of the discharged breath to rise increases. Much care is required in conducting these experiments, to avoid as much as possible, the local currents which are always present in a room.
This is a very important fact to be borne in mind; yet notwithstanding this, there are times, under certain circ.u.mstances, in which the foul air will be found in excess at the top of the room.
For the further examination of this subject, we have here a little gla.s.s-house with gla.s.s chimneys and fire-place in the first and second stories.
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As the flame of a candle is such a beautiful emblem of human life, we will remove the roof and part of the floor of the second story, and place four candles in our house. They are all of different heights, you see. We will call them a father, mother and two children.
As carbonic acid is that much dreaded poison in our breath, and the heavy portion of it which causes it to fall to the floor, we will make a little by placing a few sc.r.a.ps of common marble in this gla.s.s vessel, and pouring over it some sulphuric acid.
It is now forming, and will fall and flow across the floor the same as carbonic acid does when it pours into a bas.e.m.e.nt from the gutters on the street or filthy yards where it is formed, and before it is absorbed or diluted by the current of pure air sweeping over them.
It first kills the smallest child, because it is nearest the floor. You remember the excessive infantile mortality in this city in 1865. This is partially owing to their breathing more of this foul air near the floor, and partially owing to the great fear of their mothers and nurses, of letting the little innocents get a breath of fresh air for fear it will give them colic, and consequently they smother them to death.
The other child dies next, and then the mother, and lastly the father.
Thousands are thus poisoned to death by their own breath every year.
But did you ever see a physician"s certificate that gave you any such idea? Why do not the doctors tell the living, in such language as they can understand, what killed their friends, so they may avoid it in their own case, instead of giving it in some Latin terms which I fear many interpret to mean some special dispensation of Divine Providence instead of the true cause--their utter disregard of the laws their Creator made for the preservation of their health?
Had this family known enough about ventilation to have kept the fire-place open, with a little fire in it now and then, they would not have been thus killed.
Let us see--we will take out the fire-board which has been put in to make the room look a little neater, and with a very small light there to create a draft in the chimney.
We will again light the candles, and pour in the poisonous breath.
Ah! there goes the little one--he is hardly high enough to keep out of that deadly current flowing across the floor.
We shall have to let it in a little slower, or we will set him on a platform, as many persons who have carefully studied this subject, consider it judicious to do. Now, by the smoke from this taper, you can see the air is flowing across the floor and up the chimney.
There has been a steady current flowing in long enough to have filled the house, but the lights are all burning brightly, and you thus see the value of an open fire-place for ventilation. Thousands of lives are thus saved, and many more would be if all fire-places were kept open. I have recommended hundreds of fire-boards to be cut up for kindling-wood, as I consider this is the best use that can be made of all fire-boards.
Never stop up a fire-place in winter or summer, where any living being stays night or day. It would be about as absurd to take a piece of elegantly tinted court-plaster and stop up the nose, trusting to the accidental opening and shutting of the mouth for fresh air, because you thought it spoiled the looks of your face so to have two such great ugly-looking holes in it, as it is to stop your fire-place with elegantly tinted paper because you think it looks better.
If you are so fortunate as to have a fire-place in your room, paint it when not in use; put a bouquet of fresh flowers in every morning, if you please, or do anything to make it attractive; but never close it.
Now, there are other conditions in which a fire-place or an opening near the floor, will not answer for ventilation. This occurs in rooms where the air is made impure by burning lamps or gas, and where the fresh air entering the room is cooler than the temperature of the room itself.
To ill.u.s.trate this, we will put the roof on and take the entire floor away, or as it will be a little more convenient, we will represent it by this gla.s.s-house, using this shade for that purpose.
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This is supported some six inches from the floor, and has no bottom.
By lighting another candle and standing it outside, you can judge by comparison, of the foulness of the air inside.
The tallest one is affected first, this time. You see that is a perfectly formed light, but it gives but about half the light the one does on the outside; this is the way with many of us who are obliged to, or rather do, breathe foul air half the time.
