CHAPTER XXII.

WIND.

Q. _What is WIND?_

A. Wind is _air in motion_.

Q. _What PUTS the air in motion, so as to produce WIND?_

A. The principal causes are the _variations of heat and cold_, produced by the succession of _day and night_, and the _four seasons_.

Q. _What effect has HEAT upon the air?_

A. Heat _rarefies_ the air, and causes it to _expand_.

Q. _How do you KNOW that heat causes the air to EXPAND?_

A. If a bladder _half full of air_ (tied tight round the neck), were laid before a _fire_, the heat of the fire would expand the air so much, that the bladder would soon be _entirely inflated_; (in this case, the air in the bladder is expanded to _twice its original bulk_, by the heat of the fire).

Q. _What EFFECT is produced upon air by RAREFACTION?_

A. It causes the air to _ascend through colder strata_, as a cork (put at the bottom of a basin of water) would ascend through the water.

Q. _How do you KNOW that rarefied air ASCENDS?_

A. When a boy sets fire to the cotton of his balloon, the flame _heats the air_ inside the balloon; and the air becomes _so light_, that it ascends, and _carries the balloon with it_.

Q. _What effect is produced upon AIR by COLD?_

A. Air is _condensed by cold_, or squeezed into a smaller compass; in consequence of which, _it becomes heavier_, and descends towards the ground.

Q. _How do you KNOW that air is CONDENSED by COLD?_

A. After the bladder is _fully inflated_, (by lying before the fire), if it be taken _away from the fire_, the bladder will _collapse_, and show that it is not half full.

Q. _What is meant by the bladder "COLLAPSING?"_

A. The skin will become _wrinkled, shrivelled, and flabby_, because there is not sufficient air inside to _fill it out_.

Q. _How do you KNOW that CONDENSED air will DESCEND?_

A. As soon as the cotton of the balloon _is burnt out_, the air inside becomes _cold again_, and the balloon _falls to the earth_.

Q. _Does the SUN HEAT the AIR as it does the EARTH?_

A. No; the air is _not heated by the rays of the sun_, because air (like water) is a very _bad conductor_.

Q. _How is the AIR HEATED?_

A. By _convection_, thus:--The _sun_ heats the _earth_, and the _earth_ heats the _air resting upon it_; the air thus heated _rises_, and is succeeded by _other air_, which is heated in a similar way, till _all is warmed_ by "convective currents."

Q. _What is meant by "CONVECTIVE CURRENTS of air?"_

A. Streams of air heated by the earth, which _rise upwards_ and _carry heat with them_, are called "convective currents" of hot air.

Q. _Is the air in a ROOM in perpetual motion, as the air ABROAD is?_

A. Yes; there are always _two currents of air_ in the room we occupy, one of _hot_ air flowing _out_ of the room, and another of _colder_ air flowing _into_ the room.

Q. _How do you KNOW, that there are these TWO currents of air in every occupied ROOM?_

A. If I hold a lighted candle near the crevice _at the top of the door_, the flame will be blown _outward_ (towards the _hall_); but if I hold the candle _at the bottom of the door_, the flame will be blown _inwards_ (into the _room_).

Q. _Why would the flame be blown OUTWARDS (towards the HALL), if the candle were held at the TOP of the door?_

A. Because as the air of the room is warmed by the fire, &c., _it ascends_; and (floating about the upper part of the room) some of it escapes _through the crevice_ at the _top of the door_, and thus produces a current of air _outwards_ (into the _hall_).

Q. _Why would the flame be blown INWARDS (into the ROOM), if the candle were held at the BOTTOM of the door?_

A. Because after the warm air of the room has ascended to the ceiling, or made its escape into the hall, &c., a partial _vacuum_ is made at the _bottom of the room_; and cold air (from the hall) _rushes under the door_ to supply the void.

