520 



INDEX. 



conditions for the existence of three 

 equal roots, or of two pairs of equal 

 roots, of a binary quartic or quintic," 

 314. 



Cay ley (A.), a memoir on the theory of 

 reciprocal surfaces, 220. 



, a memoir on cube surfaces, 221. 



Chambers (C.) on the solar and lunar 

 variations of magnetic decimation at 

 Bombay : Part L, 161. 



, observations of the absolute direc- 

 tion and intensity of terrestrial magne- 

 tism at Bombay, 426. 



on the unehminated instrumental 



error in the observations of magnetic 

 dip, 427. 



Chapman (E. T.) and Smith (M. H.), 

 note on the separation of the isomeric 

 amylic alcohols formed by fermentation, 

 308. 



Chemical reactions produced by light, on 



a new series of, 92. 

 Church (A. W.), researches on turacine, 



an animal pigment containing copper, 



436. 



Claudet (A. F. J.), obituary notice of, 

 lxxxv. 



Clock, on a new astronomical, 468. 

 Clouds in the sun's outer atmosphere, on, 

 39. 



, note on the formation and pheno- 

 mena of, 317. 



Codeia, on the action of hydrochloric acid 

 on, 460. 



Compass errors, correction of essential, in 



iron-built ships, 411. 

 Compounds, isomeric, with the sulpho- 



cyanic ethers (III.), 269. 

 Copley medal awarded to Sir Charles 



Wheatstone, 145. 

 Council, list of, 128, 151. 

 Crofton (M. W.) on the proof of the law 



of errors of observations, 406. 

 Crookes (W.) on the measurement of the 



luminous intensity of light, 166, 358. 

 , addendum to description of photo- 

 meter, 369. 

 on a new arrangement of binocular 



spectrum-microscope, 443. 

 on some optical phenomena of opals, 



448. 



Cubic surfaces, nienioir on, 221. 

 Cyclone, on the origin of a, 472. 



Daubeny (C. Gr. B.), obituary notice of, 

 lxxiv. 



De Candolle (A.) elected foreign member, 

 407. 



Decimation disturbance at Lisbon, on the 

 reappearance of some periods of, 238. 



Deep sea, temperature of, 188. 



soundings, note on a self-registering 



thermometer adapted to, 482. 



Delaunay (C. E.) elected foreign member, 

 407. 



Diamonds, on the structure of, 291. 



Dip, determinations of, at some of the 

 principal observatories in Europe, 280. 



— — , magnetic, on the uneliminated in- 

 strumental error in the observations of, 

 427. 



Dupre (A.) and Page (F. J. M.) on the 

 specific heat and other physical pro- 

 perties of aqueous mixtures and solu- 

 tions, 333. 



Dredging expedition in North Atlantic, 



notice of, 140. 

 , preliminary report on, 168 ; letters 



concerning, 197. 



Eclipse of the sun, 1851, Mr. Babbage's 

 note on, 133. 



, Aug. 18, 1868, spectroscopic obser- 

 vations of, 74 ; observations of, along 

 the coast of Borneo, 81 ; Lieut. Her- 

 schel's report on, 104; Lieut. Camp- 

 bell's report on, 120 ; Captain Perry's 

 observations of, 125 ; aid by Indian go- 

 vernment towards observations of, 124 ; 

 Capt. Bennoldson's observations of, 

 125 ; Capt. Murray's observations of, 

 127 ; Capt. King's observations of, 127 ; 

 notice of, 137. 



Elagin (Lieut.), determinations of the dip 

 at some of the principal observatories 

 in Europe by the use of an instrument 

 borrowed from the Kew Observatory, 

 280. 



Electric current, measurement of velocity 

 of, 146. 



light, prismatic analysis of, 146. 



telegraph, instruments for the, 146. 



Electrical phenomena of the nerves, 378. 



Electrotonus, on, 386. 



Ellery (B. J.), account of the building in 



progress of erection at Melbourne for 



the great telescope, 328. 

 Emerald, on the structure of, 294. 

 Equal roots, note on the memoir on the 



conditions for the existence of three, &c, 



314. 



Equines, on fossil teeth of, from Central 

 and South America, 267. 



Errors of observations, on the proof of the 

 law of, 406. 



E thy lie alcohol and water, specific heat 

 of, 333 ; boiling-points of, 333 j capil- 

 lary attraction, 334 ; rate of expansion 

 and compressibility, 335. 



mustard-oil, homologues and ana- 

 logues of, 67, 69 ; action of hydrogen 

 on, 269 ; of water and hydrochloric 

 acid, 272 ; of sulphuric acid, 274 ; of 

 nitric acid, 276. 



Explosive agents, contributions to the 

 histoiy of, 395. 



