CAMBRIDGE, _1st May, 1900_. CONTENTS. PAGE INTRODUCTION 1 CHAPTER I. THE ASTRONOMICAL OBSERVATORY 9 II. THE SUN 29 III. THE MOON 70 IV. THE SOLAR SYSTEM 107 V. THE LAW OF GRAVITATION 122 VI. THE PLANET OF ROMANCE 150 VII. MERCURY 155 VIII. VENUS 167 IX. THE EARTH 192 X. MARS 208 XI. THE MINOR PLANETS 229 XII. JUPITER 245 XIII. SATURN 268 XIV. URANUS 298 XV. NEPTUNE 315 XVI. COMETS 336 XVII. SHOOTING STARS 372 XVIII. THE STARRY HEAVENS 409 XIX. THE DISTANT SUNS 425 XX. DOUBLE STARS 434 XXI. THE DISTANCES OF THE STARS 441 XXII. STAR CLUSTERS AND NEBULAE 461 XXIII. THE PHYSICAL NATURE OF THE STARS 477 XXIV. THE PRECESSION AND NUTATION OF THE EARTH'S AXIS 492 XXV. THE ABERRATION OF LIGHT 503 XXVI. THE ASTRONOMICAL SIGNIFICANCE OF HEAT 513 XXVII. THE TIDES 531 APPENDIX 558 LIST OF PLATES. PLATE I. The Planet Saturn _Frontispiece_ II. A Typical Sun-spot _To face page_ 9 A. The Sun " " 44 III. Spots and Faculae on the Sun " " 37 IV. Solar Prominences or Flames " " 57 V. The Solar Corona " " 62 VI. Chart of the Moon's Surface " " 81 B. Portion of the Moon " " 88 VII. The Lunar Crater Triesnecker " " 93 VIII. A Normal Lunar Crater " " 97 IX. The Lunar Crater Plato " " 102 X. The Lunar Crater Tycho " " 106 XI. The Planet Jupiter " " 254 XII. Coggia's Comet " " 340 C. Comet A., 1892, 1 Swift " " 358