Q. _What is meant by a "partial VACUUM being made, at the BOTTOM of the ROOM?"_

A. A vacuum means a place _from which the air has been taken_: and a "_partial_ vacuum" means, a place from which a _part of its air_ has been taken away. Thus when the air on the floor _ascends to the ceiling_, a partial vacuum is made _on the floor_.

Q. _And how is the VACUUM filled UP again?_

A. It is filled up by _colder air_, which rushes (under the _door_, and through the _window_ crevices) into the room.

Q. _Give me an ILLUSTRATION._

A. If I dip a pail into a pond and fill it with water, a hole (or vacuum) is made in the pond _as big as the pail_; but the moment I _draw the pail out_, the hole is _filled up_ by the water around.

Q. _Show how this illustration APPLIES._

A. The heated air which ascends from the bottom of a room, is as much _taken away_, as the water in the pail; and (as the void was instantly supplied by _other water in the pond_) so the _void of air is supplied_ by a current from _without_.

Q. _What is the CAUSE of WIND?_

A. The _sun_ heats the _earth_, and the _earth_ heats the _air resting upon it_; as the warm air ascends, the void is filled up by a _rush of cold air_ to the place, and this _rush of air_ we call WIND.

Q. _Does the WIND ALWAYS blow?_

A. Yes; there is always _some_ motion in the air; but the _violence_ of the motion is perpetually varying.

Q. _Why is there always SOME motion in the air?_

A. As the earth is _always turning round_, the vertical rays of the sun are always _varying_.

Q. _What do you mean by "the VERTICAL RAYS of the SUN?"_

A. The rays made at _noon-day_: when the sun is in a _direct line_ above any place, his rays are said to be "vertical" to that place.

Q. _How are the VERTICAL rays of the sun always VARYING?_

A. Suppose the brass meridian of a globe to represent the vertical rays of the sun; as you turn the globe round, _different parts_ of it will pass under the brass rim, in constant _succession_.

Q. _And is it NOON-DAY to the place over which the SUN is VERTICAL?_

A. Yes; as each place passes _under the brass meridian_, it is _noon-day_ to _one_ half, and _mid-night_ to the _other_.

Q. _Show how this ROTATION of the earth affects the AIR._

A. If we suppose the brass meridian to be the vertical sun, the whole column of air _beneath_ will be heated by the _noon-day rays_; that part which the sun has _left_, will become gradually _colder and colder_; and that part to which the sun is _approaching_, will grow constantly _warmer and warmer_.

Q. _Then there are THREE qualities of air about this spot?_

A. Yes; the air over the place which _has passed the meridian_ is _cooling_: the air under _the vertical sun_ is the _hottest_; and the air which is over the place _about to pass under the meridian_, is _increasing in heat_.

Q. _How does this VARIETY in the HEAT of AIR produce WIND?_

A. The air always seeks to _preserve an equilibrium_; so the _cold air_ rushes to the _void_, made by the _upward current of the warmer air_.

Q. _Why does not the wind ALWAYS BLOW ONE way, following the direction of the SUN?_

A. Because the direction of the wind is subject to perpetual interruptions from _hills and valleys_, _deserts and seas_.

Q. _How can HILLS and MOUNTAINS ALTER the course of the WIND?_

A. Suppose a wind, blowing from the north, comes to a mountain, as it cannot pass _through it_, it must either rush _back again_, or _fly off at one side_ (as a _marble_ when it strikes against a _wall_).

Q. _Do MOUNTAINS affect the wind in any OTHER way?_

A. Yes; many mountains are _capped with snow_, and the _warm air_ is _condensed_ as it comes in contact with them; but as soon as the _temperature of the wind_ is changed, its _direction_ may be changed also.

Suppose A B C to be _three columns of air_. A, the column of air which is _cooling down_; B, the column to which the _sun is vertical_; and C, the column which _is to be heated next_. In this case the _cold_ air of A will rush towards B C, because the air of B and C is _hotter_ than A. But suppose now C to be a _snow-capped mountain_. As the hot air of B reaches C, it is _chilled_; and (being now _colder_ than the air _behind_) it rushes _back again_ towards A, instead of following the sun.

