Hall, Chester Moor, discovers principle of achromatic, 5 Halley's comet, 207, 213 Harding discovers Juno, 149 Hebe, discovery of, 150 Hegel proves that there are only seven planets, 149 Helium in chromosphere, 73 Helmholtz, speed of sensation, 48; solar contraction, 79 Hencke discovers Astræa and Hebe, 150 Henry, 30-inch Nice telescope, 8 Heraclides promontory, 117 Hercules, 237 Herculis [alpha], double star, 242 Herodotus, valley of, 118, 119, 126 Herschel, Sir John, drawing of Orion nebula, 262 Herschel, Sir William, 4-foot telescope, 13; impairs sight, 47; misses satellites of Mars, 143, 144; rotation of Saturn, 173; discovers Saturn's sixth and seventh satellites, 186, 187; early history, 190, 191; discovers Uranus, 191; discovers two satellites of Uranus, 196; binary stars, 244; gaseous constitution of nebulæ, 260; distribution of nebulæ, 267; translation of solar system, 269 Herschelian. See Telescope, forms of Hevelius, description of Saturn, 176 Hind discovers Nova Ophiuchi, 252 Hirst, colouring of Jupiter, 159 Hirst, Miss, colouring of Jupiter, 159 Holden on solar rotation, 59, 60 Holmes, Edwin, telescope-house, 38; comet, 211 Holmes, Oliver Wendell, 'Poet at the Breakfast-table,' 13 Holwarda observes [omicron] Ceti, 248 Hooke, observation of Gamma Arietis, 240 Howlett, criticism of Wilsonian theory of sun-spots, 61 Huggins, atmosphere of Mars, 140; gaseous nature of nebulæ, 210; spectrum of Winnecke's comet, 211; discovers nebula in Draco to be gaseous, 260; spectrum of Andromeda nebula, 264 Humboldtianum, Mare, 111 Humboldt observes meteor-shower of 1799, 224 Hussey, search for Neptune, 197 Hussey, W. J., period of [delta] Equulei, 245 Huygens, improvement on telescopes, 3; aerial telescopes, 4; discovers nature of Saturn's ring and first satellite of Saturn, 177, 186; observation of [theta] Orionis, 240; of great nebula in Orion, 261 Huygens, Mount, 116 Hydrogen in chromosphere, 73 Hyginus cleft, 119 I Imbrium, Mare, 116 Iron in chromosphere, 73 J Jansen, Zachariah, claim to invention of telescope, 1 Janssen, photographs of sun, 57 Journal of British Astronomical Association, 23, 38 Juno, discovery of, 149; diameter of, 152 Jupiter, brilliancy compared with Venus, 90; period of, 155; distance of, 155; diameter of, 155; compression, volume, density, 155; brilliancy, 156; apparent diameter of, 156; belts of, 157 _et seq._; colouring, 158, 159; changes on surface of, 159, 160; great red spot, 160-164; rotation period, 163-165; resemblance to sun, 164-166; satellites of, 166-169; observation of, 169-171; visibility of satellites, 166; diameters of, 167; occultations of, eclipses of, transits of, 167 K Kaiser sea, Mars, 145