350 Clusters, Nebulce, and Occultatiuns. 



■with 18 inches of reflecting* aperture — that its nebulosity is of 

 the most perfectly milky irresolvable kind, without the slightest 

 tendency to that separation into flocculi which he perceives in 

 the nebula in Orion, nor is there any sort of appearance of the 

 smallest star in the centre of the nucleus. Secchi himself, 

 afterwards, with the far superior Merz telescope, whose admir- 

 able definition gives it, he thinks, more resolving power than 

 even the Eosse reflector, though he perceives five or six points in 

 the nucleus, admits that they are not sharp enough for stars, 

 comparing them rather to the granulations seen in the heart of 

 some comets ; and since he finds the surrounding fields for a 

 great distance equally rich in minute stars with those in which 

 the nebula occurs, concludes that the nebula is not resolvable, 

 si non peut-etre dans son centre. Bond, employing more than 

 twice the light, says, " with high powers, minute stars are dis- 

 cerned on the borders of the nucleus, but it has thus far yielded 

 no evidence of resolution ; about 50 stars are visible in the 

 same field with it ; no other equal space occurs within the 

 limits of the nebula, containing so few •" and while he estimates 

 that above 1500 stars are visible with the full aperture within 

 those limits, he asserts that they have "theundefinable, but still 

 convincing aspect of not being its components."* It is certainly 

 a singular fact that the two most remarkable nebulae in the 

 heavens, in point of combined extent and brightness, this, and 

 that in Orion, should be alike characterized by their peculiar 

 difficulty of resolution. Sir J. Herschel has indeed stated that 

 such is the general character of all elliptic as opposed to globular 

 nebulas ; and to this class (though Secchi dissents, giving it a 

 dove-tail or triangular form) our present specimen is usually 

 referred ; but we are not brought thus one step nearer to an 

 explanation of the difficulty. If, guided by its brightness and 

 dimensions, we assign to it, with Herschel I., a position of 

 comparative nearness, then its difficulty of resolution, as far as 

 the centre is concerned, might be accounted for upon the sup- 

 position of a most extraordinary compactness of aggregation, 

 but this would not explain the " milky" character of its fainter 

 parts, which ought, as in many other nebula), to exhibit their com- 

 ponents, though the central condensation may remain an impe- 

 netrable "blaze." If, on the contrary, we prefer looking upon, 

 its intractable character as an argument of exceeding remote- 

 ness, we must accept an overpowering result both as to dimen- 

 sions and splendour. In Uond's telescope its light is diffused 

 through an area -\.' long and nearly xl£' broad, not far short 



* Bond's expressions must have been somehow misunderstood by the usually 

 accurate Humboldt, who asserts, in three places, that he actually accomplished the 

 resolution, and considers it one of the most remarkable discoveries of tho time. 

 Sir J. Hi i -rip I, too, on tho same authority, spoaks of the " decisive evidence" of 

 its rosolvabilily. 



