Page:The evolution of worlds - Lowell.djvu/168

136 of the three. Next stands Dione, smaller than Tethys. Then the mass increases with Rhea, reaching its culmination in Titan, after which it declines once more. Strangely reproductive this of the curve we marked in

the arrangement of the planets themselves, even to the little inner rise and fall.

Striking as such analogous ordering is, it is not all. For, scanning the Jovian system, we find the main curve here again; Ganymede, the Jupiter or Titan of the system, standing in the same medial position as they. Lastly, taking up Uranus and his family of satellites, the same order is observable there. Titania, the largest, is posted in the centre.

Thus the order in which the little and the big are placed with reference to their controlling orb is the same