Clusters, Nebulae, and Occultations. 349 



would be difficult to identify it. The accompanying diagram 

 has no pretension to be considered as a picture, having been 

 sketched subsequently N 



from memory ; it is 

 merely intended as a 

 guide to those whose 

 telescopes have light 

 sufficient to warrant an 

 attempt upon the canals. 

 The great nebula lies,, as 

 will be at once seen, 

 between two other hazy 

 objects, making the 

 general effect still more 

 remarkable. The one, 

 small, round, and bright 

 (extremely bright j pretty 



large; 30" or 40" in S 



diameter ; with Sir J. THE GEEAT NEBTTLA IN Arawnnuu. 



Herschel's 18-inch speculum), was discovered in November, 

 1749, by Le Gentil, and is known as M(essier) 32, or 

 H(erschel, jun.) 51 (h 51, in the unassuming notation of 

 that eminent observer). It lies nearly s of the nucleus, 

 at a distance of 26'. The Earl of Rosse expresses little 

 doubt of its resolvability, as to which Bond offers no 

 opinion. The other, 18 y V, alias H 44, was discovered 

 by Miss Carolina Herschel, August 27, 1783; it is about 

 40' distant from the nucleus in a n p direction, but may be 

 brought, with a low power, into the same field with the 

 great nebula, to which its faintness offers an interesting- 

 contrast. I have thus seen it well with 3~j inches of aperture. 

 Smyth says that it lies between two sets of stars of four each, 

 each resembling the figure 7, the p group being the smaller. 

 Herschel I. gave its dimensions 30' x 12' ; his son, who 

 calls it pretty bright, about half that size (but in moonlight). 

 Bond states that it appears, under high powers, to be a coarse 

 cluster of stars. The nature of the great nebula, however, is 

 less certain than that of its companions, and notwithstanding 

 all the pains that have been taken to ascertain it, it has con- 

 tinued sufficiently mysterious. Smyth indeed states that the 

 3 -foot speculum of the Earl of Eosse showed stellar symptoms 

 at its edge ; but we have heard of no confirmation of this with 

 the fourfold light of the larger reflector. De Yico and his 

 colleagues thought they resolved the nucleus in 1841, with 824 

 of the Cauchoix achromatic, and Secchi had the same impression 

 in some very clear evenings. But this seems very improbable, 

 when Herschel II. states — in a far inferior climate it is true, but 



