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Show ANNOTATIONS AND ADDITIONS. 283 re pect to the sun and of latitude. Would not the climate of Germany be wonderfully altered, and that perhaps for centuries, if there were opened a fissure a thousand fathoms in depth, reaching from the shores of the Adriatic to the Baltic? If in the present condition of our planet, the stable equilibrium of temperature, first calculated by Fourier in his Theorie analytique de lachaleur, has been almost completely restored by radiation from the earth into space; and if the external atmosphere now only communicates with the molten interior through the inconsiderable openings of a few volcanoes-in the earlier state of things numerous clefts and fissures, produced by the frequently recurring corrugations of the rocky strata of the globe, emitted streams of heated air which mingled with the atmosphere and were entirely independent of latitude. Every planet must thus in its earliest condition have for a time determined its own temperature, which afterwards becomes dependent on the position relatively to the central body, the Sun. The surface of the Moon also shows traces of this reaction of the interior upon the crust. ( 11 ) p. 234:.-" The mountain declivities of the southern part of Mexico.'' The greenstone, in globular concretions of the mountain district of Guanaxuato, is quite similar to that of the Franconian FichtelGebirge. Both form grotesquely shaped summits, which pierce through and cover the transition argillaceous schists. In the same manner, pearl stone, porphyritic schists, trachyte, and pitch-stone porphyry, constitute rocks similar in form in the Mexican mountains near Cinapecuaro and Moran, in Hungary, in Bohemia, and in Northern Asia. (1!3) p. 236.-" The D1·agon-tree of Orotava." This colossal dragon-tree, Dracrena draco, stands in the garden of Dr. Franqui in the small town of Orotava, the ancient Ta01·o, one of the most delightful spots in the world. In June, 1799, when we ascended the Peak of Teneriffe, we measured the circumference of the tree, and found it nearly 48 English feet. Our measurement was taken several feet above the root. Lower down, and nearer to the |
