302 RECENT KESEARCIIES RELATIVE TO THE NEBULA. 



near tlic trapezium, extending towards the pouth, on each side of an axis pass- 

 ing by the apex of the region called Iluygens, of which the angle of position 

 is in the neighborhood of 180°. Some twenty of these circumvolutions have 

 been distinctly traced, whilst others, producing the same impression, arc too 

 ftiiut or too coraplicatecf to be described with precision. We may class, then, 

 according to Prof. Bond, the ncbulai of Orion among the spiral nehulce, such as 

 they were, for the first time, described by Lord Ross, with the aid of his great 

 reflecting telescope. The nebulse No. 51, of the catalogue of Messier, was the 

 first in which he discovered this spiral conformation, which had escaped both 

 the astronomers llerschel. 



Prof. Bond has observed that, in a great number of cases, the masses of neb- 

 ulous matter are associated with stars, frequently under the form of small tufts 

 extending from their southern side. He cites two remarkable instances where 

 there is a deficit of luminous matter near stars of considerable brilliancy ; the 

 first, in reference to the trapezium itself, whose obscure centre has been remarked 

 by sundry observers; the other, to the star Iota of Orion. These peculiarities 

 appear to Prof. Bond to be favorable to the supposition of a physical associa- 

 tion of the stars with the nebuLie. The existence of an an-angement in a spiral 

 form of the parts which compose it accords with the idea of a stellar constitu- 

 tion ; for among the objects which present this peculiarity of form are found 

 not only nebulie resolvable into stars, but masses of stars properly so called, 

 such, for instance, as the grand mass of stars of the constellation Hercules, 

 where the exterior stars have evidently a curvilinear arrangement. 



OTHER FACTS RELATING TO THE NEBULiE. 



M. Norman Pogson, whilst at the observatory of Dr. Lee, at Hartwell, in 

 1860, witnessed a change in the nebulae, or mass of stai's, No. 80 of the cata- 

 logue of Messier, situated in the constellation of the Scorpion, and very close 

 to a pair of A'ariable stars R and S of the Scorpion, which have been observed 

 by M. Chacornac since 1853. The 9th of May this nebulae had its usual aspect, 

 without any stellar appearance, and the 28th of the same month Mr. Pogson 

 saAV therein a star of the 7th or 8th magnitude, which has been also observed 

 since the 21st of May by MM. Luther and Auwers at Koningsberg, and which 

 the latter have estimated to be of something more than the 7th magnitude. 

 The 10th of June following, with a magnifying power of 66, the stellar ap- 

 pearance had nearly passed away, but the nebulae had a greater brilliancy than 

 usual, with a clearly marked central condensation. M. Pogson does not think 

 that this variation can be attributed to a change in the nebulae itself, but he re- 

 gards as singular that a new variable star, the third comprised in the same field 

 of vision, should be found exactly situated betv/een the earth and that nebulae. 

 This observation has been published in the twenty-first volume of the M. N., 

 p. 32. 



M. Chacornac has observed quite recently, with M. Foucault's great reflect- 

 ing telescope of plated glass, so adapted as to procure a great degree of enlarge- 

 ment, the ainiular nebulae of the Lyre, and he has ascertained that it is in reality 

 resolvable into a mass of very small stars, closely crowded together, the bright- 

 est of them occupying the extremities of the small diameter. This nebulae, in 

 an examination of several nights, presented to him the appearance of a hollow 

 cylinder, seen in a direction nearly parallel to its axis ; and its centre, as Lord 

 Ross describes it, is veiled by a curtain of nebulous matter, which converts it- 

 self into a somewhat thin stratum of little stars. M. Chacornac adds, in a com- 

 munication to Dr. Peters on this subject, dated Paris, 9th June, 1862, and pub- 

 lished in No. 1368 of the A. N., that when the view is screened from all inter- 

 fering light, the scintillation of this multitude of luminous points, occupying a 

 large portion of the surface of the retina, produces a sort of giddiness which 

 is quite cuiioua. 



