496 



PHYSICAL SCIENCES. 



HARMONICS. 



Harmonics of the fundamental note 

 in music, 140, 141. 



Harmony, property of sound regu- 

 lating, 131 ; definition of, vibra- 

 tions producing, 142. 



Hams, Sir William Snow, experiments 

 of, in electricity, 287, 288 ; light- 

 ning-conductors invented by, 293. 



Han-ison, pendulum invented by, 272. 



Hastings, coast of France distinctly 

 seen from, 157. 



Heat affecting the form of crystals, 

 107 ; evolved in chemical combi- 

 nations, 110 ; irregular decrease 

 of, in the atmosphere, 119 ; maxima 

 of, iu the solar spectrum, 215 ; 

 peculiar chemical quality of, in 

 parathermic rays, 218 ; impressions 

 traced by, .220-222; periodical 

 variations in the sun's, 225 ; dif- 

 ferent proportions of solar, reaching 

 the planets, 225, 226 ; effect of 

 the terrestrial atmosphere on lunar, 

 227 ; mode of its development in 

 opaque bodies, ib. ; sources of ter- 

 restrial, 228-238 ; irregular distri- 

 bution of, 239-247 ; laws affecting 

 its radiation, 257 ; its transmission, 

 258-262; polarization of, 264- 



267 ; undulatory theory, 267 : ab- 

 sorption and reflection of radiant, 



268 ; phenomena caused by radia- 

 tion of, 269 ; accumulation of, pro- 

 ducing light, 270 ; expansive force 

 of, 271, 272 ; modes of propaga- 

 tion, 273, 274 ; produced by mo- 

 tion and equivalent to it, 274-277 ; 

 laws regulating the force of arti- 

 ficial, 279, 280 ; power evolved by 

 application of, 280 ; identical in 

 nature with sound, 281 ; electrical, 

 288; sheet-lightning caused by, 

 294 ; phosphorescence, 294 ; de- 

 veloped by voltaic electricity, 301, 

 302 ; effect of, on electrical con- 

 ductors, 309; connexion between 

 the production of electricity and, 

 310; its direct relation to mag- 

 netism and electricity, 319, 320 ; 

 mechanical power and convertible 

 forces, 329 ; terrestrial magnetism 

 attributed to the action of, 333 ; 



HERSCHEL. 



measured by electric currents, 334 ; 

 affecting atmospheric magnetism, 

 344 ; fundamental principle of the 

 dynamic theory, 357. 



Helena, St., distinct flora of, 252. 



Helix, circular and elliptical, described 

 in polarization of light, 192, 193 ; 

 electrical experiments by means of, 

 314 ; induction of, increasing elec- 

 tric power, 322, 323. 



Heller, his observations on the comet 

 of 1556, 370, 371. 



Helmholtz, Professor, power of che- . 

 mical force estimated by, 112 ; his 

 calculation of the chemical force 

 developed by combustion, 278 ; of 

 the amount of latent force in our 

 system, 280. 



Hemisphere, cause of excess of cold in 

 the southern, 241; superficial ex- 

 tent of land in northern and south- 

 ern, 244. 



Henley, Mr., magneto - electric ma- 

 chine constructed by, 325. 



Henderson, Professor, parallax of 

 a Centauri calculated by, 387 ; of 

 Sirius, 389. 



Henry, Professor, experiments of, on 

 magnetism, 315. 



Herapath, Mr., his view of elastic: 

 force preferred to Sir Humphry 

 Davy's, 276. 



Hercules, eclipse of a double star in, 

 398 ; globular nebulous cluster. 

 414. 



Herschel, Sir William, observations 

 of Saturn's and Uranus's satellites 

 by, 32, 33 ; theory of, regarding 

 the solar constitution, 41 ; cause 

 of effects of light in eclipses ac- 

 cording to, 42 ; rotation of Jupiter's 

 satellites determined by, 70 ; mu- 

 tual independence of light and heat, 

 214, 215 ; influence of the sun's 

 spots on heat, 225 ; point of maxi- 

 mum heat in the solar spectrum, 

 263 ; comet of 1811 observed by, 

 374 ; its luminous envelopes exa- 

 mined, 375 ; the Milky Way exa- 

 mined by, 385 ; his discovery of 

 the orbital motions of double stars, 

 388 ; catalogue of double stars by. 



