A Guide To The Scientific Knowledge Of Things Familiar - novelonlinefull.com
You’re read light novel A Guide To The Scientific Knowledge Of Things Familiar Part 39 online at NovelOnlineFull.com. Please use the follow button to get notification about the latest chapter next time when you visit NovelOnlineFull.com. Use F11 button to read novel in full-screen(PC only). Drop by anytime you want to read free – fast – latest novel. It’s great if you could leave a comment, share your opinion about the new chapters, new novel with others on the internet. We’ll do our best to bring you the finest, latest novel everyday. Enjoy
Q. _Why is the TIN FOOT-WARMER covered with FLANNEL?_
A. 1st--To prevent the perspiration of the foot from taking off the _polish_ of the tin:
2ndly--Flannel is a _very bad conductor_; and, therefore, helps to keep the tin hot _longer_: and
3rdly--If the feet were _not protected_, the conducting surface of the tin _would feel painfully hot_.
Q. _What harm would it be if the POLISH of the tin were injured by the perspiration of our feet?_
A. _Polished_ tin throws off its heat _very slowly_; but dull, scratched, painted, or dirty tin, _throws off its heat very quickly_: if, therefore, the tin foot-warmer were to _lose its polish_, it would _get cold in a much shorter time_.
Q. _Why are FURNACES and stoves (where much HEAT is required) built of porous BRICK?_
A. As bricks are bad conductors, they _prevent the escape of heat_: and are, therefore, employed where great heat is required.
Q. _Why are FURNACE DOORS, &c. frequently COVERED with a paste of CLAY and SAND?_
A. Because this paste is a _very bad conductor of heat_; and, therefore, prevents the _escape of heat from the furnace_.
Q. _If a stove be placed in the MIDDLE of a room, should it be made of bricks or IRON?_
A. A stove in the _middle of a room_ should be made of _iron_; because iron is an _excellent conductor_, and rapidly communicates its heat to the air around.
Q. _Why does the Bible say, that G.o.d "giveth SNOW like WOOL?"_
A. As _snow is a very bad conductor of heat_, it protects vegetables and seeds from the frost and cold.
Q. _How does the non-conducting power of SNOW PROTECT VEGETABLES from the FROST and cold?_
A. As snow is a bad conductor, it prevents the _heat_ of the earth _from being drawn off_ by the cold air which rests upon it.
Q. _Why are WOOLLENS and FURS used in COLD weather for CLOTHING?_
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.
Q. _Do not woollens and furs actually IMPART heat to the body?_
A. No; they merely _prevent the heat of the body from escaping_.
Q. _Where would the heat ESCAPE to, if the body were NOT wrapped in wool or fur?_
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.
Q. _What then is the PRINc.i.p.aL USE of CLOTHING in winter-time?_
A. _To keep the body air-tight_; and prevent the _external air_ (or wind) from _coming into contact with it_, to absorb its heat.
Q. _Why are BEASTS COVERED with FUR, HAIR, or WOOL?_
A. Because fur, hair, and wool are very _slow conductors of heat_; and (as dumb animals cannot be clad like human beings) G.o.d has given them a _robe of hair_ or wool, to _keep them warm_.
Q. _Why are BIRDS covered with DOWN or FEATHERS?_
A. Because down and feathers are _very bad conductors of heat_; and (as birds cannot be clad like human beings) G.o.d has given them a _robe of feathers to keep them warm_.
Q. _Why are WOOL, FUR, HAIR, or FEATHERS such SLOW CONDUCTORS of heat?_
A. Because a _great quant.i.ty of air_ lurks entangled between their fibres; and _air is a very bad conductor of heat_.
Q. _If AIR be a BAD CONDUCTOR of heat, why should we not feel as warm WITHOUT clothing, as when we are wrapped in wool and fur?_
A. Because the air (which is cooler than our body) _is never at rest_; and, therefore, fresh particles (perpetually pa.s.sing over our body) _keep drawing off the heat little by little_.
Q. _Why does the ceaseless CHANGE of air tend to DECREASE the WARMTH of a naked body?_
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_.
Q. _Does the AIR (which encases a naked body) become by contact as WARM as the BODY itself?_
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 pa.s.ses on.
Q. _Why do we feel COLDER in WINDY WEATHER, than in a CALM day?_
A. Because (in windy weather) the particles of air _pa.s.s over us more rapidly_; and every _fresh_ particle takes from us _some_ portion of heat.
Q. _Show the wisdom of G.o.d in making the AIR a BAD CONDUCTOR._
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_.
