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Show 154 ACTION general principle in this has been already noticed and illustrated at some length in the case of water, but there are still more magnificent displays of the triumph of heat over matter, which take place on the great scale. Volcanoes, whether under the .dry land or the sea, are instances of that kind of actiOn, and so also are earthquakes ; and the chief differe.nce betwe.en these is, that. in the volcano the heat dnv.es the expanding matters through one apertu!e, whlle in the case of the earthquake, the escape 1s by one rent or many rents. The difference between the eruption of the volcano and the shock of the earthquake very much resembles that between shots which "blow out" with a loud report and shots that smoulder, in the blasting of rocks. The shot with the loud report may raise a few fragments, and send them to a considerable distance, but it is the smouldering shot that tears the rock to pieces. Just sb the volcano may raise to the SUII_lmit of the loftiest mountain, from a great depth m the earth, a vast mass of materials, and according as those materials may happen to be, it may J?OUf ovet the mountain, and even over the surroundmg country, a deluge of boiling vJater, or boiling mud; or it may cast red-hot stones and cinders, and volley masses the size of little hills, red-hot, to great ele .. vations in the air, from which they may descend with crashes like thunder; it may- turn day into night bv clouds of ashes in the air, and those clouds may fall (as they have fallen) upon cities, and bury them and all their inhabitants, or they may be wafted across the seas and produce disease and famine in other countries; or the mountain may give a specimen of the mode in whiGh nature can play the founder, and after the most stubborn strata of the earth hav.e been molten, the fiery flooq may be poured from the mighty crucible, roll down the ~lope, and proceed over tbe country~ tumbling and curdling, and creeping more and more slowly; but still so OF HEAT. 155 terrible in its heat that all the vegetation is on fire·, and the abodes of mankind crU'mbling into powder at a considerable dist.ancP before its match of terrific desolation. So also, if it is situated under the sea, no matter for the depth, let there be but heat enough, and the so:bstanC'e which opposes that will be sent burnirtg to the atmosphere, although the very depth of mid-ocean lie between. Indeed, the water tends in two ways to facilitate the ascent of the submarine volcano. First, it consolidates · the external crust by cooling it, and thus prevents the spread of the matter over the bottom ; and, fn the s·econd place, as water presses in proportion to the depth, and presses equally in all directions, the pressute on the top or any mass is less· than the pressure upon an equal portion on one of the sides. Thus, there is a considerable resemblance between the ascent of a volcanic column through the water o( the sea, and the ascent of a column of smoke through the air; and so, by means of the cooling influence and pressure of the water acting jointly, buildings may be erected there far more gigantic than any which man, or any power of nature w"ith which we are acquainted, could erect upon the land. Those who look at the productions of nature, without taking· nature's powers of producing into the account, are in the habit o( considering it a very marvellous thing to find shells and other productions which are not on:Iy of the sea:, but of the very depths of the sea, near the summits of some of the loftiest ~?un~ains on t~e s~rface of the earth; but truly it It IS difficult to unagme how the case could be otherwise; for there is nowhere on the globe an apparatus in which great mm.rntains could be manufactured but just the great ocean; and it is very likely that so· much of the earth's surface is covered with the ocean just in order that those powers with whieh the Almighty has endowed matter for the accomplishment of his pleasure, and which, measureless |