Another cause is the too close vicinity of a hill or buildings higher than the top of the chimney, and the remedy for this is to raise the chimney.
Another cause is the descent, into unused fireplaces, of smoke from other chimneys near. The remedy is to close the throat of the unused chimney.
Another cause is a door opening toward the fireplace, on the same side of the room, so that its draught passes along the wall and makes a current that draws out the smoke. The remedy is to change the hanging of the door so as to open another way.
Another cause is strong winds. The remedy is a turn-cap on top of the chimney.
Another cause is the roughness of the inside of a chimney, or projections which impede the passage of the smoke. Every chimney should be built of equal dimensions from bottom to top, with no projections into it, with as few bends as possible, and with the surface of the inside as smooth as possible.
Another cause of poor draughts is openings into the chimney of chambers for stove-pipes. The remedy is to close them, or insert stove-pipes that are in use.
Another cause is the falling out of brick in some part of the chimney so that outer air is admitted. The remedy is to close the opening.
The draught of a stove may be affected by most of these causes. It also demands that the fireplace have a tight fire-board, or that the throat he carefully filled. For neglecting this, many a good stove has been thrown aside and a poor one taken in its place.
If all young women had committed to memory these causes of evil and their remedies, many a badly-built chimney might have been cured, and many smoke-drawn tears, sighs, ill-tempers, and irritating words avoided.
But there are dangers in this direction which demand special attention. Where one flue has two stoves or fireplaces, in rooms one above the other, in certain states of the atmosphere, the lower room, being the warmer, the colder air and carbonic acid in the room above will pass down into the lower room through the opening for the stove or the fireplace.
This occurred not long since in a boarding-school, when the gas in a room above flowed into a lower one, and suffocated several to death. This room had no mode of ventilation, and several persons slept in it, and were thus stifled. Professor Brewer states a similar case in the family of a relative. An anthracite stove was used in the upper room; and on one still, close night, the gas from this stove descended through the flue and the opening into a room below, and stifled two persons to insensibility, though, by proper efforts, their lives were saved. Many such cases have occurred where rooms have been thus filled with poisonous gases, and servants and children destroyed, or their constitutions injured, simply because housekeepers are not properly instructed in this important branch of their profession.
FURNACES.
There is no improved mechanism in the economy of domestic life requiring more intelligent management than furnaces. Let us then consider some of the principles involved.
The earth is heated by radiation from the sun. The air is not warmed by the passage of the sun's heat through it, but by convection from the earth, in the same way that it is warmed by the surfaces of stoves. The lower stratum of air is warmed by the earth and by objects which have been warmed by radiated heat from the sun. The particles of air thus heated expand, become lighter, and rise, being replaced by the descent of the cooler and heavier particles from above, which, on being warmed also rise, and give place to others. Owing to this process, the air is warmest nearest the earth, and grows cooler as height increases.
The air has a strong attraction for water, and always holds a certain quantity as invisible vapor. The warmer the air, the more moisture it demands, and it will draw it from all objects within reach. The air holds water according to its temperature. Thus, at fifty-two degrees, Fahrenheit's thermometer, it holds half the moisture it can sustain; but at thirty-six degrees, it will hold only one eighty-sixth part. The earth and all plants and trees are constantly sending out moisture; and when the air has received all it can hold, without depositing it as dew, it is said to be saturated, and the point of temperature at which dew begins to form, by condensation, upon the surface of the earth and its vegetation, is called the dew-point. When air, at a given temperature, has only forty per cent of the moisture it requires for saturation, it is said to be dry. In a hot summer day, the air will hold far more moisture than in cool days. In summer, out-door air rarely holds less than half its volume of water. In 1838, at Cambridge, Massachusetts, and New-Haven, Connecticut, at seventy degrees, Fahrenheit, the air held eighty per cent of moisture.
In New Orleans, the air often retains ninety per cent of the moisture it is capable of holding; and in cool days at the North, in foggy weather, the air is sometimes wholly saturated.
When air holds all the moisture it can, without depositing dew, its moisture is called 100. When it holds three fourths of this, it is said to be at seventy-five per cent. When it holds only one half, it is at fifty per cent. When it holds only one fourth, it is at twenty-five per cent, etc.
Sanitary observers teach that the proper amount of moisture in the air ranges from forty to seventy per cent of saturation.
Now, furnaces, which are of course used only in winter, receive outside air at a low temperature, holding little moisture; This it sucks up, like a sponge, from the walls and furniture of a house. If it is taken into the human lungs, it draws much of its required moisture from the body, often causing dryness of lips and throat, and painfully affecting the lungs. Prof. Brewer, of the Scientific School of New-Haven, who has experimented extensively on this subject, states that, while forty per cent of moisture is needed in air to make it healthful, most stoves and furnaces do not, by any contrivances, supply one half of this, or not twenty per cent. He says most furnace-heated air is dryer than is ever breathed in the hottest deserts of Sahara.
Thus, for want of proper instruction, most American housekeepers not only poison their families with carbonic acid and starve them for want of oxygen, but also diminish health and comfort for want of a due supply of moisture in the air. And often when a remedy is sought, by evaporating water in the furnace, it is without knowing that the amount evaporated depends, not on the quantity of water in the vessel, but on the extent of evaporating surface exposed to the air. A quart of water in a wide shallow pan will give more moisture than two gallons with a small surface exposed to heat.
There is also no little wise economy in expense attained by keeping a proper supply of moisture in the air. For it is found that the body radiates its heat less in moist than in dry air, so that a person feels as warm at a lower temperature when the air has a proper supply of moisture, as in a much higher temperature of dry air. Of course, less fuel is needed to warm a house when water is evaporated in stove and furnace-heated rooms. It is said by those who have experimented, that the saving in fuel is twenty per cent when the air is duly supplied with moisture.
There is a very ingenious instrument, called the hygrodeik, which indicates the exact amount of moisture in the air. It consists of two thermometers side by side, one of which has its bulb surrounded by floss-silk wrapping, which is kept constantly wet by communication with a cup of water near it. The water around the bulb evaporates just in proportion to the heat of the air around it. The changing of water to vapor draws heat from the nearest object, and this being the bulb of the thermometer, the mercury is cooled and sinks. Then the difference between the two thermometers shows the amount of moisture in the air by a pointer on a dial-plate constructed by simple mechanism for this purpose.
There is one very important matter in regard to the use of furnaces, which is thus stated by Professor Brewer:
"I think it is a well-established fact that carbonic oxide will pass through iron. It is always formed in great abundance in any anthracite fire, but especially in anthracite stoves and furnaces. Moreover, furnaces always leak, more or less; how much they leak depending on the care and skill with which they are managed. Carbonic oxide is much more poisonous than carbonic acid. Doubtless some carbonic oxide finds its way into all furnace-heated houses, especially where anthracite