IXDEX. 



487 



COMPRESSION. 



Compression of the terrestrial sphe- 

 roid, calculations of, 48-51 ; cause 

 of the great, in Jupiter, 66 ; mea- 

 sures of, from pressure of super- 

 incumbent mass, 78 ; effect of, on 

 magnetic action, 351. 



Concord, a, in music, 142. 



Conductors of electricity, 284, 285 ; 

 lightning, 293 ; molecular struc- 

 ture determinmo- the power of, 

 303. 



Conic sections, conditions compelling 

 bodies in space to move in, 5 ; 

 principle determining their nature, 

 11. 



Constellations, nearest the sun, 390 ; 

 where the orbit of the solar system 

 lies, 406 ; occupied by the nebulous 

 system, 417. 



Contraction caused by cold, 271, 272. 



Coolr, Captain, object of his first 

 voyage, 53. 



Cooper, Mr., list of missing stars 

 drawn up by, 395. 



Copper, electricity communicated to 

 plates of, 220 ; lightning-conduct- 

 ors of, 293 ; ncticm of an electro- 

 magnet on, 351, 552. 



Cordier, temperature of mines ob- 

 served by, 228. 



Cordilleras, effect on temperature of 

 their table-lands, 241. 



Corn, a, field used to illustrate the 

 propagation of sound, 129, 130. 



Cornwall, hot-springs in mines of, 

 229. 



Corona australis, nebula in, 414. 



Corpuscular theory of light, 167 ; 

 phenomena disproving, 171, 175, 

 176. 



Coseguina, volcanic irruption of, 233. 



Coulomb, instalment measuring elec- 

 trical intensity, invented by, 287. 



Creation, vastness and magnificence 

 of, 2. 



Crimea, cause of the great storm in 

 the, 122. 



Cross, Mr., voltaic battery with con- 

 stant action invented by, 300. 



Cross, the Southern, vacant patches 

 of the Milky Way near, 386. 



Crystallization defined, 106 ; forms 



CURVES. 



of, their variety affected by tem- 

 perature, 107, 108 ; permanent and 

 variable forms, 108, 109 ; cleavages 

 in, 109 ; common to all substances, 

 6. ; by the agency of electricity, 

 308, 309. 



Crystals, conditions determining their 

 forms, 107-109 ; optic axes of, 

 183 ; used in polarizing light, 186, 

 188 ; changes in, effected by com- 

 pression, 189; transmission of rays 

 of heat by, 258; expansion of, by 

 . heat, 272, 273 ; formed by electri- 

 city, 308 ; action of magnetism in, 

 349, 350 ; circumstances determin- 

 ing the set of, 350, 351 ; effect of 

 temperature on magnetized, 352. 



Gumming, Professor, experiments of, 

 in thermo-electricity, 333. 



Currents, two great, setting from each 

 pole towardsthe equator, 100 ; prov- 

 ing the rotation of winds, 124, 125. 



, electric, flow of, regulated by 



Volta, 297-299 ; characteristics of 

 Voltaic, 301 ; conductors, non- 

 conductors of, 309 ; continuous 

 flow of Voltaic, 312 ; action of, on 

 magnets, 313-315 ; reciprocal and 

 mutual action of magnetic and 

 electric, 316,317 ; Ampere's theory 

 of, unsolved difficulties, 317, 318 ; 

 effect of, on polarized rays, 319; 

 electric, evolved by magnets, 322, 

 323 ; their power of producing 

 induction, 324 ; direction of, pro- 

 duced by rotation, 330-332 ; evolved 

 by application of heat, 332, 333 ; 

 produced by intersecting magnetic 

 curves, 339 ; induced by crossing 

 terrestrial lines of magnetic force, 

 342. 



Curves, described by bodies projected 

 in space, 5. 



, magnetic, 338 ; electricity pro- 

 duced by intersecting, 339 ; nature 

 of, proved by Dr. Faraday, 339, 

 340 ; terrestrial, 341, 342 ; extent 

 of the range of terrestrial, 344 ; 

 complete connected system of the 

 terrestrial, 345 ; inductive effect on 

 the Atlantic telegraph, 346 ; dia- 

 magnetic, 348. 



