Let me give you first a suggestion for summer ventilation. Did you ever shingle the south side of a barn on a calm, hot, sunny day in July, thermometer at ninety degrees in the shade? Did you ever lay your hand on a black slate or tin roof exposed to the direct rays of a midsummer sun? Have you ever, at the close of some hot, labor-spent day in August, sat out of doors until the evening air became deliciously cool, and then climbed to your attic dormitory, there to spend a sleepless night in perspiration and despair, anathematizing the man who built and the fate which compelled you to occupy such a chamber of torment?

Now, there is no good reason why the rooms immediately under the roof of a house should be any more uncomfortable on account of heat than those of the first story. Nay, more, by the simplest application of common-sense, these upper rooms may be so coolly ventilated that the hotter the sun pours his rays upon the roof the more salubrious shall be your palace in the sky. And this I call a triumph of genius, making the seemingly destructive wrath of the elements to serve and save us.

M. Figuier tells us with just how many hundred thousand horse-power the sun, by the caloric of its beams, operates upon the surface of the earth. I cannot tell precisely how much force is spent upon the roofs of the houses that cover so much of the good mother's bosom in certain localities, but I know that it is wonderfully great, and that rightly controlled it will make the s.p.a.ce immediately under these roofs cool instead of hot.

And this is the way to cause the heat of a burning sun to cool the attic chamber: Make the s.p.a.ce between the rafters on the sunny sides of your building as smooth and un.o.bstructed as possible. Arrange openings into the outer air at the lower end of each, simple or complex, according to your taste and ability. Provide also means for closing the same in cold weather. Be sure that these s.p.a.ces, or flues, are enclosed either by lath and plaster, or by smooth boards, quite to the highest part of the roof, whether your rooms are finished to the top or not,--and provided with an abundant outlet at the top. This may also be as simple as the dorsal breathing-holes of a tobacco barn, gorgeously imposing as an Oriental pinnacle, or it may be a part of the chimney; only let it be at the very summit, ample, and so arranged that an adverse wind shall not prevent the egress of the rising currents of air. Mind this, too; it is by no means the same thing to let these flues open into a loft over the attic rooms, with windows in gables or other outlet.

Now, do you not see that as soon as the sun has warmed the flues, there will be a stiff breeze blowing, not over the roof, but really between the roof and the house, and the hotter the sun the stiffer the breeze; in the words of one who has tried it,--"a perfect hurricane."

That is, the lath and plaster, or sheathing, which forms the inner roof, is shaded by a canopy of slate, shingles, or tin, and fanned by a constant breeze as cool at least as the outer air. But we can do vastly better than that. Instead of opening the lower ends of these flues to the outer air, they may be extended wherever the needs of the house require, or its construction will allow.

Let me remind you, under the head of general principles, that there is no such thing as "suction." Of course, you know it when you stop to think, but bear it in mind, and wherever the motive-power seems to be applied on which you rely to lift the column of air, remember that if raised at all it must be raised from the bottom. Maybe you will discover room for a moral here.

This summer ventilation is simple enough, and relates rather to comfort than to health. The great question in building, for New England and similar climates, is, indeed, how to keep our houses warm, and, without great expenditure of fuel, have a constant change of air.

As you suggest, we have learned that wood costs eight or ten dollars a cord instead of the mere labor of cutting and hauling; hence we have shut the mouths of the old-time fireplaces, mouths that it would cost a fortune to feed. We find the value of building-timber increasing every year; so we make thinner walls, lined outside and inside with paper, and have cold houses, no fresh air, anthracite coal, and disease. Our grandfathers carried foot-stoves to church, where they sat and shivered, sometimes with the cold, sometimes at the doctrines.

We have warm air and stale. Let us hope our children will have warmth and freshness for body and soul. They, in their homes, had big fireplaces, loose doors, rattling windows, cracks in the walls, and as they lay in bed looked at the stars through the c.h.i.n.ks in the roof, or felt the snow blow on their cheeks which were ruddy with health and vigor. We have cylinder stoves, double windows, tight walls plastered and papered, and pale faces.

[Ill.u.s.tration: GOOD OLD TIMES.]

Yet we build and furnish more wisely than our ancestors. They ventilated because they couldn't help it, couldn't afford to build as we do, and could afford to burn an acre of woodland every year.

It is no light task you have set me preliminary to an honorable discharge. Next to theology and government finance there is no subject on which the doctors differ and dogmatize as in this matter of warming and ventilating, most of them preferring that the universe should suffocate rather than their pet theories and furnaces be found wanting. (I'm not speaking of the theologians.)

