CHAPTER VI.
THE SEASONS.
Why their varying Temperature?
The usual explanation of these phenomena, i. e., the influence of direct and oblique sun-rays, has ever seemed insufficient and unsatisfactory; especially in view of the fact that the heat comes not from the sun by continuity after the manner of progression as from a heated body.
A philosophy more exact and consistent may be found in the development of the theory already advanced, and which is illustrated in the following plates.
The maximum of heat at the surface of the earth bears a very constant and intimate relation to the line of greatest diameters of the sun and earth.—Pl. II. a.
Through this line the heat-producing functions of these great spheres are in operation in the highest degree.