128 



of rather coarse stars, and resembling Messier 13." Any in- 

 crease of brightness towards the centre seemed to proceed 

 from the greater depth of stars there rather than from any- 

 notable difference of their magnitude. But the second class 

 presents much more interesting phenomena : the appearances 

 which previous observers had described as sudden condensa- 

 tion, nuclei, or even single or multiple central stars, proving 

 to be clusters of comparatively bright stars, surrounded by 

 much larger collections of minute ones. A very beautiful 

 example of this is 1456, fig. 41, M. 94, described in the cata- 

 logue as " very suddenly much brighter, almost up to a 

 nipple-shaped nucleus:" it proved, however, to be "avast 

 circular cluster of stars, with ragged filaments, in which, and 

 apparently central, is a globular group of much larger stars, 

 power 400." The same system of arrangement (which seems 

 very common) occurs also in 706, 748, 805, and many others: 

 it is also found in the magnificent clusters 1663, M. 3; 1558, 

 M. 53; and 1916, M.S. In these, the splendour of which 

 is not to be described, besides the stars visible in other instru- 

 ments (which here seem of the first or second magnitude), the 

 whole field is crowded with others much smaller, to such a de- 

 gree that, had the first been absent, these would still have been 

 noted as remarkable objects. The interior group is not, how- 

 ever, always central or symmetrical, but has knots of greater 

 condensation, which sometimes (as in 1385) are''alone visible 

 in smaller telescopes, and then look like " twin nebulae ;" 

 at others (as in 739), like stars. In 1622, fig. 25, M. 51, 

 which is so well known from a sort of resemblance to Saturn, 

 and from the more exact analogy which, as Sir John Herschel 

 has well remarked, it bears to the Milky Way, we have ano- 

 ther different development of this arrangement. Here also 

 the central nebula is a globe of large stars ; as indeed had 

 been previously discovered with the three feet telescope : but 

 it is also seen with 560 that the exterior stars, instead of being 

 uniformly distributed as in the preceding instances, are con- 