Let me restate a few general principles, simple and obvious, yet so important that we must not risk forgetting them. Air runs away with heat fast enough if allowed to move. Confined it is a more effectual barrier than granite walls and plates of steel. Hence the s.p.a.ces in the wall should not extend its whole height unless for local ventilation. Cut them off surely at each floor, and as much oftener as you please; also make the floors tight and warm. Deafen with mortar if you can afford it, and do not allow the open s.p.a.ces between the floor-timbers to extend unbroken through the house, or fail to close them between the rafters when the ceiling of the highest story is above the plates. If you wish to warm the entire house, it will be good economy to lath and plaster along the under side of the rafters quite to the ridgepole. Finally put on your double windows, and you are ready for winter quarters.

In theory, the house being once warmed, the temperature within should scarcely change, even if the fire goes out. Practically, the walls cannot hold this subtile caloric, however scientifically they are padded. There will be crevices, too, though the prince of joiners builds your house, through which the warm air will escape. But replenishing this inevitable loss would be a small matter, if the breath of life were a needless luxury. Unless, however, we are willing to suck poison into our veins with every breath we draw, slow but sure,--poison expired from our lungs and emanating from our bodies, poisonous gases liberated by the combustion of fuel, poison dust and decay from the waste of inorganic material,--we must have a never-ceasing supply of fresh air around us everywhere and always. Now this incoming fluid, cold as ice, eats fuel like a hungry giant, yet we must receive it with open arms, and, as soon as fairly warmed, send it off through the ventilating flue, bearing whatever noxious elements may chance to be afloat, and, of course, much of the warmth we love and buy so dearly. We have then to supply these three sources of loss. Obviously for economy the two former must be prevented to the utmost, the latter rigidly controlled.

Thus far, except the old fogies who don't believe in ventilation, we can all travel together harmoniously. Now our way divides, the doctors begin to differ, and the patients begin to die.

The first fork is at the two modes of warming, direct and indirect.

The former includes stoves of all sorts,--sheet or cast iron, porcelain, soapstone, brick or pottery, box or cylinder, for wood or coal, air-tight, Franklin, "cannon," or base-burner, parlor cook or kitchen cook, charcoal basin, warming-pan or foot-stove,--anything in which you can build a fire. It includes open grates and fireplaces, ancient or modern, large or small; it includes steam-pipes, hot-water pipes, and stove-pipes; and last, but not least, steam-radiators, than which it has never entered into the heart of man to conceive anything more surprising and unaccountable,--flat, pin-cushiony things, big as a bedquilt, dangerous-looking hedgehoggy affairs, some huge and bungling, others frail and leaky, but radiators still. In brief, the heating apparatus, whatever it may be, stands in the room to be warmed.

By the indirect mode it is enclosed in a chamber more or less remote, commonly called a furnace, and made of brick, sheet-iron, or wood lined with tin. Into this chamber cold air is admitted from some source, and escapes by its own levity, usually through tin pipes, to the rooms where the heat is needed. Sometimes it is driven out by mechanical means.

The advocates of the latter indirect mode claim for it many advantages. It is apparently clean. There are no ashes to be taken up, no hearths to sweep, no andirons to polish, no stoves to black.

One fire will warm the entire house if well arranged, and, for a trump card, there may be a supply of fresh air straight from the north pole, but agreeably warmed, constantly entering the room.

The objections are less numerous but more weighty. The liability to imperfect construction and careless management often makes a furnace, especially a cast-iron one, a savor of death unto death rather than of health and comfort; also, when we are warmed by air thrown into a room at a high temperature, and dry at that, a greater degree of heat is necessary for comfort than if our bodies and clothing absorb heat from a radiating surface. The furnace, in short, compels us to breathe an atmosphere highly rarefied. We have the most careful and competent authority for believing this to be gravely injurious.

Direct radiation from stoves, or other heating apparatus, except open fireplaces, is, moreover, economical of fuel, but, on the other hand, unless abundant ventilation is provided, the atmosphere in rooms thus warmed soon becomes unfit for respiration.

Now you may stop and think. Next time you shall have the conclusion of the whole matter.

LETTER x.x.xIX.

From John.

HOW TO DO IT.

MY DEAR ARCHITECT: I'm in a hurry. Let me ask you a few square questions. Give me square answers if you can; if not, say so. What kind of a furnace shall I get? I've interviewed about a dozen; each one is warranted to give more heat, burn less coal, leak less gas, give less trouble and more satisfaction, than all the others put together. I suppose you object to cast-iron, because it's liable to be heated red-hot and burn the air.

Is wrought-iron any better?

Shall I put the registers in the floors or in the part.i.tions?

What do you say to steam?

How shall I ventilate?

Will it answer to have the ventilating flues in the outer walls?

