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  Saturn and its System 87

JOVIAN SYSTEM.

Inclination of Orbit Plane to Planet's Equatorial Plane.
I. Io . . . . . . . . . 0' 0"
II. Europa . . . . . . . 1' 6"
III. Ganymede . . . . . . 5' 3"
IV. Callisto . . . . . . . 24' 35"

Here, again, the inclinations increase as we go out, and the smooth curve representing them is,

Fig. XII.
Fig. XII.

when reduced in scale, almost the counterpart of the Saturnian.

Force occasioning this due to planet.Clearly some force has operated to compel the satellites to travel in the planet's equatorial plane, due to planet, and this force has emanated from the planet, since it grows less potent as one departs from him.