[263] All the feldspars are calculated as anorthite. Augite is used for hypersthene, ilmenite is included with magnetite, and all minerals are calculated as if of the isometric system.
[264] Physics of the Earth’s Crust, Chap. VIII.
[265] Penn Monthly, Philadelphia, May, 1876.
[266] The following conclusion by an eminent authority has come to our notice since this was written:
L’influence des marées océanienes sur la durée du jour est donc tout à fait minime et n’est nullement comparable à l’effet des marées dues à la viscosité et à l’elasticité de la partie solide du globe, effet sur lequel M. Darwin à insisté dans une series de Mémoires du plus haut intérêt. Par H. Poincaré, Bulletin Astronomique, tome XX (June, 1903), p. 223.
[267] On the Secular Changes in the Elements of the Orbit of a Satellite revolving about a Tidally-distorted Planet. Phil. Trans., Roy. Soc., Pt. II, 1880.
[268] Jour. Geol., Vol. VI, 1898, p. 65.
[269] Quar. Jour. Geol. Soc., Vol. 39, 1883, p. 140. Everett (Units and Physical Constants) gives 837 × 106 for steel, but as the modulus for granite seems low, we have taken the lower estimate for steel to avoid exaggerating the ratio between them.
[270] Nat. Phil. Thompson & Tait, Vol. II, p. 424, 1890.
[271] Computations made at the request of the authors. See also Fisher, Physics of the Earth’s Crust, p. 36.