There seems to be no doubt that the foul air should be drawn from the bottom of a room; but if it's cold, how am I to get it to the ventilator on the top of the house? If a room is as tight as a fruit-can, a chimney might draw like a yoke of oxen without doing any good, and Nebuchadnezzar's furnace wouldn't drive air into it unless, in both cases, the inlets and outlets were about equal! When I go to sleep in such a room I want to be sure the dampers won't get accidentally shut.

Give me your opinion on these points, but don't make a long story or a tough one. If a house is to be kept warm from turret to foundation-stone, I don't see that shutting up the s.p.a.ces between the timbers would amount to much, except to stop sounds from echoing through them; but when the attic is as cold as out-doors, it's plain that the cold air will be always crawling down next the inside plastering of every room in the house if it finds a chance.

Yours,

JOHN.

LETTER XL.

From the Architect.

THE BREATH OF LIFE.

DEAR JOHN: No man ever built himself a house without getting out of patience before it was finished.

Among all the furnaces you have examined, a certain one is doubtless better for you than any other; when I find out which one, you shall be informed. Reliable testimony on the subject can only be given by some one who has tried different kinds in the same house under similar circ.u.mstances for a considerable time. As we never have two seasons alike, and do have about three new first-cla.s.s furnaces every year, it is difficult to find this valuable witness. Printed testimonials are worth three or four cents per pound. I do not know that cast-iron furnaces are more liable to be overheated than others, and you cannot "burn the air" with them if they are, unless you burn the furnace too.

You may fill a room with air, every mouthful of which has been pa.s.sed between red-hot iron plates, not over half an inch apart, and I do not suppose the essential properties of the air will be perceptibly changed, or hurt for breathing when properly cooled.

The danger from cast-iron is in its weakness, not in its strength.

You speak of poison carbon. Carbonic acid is not poison. It is harmless as water,--just. It will choke you to death if you are immersed in it. Trying to breathe it in large quant.i.ties will strangle you. But we drink it with safety and pleasure, and may breathe a little of it, even as much as thirty per cent, for a short time, without serious harm. But carbonic oxide, which is also liberated from burning anthracite, is an active poison, and one per cent of it in the air we breathe may prove instantly fatal. Now it is fully proven that these gases laugh at cast-iron and pa.s.s through it freely whenever they choose. Wrought-iron plates are supposed to be more impervious.

The popular notion that foul air must be drawn from the bottom of a room is based, I think, upon a superficial knowledge of the weight of carbonic acid, an ignorance of the law of the diffusion of gases,--upon a realizing sense of the cost of coal, and an insensibility to the worth of fresh air. Even such unreliable witnesses as our senses a.s.sure us that the air at the top of a high room--say the upper gallery of an unventilated theatre--is far less salubrious, though not overheated, than that below. We know, too, how quickly the sulphurous gas that sometimes escapes from those warranted furnaces not only ascends through the tin pipes, but rises in the open stairway if it has a chance. The hurtful carbonaceous gases doubtless go with it, and are then diffused through the room.

The most forcible objection to allowing the air to escape through the ceiling is that it is a wanton waste, not only of heat, but of the fresh air that has just come from the north pole by way of the furnace and cold-air box, and which, by virtue of its warmth, goes in all its purity straight to the ceiling. Accordingly the heavy cold air lying near the floor and laden with poison must be drawn out through the ventilating flue, till the upper warmth and freshness fall gently on our heads, like heavenly blessings.

Let me digress here to answer another question. No, don't put your ventilating flues in the outer walls if you expect the air to rise through them in cold weather; for it will not, if they reach the moon, unless it is warmer than that lying at their base. You may as well expect water to rise from the cistern to the tank in the attic because the pipe runs there, as that air will rise simply because there is a pa.s.sage for it. Sometimes holes are made into the chimney-flues, but this is robbing the stoves or the fireplaces. It is better to build an independent flue so close that it shall always feel the heat from the black warm heart of the chimney, for warmed by some means it must be. Yet warm air does not choose to rise. It falls like lead unless lifted by something heavier than itself.

To return to the former point. When you can warm within a ventilating flue all the air pa.s.sing through it more economically than you can warm the same quant.i.ty in the room from which it is taken, then you may admit the air to feed this same flue near the bottom and perhaps save fuel; but I doubt whether the remaining air will be any purer than if an equal amount had been allowed to escape near the ceiling.

The answers to your square questions necessarily dovetail. The hot-air registers should always be in the part.i.tions if possible. It saves sweeping dust into the pipes; it saves cutting the carpets; it lessens the risk of a debilitating warm bath to people addicted to standing over them; it diffuses the heat more evenly through the room; and, owing to this better diffusion, there is less waste through the ventilating outlet at the top of the room, if it should be there.