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CHAPTER XI.
Nothing had more perplexed me in seeking to reconcile my sense to the existence of regions extending below the surface of the earth, and habitable by beings, if dissimilar from, still, in all material points of organism, akin to those in the upper world, than the contradiction thus presented to the doctrine in which, I believe, most geologists and philosophers concur—viz., that though with us the sun is the great source of heat, yet the deeper we go beneath the crust of the earth, the greater is the increasing heat, being, it is said, found in the ratio of a degree for every foot, commencing from fifty feet below the surface. But though the domains of the tribe I speak of were, on the higher ground, so comparatively near to the surface, that I could account for a temperature, therein, suitable to