Q. _How can the OCEAN affect the direction of the WIND?_

A. When the ocean rolls beneath the _vertical sun_, the water is _not made so hot_ as the _land_; and (as another _change of temperature_ is produced) another obstacle is offered to the _uniform direction of the wind_.

Q. _Why is not the WATER of the sea made so HOT by the vertical sun, as the surface of the LAND?_

A. 1st--Because the _evaporation_ of the sea is greater than that of the land:

2ndly--The waters are _never still_: and

3rdly--The rays of the sun strike _into_ the water, and are _not reflected from its surface_, as they are by _land_.

Q. _Why does the EVAPORATION of the sea prevent its surface from being HEATED by the vertical sun?_

A. As water _absorbs_ heat by being _converted into vapour_; the surface of the sea is continually _losing heat by evaporation_.

Q. _How does the MOTION of the sea prevent its surface from being HEATED by the vertical sun?_

A. As one portion is heated _it rolls away_, and is succeeded by _another_; and this constant motion prevents _one_ part of the sea from being heated _more than another_.

Q. _How is the WIND affected by the SEA?_

A. When air from the hot earth _reaches the sea_, it is often _condensed_, and either rushes _back again_, or else its violence is very greatly _abated_.

Q. _Do CLOUDS affect the WIND?_

A. Yes. As passing clouds screen the direct heat of the sun from the earth, they diminish the _rarefication of the air also_: and this is _another_ cause why neither the strength nor direction of the wind is _uniform_.

Q. _Would the winds blow regularly from east to west, if these OBSTRUCTIONS were REMOVED?_

A. Without doubt they would. If the whole earth were covered with _water_, the winds would always _follow the sun_, and blow from east to west. Their irregularity is owing to the interspersion of _sea and land_, and the irregularities of the earth's surface.

Q. _Do winds NEVER blow REGULARLY?_

A. Yes; in those parts of the world, where these obstructions do not exist; as on the Atlantic and Pacific Ocean, the winds are pretty uniform.

Q. _What are the winds, which blow over the ATLANTIC and PACIFIC Ocean, called?_

A. They are called "Trade Winds."

Q. _Why are they called TRADE WINDS?_

A. Because (as they blow uniformly in one direction) they are very convenient to those who _carry on trade_ by means of these oceans.

Q. _In what DIRECTION do the TRADE WINDS blow?_

A. That in the _northern_ hemisphere blows from the _north-east_: that in the _southern_ hemisphere from the _south-east_.

Q. _Why do they not blow from the FULL NORTH and SOUTH?_

A. Because the _polar current_, combining with the _equatorial current_, give the wind a _new direction_.

Q. _What is the CAUSE of the EQUATORIAL current?_

A. The rotation of the earth upon its axis.

Q. _What is the cause of the POLAR CURRENT?_

A. As the heat in the _torrid zone_ is always _greatest_, and at the _poles_ the _least_, therefore a constant current of air rushes _from the poles_ towards the _equator_.

Q. _How does the COMBINATION of these two currents give a new direction to them both?_

A. When these currents of air meet at the equator, they _clash together_, and fly off in a new direction.

Q. _Do trade winds blow from the north-east and south-east ALL the YEAR ROUND?_

A. Yes, _in the open sea_; that is, in the Atlantic and Pacific Oceans for about 30 degs. each side of the equator.

Q. _Do the TRADE WINDS blow uniformly from north-east and south-east in the INDIAN OCEAN?_

A. No; nor yet in those parts of the _Atlantic_ and _Pacific_ which _verge on the land_.

Q. _Why do not the trade winds blow uniformly from north-east and south-east in the INDIAN OCEAN?_

A. Because when Arabia, Persia, India, and China, are exposed to the enormous heat of their summer sun, the _air is so rarefied_, that the colder air from the south pole rushes _towards these nations_, and not to the _equator_; in consequence of which, a SOUTH-WEST wind is produced for _six months of the year_.

