CONTESTS.

XI

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LECTURE XII.-THE PLANET JUPITER.

The Apparent Size of Jupiter —Its Internal Constitution—Gravity upon itsSurface—Centre of Gravity of Jupiter and the Sun —The Orbit andVelocity of Jupiter—Velocities of a Point upon its Equator —Its Belts—The Great Red Spot—Drawings of the Planet —The Period of itsAxial Rotation—An Equatoreal White Spot—Transits of Satellites andtheir Shadows across the Red Spot—The Habitability of Jupiter . . 294

LECTURE XIII.—THE SATELLITES OF JUPITER.

The Discovery of the Satellites by Galileo Galilei —Their Orbits, Periods,and Distances—Their Sizes—Bode’s Law—Their Densities—TheirEclipses—Laplace’s Relation between the Movements of the ThreeInnermost—Their Occultations—Their Transits, and the Transits oftheir Shadows—Eclipses of the Sun upon Jupiter—Physical Pecu-liarities of the Satellites—The Velocity of Light —The Paths of theSatellites in Space..

LECTURE XIV.—THE PLANET SATURN.

The Size and Orbit of Saturn—The Phases of its Rings —Disappearances ofthe Rings—History of the Successive Discovery of the Rings—TheirPhysical Constitution—Measurements of the Rings—Saturn seen fromthe Rings—The Rings seen from Saturn—Eclipses of the Sun causedby the Rings—The Eight Satellites of Saturn—Comparison of Saturn’sSystem of Satellites with the Planets of the Solar System—The Satel-lites seen from Saturn—Transits of the Satellite Titan .... 354

LECTURE XV.—THE PLANETS URANUS AND NEPTUNE .

The Discovery of Uranus in 1781—Previous Observations of it as a Star—

Its Orbit, Size, Weight, etc.—Its Four Satellites—The Probable Inclina-tion of its Axis—Explanation of the Orbital Movement of its Satellites—The Discovery of Neptune in 1846—Its Perturbations of the Move-ment of Uranus—Its Orbit, Velocity , etc.—Its Satellite—The PossibleExistence of Trans-Neptunean Planets—The Passages of the MajorPlanets through the Perihelia of their Orbits—Conclusion . . . 393