must be attended with most beneficial consequences; but as the sea, for its purity, is not dependent on any one cause, so the atmosphere, besides these external restoratives, will be found to contain, in its own bosom, a correcting principle, which developes itself by its salutary operations, as we shall soon have occasion to notice, in speaking of some of the most remarkable of the phenomena of the atmosphere. CHAP. XV. PHENOMENA OF THE ATMOSPHERE. "Of what important use to human kind, It drives the clouds, and ventilates the skies; The Wind. SOMETIMES there is a profound calm; every wind is hushed; not a zephyr breathes over the face of creation, and not a breeze disturbs the glassy expanse of the lake; but the appearance is deceitful and short-lived; all on a sudden the wind is heard rustling among the branches-it gathers strength as it proceeds, and grows up into the majesty of a storm. Now the raging tempest spends its fury; houses are swept from their foundations; navies are rent from their anchors; trees are torn up by the roots. This we call wind; and whether its effects appear in the fury of the gale, the violence of the hurricane, the impetuosity of the whirlwind, the dryness of the harmattan, the deleteriousness of the sirocco, or the mortifying influence of the samiel, it becomes us not to repine at the dispensations of the Almighty, or account those the most deplorable evils, which are wisely sent us for the best of purposes. We have already noticed the bad effects that would accrue, were it not for the agitation of the ocean; but more dreadful would be the consequences, Did neither air nor ocean feel the wind. Motion is the soul of the universe; it is as necessary in the air as in the ocean, and both are no less indispensable than the motion of the sap of plants, and the circulation of the blood in animals. It is, however, happily so ordered, that where putrefaction in a state of quiescence would soon prevail, wholesome breezes and salutary gales alternately spring up, to sweep destruction from the aerial fluid, and where heat is felt to an alarming degree, the atmosphere extends its airy wings to fan a fainting world. "This principle, as Dr. Gregory observes, we find realized on a great scale in what are called the trade winds, which blow constantly from east to west, near the equator. The sun rises in the east and sets in the west, consequently the air will be heated gradually from east to west, and the wind will blow in that direction." The same cause, this author remarks, will explain "the land and sea breezes in the tropical climates;" and the monsoons, though the theory of them be more complicated, originate in the same cause. And as it is not only necessary that there be a continual agitation kept up in the ocean, by means of the tides and currents, but, in order to prevent its wa. ters from being contaminated by those numerous loads of filth which are, from all quarters, poured into it, it is also requisite that it be furnished with something of a correcting nature, which it has in its saltness. So in the atmosphere, besides the perpetual motion kept up in it by means of the winds, and the beneficial consequences proceeding from vegetation and the agitation of the waters, there must be also some correcting quality, especially prevalent in the upper regions, where a number of the most noxious particles, and a considerable quantity of vitiated effluvia, must ascend, perhaps beyond the reach of the other purifying agents. This, it is probable, is the chief cause of the electric fluid, which, although it is found to pervade the whole mass of creation, is supposed to be much more copious in the upper than in the lower parts of the atmosphere. In the lower regions of the firmament, indeed, the tremendous noise of the thunder is heard, and the vivid lightnings are seen to flash; but these only happen on extraordinary occasions, or where their pre sence is absolutely necessary to restore the equilibrium of the lower tracts, in the same manner as the tempest is sometimes sent to agitate, in an uncommon degree, the surface of the ocean; but far more frequent, we may suppose, is the busy working of the lightning in the higher regions of the air, although it may be concealed by the density of its lower extremities at times from our view. The glancing of the wild fire, as the vulgar style it, and the playful skipping of the aurora borealis, give us sufficient intimation, that, in the silent hours of rest and repose, the great Supreme faints not, neither is weary, but is busily employed in the unceasing operations of his providence, when our senses are locked in midnight slumbers, and refreshing sleep stretches her balmy wings over a fatigued world. Besides these, which may be called the principal, there are also a number of other fiery meteors. Fireballs, in all the glare of terrific magnificence, are sometimes seen to rush across the hemisphere. Falling stars are observed to shoot with astonishing rapidity. The Ignis-fatuus, Will-with-the-wisp, or Jack-with-a lanthorn, as it is called, glides along by the sides of hedges or ditches in moist situations, and sometimes takes up his abode among the graves of the dead, or is seen in the neighbourhood of dunghills; but these, as well as the fiery Dragon, the skipping Goat, the Dart and the Lamp, with every other appearance that the unsubstantial and airy form may assume, may all be accounted for on the principles of electricity. Watery Meteors. In the regions of the air, a variety of watery meteors are formed. Here are fogs, the creation of those collections of vapours which chiefly rise from fenny, moist places. These become more visible as the light of day decreaseth, and, uniting with those that rise from the waters, so as to fill the air with their humid particles, are called mists. Sometimes, especially in the summer months, our morning walks sparkle with pellucid drops, and transparent globules hang pendant from every leaf, in the form of pearly dew. In the atmosphere, the balancings of the clouds are preserved, till these swimming lakes are commissioned to discharge their contents, not in deluging torrents, confined to particular spots, but in refreshing showers, widely spread abroad in the form of drops of rain. Here, too, that wonderful phenomenon snow takes its rise, which is said to be composed of such vapours as are frozen while the particles are small; and hail, which is rain frozen, as hoar frost is said to be of the dew. Water-spouts may be reckoned among the number of watery meteors; but, having already been noticed in a preceding chapter, (chap. x.) we shall pass them over, and proceed to the consideration of a few of the most remarkable Celestial Appearances. The wonderful and beautiful colours which we observe in the clouds, is owing to their particular situ |