Q. _How does it blow for the OTHER 6 months?_

A. When the sun has left the _northern_ side of the equator for the _southern_, then the _southern part of the torrid zone_ is most heated; and the cold air from the north (rushing towards the southern tropic) is diverted to the NORTH-EAST, where it continues for the _other_ six months of the year.

Q. _What are the six-month trade winds called?_

A. They are called MONSOONS; and blow from the _north-east_ from September to April, and from the _south-west_ for the _other_ six months of the year.

Q. _Have WE any regular winds in ENGLAND?_

A. No; our island (having a _continent on one side_, and a _sea on the other_) has a most _variable_ climate.

Q. _Have the winds in England NO general direction throughout the year?_

A. We generally find that _easterly_ winds prevail during the _spring_ of the year, and _westerly_ winds are most common in the _summer_ and _autumn_.

S-West winds are most frequent in July and August. N-East winds in January, March, April, May, June; and most seldom in July, September, and December.

Q. _When are the WINDS in ENGLAND generally the HIGHEST?_

A. The winds in December and January are generally the highest. Those in February and November the next; and those in August and September the least boisterous.

Q. _Why are the winds of Europe generally HIGHEST in DECEMBER and JANUARY?_

A. Because the sun is _furthest south_ in those months; and (as the heat in these northern regions rapidly _decreases_) the _contrast between our temperature_ and that of the _torrid zone_ is greater in December and January, than in any _other_ two months throughout the year.

Q. _Why does this CONTRAST of heat increase the VIOLENCE of the WINDS?_

A. As the air always seeks to _preserve an equilibrium_, therefore the _greater the contrast_, the more violent will be the rush of air to _equalize_ the two volumes.

Q. _Why are the winds in Europe generally the most PLACID during the months of SEPTEMBER and AUGUST?_

A. August and September are our _warmest months_, when we approach nearer to the heat of the torrid zone than in any _other two months_; therefore, the air (to and from the equator) _moves with less velocity_ in our northern hemisphere.

Q. _Show the GOODNESS and WISDOM of GOD in the constant tendency of air to equilibrium._

A. If the cool air of the polar regions did not rush into the torrid zone, _it would become so hot_, that no human being could endure it. If (on the other hand) the hot air from the torrid zone did not modify the polar regions, they would soon become _insufferably cold_.

Q. _Why are EAST WINDS in England generally DRY?_

A. Because, as they come over the _vast continents_ of Asia and Europe, they absorb _very little water_.

Q. _Why does their imbibing so little water make them DRY winds?_

A. Being thirsty when they reach our island, they readily imbibe moisture from the air and clouds; and, therefore, _bring dry weather_.

Q. _Why is the NORTH WIND in England generally COLD?_

A. The north wind comes from the _polar regions_, over mountains of snow, and seas of ice; in consequence of which, it is very _cold_.

Q. _Why are NORTH WINDS in England generally DRY and biting?_

A. As they come from regions _colder than our own_, they are _warmed by the heat of our island_; and (as their temperature is raised) _they absorb moisture_ from every thing they touch; in consequence of which, they are both _dry and parching_.

Q. _Why is the SOUTH WIND generally WARM in England?_

A. The south wind comes over the hot sandy deserts of Africa, and is heated by the land it traverses.

Q. _Why does the SOUTH WIND often bring us RAIN?_

A. The south wind (being much _heated_ by the hot sands of Africa) _imbibes water very plentifully_, as it passes over the Mediterranean Sea and British Channel.

Q. _Why does the SATURATION of the south wind cause RAIN?_

A. As soon as it reaches our cold climate, _it is condensed_, and its vapour is squeezed out (as water from a wet sponge).

Q. _Why are WEST WINDS in England generally RAINY?_

A. The west winds come over the _Atlantic Ocean_, and are laden with _vapour_: if, therefore, they meet with the least _chill_, some of the vapour is squeezed out.

