appears, it was bound to do, and ought by all means to have done. We have our misgivings that it is equally bound, by the calculations which convict it of this neglect of duty, to blow away any man of ordinary stature who ventures out of doors when the weather is not calm. But we have too much respect even for the failings of the wind, to do more than hint at these its little weaknesses.

Indeed, our readers are already so occupied with the wonders and beauties of the great Exhibition, and already read so much about them, that we purposely avoid the subject for the present. Therefore, if our discourse concerned only the grievous default and bankruptcy of the wind, in that connection, it would end here, and take its place in literature by the side of Sancho Panza's untold story, and the condensed Encyclopædia of information which Mr. Dangle ought to have perused in the nod of Lord Burleigh. We have another range before us, however, and proceed.

The clown in "Twelfth Night" might have been a good geologist when he sang

"A great while ago the world began,
With hey, ho, the wind and the rain !"

for the wind and the rain have written illustrated books for this generation, from which it may learn how showers fell, tides ebbed and flowed, and great animals, long extinct, walked up the craggy sides of cliffs, in remote ages. The more we know of Nature, in any of her aspects, the more profound is the interest she offers to us; and even in this atom of knowledge alone, we might surely get something to think about, out of a wet day. We do not defend a wet day. We know that a wet Sunday in a country inn, when the rain falls perseveringly, between the window and the opposite haystack-when rustics lounge under penthouse roofs, or in barn or stable doorways, festooning their smock-frocks with their pocketed hands, and yawning heavily-when we pity the people sitting at the windows over the way, and think how small and dark their houses look, forgetting that they, probably, pity us too, and think no better of the Griffin, where we have put up-is not promotive of cheerfulness. We know that the same Sunday in a town or city, when

stones-when dripping umbrellas make a dismal dance all down the street-when the shining policeman stops at the corner to throw the wet off himself, like a water-dog when all the boys in view go slinking past, depressed, and no boy has the heart to fly over a post-when people wait under the archway, peeping ruefully out at splashed and draggled stragglers fagging along under umbrellas: or at other stragglers who, having no umbrellas, are completely varnished from head to foot with rain-when the chimney-smoke and the little church weathercock fly round and round, bewildered to find that the wind is everywhere-when the flat little church bell seems vexed that the people won't come in, and tinkles discontentedly, while the very beadle at the door is quenched and querulous-does not inspire a lively train of thought. Still, without constantly measuring the rain-fall like the enthusiasts who write to the newspapers about it, or without asserting, like the oldest inhabitant, (who has never been right in his life since his promotion to that elevation,) that it never rained before as it rains now, we may find matter for a few minutes' talk, even in such weather.

It is raining now. Let us try.

The wind to-day is blowing from the northwest, and it flings the rain against our window-panes. That boy, Tom, will be very wet, for he is out in it without an umbrella. Here he comes, glowing like a forge to which the gale has only served as bellows! He enjoys his dripping state, and tells, with enthusiasm, how

"the wind began again with a burst Of rain in my face, and a glad rebound From the heart beneath, as if, God speeding me, I entered his church-door, Nature leading me."

But we pack him off to change his clothes; and stop his quotation summarily.

We saw, the other day, how winds were caused, like currents of the sea, by inequalities of temperature. The heated air expands near the equator, rises and runs over towards either pole in two grand upper currents, under which there flow from north and south two deluges of colder air, to occupy the space vacated. These currents do not flow from due north and due south, because, as the earth rolls every day once

round itself from west to east, air that has acquired slow movement at the poles, finds the globe travelling too fast for it at the equator, and is obliged, therefore, to drop more and more behind.

The current from the north becomes a northeast wind; that from the south is not due south, but southeast. These winds are constant, where there is no local interference, within about twenty-eight degrees on each side of the equator, being, in fact, the northeast and southeast trade-winds. Why do they not blow all the way from pole to tropic?

There, you have the upper current to consider; the hot air that ascended at the equator has been gradually cooling, and becoming therefore denser-heavier-as it ran over the cold current below. The cold air from the pole, too, had been getting warmer, therefore lighter, on its travel; so that in temperate climates, to which we belong, it becomes a disputable point between the two currents which shall have the upper, which the lower seat. In these regions, therefore, there is no uniform wind; but as the currents from the equator generally succeed in maintaining that it is now their turn to go below, winds from the south prevail outside the trade-winds north of the equator, which are, of course, represented by north winds on the other hemisphere. Southwest and northwest these winds are, because they are fast currents, which started from the earth where it was rapidly revolving, and vote polar regions slow. Winds from the southwest then prevail in Europe; and the south wester now blowing whistles with immoderate exultation at a victory over some polar current with which it has for the last few days been exchanging blows.

