[76] The reader should turn to Kepler's immortal work, "De Motibus Stellæ Martis," for the manifold attempts of the astronomer to bring calculation into agreement with observation. In every page is revealed what has been finely called "the passionate patience of genius."
[77] There is certainly no exaggeration in comparing the earth to a point, since the diameter of the sun is 112 times that of the earth, and its mean distance a little more than 12,000 terrestrial diameters: the earth is but a microscopical point in space, if we compare it to the place occupied by the central luminary.
[78] Reference is here invited to Humboldt's thermal and isothermal lines. See Dr A. K. Johnston's "Physical Atlas," and Humboldt's "Kosmos."
[79] Sir J. Herschel, "Preliminary Discourse on the Study of Natural Philosophy."
[80] Professor Balfour's "Manual of Botany," pp. 566-568.
[81] Pliny, "Hist. Nat.," xxii. 46.
[82] Martial, "Epigram.," i. 21.
[83] "Annales des Sciences Naturelles," i. 18.
[84] Count de Castelnau, "Histoire Naturelle des Coléoptères," i. 7.
[85] As recorded, in a condensed form, in The Academy (Feb. 12, 1870), pp. 131, 132.