Page:The Solar System - Six Lectures - Lowell.djvu/103



A second lies inside the first. In the solar system, our Earth occupies this place; in the Jovian, lo; in the Saturnian, Tethys; in the Uranian, Ariel.

Plotted in curves, the profiles of the four systems show a striking family resemblance, as can be seen from the diagram; and from what we have noted of the probabilities in the case, we cannot doubt that this betokens a law of system development.