506 



PHYSICAL SCIENCES. 



MUSICAL. 



Musical instruments constructed by 

 Professor Wheatstone, 143. 



NAPLES, comet discovered from, 370. 



Nautical Almanac, computations for 

 calculating longitudes, 43 ; time 

 calculated by, 84. 



Navigation, importance of lunar mo- 

 tions in, 42 ; laws of storms to be 

 observed in, 127, 128. 



Neap-tides, 96, 99. 



Nebulae, number and general aspect of, 

 407 ; catalogues, 407, 408 ; classes, 

 408 ; irregular, 408, 409 ; of definite 

 form, 409 ; spiral, 409, 410 ; an- 

 nular, 410, 41 1 ; elliptical, double, 

 411 ; distance of a nebulous star 

 discoverable, 411, 412 ; aspect and 

 colour of planetary, 412 ; elliptical 

 common, 413 ; globular clusters, 

 413-415; resolution of, 415; star 

 clusters, 415, 416; probable law 

 of motion, 416 ; distribution of, 



416, 417; the megallanic clouds, 



417, 418 ; round n Argils, 418, 

 419 ; remote systems, 419 ; invi- 

 sible solar, 421 ; meteors falling 

 from, 422. 



Nebulous appearances of a comet, 

 364 ; extent of, matter surround- 

 ing a comet, 373 ; its A-ariable 

 brilliancy, 374 ; appearances round 

 the sun, 412. 



stars, 411, 412. 



Needle, magnetized, effect of Voltaic 

 electricity on a, 312, 313 ; sus- 

 pended by means of electricity, 

 314; condition of its deviation by 

 an electric current, 317. 



Negative electricity defined, 282 ; 

 mode of exciting, 283. 



impressions in photography, 



204. 



Neptune, periodical variations in his 

 orbit, 22 ; revolution of his satel- 

 lite from east to west, 33 ; re- 

 moteness of, 54; anticipation of 

 discovery, 61 ; orbit and motions 

 of, determined, 62 ; his diameter, 

 mean distance from the sun, 63 ; 

 temperature of, 225 ; action of, on 

 Halley's comet, 363. 



NODES. 



Neutral phosphate of soda, its crys- 

 tals, 109. 



New Mexico, monsoons occasioned by 

 its deserts, 124. 



Newton, Sir Isaac, steps of his argu- 

 ment for the universal influence of 

 gravitation, 3 ; his discoveries of 

 modes of attraction, 4 ; motions of 

 bodies projected in space, ascer- 

 tained by, 5 ; form of a fluid 

 mass in rotation ascertained, 45 ; 

 problem occupying astronomers 

 since, 64 ; discrepancy between his 

 theory of tides and observations, 

 96 ; compound nature of white 

 light proved by, 159 ; his analysis 

 of the solar spectrum disputed, 

 161 ; his theory of light disproved, 

 1 67 ; measurements of coloured 

 rays, 172, 173 ; scale of colours, 

 174 ; decisive experiment disprov- 

 ing the theory of light, 202 ; re- 

 marks on the transmission of 

 gravity, 355. 



Niagara, the falls of, not independent 

 of the influence of astronomy, 1. 



Nickel, sulphate of, change in its 

 crystals, when exposed to the sun, 

 107. 



Niepce', M., photographic pictures 

 rendered permanent by, 204 ; dis- 

 covery in photography suggested, 

 207 ; colours of images of the sun 

 taken, 213 ; experiments by, on 

 saturation of substances with light, 

 296. 



Nismes, discovery of a telescopic 

 planet at, 21. 



Nitrogen, proportion of, in the at- 

 mosphere, 117; spectrum from, 

 303 ; iron volatilized by the Vol- 

 taic arc in, 304 ; unaffected by 

 magnetism, 344. 



Nobili, M., direction of electric cur- 

 rents ascertained by, 333. 



Nodes, ascending and descending, of a 

 planet defined, 9 ; movement of 

 their lines in secular disturbances, 

 14; advance and recession of, 18; 

 supposed recession of, on the equa- 

 tor of the solar system, 24 ; of the 

 moon, period of their sidereal re- 



