118 Clusters and Nebulce. 



to be tracing the working of some widely diffused law. This 

 object deserves careful study, and in the finest weather, if our 

 instrument gives any hope of its resolution. Sm. remarks that 

 /'it is indeed truly glorious, and enlarges on the eye by studious 

 gazing." 



Not far from 13 M. we meet with another cluster — 



21. The Second Cluster in Hercules, or 92 M. It is not 

 quite so easy to find, but well worth the trouble. At some 

 distance from Wega, njp, we notice two conspicuous 2-mag. stars, 

 a few degrees apart, /? and 7 Draconis, marking the Dragon's 

 head, of which /3 is p. About half way from it Herculis, men- 

 tioned in finding our last object, to ft Draconis, a little sweep- 

 ing will discover our cluster, which is a very beautiful brilliant 

 mass, smaller than the last, but considerably brighter and less 

 resolvable, though still evidently of a starry character. 

 Smyth calls it ' ' a large, bright, resolvable cluster, with a very 

 luminous centre and irregular streamy edges," 7' or 8' in 

 diameter in $'s reflectors. It is not referred to in H.'s cata- 

 logue. Messier discovered it in 1781. 



We now turn to a different quarter of the heavens, in 

 search of a similar object — 



22. The Cluster in Pegasus, or 15 M. We must refer to 

 our old acquaintance e Pegasi (Double Stars, No. 65, Intellec- 

 tual Obseever, Dec, 1862, p. 375). Between it and 7 Delphini 

 (No. 63), at about one-fourth the distance from the former, the 

 finder will show us four small stars at once in its field, one of 

 which is rather fainter and more hazy than the rest. This is 

 our cluster. It is not unlike 92 M. in size and general appear- 

 ance, equally beautiful, bright, and condensed in the centre ; 

 resolvable, but not resolved, in ordinary instruments; revealing 

 its starry nature in proportion to the stedfastness of the ob- 

 server's gaze. With a low power the field is a striking one. 

 Sm. describes it as a noble cluster, with stragglers branching 

 from a central blaze, and says, ' ' under a moderate magnifying 

 power, there are many telescopic and several brightish stars in 

 the field, but the accumulated mass is completely insulated, 

 and forcibly strikes the senses as being almost infinitely beyond 

 those apparent comites." H. calls it " superb," and speaks of 

 it as "very compressed; irregularly round; very small stars 

 15 m. — comes up to a perfect blaze in the centre — not the con- 

 densation of a homogeneous globe ; it has straggling streams 

 of stars, as it were, drawing to a centre — 4' or 5' diameter." 

 From this reference to the aspect of a homogeneous sphere, 

 compared with the description of 13 M., we may find it interest- 

 ing to notice the way in which the internal constitution of such 

 clusters may be estimated. If we draw a circle upon a piece 

 of paper to represent the section of a globular space filled 



