58 Clusters of Stars and Nebula?. 



be fully indicated by the sparkling points of light which mark 

 the places of the brighter individuals, or, perhaps, the spots 

 where two or three fall into the same line of sight. Such an 

 object would be called an " imperfectly resolved nebula," a 

 Latin word signifying fog, and well expressing the distinctive 

 aspect of these bodies. Others, refusing to give up separately 

 their component stars, present a mottled or granulated appear- 

 ance, which the experienced observer well understands, and 

 which enables him to class them as " resolvable nebulas," that 

 is, nebulas which would, under other circumstances of distance 

 or optical power, be resolved into stars. While lastly there 

 are those, whose light is so milky, to use an epithet introduced 

 by the elder Herschel, so uniform in its diffusion, as to mask 

 completely their starry nature, and to render them " irresolv- 

 able." This remarkable and instructive progression cannot be 

 adequately exemplified to the naked eye, because it so happens 

 that we have no good specimen of a globular cluster sufficiently 

 near to us to form the first step in the scale by its sensible 

 resolution; but every telescope of sufficient power to resolve 

 fairly the nearer clusters exhibits a series of this kind, passing 

 from the group or cluster, which is a fully resolved nebula, to 

 the irresolvable nebulosity which from analogy is, or may be, 

 a group or cluster at an unapproachable distance; and each 

 telescope has a series of its own, corresponding with its optical 

 capacity ; every increase of aperture, by its greater resolving 

 power, increasing the number of groups and clusters at the 

 expense of nebulas, and yet so adding to the ranks of the latter 

 by the addition of still fainter and more evanescent objects, 

 that the sum total still goes on progressing, as though it were 

 actually illimitable. Many an aggregation which appears but 

 as a dim and hazy speck in our smaller telescopes, is wholly 

 disentangled into separate stars by the reflectors of the Earl of 

 Rosse, or Lassell, or Chacornac, or by achromatics such as 

 those of Clark, or Bond, or Struve, or Secchi ; while these 

 again convert the " milky " into the " resolvable " nebulas, and 

 draw out of the unknown depths of space yet further, and 

 obscurer, and previously imperceptible evidences of the incom- 

 prehensible magnitude of this great and wonderful universe. 



Snob is a broad and simple view of this grand subject. 

 Whether this apparent simplicity is founded in the truth of 

 nature, or whether it may prove one of those premature 

 lali/.alions wliirli only obstruct the path while they seem 

 to dear it, need not be discussed at the present time, though 

 it will ultimately come before us. Pmt it is desirable, be lore 

 proceeding further, to obviate any misconception which might 

 from this mode of statement. We must bear in mind that 

 our two assumptions, of* sphericity of form in the mass, and 



