INDEX. 



511 



Diameter, apparent, of the sun and 



planets, 44, 63. Note 110. 

 Dicotyledonous plants, 305. 

 Diffraction of light, 195, 202. Notes 



193, 196, 197. 

 Dip, magnetic, 342. 

 Dipping needle, 341 et seq. 

 Disc, the apparent surface of a heavenly 



body, 34. 

 Dispersion of light, 183. Note 90. 



on the undulatory theory, 221. 



Displacement of Jupiter's orbit and 



equator, 33. Note 90. 

 Distance of the sun and planets, 61. 



Note 132. 



of the moon, 6, 39. Note 1?. 



, perihelion, 12. Note 57- 



of the fixed stars, 416. 



, lunar, 43. 



, inverse square of the, 6. Note 23. 



, zenith, 99. Note 149. 



Disturbing force, 16. Note 63. 



of the sun , 40 , 94. Note 1 01 . 



of the planets on the moon, 41. 



of the moon on the earth, 89. 



of the moon on herself, 41. 



Division of time, 93. 



> decimal, 95. 



Doebereiner, M., his experiments on 



the combustion of platina, 122. 

 Dollond, Mr., his achromatic telescope, 



184. 

 Double refraction, 202. Note 200. 



stars, 416 et seq. 



Dusejour, M., proves that a comet can- 

 not remain long near the earth, 386. 

 Dynamical equator, 343. 



Earth, form of the, 7, 50. 



, from arcs, 53. 



, from pendulum, 55. 



, from lunar theory, 45. 



, from precession and nutation, 57. 



, from the mean of all, 57. 



, mean diameter, circumference, 



polar and equatorial radius of the, 54. 



, density of the, 65, 88. 



, internal structure of the, 88. 



Earth, central heat, and temperature 



of the, 81 et seq., 277 et seq. 



, magnetism of the, 341. 



, magnetic by induction, 378. 



, rotation of the. See Rotation. 



Earthquakes, 283. 



, noise of, 154. 



Echoes, 153. 



Eclipses of the sun , 46. Note 1 14. 



of the moon, 45. Note 109. 



of Jupiter's satellites, 34. Notes 



93, 94. ' 



- of the planets, 47. 

 Ecliptic, 11. 



-, plane of, 12. 



, secular variation of, 22, 90, 92. 



Egyptians, their year and week, 96. 

 Elastic bodies, vibrations of, 156 et seq. 



See Vibration. 

 Elasticity of the atmosphere, 131 et 



seq. 



of matter, 114. 



Electric induction, 314. 



intensity, 315 et seq. 



tension, 31 7 



clouds, 320. 



currents, 330, 355, 361 et seq. 



machines, 380. 



Electricity, common, 310. 



, effects of, 321, 325. 



, sources of, 310, 318. 



, atmospheric, 320. 



, velocity of, 323. 



, voltaic, 330 et seq. 



, animal, 340. 



, thermal, 374. 



by rotation, 371. 



producing rotation, 356. 



of metallic veins, 379. 



, magneto, 365. 



, identical with magnetism, 366. 



, identity of all the kinds, 383. 



Electrics and non-electrics, 312 et seq. 

 Electro-magnetism, 355. 



magnetic induction, 358. 



magnets, 359, 368. 



dynamic cylinders, 361. Note 219. 



dynamics, 361. 



Elements of the planetary orbits, 11. 



Note 57. 

 , how founded from observation, 67. 



Note 135. 