We often think, by comparing ourselves with others around us, that we are pretty fair specimens of humanity, while really we do not give more than half the light in the world that we ought to do, and kill ourselves before our work is half done.
You see the two tallest are dead already, and the others will soon follow--there they go. Here is the bottom of the house removed, and yet these candles all went out for want of fresh air.
Therefore, when we see the air is made impure by burning candles or gas lights, owing to its exceeding heat, the foul air is mostly at the top of the room, and especially when the fresh air enters cooler than the air in the room. We will find, however, that in a very few minutes the candles will relight long before the contained air or the gla.s.s shade cools down to the temperature of the room.
The products of combustion, like those of respiration, are heavier than the ordinary atmosphere, and consequently fall to the floor very soon if not removed while very hot, by special openings immediately over them in the ceiling; after it has thus fallen, provision must be made for its removal from the level of the floor, in connection with the foul air from the breath.
I hope that by these few simple experiments, and the statistics presented here this evening, we have strengthened your previous convictions of the importance of fresh air, because we are well aware that you will find, as you proceed in your investigations of this subject, that it is frequently surrounded with complications; yet the laws governing the circulation of air of different temperatures, are as fixed and immovable as the laws governing the rising and setting of the sun, and with a very little careful investigation, can be easily understood.
And we believe no similar amount of money or thought, will produce a greater amount of satisfaction than the increased health, strength and happiness thus secured.
LECTURE II.
As I stated in our last lecture, much interest is being awakened, in this country and in Europe, by recent investigations showing the enormous numbers of untimely deaths that are caused throughout all cla.s.ses of society by foul air.
It would have been a startling announcement, ten years ago, to have stated that impure air caused as many deaths, and as much sickness, as all other causes combined, and yet the most diligent and accurate investigations are rapidly approaching that conclusion.
Few really comprehend the immense pecuniary loss, to say nothing of the amount of suffering, that we endure by this extra and easily preventible amount of sickness.
I propose, this evening, to enter upon the consideration of one of the most important parts of our subject--_the effect produced by_ HEAT _upon the movements of air_.
I think it probable that many of us do not comprehend the actual reality of the air.
We are apt to say of a room that has no carpet and furniture in it, that it has nothing in it, while, if it is full of air, it has a great deal in it.
A room between twenty-seven and twenty-eight feet square contains one ton of air--a real ton, just as heavy as a ton of coal. Now, there is not only twenty-seven feet, but more than twenty-seven miles of air piled on top of us. The pressure of the atmosphere at the level of the ocean is about fifteen pounds to the square inch. An ordinary sized man sustains a pressure of about fifteen tons, and were it not that this pressure is equal in all directions, we would be crushed thereby.
We must accustom our minds, therefore, to consider air a real substance, and that it is as totally unable to move itself, or to be moved, without _power_, as water or coal. It requires just as much power to move a ton of _air_ from the cellar to the second story, as it does a ton of coal.
Heat is the great moving power of air. Those whose attention has not been especially directed to the subject of the amount of power exerted by the sun"s rays upon the earth, have little conception of its magnitude.
The power of all the horses in the world, added to the power of all the locomotives, and of all the immense steam engines in all the world, express but a small fraction of the power exerted by the sun"s rays upon the earth. It is estimated to be sufficient to boil five cubic miles of ice-cold water every minute.
His rays are the chosen power of the Creator for moving all matter upon the globe. It is his rays that lie buried in the vast coal fields beneath the earth. His rays cause every spear of gra.s.s to grow, rear the mighty oak, form the rose, burst its beautiful buds, and send its perfume through the air.
No bird warbles its sweet music in the air, no insect breathes, save by his power, and all animals love to bask in the genial glow of his light and heat. He rolls the scorching air of the tropics to frozen lands, and wafts the ships across the seas. He forces the heated waters of the equator to the poles, tempering all the earth. He lifts the water from the sea to sprinkle all the land and cap the distant mountains with eternal snow.