A. Because they are very bad conductors of heat; and, therefore, prevent the warmth of the body from being drawn off by the cold air.

A. No; they merely prevent the heat of the body from escaping.

A. The heat of the body would fly off into the air; for the cold air (coming into contact with our body) would gradually draw away its heat, till it was as cold as the air itself.

A. To keep the body air-tight; and prevent the external air (or wind) from coming into contact with it, to absorb its heat.

A. Because fur, hair, and wool are very slow conductors of heat; and (as dumb animals cannot be clad like human beings) God has given them a robe of hair or wool, to keep them warm.

A. Because down and feathers are very bad conductors of heat; and (as birds cannot be clad like human beings) God has given them a robe of feathers to keep them warm.

A. Because a great quantity of air lurks entangled between their fibres; and air is a very bad conductor of heat.

A. Because the air (which is cooler than our body) is never at rest; and, therefore, fresh particles (perpetually passing over our body) keep drawing off the heat little by little.

A. Thus:—the air which cases the body absorbs as much heat from it as it can, while it remains in contact; it is then blown away, and makes room for a fresh coat of air, which does the same.

A. It would do so, if it remained motionless; but as it remains only a very short time, it absorbs as much heat as it can in the time, and passes on.

A. Because (in windy weather) the particles of air pass over us more rapidly; and every fresh particle takes from us some portion of heat.

A. If air were a good conductor (like iron and stone) the heat would be drawn so rapidly from our body, that we must be chilled to death. Similar evils would be felt also by all the animal and vegetable world.

A. Yes; touch your tongue against the shell at the larger end; if it feels warm to the tongue, the egg is stale; if not, it is new-laid.

A. Between the shell and the “white of the egg” there is a small quantity of air, which expands in a stale egg, from the shrinking of the white.

A. As air is a very bad conductor, the more air an egg contains, the less heat will be drawn from the tongue when it touches the shell.

A. The fan puts the air in motion, and makes it pass more rapidly over their face; and (as the temperature of the air is always lower than that of the human face) each puff of air carries off some portion of heat from the face.

A. No; fanning makes the air hotter and hotter.

A. By causing the air continually to absorb heat from the human body which it passes over.

A. Fanning makes the air hotter, but the face cooler; because it keeps taking the heat out of the face, and giving it to the air.

A. The breath causes a rapid change of air to pass over the broth; and (as the air is not so hot as the broth) it keeps absorbing heat, and thus makes the broth cooler and cooler.

A. No; air is a very bad conductor; unless, therefore, the change be rapid, the air nearest the surface of the broth would soon become as hot as the broth itself.

A. No; not instantly. Air is so bad a conductor, that it parts with its heat very slowly: unless, therefore, the air be kept in continual motion, it would cool the broth very slowly indeed.

A. Wind is only air in motion; and the more quickly the air passes over our body, the more rapidly it absorbs the heat therefrom.

A. Because every fresh gust of air absorbs a fresh portion of heat; and the more rapid the succession of gusts, the greater will be the quantity of air absorbed.

A. No; if the air were hotter than our body, it would feel insufferably hot.

A. Because then the wind would add to the heat of our body, instead of diminishing it.

A. Not in this country: in the hottest summer’s day, the air is always 10 or 12 degrees cooler than the human body.

A. No; the power of conducting heat depends upon the continuity of matter; if the particles of which a thing is composed are not continuous, they have very little power to conduct heat.

A. Because the earth is a bad conductor of heat; and, therefore (although the ground be frozen) the frost never penetrates above an inch or two below the surface.

A. Because the earth is a bad conductor of heat; and, therefore, (although the surface be scorched with the burning sun) the intense heat cannot penetrate to the roots of the plants and trees.

A. If the heat and cold could penetrate the earth (as freely as the heat of a fire penetrates iron), the springs would be dried up in summer and frozen in winter, and all vegetation would perish.

A. As the earth is a bad conductor, the burning rays of the sun can penetrate only a few inches below the surface; in consequence of which, the springs of water are not affected.

A. 1st—Because the overhanging foliage screens off the rays of the sun:

2ndly—As the rays of the sun are warded off, the air (beneath the tree) is not heated by the reflection of the earth: and

3rdly—The leaves of trees, being non-conductors, allow no heat to penetrate through them.

A. The dry skin prevents the wind from penetrating to their body; and as the fur contains a quantity of air between its hairs (which soon becomes heated by the body) the Laplander is clad in a case of hot air, impervious to the cold and wind.

A. Linen is a much better conductor than cotton; and, therefore, (as soon as it touches the body) it more rapidly draws away the heat, and produces a sensation of cold.

