8. It results from this conical movement of the axis that the poles of the Earth do not constantly regard the same points in the heavens; that the polar star is not always the same; that the poles are gradually more or less inclined toward the sun, and receive from it more or less direct rays. Whence it follows that Iceland and Lapland, for example, which are under the polar circle, will, in a given time, be able to receive the solar rays as though they were in the latitude of Spain or Italy; and that, in the extreme opposite position, Spain and Italy will have the temperature of Iceland and Lapland; so in succession at every renewed period of 25,000 years. *
* The gradual displacement of the isothermal lines, a phenomenon recognized by science in such a positive way as the displacement of the sea, is a material fact that supports this theory.