488 



IND2X. 



magnetic storms, 141 ; polar 

 light, 151 ; reaction of the 

 interior on the surface, 162 

 (see also Earthquakes, Volcanoes); 

 thickness of the crust of, pro- 

 bably very unequal, 169. 



Earthquakes, variety of views as 

 to their cause, 167 ; the impulse, 

 167 ; translatory movements, 

 173; subterranean noises, 178; 

 velocity of propagation, 179 ; 

 distinguished, but improperly, 

 aa Plutonic and Volcanic, 180 ; 

 three groups of phenomena 

 which indicate the existence of 

 one general cause, 183 ; list of 

 memorable examples of these 

 phenomena, 183. 



Earth-waves in volcanic phe- 

 nomena, 171. 



Eastern Asia, volcanoes of the 

 islands of, 367. 



Eclgecombe, Mount, a volcano, 

 269, 418; another in New 

 Zealand, 397. 



Edinburgh, beautiful aurora ob- 

 served at, 158. 



Edrisi on the land of Gog and 

 Magog, 359. 



Eifel, extinct volcanoes of the, 

 231 ; two kinds of volcanic 

 activity distinguishable, 232 ; 

 Mitscherlich on the minerals, 

 235 ; Ehrenberg on the infusoria, 

 237. 



Elburuz, as an extinct volcano, 362. 



Elevation, question of the in- 

 fluence of, on magnetic dip and 

 intensity, 114 ; craters of, dis- 

 tinguished from true volcanoes, 

 227. 



Elias, Mount, a volcano, 252, 419. 



Elliot, Capt., on the magnetic 

 equator, 105. 



Ellipticity of the earth, specula- 

 tions of the ancients on the, 26 ; 

 Bessel's determination, 27. 



El Nuevo, a volcano, 274. 



El Viejo, a volcano, measurements 

 of, 274. 



El Volcancito, now a mountain of 

 ashes, 321. 



Emanations from fumaroles, their 

 nature, 424. 



Enceladus. See Typhon. 



England, volcanic phenomena in, 

 350, 483. 



Equator, magnetic. See Magnetic 

 equator. 



Erebus, Mount, the volcano, 103, 

 249. 



Ermau on the magnetic equator, 

 105 ; his researches on the vol- 

 canoes of Kamtschatka, 363. 



Erupted blocks, 479. 



Eruption, masses of, considera- 

 tions on, 225; craters of, 226. 



Eruptions of volcanoes, considera- 

 tions on the general laws of, 

 255 ; varying heights to which 

 matters are cast, 264. 



Etna, eruptions of, usually occur 

 within a space of six years, 255 ; 

 periods of its greatest activity, 

 257 ; height to which ejected 

 matters attain, 265 ; its tra- 

 chytes, 165. 



Euboea, Strabo's description of an 

 earthquake in, 225. 



Europe, active volcanoes of, 349 ; 

 extinct volcanoes and volcanic 

 phenomena, 231, 238, 350, 483. 



Faraday's discovery of the para- 

 magnetic force of oxygen, 78 ; 

 important results expected from 

 it, 82, 99; on diamagnetism, 

 49, 78. 



Fairweather, Mount, a volcano, 4 1 8. 



Felspar, variety of minerals com- 

 prised under the denomination 

 of, 457, 474. 



Ferdinandea, the volcanic island, 

 349. 



Figure of the earth, attempts to 

 solve the problem, 13 ; deter- 

 minations of Bessel, 14 ; earlier 

 observations, 16. 



Fissures caused by earthquakes, 

 173; volcanic, 226, 228; vol- 