Q. _Why is a fine CLEAR DAY sometimes OVERCAST in a few minutes?_

A. Because some _sudden change of temperature_ has condensed the vapour of the air _into clouds_.

Q. _Why are CLOUDS sometimes DISSIPATED quite as suddenly?_

A. Because some _dry wind_ (blowing over the clouds) has _imbibed their moisture_, and carried it off in invisible vapour.

Q. _Why does a SOUTH-WEST wind bring us RAIN?_

A. As it comes from the _torrid zone_, and _crosses the ocean_, the hot wind is _laden with vapour_; and as some of the heat escapes (as soon as it reaches our northern island) the _vapour is condensed_, and precipitated as rain.

Q. _Why does a NORTH-EAST wind RARELY bring RAIN?_

A. As it comes from a climate _colder than our own_, its capacity for imbibing vapour is _increased_ when it reaches our island; in consequence of which, it _dries the air_, dispels the clouds, and promotes evaporation.

Q. _Why does WIND sometimes bring RAIN, and sometimes FINE weather?_

A. If the wind be _colder than the clouds_, it will condense their vapour into _rain_: if the wind be _warmer than the clouds_, it will _dissolve_ them, and cause them to disappear.

Q. _Why are MARCH winds DRY?_

A. Because they generally blow from the east or north-east; and, therefore, _sweep over the continent of Europe_.

Q. _What is the USE of MARCH winds?_

A. They _dry the soil_ (which is saturated with the floods of February), _break up the heavy clods_, and fit the land for the _seeds_ which are committed to it.

Q. _Why does "MARCH COME IN like a LION?"_

A. Because it comes in with _blustering east winds_, which are essential to dry the soil, which would otherwise _rot the seed_ committed to it.

Q. _Why does "MARCH GO OUT like a LAMB?"_

A. Because the water (evaporated by the high winds) falls again in _showers_ to fertilize the earth, and _breaks the violence of the winds_.

Q. _Why is it said that "A bushel of MARCH DUST is worth the king's ransom?"_

A. Because it indicates that there has been a continuance of _dry weather_; and unless _March be dry_, the seed will rot in the wet soil.

Q. _Why is it said "A DRY cold MARCH never BEGS BREAD?"_

A. Because the _dry cold winds_ of March prepare the soil for _seeds_, which germinate, and produce fruit in the autumn.

Q. _Why is it said that "A WET MARCH makes a SAD autumn?"_

A. Because, if _March be wet_, so much of the seed _rots in the ground_, that the autumn crops are spoiled.

Q. _Why is it said that "MARCH FLOWERS make NO summer BOWERS?"_

A. Because, if the _spring be very mild_, vegetation gets too forward, and is _pinched by the nightly frosts_, so as to produce neither fruits nor flowers.

Q. _Why is it said "A LATE SPRING makes a FRUITFUL YEAR?"_

A. Because if the vegetation of spring be _backward_, the frosty nights will _do no harm_; for the fruits and flowers will not put forth their tender shoots, till the nights become _too warm to injure them_.

Q. _Why is it said that "APRIL SHOWERS bring MAY FLOWERS?"_

A. Before seeds can germinate, _three_ things are essential:--Darkness, Heat, and Moisture. April showers supply the principal nourishment on which seeds depend for existence.

Q. _Does RAIN-water possess any fertilizing properties BESIDES that of mere MOISTURE?_

A. Yes; rain-water contains "AMMONIA," to which much of its fertilizing power may be attributed.

(Ammonia is a compound of nitrogen and hydrogen. Common hartshorn is only ammonia and water.)

Q. _Why has God made NOVEMBER a very RAINY month?_

A. Because the rain hastens the _putrefaction of the fallen leaves_, and this makes the earth fertile.

Q. _Why is there MORE rain FROM SEPTEMBER to MARCH than from March to September?_

A. From September to March, the temperature of the air is _constantly decreasing_; on which account, its _capacity for holding vapour_ is on the _decrease_, and the vapour is precipitated as rain.

