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Show ; . ... .. • .. • l ~ • 138 THUNDER AND LIGHTNING. gether impossible to obtain by any modification of the sun's direct light, but it answers many other important purposes in the economy of nature. When the sky is darkened with clouds, even to the deepest gloom of a close November day, and over the black earth or the barren moor, which drinks up all that falls upon it, the little fragment of solar light, that glimmers by countless refractions and zigz~gs through the little drops that compose the th1ck clouds, has no resemblance whatever to moonlight. The fact is, that those little drops decompose the light, as well as retain and reflect back again a cu11sidera.ble portion of it ; and the light which redches the earth at those times is a melee of little rainbows, each probably not so broad as a spider's thread, in which one colour so falls upon and blots another that the compound has hardly any colour at all. We know httle of those matters ; but as dry air is as perfect a non-conductor of electricity as dry glass, it is exceedingly probRble that when clouds arrive at a certain degree of density, they actually extract their own lightning out of the sunbeams ; and that that which gleams and strikes, and makes air strike against air with as loud a sound as if rock were dashed against rock, or mountain against mountain, is nothing more than the red light, and the heating and oxidizing rays of the sun, collected by the minute drops of water, and tempered by one of those curious processes in Nature's chymistry which hu · man skill cannot imitate. The subject is one upon which it is altogether impossible to have experimental information; but as thunder and lightning are among the most striking, and, according to circumstances, among the most sublime, and even the most terrific of natural appearances, it is altogether impossible to observe nature without speculating about them; besides, the countries where there is the greatest heat and the warmest seasons are those in which there is most THUNDER-STORMS. 139 thunder. Thunder-storms are also most violent, or rather one should say grandest, when the clouds are formed in an atmosphere which has for a considerable time previously been dry as well as warm. We see that in our own country. We have often violent thunder-storms, with showers of very short duration, and very local and limited in their range ; we have also thuq.der-storms at the commencement of broken and rainy weather ; but when the rain fairly sets in, and extends over a large tract of country, it lightens and thunders no more. In tropical court tries, where there are seasonal- winds, or monsoons, some dry from the land, and others moist from the sea, the Iig·htning and thunder at the commencement of the rainy monsoon are often, and indeed generally, absolutely terrific. When the south-west monsoon sets in upon the west coast of India, and is directed upward by the ridge of mountains that skirts that shore, the strife between it and the warm and dry air over the Balaghaut country above the mountains, is terribly sublime. It lightens as though the air were ten thousand furnaces ; all the artillery in the world would be but as an infant's cry to the thunder ; and the rain falls so fast, and so consolidated, that the trees are broken or uprooted like dned stubble, and the rocks scattered about as if they were pebbles. In some parts of South America, where the plains are parched up by the summer heat, and the snowy summits of the Andes are at no very great distance, the thunderstorms are said to be even more violent ; and in tropical, and even in southern Africa, their violence is equal, if not greater. That thunder-storms occur during the night is no argument against their formation by the action of the light and heat of the sun ; and the close connexion between them and heat and light is proved by the fact that lightnings very generally accompany the smoke of volcanoes, and are the more brilliant the more violently the fire r.ages in these. lnde .. |