A. The fine fibres of the cambric have a strong capillary attraction for moisture; and are excellent conductors of heat: thus the moisture and heat are both abstracted from the face, and a sensation of coolness is produced.

“Capillary attraction,” i. e. the attraction of a thread or hair. The wick of a candle is wet with grease, because the melted tallow runs up the cotton from capillary attraction.

A. The coarse fibres of cotton have much less capillary attraction, and are nothing like such good conductors as linen: and, therefore, wiping the face with a cotton handkerchief, increases the sensation of warmth.

A. To conduct heat, is to transmit it from one body to another through a conducting medium: to absorb heat, is to suck it up, as a sponge sucks up water.

A. Black cloth absorbs, but does not conduct heat: thus, if black cloth be laid in the sun, it will absorb the rays very rapidly; but if one end of the black cloth be made hot, it would not conduct the heat to the other end.

A. No; every good conductor of heat is a bad absorber of it; and no good absorber of heat can be a good conductor also.

A. No; iron is a good conductor, but a very bad absorber of heat.

A. Because the metal fender and fire-irons have very little capacity for absorbing heat; although they are soon made hot (by conduction), when placed in contact with the hot fire or stove.

A. The black soot absorbs heat very quickly from the fire, and the metal conducts it to the water.

A. Because the bottom and sides of a new kettle are clean and bright; but in an old kettle are covered with soot.

A. Bright metal does not absorb heat, but reflect it (i. e. throw the heat back again); and as the heat is thrown off from the surface of bright metal, therefore, a new kettle is longer boiling.

A. The black outer dress quickly absorbs heat from the sun, and conveys it to the body; and the white linen (being a bad absorbent) abstracts no heat from the warm body.

A. White throws off the heat of the sun by reflection, and is, therefore, a very bad absorbent of heat; in consequence of which, it never becomes so hot from the scorching sun as dark colours do.

A. White will not absorb heat, like black and other dark colours; and, therefore, white dresses are not so warm as dark ones.

A. For outside garments black is the warmest, and then such colours as approach nearest to black (as dark blue and green). White is the coldest colour for external clothing.

A. Because dark colours absorb heat from the sun more abundantly than light ones.

A. If a piece of black cloth and a piece of white were laid upon snow, in a few hours the black cloth will have melted the snow beneath; whereas the white cloth will have produced little or no effect upon it at all.

N. B. The darker any colour is, the warmer it is, because it is a better absorbent of heat. The order may be thus arranged:—1. Black (warmest of all).—2. Violet.—3. Indigo.—4. Blue.—5. Green.—6. Red.—8. Yellow: and 9. White (coldest of all).

A. 1st—Because the black absorbs the solar heat: and

2ndly—The kid will not allow the heat of the hand to escape through the glove.

A. 1st—Because thread absorbs the perspiration of the hands: and

2ndly—It conducts away the heat of our hot hands.

A. As Lisle thread gloves are generally of a grey or lilac colour, they do not absorb solar heat.

A. Bright tin reflects (or throws back) the heat, which issues from the fire in rays; and (by reflecting the heat upon the meat) assists greatly in roasting it.

A. If the tin reflector were painted, it would be utterly spoiled, because it would then absorb heat, and not reflect it at all. A plate-warmer should be kept very clean, bright, and free from all scratches.

A. If a reflector be spotted, dull, or scratched, it will absorb heat, instead of reflecting it; and, therefore, would be of no use whatsoever as a reflector.

A. Tomb-stones being white, will not absorb heat, like the darker grass and gravel; and, therefore, the white tombstones (being so much colder) retain the hoar-frost after it has melted from other things.

A. Though the black skin of the negro absorbs heat more plentifully than the white skin of a European, yet the blackness prevents the sun from blistering or scorching it.

A. If you put a white glove on one hand, and a black glove on the other (when the sun is burning hot), the hand with the white glove will be scorched, but not the other.

A. The hand with the black glove will feel the hotter, but it will not be scorched by the sun; whereas the hand with the white glove (though much cooler) will be severely scorched.

A. Because the black colour absorbs the heat,—conveys it below the surface of the skin, and converts it to sensible heat and perspiration.

A. Because the white will not absorb the heat; and, therefore, the hot sun rests on the surface of the skin, and scorches it.

A. The black colour of a negro’s eyes defends them from the strong light of the tropical sun. If a negro’s eyes were not black, the sun would scorch them, and every negro would be blind.

A. Because bright metal will not absorb the heat of the summer sun, like an earthen vessel.

A. Because bright tin will not suffer the heat of the boiling water to escape in rays, as an earthen vessel does.

A. To reflect heat, is to throw it back in rays from the surface of the reflecting body, towards the place from whence it came.