Q. _Why is there LESS rain FROM MARCH to SEPTEMBER, than from September to March?_

A. From March to September, the temperature of the air is _constantly increasing_; on which account, _its capacity for holding vapour_ is on the _increase_, and very little is precipitated as rain.

Q. _Why is the RISING SUN in summer accompanied with a BREEZE?_

A. Because the heat of the rising sun _stops the radiation of heat_ from the earth, and _warms its surface_.

Q. _How does this WARMTH produce a BREEZE?_

A. The air (resting on the earth's surface) is _warmed by contact_, ascends upwards, and _colder air rushes in_ to fill up the void, which is the cause of the _morning_ breeze.

Q. _Why is there often an EVENING BREEZE during the summer months?_

A. The earth _radiates heat at sun-set_, and the air is cooled down quickly by contact: this condensation causes a _motion in the air_, which is the evening breeze.

Q. _Why are TROPICAL ISLANDS always subject to a SEA-breeze every MORNING (i. e. a breeze blowing from the sea to the land)?_

A. The solar rays are unable to heat the surface of the _sea_ as they do the _earth_; therefore, the _air resting on the earth_ is more _heated_ than the _air resting on the sea_; and the colder sea air blows _inland_ to restore the equilibrium.

Q. _Why is the LAND BREEZE UNHEALTHY?_

A. Because it is frequently loaded with exhalations from _putrefying animal_ and _vegetable_ substances.

Q. _Why is the SEA BREEZE fresh and HEALTHY?_

A. Because it passes over the fresh sea, and is _not_ laden with noxious exhalations.

It is _healthy_, therefore, to walk on the sea-beach before ten o'clock in the morning; but _unhealthy_ after sun-set.

Q. _Why is there generally a fresh breeze from the SEA (in English watering places) during the summer and autumn MORNINGS?_

A. As the _land_ is _more heated by the sun_ than the _sea_; therefore, air resting on the _land_ is hotter than air resting on the _sea_; in consequence of which, cooler sea air glides _inland_, to restore the equilibrium.

Q. _Why does the SEA BREEZE feel COOL?_

A. As the sun cannot make the surface of the _sea_ so hot as the surface of the _land_; therefore, the air which blows from the sea, feels _cooler than the air of the land_.

Q. _Why are TROPICAL ISLANDS subject to a LAND BREEZE every EVENING (i. e. a breeze blowing from the land towards the sea)?_

A. The _surface of land_ cools down _faster_ (after sun-set) than the surface of the _sea_: in consequence of which, the air of the cold land _is condensed, sinks down_, and spreads itself into the warmer _sea air_, causing the LAND BREEZE.

Q. _Why is the LAND BREEZE COOL?_

A. As the surface of the land is cooled at sun-set _quicker than the surface of the sea_; therefore, the seaman feels the air from the land to be chill.

Q. _Why is the TEMPERATURE of ISLANDS more EQUABLE than that of CONTINENTS?_

A. Because the _water_ around the island _absorbs_ the extreme heat of summer, and _gives out_ heat to mitigate the extreme cold of winter.

Q. _Why does the sea round an island GIVE OUT heat in winter?_

A. Unless the _sea be frozen_ (which is rarely the case), it is _warmer_ than the frozen land; and, therefore, the warmth of the sea air (mixing with the cold land air) helps to mitigate the intense cold.

Q. _Why are there WAVES in the sea?_

A. The wind (acting on the surface of the sea) _piles up ridges of water_, which leave behind an _indentation_: as the water on all sides rushes to _fill up this indentation_, the disturbance spreads on all sides, and billow rolls after billow.

Q. _Why does WIND in England generally feel COLD?_

A. Because a _constantly changing surface_ comes in contact with our body, to draw off its heat.

Q. _Why is a ROOM (even without a fire) generally WARMER than the OPEN AIR?_

A. As the air in a room is _not subject to much change_, it soon becomes of the same temperature as our skin, and no longer feels cold.

