Cassegrain. See Telescope, forms of Cassini uses aerial telescope, 4; discovers four satellites of Saturn and division of ring, 4; observations on Jupiter, 160; discovers division in Saturn's ring, 177; four satellites of Saturn, 184, 186, 187 Cassiopeiæ [eta], double star, 242; Nova, 252 Castor, 234; double star, 242; binary, 245 Caucasus, lunar, 116 Cauchoix constructs 12-inch O.G., 6 Celaeno, 256 Celestial cycle, 18 Centauri [alpha], 231, 234 Ceres, discovery of, 149; diameter of, 152; reflective power, 152 Ceti [zeta], naked-eye double, 241; Mira ([omicron]) variable star, 248; period, 249 Challis, search for Neptune, 199 Chambers, G. F., on comets, 208-209; number of comets, 209 Chromosphere, 71, 73, 76; depth of, 73; constitution of, 73 Clark, Alvan, constructs 18-1/2-inch, 8; 26-inch, 8; 30-inch Pulkowa telescope and 36-inch Lick, 8; 40-inch Yerkes, 9 Clavius, lunar crater, 113, 114, 120 Clerke, Miss Agnes, 60, 73; climate of Mercury, 85; on Mars, 139; albedo of asteroids, 152; Jupiter's red spot, 161; on comet 1882 (iii.), 218; on Mira Ceti, 248 Clerk-Maxwell, constitution of Saturn's rings, 179 Cluster variables, 259 Clusters, irregular, 256; globular, 258 Coggia's comet, 211 Coma Berenices, 256 Comas Solà, rotation of Saturn, 174 Comet of 1811, 206; of 1843, 206, 215, 216; of Encke, 207; of Halley, 207, 213; Brooks, 210; Donati, 205, 210; Tempel, 211; 1866 (i.), 214, 224; Winnecke, 211; Coggia, 211; Holmes, 211; Biela, 213; and Andromeda meteors, 214, 215, 224, 225; great southern (1901), 211; Wells, 213; of 1882, 213, 216-219; De Vico, 213; Brorsen, 213; of Swift 1862 (iii.), and Perseid meteors, 214, 224; great southern (1880), 216; of 1881, 216; of 1807, 216 Comets, 203 _et seq._; structure of, 205; classes of, 206-208; number of, 209; spectra of, 211-213, 218; constitution of, 212, 218; connection with meteors, 214, 215, 224; families of, 215-218; observation of, 219-222 Common 5-foot reflector, 12; photographs Orion nebula, 262 Constellations, formation of, 237, 238 Contraction of sun, 79 Cooke, T., and Sons, 25-inch Newall telescope, 8; mounting of 6-inch refractor, 31 Copernicus, prediction of phases of Venus, 92; lunar crater, 114; ray system of, 120, 121 Corona, 71, 72, 76; tenuity of, 71; variations in structure, 71; minimum type of, 71, 72; maximum type of, 72; constitution of, 72 Corona Borealis, 238; Nova in, 252 Coronal streamers, analogy with Aurora, 71 Coronium, 72, 73 Cottam, charts of the constellations, 278 Crape ring of Saturn, 178 Craters, lunar, 109, 112; ruined and 'ghost,' 111; number and size, 112; classification of, 112