and of never exceeding those limits. Thus to explain the fact that the habitable earth has not, as originally, so warm a temperature as the north, we need not have recourse to any supposition of a central fire suddenly extinguished, like an oven that becomes cold, or to any other violent hypothesis of the same kind; for this fact may be sufficiently accounted for by the last great revolution of Nature--the general deluge, which as may be assumed with great probability, produced a change in the heretofore much purer, balmier, and more genial atmosphere. That, towards the equator, the position of the earth's axis has undergone a change, and that thereby this great revolution in the earth's climate was occasioned, is indeed a bare possibility; but until further proof, this must be regarded as a purely gratuitous hypothesis. But without subscribing to these fanciful suppositions, and mathematical theories, and without wishing to penetrate, with some geologists, into the hidden depths of the earth in quest of an imagined central fire, we shall find on the inhabited surface of the globe, or very near it, many proofs and indications of the once superior energy of the principle of fire--a principle whereof volcanoes whether subsisting or extinct, and the kindred phenomena of earthquakes, may be considered the last feeble, surviving effects; for not basalt only, but porphyry, granite, and in general all the primary rocks, and those which, according to the classifications of geologists, are more immediately akin to them, can be proved to be of a volcanic nature with as much certainty, as we can trace, in the horizontal secondary formations, the destructive influence and operation of the element of water. Hence this layer of subterraneous, though now in general slumbering fire, with all its volcanic arteries and veins of earthquakes, may once have been as widely diffused over the surface of the globe as the element of water, now occupying so large a portion of that surface. As volcanic rocks exist in the ocean, or rather at its bottom, and as their eruptions burst through the body of waters up to the surface of the sea; as their volcanic agency gives birth to earthquakes, and not unfrequently raises and heaves up new islands from the depths of the ocean; naturalists have concluded, with reason from these various facts, that the volcanic basis of the earth's surface though tolerably near, must still be somewhat deeper than the bottom of the sea. And without stopping to examine the hypothesis relative to the immeasurable depth of the ocean, the opinion which fixes the earth's basis at about 30,000 feet, or one geographical mile and a half below the surface of the sea, does not exceed the modest limits of a well-considered probability. In the present period of the globe, water is the predominant element on the earth's surface. But if that volcanic power which lies deeper in the bosom of the earth, and the