"PALLAS" (Minor planet), 38 Parabola, 34 "Perseids" (Meteors), 80 Photography, 46 Photosphere, 69 "Pilgrim" star, 88 Piazzi, 38 Planets, 17 Pole of the Heavens, 13 Pontécoulant, 37 Precession of the Equinoxes, 36, 83 "_Principia_," 36 Prominences, 73 "Ptolemæus" (Lunar crater), 60 Ptolemy, 24, 81 RADIANT POINTS, 80 Radius Vector, 28 Reflectors, 47 Refractors, 47 SATURN, 18, 78-79 Schiaparelli, 63 Schwabe, 69 Seconds of arc, 44 Sirius, 53 Solar System, Tables of, 56-58 Somerville, Mrs., 89 Spheres, Planetary, 21 Spörer, 71 Spörer's Law, 71 Star catalogues, 81-83 ---- clusters, 88 ---- drift, 85 Stars, fixed, 84 ---- proper motions of, 84 Sun, 11, 12, 14, 21, 32, 67-77 ---- distance of, 51 ---- dials, 43 Sun spots, 69 ---- spot maximum, 71 ---- ---- minimum, 71 "Sun's Way," 85 TELESCOPE, Invention of, 45 Transit Circle, 82 Tycho Brahe, 27, 44, 88 "Tycho" (Lunar crater), 59, 60, 61 URANUS, 38, 79 VARIABLE stars, 86 ---- ----, Long period, 87 Venus, 18, 27, 67 "Vesta" (Minor planet), 38 YOUNG, C. A., 74 ZENITH, 17, 88 Zodiac, Signs of, 14, 15, 16, 43 Printed by BALLANTYNE, HANSON & Co. Edinburgh & London * * * * * "We have nothing but the highest praise for these little books, and no one who examines them will have anything else."--_Westminster Gazette_, 22nd June 1912. THE PEOPLE'S BOOKS THE FIRST NINETY VOLUMES The volumes issued are marked with an asterisk SCIENCE