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LECTURE VI.—THE PLANET MERCURY.
Intra-Mercurial Planets—The Size, Speed , and Orbit of Mercury —Naked-eye Observations of Mercury —Solar Light and Heat upon Mercury —
Its Habitability—Schroter’s Observations of Mercury —Its Transitsacross the Sun ’s Disc . . . . . . . . . .188
LECTURE VII.—THE PLANET VENUS.
The Size and Orbit of Venus—Epochs of its Maximum Brightness—ItsPhases—Its Visibility in the Day-time—The Rotation of Venus uponits Axis—Its Atmosphere—La Lumiere Cendree—The supposed In-clination of its Axis—Its Habitability.loo
The Seasons of the Earth ’s Year—The Poles of the Heavens seen fromDifferent Terrestrial Latitudes—The Sun ’s Diurnal Path—GlacialEpochs—The Eccentricity of the Earth ’s Orbit—The Shape of the
LECTURE IX.—THE EARTH ( continued ).
Proofs of the Earth ’s Rotation—Falling Bodies—Foucault’s Pendulum—TheGyroscope—Centrifugal Force—Artillery Experiments—The Weight ofthe Earth —The Cavendish Experiment—The Harton Colliery Experi-ment—The Solidity of the Earth—Sidereal and Mean Solar Days—Change of the Length of the Sidereal Day . . . . . . 1ST
LECTURE X.—THE PLANET MARS.
Variations in the Distance of Mars from the Earth —Its Oppositions—ItsRotation—Its Polar Snows—Its Seas and Continents—Charts andDrawings by Various Observers—Its Atmosphere, Temperature, andHabitability—Discovery of its Satellites —Their Movements as seenfrom Mars —The Faintness of their Light—Smallness of the Tides theywould produce upon Mars—Solar Tides upon Mars —The Weight ofMars —Transits of Deimos and Pliobos across the Sun .... 220
LECTURE XI.—THE MINOR PLANETS.
Reasons for so naming them—Bocle’s Law—The Zone within which theyoccur—Recent Rapid Rate of their Discovery—Faintness of their Light—Eccentricities and other Peculiarities of their Orbits—Their Sizes—Their Aggregate Weight—Explanation and Discussion of the Hypothesisof Olbers —Other Theories of their Origin.2(15