P. 327.—In the _Comptes Rendus_ for March 2, 1891, M. Bigourdan has a paper on the variability of the nebula N.G.C. 1186, situated near Algol. This nebula was discovered by Sir W. Herschel in 1785, and though Sir J. Herschel re-observed it in 1831, Lord Rosse looked for it without success in 1854 and 1864. On Nov. 8, 1863, D’Arrest failed to detect the nebula, though he searched for it with assiduity at a time when the sky was very favourable. He was led to conclude that the object did not exist. M. Bigourdan finds that the nebula is again visible in the position indicated by the two Herschels, viz. R.A. 2^h 54^m 20^s, Dec. +42° 10′, he having observed it on Jan. 31 and Feb. 26, 1891. It is difficult to believe that this object could have escaped the scrutiny of Lord Rosse and D’Arrest in 1854, 1863, and 1864; hence the variation is probably real. The nebula may be easily found, as it is very near the binary B.D. +42° (1123 G.C.), the position of which for 1891 is R.A. 2^h 58^m 6^s, Dec. +42° 29’ (‘Nature,’ March 12, 1891). P. 329.—While examining the Pleiades on the night of November 14, 1890, Mr. Barnard discovered a new and considerably bright, round, cometary nebula 36″ S. and 9″ following Merope. The reason why this nebula has not been detected by photography is because it is so near Merope that the over-exposed light from the star obliterates it. But it is certainly very strange that the object alluded to has never been telescopically discovered before; for the Pleiades have been scrutinized repeatedly with all sorts of telescopes, and particularly since Tempel announced his discovery of a large faint nebula involving Merope in 1859. Mr. Barnard says the new nebula is 30″ in diameter, and that it is visible in a 12-inch refractor when Merope is hidden with a wire. INDEX. Action in Sun-spots, Cyclonic, 108. Active volcanoes on the Moon, 120. Adams theoretically discovers Neptune, 222. Advantage of Equatoreals, 54. Aerolites, 264. Air and water on the Moon, Absence of, 115. Algol, 310. Alleged satellite of Venus, 152. Almanacks, 83. Alphabet, Greek, 287. Alpine Valley, 127. Altitudes of markings on Jupiter, 185. Amateur’s first view of Mercury, 139. Ancient ideas concerning meteors, 260. Andromeda, Great Nebula in, 334. Andromedes, 276. Angles of Position, Measurement of, 291, 306. Announcement of a new comet, 244. Annual rate of cometary discoveries, 255. Antares, 309. Anthelme, Discoverer of a new star in 1670, 313. Apennines, 132. Aperture and Power required for Comet-seeking, 252. Apparitions, Meteoric, 261. Appearance of Comets, 228. —— of Mars, 155. Aquarids, 275. Archimedes, 127. Argelander’s magnitudes of stars, 294. Aristarchus, 120. Ascertaining positions of Comets, 257. Aspect of the rings of Saturn, 204. Atmosphere of Jupiter, 177. —— of Mars, 161. —— of Mercury, 139. —— of Venus, 151.