Q. _Why do we generally feel COLDER out-of-doors?_

A. Because the air (which surrounds us) _is always changing_; and as fast as _one_ portion of air has become warmer by contact with our body, _another colder portion_ surrounds us to absorb more heat.

Q. _Why are HOT FOODS made COOL by BLOWING them?_

A. Blowing causes the air (which covers the hot food) _to change more rapidly_; in consequence of which, the hot air is _quickly blown away_, and gives place to fresh _cold air_.

Q. _Why do ladies FAN THEMSELVES in hot weather?_

A. By the action of the fan, _fresh particles of air_ are perpetually brought in contact with the face, and every fresh particle of air _absorbs some heat_ from the skin.

Q. _Does the fan COOL the AIR?_

A. No; it makes the _air hotter_, by imparting to it the heat _out of our face_: but it cools the _face_ blown upon, by transferring its heat to the _air_.

Q. _Is the AIR in SUMMER time ever so hot as our bodies?_

A. No, not in England. In the hottest day in summer, the air of England is 15 or 20 degrees cooler than the human body.

Q. _How fast does wind travel?_

A. A gentle breeze goes at about the rate of 5 miles an hour. A high wind from 20 to 60. A hurricane from 80 to 100 miles an hour.

Q. _How is the VELOCITY of WINDS ascertained?_

A. By observing the velocity of the clouds, and by an instrument for the purpose.

This instrument is called an ANEMOMETER.

Q. _How is the VELOCITY of the CLOUDS ascertained?_

A. By observing the speed of their shadow along the ground; which is found in a high wind to vary from 20 to 60 miles an hour.

Q. _Why is there always a strong DRAUGHT through the KEYHOLE of a door?_

A. As the air of the room we occupy is _warmer than the air in the hall_, therefore the cold hall air _rushes through the keyhole_ into the room, and causes a draught.

Q. _Why is there always a strong DRAUGHT UNDER the DOOR, and through the crevice on each side?_

A. The cold air _rushes from the hall_ under the door, &c. into the room, to supply the _void_ caused in the room (by the escape of warm air up the chimney, &c.)

Q. _Why is there always a DRAUGHT through the WINDOW crevices?_

A. The external air (being colder than the air of the room we occupy) rushes through the window crevices _to supply the deficiency_, caused by the escape of air up the chimney, &c.

Q. _Why is there more DRAUGHT if you open the LOWER SASH of a window, than if you open the UPPER sash?_

A. If the _lower_ sash be open, the _cold external air_ will rush more freely _into the room_; but if the _upper_ sash be open the _heated air of the room_ will _rush out_; and (of course) there will be less draught.

Q. _By which means is the ROOM better VENTILATED, by opening the lower or the upper sash?_

A. A room is better _ventilated_ by opening the _upper sash_; because the hot vitiated air (which always ascends towards the ceiling) _can better escape_.

Q. _By which means is a HOT ROOM more quickly COOLED--By opening the upper or the lower sash?_

A. A hot room is _cooled more quickly_ by opening the _lower sash_; because the cold air can enter more freely by an _under_ current, than by one _higher up_.

Q. _Why does WIND DRY damp LINEN?_

A. Because dry wind (like a dry sponge) imbibes the particles of vapour from the surface of the linen, as fast as they are formed.

Q. _Which is the HOTTEST PLACE in a church, chapel, or theatre?_

A. The gallery.

Q. _Why is the GALLERY of all public places HOTTER than the lower parts of the building?_

A. Because the heated air of the room _ascends_, and all the _cold air_ (which can enter through the doors and windows) _keeps to the floor_, till it has become heated.

Q. _Why do PLANTS often grow out of WALLS and TOWERS?_

A. Because sometimes the _wind_ blows the seed there with the dust; and sometimes _birds_ (flying over) drop the seed which they had formerly eaten.