A. All bright surfaces, and light colours.

A. No; those things which absorb heat best, reflect heat worst; and those which reflect heat worst, absorb it best.

A. Because if any thing sucks in heat like a sponge, it cannot throw it off from its surface; and if any thing throws off heat from its surface, it cannot drink it in.

A. Because light coloured and highly polished metal makes the best of all reflectors.

A. Because the bright tin front throws the heat of the fire back again, and will not allow it to penetrate to the wood behind.

A. Polished metal is a conductor of heat, only when that heat is communicated by actual contact; but whenever heat falls upon bright metal in rays, it is reflected back again, and the metal remains quite cool.

A. If a piece of tin were thrust into a fire, it would be in actual contact with the fire; but if it be held before a fire, the heat of the fire falls upon it in rays.

A. The tin reflector throws the heat of the fire back upon the meat; and, therefore, assists the process of roasting and helps to keep the kitchen cool.

A. Because it confines the heat to the hearth, and prevents it from being dispersed throughout the kitchen.

A. As glass is a reflector, it reflects the heat of the lamp back upon the flame; in consequence of which, less carbon escapes unconsumed (as smoke).

A. 1st—Because dust absorbs heat: and

2ndly—As it destroys the blackness of our shoes, it prevents them from throwing off the heat of our feet in rays.

A. Glass is a reflector; and, therefore, throws the rays of the candle back into the room, and thus prevents our seeing into the road or street.

A. The pupil of the eye expands greatly, when persons are in the dark; and, therefore, when any one in the dark street looks into a light room, his dilated pupil sees every thing distinctly.

A. Air is heated by the reflection of the earth, and not by the rays of the sun; and, as there is no earth round a mountain-top to reflect heat, therefore, it remains intensely cold.

A. Radiation means the emission of rays: thus the sun radiates both light and heat; that is, it emits rays of light and heat in all directions.

A. When the two bodies are separated by a non-conducting medium: thus the sun radiates heat towards the earth, because the air comes between (which is a very bad conductor).

A. On the roughness of the radiating surface: thus if metal be scratched, its radiating power is increased, because the heat has more points to escape from.

A. Yes; and because burning fuel emits rays of heat, therefore we feel warm when we stand before a fire.

A. Because the fire radiates heat upon the face; which (not being covered) feels the effect immediately.

A. The rest of the body is covered with clothing, which (being a bad conductor of heat) prevents the same sudden and rapid transmission of heat to the skin.

A. Yes. Those substances which radiate most, also absorb most heat: and those which radiate least, also absorb the least heat.

A. Yes; all things radiate heat in some measure, but not equally well.

A. All dull and dark substances are good radiators of heat; but all light and polished substances are bad radiators of heat.

A. As polished metal is a very bad radiator of heat, it keeps the water hot much longer; and the hotter the water is, the better it “draws” the tea.

A. Because the heat of the water flies off so quickly through the dull black surface of the tea-pot, that the water is rapidly cooled, and will not “draw” the tea.

A. Yes; because they set it on the hob “to draw;” in which case, the little black tea-pot will make the best tea.

A. Because the black tea-pot will absorb heat plentifully from the fire, and keep the water boiling hot: whereas, a bright metal tea-pot (set upon the hob) would throw off the heat by reflection.

A. Yes; when the tea-pot is set on the hob “to draw,” the black earth is the best, because it absorbs heat: but when the tea-pot is not set on the hob, the bright metal is the best, because it radiates heat very slowly, and therefore keeps the water hot.

A. Because the bottom and back are covered with soot; and the black soot rapidly absorbs the heat of the glowing coals.

A. As they do not come in contact with the fire, they cannot absorb heat; and (being bright) they will not suffer the heat to escape by radiation.

A. All those parts which come in contact with the fire should be covered with soot, to absorb heat; but all the rest of the saucepan should be as bright as possible, to prevent the escape of heat by radiation.

A. Because on Saturday the front and top of the kettle are generally cleaned and polished; but the bottom and back of the kettle are never cleaned.

A. Because they come in contact with the fire, and (while they are covered with black soot) absorb heat freely from the burning coals.

A. Because polished metal will not radiate heat; and, therefore, (while the front and top of the kettle are well polished) the heat is kept in, and not suffered to escape by radiation.

A. White will not radiate heat: if, therefore, the inside of a boiler be white, the liquor in it is kept hot much longer.

A. Black soot is a very bad conductor of heat; and, therefore, the heat of the boiling water is some considerable time, before it gets through the soot which adheres to the bottom of the kettle.