INDEX. 



451 



Gravitation, a consequence of elec 

 trie action, 97 et seq. 



Gravity, the direction of, 43. 



Great inequality of Jupiter and Sat- 

 urn, 24, 83. 



Great comet of 1843, 350. 



Grimaldi, his discovery of colored 

 fringes on the borders of shadows, 

 169. 



Grylli, grasshoppers, crickets, lo- 

 custs, &c., 125, 126. 



Gymnotus elect ricus, 299. 



H. 



Haidinger. M., his experiments on 

 crystalization, 105. 



Hall, the first to construct an achro- 

 matic telescope, 159. 



Bailey's comet, 341. 



Hanstein, Professor, discovers all 

 substances to be magnetic in a 

 certain position, 305. 



Harmonic divisions of a musical 

 string, 134. 



divisions of a column of air, 



137. 



Harmony, 136. 



Harris, Mr. Snow, his experiments 

 oa electricity, 276 et seq. 



Harrison, Mr., his compensation pen- 

 dulum, 224. 



Hearing, the extent of, 126. 



, experiments of Dr. Wollaston 



on, 125. 



, experiments of M. Savart on, 



126. 



Heat, theory of, 206. 



, transmission of, 208. 



of various kinds, 210. 



, solar, trcnsmission of, 213. 



, maximum point of, in solar 



spectrum, 214. 



, polarization of, 215. 



, analogy between light and, 



218. 



, radiant, 220. 



, expansion by, 222. 



, propagation of, 225. 



, latent, 227. 



, application of, 229. 



, supposed to consist of undu- 

 lations of the ethereal medium, 

 230. 



, solar, 231 et seq. 



, quantity of solar, 252. 



, quantity of solar lost and gain- 

 ed by the earth, invariable, 261. 



, central, of earth, 241 et seq. 



Heat, superficial, of earth, 252. 



, distribution of, 253. 



, influence of, on vegetation, 



262. 



Height of atmosphere, 114. 



of tides, 91. 



of mountains, 7. 



Heliacal rising, 80. Note 146. 



Helix, circular and elliptical, 186. 



Henry, Professor, his temporary 

 magnet, 317. 



Herschel, Sir William, his discov- 

 ery of the satellites of Saturn and 

 Uranus, 32 ; of the rotation of Ju- 

 piter's satellites, 65 ; of the calo- 

 rific rays of the solar spectrum, 

 199. His observations on the point 

 of maximum heat in the solar 

 spectrum, .214. His account of 

 the nucleus of the comet of 1811, 

 352. Number of fixed stars he 

 saw in one hour, 361. His cata- 

 logue of double stars, and discov- 

 ery of the. binary systems, 365. 

 His observations of TT Serpentarii, 

 and of g Orionis, 368. On the 

 motion of the solar system, 370. 

 His observations on the Milky 

 Way, 374. On clusters of stars, 

 375. On the nebulae, 376. His si- 

 dereal astronomy, 381. 



Herschel, Sir John, his estimation 

 of the thickness of Jupiter's ring, 

 62. He ascribes the decrease of 

 the earth's temperature to the se- 

 cular variation of the eccentricity 

 of the earth's orbit, 70. On the 

 decrease of heat in the northern 

 hemisphere, ib. Proposes the use 

 of equinoctial time, 81. His re- 

 marks on the clearness of sound 

 during the night, 130. On thun- 

 der, 132. His discovery of two 

 new prismatic colors, 156. His 

 argument in favor of the undula- 

 tory theory of light, 169. On the 

 phenomena of polarization of 

 light, 172. On polarizing appa- 

 ratus, 183. His discoveries in the 

 photographic spectrum, 197. On 

 the discontinuity of calorific spec- 

 trum, 206. His discovery of the 

 parathermic rays, 231. His theory 

 of volcanic action, 249. Supposes 

 the ether may be in motion, 350. 

 On the contraction of the heads 

 of comets, 356. On the gravita- 

 tion of the binary systems, 362. 

 His estimation of the distances of 



