Their cause and nature—Eclipse limits—Eclipse maps—Recurrence and prediction of eclipses.

The clock—Radiant energy—Mirrors and lenses—The telescope—Camera—Spectroscope—Principles of spectrum analysis.

Numerical data—Phases—Motion—Librations—Lunar topography—Physical condition.

Numerical data—Chemical nature—Temperature—Visible and invisible parts—Photosphere—Spots—Faculæ—Chromosphere—Prominences—Corona—The sun-spot period—The sun's rotation—Mechanical theory of the sun.

Arrangement of the solar system—Bode's law—Physical condition of the planets—Jupiter—Saturn—Uranus and Neptune—Venus—Mercury—Mars—The asteroids.

Motion, size, and mass of comets—Meteors—Their number and distribution—Meteor showers—Relation of comets and meteors—Periodic comets—Comet families and groups—Comet tails—Physical nature of comets—Collisions.

Number of the stars—Brightness—Distance—Proper motion—Motion in line of sight—Double stars—Variable stars—New stars.

Stellar colors and spectra—Classes of stars—Clusters—Nebulæ—Their spectra and physical condition—The Milky Way—Construction of the heavens—Extent of the stellar system.

Logical bases and limitations—Development of the sun—The nebular hypothesis—Tidal friction—Roche's limit—Development of the moon—Development of stars and nebulæ—The future.