on the nebula in Vulpes, 333; 

 his description of the Magellanic 

 Clouds, 342 ; on the black specks 

 and Coal-bags of the southern 

 hemisphere, 347; on the heat of 

 the Moon's surface, 461. 

 Herschel, Miss, discovery of a ne- 

 bula by, 318 

 Hipparchus mentions nebulous 



stars, 293. 



Houzeau's observations on the zo- 

 diacal light, 565. 



Humboldt, Alexander von, works of, 

 quoted in various notes 

 Asie Centrale, 453, 589. 

 De Distributione Geographica 



Plantarum, 451. 

 Exarnen critique de 1'Histoire 

 de la Geographic du Nou- 

 veau Continent, 294, 315, 

 317, 338, 490. 

 Kleinen Schriften, 440. 

 Voyage aux Regions equinox - 



iales, 484, 581- 



Vues des Cordilleres et Monu- 

 mens des peuples indigenes 

 de 1'Amerique, 417, 540. 

 Recuil d'observations astrono- 



miques, 484. 

 Huygens discovers the nebula in the 



sword of Orion, 299, 327. 

 Hygeia, discovery of, 421 ; elements, 



508. 

 Hyperion, a satellite of Saturn, 523. 



Intensity of the solar light on the 



planets, 461. 

 Interior comets, 555. 

 Interior planets, 424. 

 Irene, discovery of, 421 ; elements, 



508. 

 Iris, discovery of, 421 ; elements, 



508. 

 Irregular nebulous masses, 321 ; 



situate near the Milky Way, 322 ; 



extraordinary size and singular 



forms, 326. 

 Isaac, Aben Sid Hassan, introduces 



the latinized term nebulosae into 



the Alphonsine Tables, 294. 



Jacob, Captain, on the nebula 



round r) Argus, 332. 

 Japetus, a satellite of Saturn, 523. 

 July, falling stars in, 579. 

 Juno, discovery of, 421 ; elements, 



508. 

 Jupiter, numerical data, 511 ; 



streaks, or girdles, 513. 

 Jupiter's satellites, numerical data, 



515. 



Kant's speculations on nebulse and 

 star-formation, 301. 



Kepler on planetary distances, 433j 

 laws of planetary motion dis- 

 covered by, 599. 



Lacaille, his classification of ne- 

 bulae, 300. 



Lambert's speculations on nebulae, 

 301. 



Lassell, discovery of a satellite of 

 Saturn by, 523; of satellites of 

 Neptune by, 532. 



Laurentius stream of falling stars, 

 579. 



Le Gentil's study of nebulae, 

 301. 



Leonardo da Vinci, Earth-light 

 known to, 483. 



Levenier and Adams, claims to 

 the discovery of Neptune, 529. 



Lexell's Comet, 547. 



Light, time required to traverse the 

 radius of the Earth's orbit, 361 ; 

 solar and artificial, 393; differ- 

 ence of intensity in the different 

 planets, 461. 



Light, zodiacal. See Zodiacal light. 



Light-clouds, comets so styled by 

 the Greeks, 533. 



Lucerna Mundi, the Sun, 359. 



Lunar atmosphere disproved, 486. 



Lunar spots, 488. 



Magellanic Clouds, early notices of, 

 294: termed Cape-clouds by the 

 Portuguese, 335 ; general adop- 

 tion of the name, 339 ; described 

 by Sir John Herschel, 342 ; not 



