INDEX. 



501 



LAYANG. 



temperature in different, 246, 247 ; 

 of wine-growing, 250 ; magnetic 

 storms varying with, 345. 



Layang, observations made at, 1100 

 years before the Christian era, 88. 



Le Sueur, specific diversity of marine 

 animals observed by, 254. 



Le Verrier, M., principle of La 

 Grange applied by, 21 ; zone of in- 

 stability found, ib. ; discovery of 

 Neptune, 62 ; his observations on 

 atmospheric waves, 122 ; comets 

 identified by, 362; his table of 

 comets' orbits, ib. 



Lecaille, his globular nebulous cluster, 

 414 ; nebula, 418. 



Lenticular nebulae, 409 ; haze sur- 

 rounding the sun, 412. 



Leo, nebulous system in, 417. 



Leon-Faucault, M., velocity of light 

 in air and water ascertained by, 

 202. 



Lerius, banks of algae found by, 253. 



Leslie, Professor, compression of air 

 calculated by, 78 ; experiments on 

 radiation of heat, 257. 



Lexel, observations of, on the comet 

 of 1770, 361, 362. 



Libra, the five great planets in con- 

 junction near, 42. 



Librations of the moon, of Jupiter's 

 satellites, 69 ; of a Centauri, 399. 



Lichen, red, growing on snow, 249. 



Light, rate of its velocity, 31 ; truth 

 deduced from the uniformity of its 

 velocity, 32 ; from the aberration 

 of, ib. ; period required to reach the 

 earth from a Centauri, 54 ; action 

 of the atmosphere on, 153 ; con- 

 ditions regulating the transmission 

 and reflection of, 156 ; loss of, 

 transmitted by the horizontal stra- 

 tum, 157 ; effects of transmission 

 through the atmosphere, 158 ; New- 

 ton's analysis of, 1 59 ; Brewster's, 

 161 ; phenomena disproving New- 

 ton's theory, 167, 168 ; undulatory 

 theory, 168-170 ; conditions af- 

 fecting its intensity and colour, 

 170 ; experiments testing the mu- 

 tual relations of colour and, 171- 

 175 ; law of its absorption identical 



LIQUIDS. 



with a law of motion, 175-177 ; 

 repeated vibrations producing the 

 sensation of, 178; polarized, de- 

 fined, 179 ; modes of polarization, 

 substances polarizing, 179-185 ; ac- 

 cidental polarization of, 195; de- 

 graded, or fluorescence, 196 ; objec- 

 tions to the undulatory theory 

 analyzed and disproved, 199-202 ; 

 comparative velocity of, in air and 

 water, 202 ; pictures produced by 

 reflected, 203-207; rays of, inde- 

 pendent of heat, 214, 215; com- 

 parative amounts of solar and lunar, 

 225 ; different measures of illumina- 

 tion from, 227 ; influence of, on 

 vegetation, 249 ; colour developed 

 without the influence of, 253 ; se- 

 parated from heat by Melloni, 265; 

 produced by accumulation of heat, 

 270 ; law regulating the force of 

 artificial, 279, 280 ; electrical, 288, 

 289 ; produced by voltaic electri- 

 city, 302 ; stratifications of the 

 electric, 306 ; influence of mag- 

 netism and electricity on, 319, 320 ; 

 of comets, 379-381 ; of the fixed 

 stars, 401-404. 



Lightning, development of heat ex- 

 hibited by, 276, 277 ; experiment 

 showing the velocity of, 289 ; 

 theory of, 292 ; the back stroke, ib. ; 

 force of the direct stroke, 293 ; 

 sheet, 294 ; effect of, on the com- 

 pass, 312. 



Lime, carbonate of, variety of form 

 in its crystals, 1 07 ; invariable form 

 ultimately assumed by, 109. 



Lines of magnetic force, 338, 339; 

 experiment ascertaining the form of, 

 339, 340; terrestrial, 341, 342; 

 extensive courses of, 344 ; a con- 

 nected system, 345 ; diamagnetic, 

 348. 



Lion, the, conjunction of planets in, 

 42. 



Liquids, balance of forces constituting, 

 104, 105 ; action of capillary at- 

 traction on, 113-116. 



possessing the property of cir- 

 cular polarization of light, 190, 

 191-193. 