Well, you say, there must be a pretty clashing of cymbals when the great tradewinds from the north and south run against one another; and they must do that somewhere near the equator. Yes, the scene of their collision occupies a broad band about six degrees north of the equator, more or less. The trade-winds of the southern hemisphere encroach over the line at all seasons, owing to peculiarities of land and water; but the limits of the trade-winds are not marked out by a fixed straight line. They vary, in extent, with the season, and their outline varies with the nature of the earth

or water over which they blow. But the scene of collision, as we said, forms a broad zone always north of the equator, which is called the zone of the variable winds and calms. Here it is that a great ascending current strikes off the antagonists on either hand; and then if we are in the current, we perceive no wind; and if we hold a lighted candle in the air, its flame ascends unwavering; but a few feet from the ground we can feel nothing of the upward rush which we denominate a calm. With this current rises a vast mass of vapor, and the sun's decline, or a touch from the trade-wind, or the coldness of the upper air, condenses this; and down come sheets of rain, attended with electrical explosions. How the tradewinds, when they come together, twist and twirl, and generally how two winds cause an eddy, and a veering of the weathercock when they come down upon each other, any man may understand who ever sat by a brookside. Currents of water coming upon each other, round the stones, from different directions, act upon each other just as the air-currents act carving miniature gales and model whirlwinds from a kindred element.

Within this zone of variable winds and calms, vapor ascends perpetually, and rain falls almost every day; the rainy season being distinguished only by a more determined drench, just as a doctor, paid by items, pours forth more bottles in the season of an epidemic, though he at all times is unmercifully liberal. That vapor rises from water and from every moist body under the influence of heat, any body knows. The greater the heat the more the vapor; but even in winter, from the surface of the ice-field, vapor rises. The greater the heat, the greater the expansion of the vapor. It is the nature of material things to expand under heat, and to contract under cold; so water does, except in the act of freezing, when for a beneficent purpose it is constituted an exception to the rule. Vapor rises freely from lakes, rivers, and moist land; but most abundantly, of course, it rises from the sea, and nowhere more abundantly than where the sun is hottest. So it rises in the zone of variable winds and calms, abundant, very much expanded, therefore imperceptible. There comes a breath of colder air on the ascending current; its temperature falls; it had contained as much vapor as it would

hold in its warm state; when cooled it will not hold so much; the excess, therefore, must part company, and be condensed again; clouds rapidly form, and as the condensation goes on in this region with immense rapidity, | down comes the discarded vapor in the original state of water, out of which it had been raised; down it comes, a hogshead in each drop. Sudden precipitation, and the violent rubbing against each other, of two air currents unequally warmed, develops electricity, and then in this zone you can hear such thunder, and behold such lightning, as we quiet folks at home are never plagued with.

We may stop here to remark that in all climates this is the whole theory of rain. Our present weather is sufficient illustration. There was a noisy wind from the southwest this May morning-a wind from the warm regions which has come over the sea loaded with vapor. Though violent, it felt warm to the face; but in the sky were scattered clouds, and the wind veered frequently towards the north with sudden showers, one of which pelted upon Tom. It was a contest between the southwest current, and a current from the north, which now and then forced a way down, and where it did so, cooled the atmosphere, and obliged it to part with some of its vapor, either in the form of clouds or rain. The winds are quiet now, and if you look out, you will see that the fight is over, and the southwest beaten after all its crowing; north wins. You see by the smoke that there is a north wind, which, being a cold polar current, cannot hold, in an expanded state, one half of the vapor brought into our atmosphere by the southwest. The north wind, therefore, marks its victory by a general precipitation; the whole sky is uniformly clouded, and a steady rain falls, and will fall, until the balance is restored When the north wind has turned out of the sky all the vapor that it cannot manage, we shall have fine weather, until a warm wind interferes. The warm wind, then, must bleed some drops before it gains possession, but, having conquered, will possess a sky containing less than its due quantity of vapor; therefore precipitation will not be continued. The southwest wind, however, soon brings moisture with it; and then, if the noon be fine, clouds form at evening, when the temperature falls, and it may rain at night,

Every thing contains its regulated quantity of latent heat-a body in the form of air more than a liquid, and a liquid more than a solid. Latent heat is a sensible heat mysteriously transformed, used in the processes of nature, swallowed up, become insensible. Water contains more of this, then, in the state of a thin vapor than in the condensed form. When, therefore, clouds form, heat that was used up and made latent is restored and rendered sensible; that is one reason why cloudy weather is warm. After a shower, the whole earth is moist, and evaporation takes place on the entire surface. Water, to become vapor, seizes, appropriates, and thrusts into the latent form some of the sensible heat lying in its neighborhood, and, therefore, a coolness or a chill succeeds the rain. But there is chill, also, during the rain-fall, when the condensation is at its greatest; how is that? Doubtless you know that air and water conduct heat but badly. You could not heat a tub of water from the top, and the sea retains through all seasons a remarkable imperturbability as to its temperature. So you, or the sun, cannot heat any amount of air from the top; but the sun's rays that reach the earth warm that, and it retains the warmth, and radiates it back again; and so it is the heat of the sun sent from our own earth which fills the air about us. If we walked on such high stilts as to raise our mouths and noses far above the sod, we should be very glad to have our stilts cut shorter; for the radiant heat lessens as we rise from the earth's surface, in proportion no less rapidly than light lessens as we quit a candle; and at any distance from the earth the atmosphere is very cold. So rain descending from the cold heights brings a chill with it. So clouds that cover over the earth and prevent its heat from radiating into space, but rather reflect it back again, act as a blanket does over a man's warm body when he is in bed, and so we have a second reason why it is warm-close-in cloudy weather.

Since water retains in a remarkable degree an even temperature, and land heats and cools in correspondence with all changes of the sun, it follows that where land and water are commingled, inequalities of temperature will be various and frequent; every inequality being the cause of a wind, and the water supplying copious material for