Mercury, 18; nearest planet, 19; unfavorable situation for observation, 20; easily recognized, 22; age of, 34; dense matter of, 37; long known, 38; inferior planet, 40; terrestrial planet, 41; irregularities of, 44–45; number of revolutions, 47; orbit, 48; apparent motions, 57–58; transits, 61; distance from ecliptic, 72–73; color, 80, 86; in Scorpio, 87; elusiveness of, 93–95; how to find, 96–100, 259; distance and brightness of, 101–105; size, 106–110; relation to sun, 111–118; transits, 119–121; lack of atmosphere, 144, 146; resemblance to Mars, 153; Bode’s law and, 245. Milky Way, 87, 88, 89. Mimas, satellite of Saturn, 222. Minor planets, 19. Mizar, star in Great Dipper, 105, 236. Moon, 23; once called planet, 39; distance from ecliptic, 73. Moulton, Professor, 178. Neptune, discovery, 15; distance from sun, 19, 43; not visible to naked eye, 20; age, 34; diffuse matter of, 37; unknown to ancients, 40; superior planet, 41; influence on comets, 44; one revolution, 47; orbit, 48; movement of, 65; distance from earth, 234; discovery, 235–237, 247; symbol, 238; atmosphere, 239–240; satellite, 241; motion, 242; brightness, 243. Oberon, satellite of Uranus, 232–233. Orion, 123. Pallas, planetoid, 251. Phecda, star in Great Dipper, 104. Phobos, satellite of Mars, 180–181, 202. Phœbe, satellite of Saturn, 222–223. Pisces, constellation in zodiac, 76–77, 90–92, 160, 187, 212, 242. Pleiades, 79–80, 153, 188, 210. Præsepe, or the Bee-hive, 82, 211–212. Regulus, star in the constellation of Leo, 83–84, 188, 212. Rhea, satellite of Saturn, 222–223. Sagittarius, constellation of zodiac, 76, 87–88, 91–92, 186, 189, 209, 212, 229. Saturn, rings and moons of, 12, 218–223; distance from sun, 13, 19; attraction between Jupiter and, 15, 185; size and importance, 20; object-lesson from, 29; long known, 38; superior and outer planet, 41–42; influence on comets, 44; length of year on, 47; movement, 65; distance from ecliptic, 72; satellites, 106; color, 206, 209, 259; as evening star, 207; slight motion, 208; circuit of skies, 209–213; size and distance, 213–215; surface aspects, 215–216; day and night, 217–218; seasons, 224; symbol, 224; Bode’s law and, 245–246; how to recognize, 260–264. Schiaparelli, 174–175. Scorpio, constellation of zodiac, 76, 85–88, 91–92, 127, 153, 186, 188, 212–213. Sidereal year, 49–50. Sirius, the dog-star, 123. Spica, 84–85, 188.