[141] Miller's "Testimony of the Rocks," p. 221.
[142] Sir William Thomson supposes that temperature to have been at least 7000° Fahr. See Thomson and Tait's "Natural Philosophy," vol. i. p. 716.
[143] "Fragments of Science," p. 158.
[144] Thomson and Tait, "Natural Philosophy," vol. i. p. 714. Winchell, "Sketches of Creation," p. 407.
[145] Mayer, "Celestial Dynamics: Correlation and Conservation of Forces," p. 315. The palæobotanist Heer has described many species of tropical plants from Greenland, Alaska, and Spitzbergen.
[146] Thomson and Tait, "Natural Philosophy," vol. i. p. 714. Observations on over forty artesian wells in Central Alabama show an average increase of temperature of 1° for every 47 feet of descent.—Dr. Winchell, in "Proceedings of American Association," part ii. p. 102.
[147] Thomson and Tait, "Natural Philosophy," vol. i. p. 714.
[148] Pouillet estimates that the heat which reaches the surface of the earth from its interior at 200 cubic miles per diem. A cubic mile is the quantity of heat necessary to raise a cubic mile of water 1° Centigrade in temperature.
[149] Thomson and Tait, "Natural Philosophy," vol. i. p. 716.
[150] Thomson and Tait, "Natural Philosophy," vol. i. p. 721.