INDEX. 



449 



Earthquakes, 248. 



, noise of, 132. 



Echoes, 13-2. 



Eclipses of the sun, 40. Note 1 14. 



of the moon, 39. Xote 109. 



of Jupiter's satellites, 29. Notes 



93, 94. 



of the planets, 41. 



Ecliptic, 8. 



, plane of, 10. 



, secular variation of, 19, 75, 77. , 



Egyptians, their year and week,' 80. j 

 Elastic bodies, vibrations of, 135 et 



seq. See Vibration. 

 Elasticity of the atmosphere, 112 et \ 



of matter, 96. 



Electric induction, 276. 



intensity, 277 et seq. 



tension, 278. 



clouds, 281. 



currents, 291, 314, 319 et seq. 



and magnetic currents, 319 et 



seq. 



machines, 333. 



Electricity, common, 271. 



, effects of, 282, 86. 



, sources of, 271, 280. 



, atmospheric. 281. 



, velocity of, 284. 



, Voltaic, 290 et seq. 



, animal, 299. 



, thermal, 328. 



by rotation, 325. 



producing rotation, 316. 



of metallic veins, 332. 



, magneto, 322. 



, identical with magnetism, 325. ; 



, identity of all the kinds, 336. j 



Electrics and non-electrics, 271 et ] 



seq. 



Electro-magnetism, 314. 

 magnetic induction, 317, 318. 



magnets, 317. 



dynamic cylinders, 319. Xote 



219. 



dynamics, 319. 



Elements of the planetary orbits, 9. 

 Note 57. 



, how founded from observa- 

 tion, 58. Note 135. 



Elements of parabolic orbits, 339. 



of stellar orbits, 364. 



Ellipse, a conic section, 5. Note 24. 



, the limits of, 187. Note 210. 



Ellipsoid, oblate and prolate, 4. 

 Note 9. 



of revolution, 44. Note 119. 



, terrestrial. 49. 



29 



Elliptical or true motion, 8. Note 

 39. 



Encke, Professor, his determination 

 of the orbit and motion of the 

 comet named after him, 346. Of 

 its acceleration, 346. And of the 

 orbit of the star 70 Ophiuchi, 367. 



Epoch, the, 10. 



, longitude of the, 10. 



Equation of the centre, 9, 34. Note 

 48. 



of time, 78. 



Equator, 4. Note 11. 



Equilibrium, stable and unstable, 12. 

 Note 60. 



Equinoctial, 9. Note 46. 



Equinoxes, 9. Note 46. 



Era, the Christian, 80. 



Eratosthenes 'measures a degree of 

 the meridian between Syene and 

 Alexandria, 48. 



Ether, its nature, 171. 



Ethereal medium, 21, 97, 171. 



, temperature of, 239. 



, resistance of, 337. 



, vibrations of, 171, 193, 194. 



, elasticity of, 31. Note 99. . 



Eudoxiis describes the state of the 

 heavens about the time of the 

 Trojan war, 84. 



Evection, a lunar inequality, 34. 

 Note 103. 



Eccentricity, 9. Note 52. 



, secular variation of the, 17. 



of the orbits of Jupiter's satel- 

 lites, 27. 



of lunar orbit constant, 36. 



of the terrestrial orbit diminish- 

 ing, 19. 



of the terrestrial orbit, its varia- 

 tion the cause of the acceleration 

 in the moon's mean motion, 37. 



Expansion of substances by heat, 

 222. 



Extraordinary refraction, 150. 



ray and image, 173. 



F. 



Fall of heavy bodies, 6, 49. 



at the surface of the sun and 



planets, 56. 



Fall of meteorites, 381. 



Faraday, Dr., reduces the gases to a 

 liquid state. 99. His causes of 

 affinity, 103. His experiments on 

 spontaneous combustion, ib. His 

 theory of the aurora, 289. His 

 views nf electro-chemical decom- 



