VII.--ECLIPSES 101 Their cause and nature--Eclipse limits--Eclipse maps--Recurrence and prediction of eclipses. VIII.--INSTRUMENTS AND THE PRINCIPLES INVOLVED IN THEIR USE 121 The clock--Radiant energy--Mirrors and lenses-- The telescope--Camera--Spectroscope--Principles of spectrum analysis. IX.--THE MOON 150 Numerical data--Phases--Motion--Librations--Lunar topography--Physical condition. X.--THE SUN 178 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. XI.--THE PLANETS 212 Arrangement of the solar system--Bode's law-- Physical condition of the planets--Jupiter-- Saturn--Uranus and Neptune--Venus--Mercury-- Mars--The asteroids. XII.--COMETS AND METEORS 251 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. XIII.--THE FIXED STARS 291 Number of the stars--Brightness--Distance--Proper motion--Motion in line of sight--Double stars-- Variable stars--New stars. XIV.--STARS AND NEBULÆ 330 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. XV.--GROWTH AND DECAY 358 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. APPENDIX 383 INDEX 387 LIST OF LITHOGRAPHIC PLATES FACING PAGE I.--Northern Constellations 124 II.--Equatorial Constellations 190 III.--Map of Mars 246 IV.--The Pleiades 344 Protractor _In pocket at back of book_ LIST OF FULL-PAGE ILLUSTRATIONS