Combustion, facts relating to, xxviii, 70. ----, observations on, _S. Morey_, xxv, 146. ---- of chlorine by olefiant gas, x, 365. ---- of coal strata, products of, viii, 382. ---- with spongy platina discovered, vii, 387. ----, spontaneous, iii, 383; v, 201; xxii, 161; xxvii, 178. ----, ----, of various substances described, _J. Mease_, xxxiii, 147. ---- of ashes, xlii, 165.^f Comet of 1819, ii, 374. ---- of 1822, notice of, ix, 199, 367. ---- of 1823, 1824, observations on, viii, 315. ----, Olbers's elements of, xiii, 189. ----, Biela's, notice of, xxiii, 390. ----, ----, elements of, 1832, xxiv, 346; xxv, 191; xxviii, 398. ----, ----, supposed possibility of collision with Encke's, xxiv, 346. ---- of July, 1832, _J. J. Littrow_, xxiv, 348. ----, discov'd Ap. 8, 1834, xxvi, 402. ----, Halley's, 1835, xxix, 155. ----, ----, _E. Loomis_, xxx, 209. ----, ----, remarkable phenomena of, xxxv, 285. ----, Encke's, remarks on, xxiv, 346; xxxiii, 15; xxxv, 388. ----, ----, notice of, xxxvii, 191. ----, Dec., 1839, Galle's first, notice of, xxxviii, 378; xl, 207. ----, Jan., 1840, Galle's second, notice of, xl, 40, 207. ----, March, 1840, Galle's third, notice of, xl, 207. ----, October, 1840, the third of 1840, Bremicker's, xl, 207. ----, of October, 1842, discovered by _M. Laugier_, xliv, 211. ----, great, of 1843, xliv, 412; xlv, 188^f, 229. ----, great, of 1843, elements of, _S. C. Walker_ and _E. O. Kendall_, xlv, 188.^f ----, second of 1843, xlv, 230. ----, third of 1843, xlvi, 210. ----, De Vico's, xlviii, 219,[F] 402. ----, ----, first seen in the U. States by _H. L. Smith_, xlvii, 419. ----, southern, of December, 1844, observations on, xlviii, 402; xlix, 220. ----, D'Arrest's, Dec. 28, 1844, xlviii, 403. ----, Mauvais's, xlix, 220. ----, second of 1845, xlix, 220. ----, third of 1845, xlix, 220. ----, on the observations of, _P. J. Rodriguez_, xvi, 94.^f ----, nature of, _W. A. Norton_, xlvi, 104. ----, on the tails of, x, 395; xxxiii, 5, 11. ----, ----, _W. Mitchell_, xxxviii, 35; xl, 59. ----, ----, of Halley's, _B. F. Joslin_, xxxi, 142, 324. ----, ----, formation of, _W. A. Norton_, xlvi, 104.^f ----, possible collision of two, _J. J. Littrow_, xxiv, 346. ----, medal for discovery of, by the King of Denmark, xxiii, 391. _Commun, J. du_, on the causes of fresh water springs, xiv, 174.^f ----, hypothesis on volcanoes and earthquakes, xv, 12.^f ----, ---- ----, objections to, xv, 25. ----, ---- ----, strictures on, xvi, 51. Compass, mariner's, on the invention of, _A. Humboldt_, xl, 242. ----, microscopic, _J. Locke_, xxiii, 237.^f ----, surveyor's, improvements in, by _T. Kendall_, xix, 337.^f ----, pivots, on the use of native alloy for, xli, 67. [Footnote F: At this place, erroneously called _Faye's_ comet.] Complaisánts, on board a vessel in the Mediterranean, xvi, 171. Compression of water, xiii, 189. Comptonite, a new species, iv, 28.