Clusters and Nebulae. 209 



CLUSTEES AND NEBULAS. 



The next object will, perhaps, cost us some trouble in find- 

 ing, but we shall certainly not regret it, if sufficient optical 

 power is at our command. We must first of all turn to the 

 fine pair, £ Aquarii, No. 66 of our Double Star List (Intellec- 

 tual Observes, December 1862, p. 375). A little p the triangle 

 including it, we shall see a 8 mag. star, a Aquarii, and some 

 way further sp, another similar to it, /3 of the same constella- 

 tion. We must now make out e Pegasi, No. 65 (as above), 

 which was recently our guide to the cluster 15 M, and in a 

 line between /3 Aquarii and e Pegasi, about |rd of the distance 

 from the former, we must sweep about till we perceive a nebu- 

 lous speck in the finder. Unfortunately it is not at first sight 

 very unlike a 6 mag. star, of which there are several in this 

 region ; so that we cannot be sure of having it at once, like some 

 of our recently-examined clusters ; but it is well worth while 

 to attack every suspicious-looking object in succession, till we 

 have got the right one. It will be our — 



23. The cluster in Aquarius, or 2 Messier; discovered by 

 Maraldi while looking after a comet in 1746. With a low 

 power we shall see it as a bright nebulous globe, with perhaps 

 some appearance of resolvability. Its future aspect, as we 

 seek a further acquaintance, will depend upon the capability of 

 our telescope. $ of course resolved it, and it is one of the few 

 objects on which we read of the working of his 40 foot 

 reflector. I have seen it distinctly granulated with 144 upon 

 3^ inches ; with 5| inches its brightness makes it a superb 

 object, and one of the very finest of its class ; resolvable with 

 any power, but merely so far as to show its starry composition. 

 A very fine silver-on-glass speculum, the workmanship of Mr. 

 With, of Hereford, 8 inches in diameter, goes deeper into 

 it, and brings out, though feebly, a wonderful picture of crea- ' 

 tive energy. To comprehend its full glory, the resolving 

 power of a still greater aperture should be brought to bear 

 upon it. Sir J. Herschel, in the use of an 18jinch speculum, 

 speaks of it as " a most glorious cluster of stars 15 mag. com- 

 pressed up to a blaze. Its most crowded part takes 6 s. to pass 

 the wire, but there are straggling stars, although few, of the 

 same size as the rest. There must be thousands of them. The 

 total light of the cluster not exceeding a star 6 m., it follows 

 that several thousand stars 15 m. =1 of 6 m." At another 

 time he calls the stars 12, 13, and 14 mag., and says, " they 

 are evidently . globularly arranged, and not internally con- 

 densed towards the centre more than the spherical form would 

 make them appear to be ; but in the middle they blend into a 

 blaze of light. It is like a heap of fine sand ! With 9 inches 



