346 Clusters and Nebulce. 



cepts by absorption a certain number of them, such as our sun 

 appears to be, we must probably regard these objects, or at 

 least their photo-surfaces, as enormous masses of luminous gas 

 or vapour ; for it is alone from matter in the gaseous state 

 that light consisting of certain definite refrangibilities only, 

 as is the case with these nebulae, is known to be emitted." 

 And in allowing the possibility, he shows the great improba- 

 bility of the existence of suns endowed with such conditions 

 of luminosity, and of their being clustered into these systems. 

 One thing, however, is evident. Our enterprising countrymen 

 have entered upon inquiries whose interest it would be difficult 

 to over-estimate. They may indeed lead to nothing beyond 

 an increased conviction of the limitation of human knowledge, 

 and the overpowering and inscrutable variety of the works of 

 the Creator, but that conclusion alone will fully repay the 

 trouble of their prosecution. The investigators have opened 

 out for us a glorious vista, and however dim, or even unintelli- 

 gible, may be the objects seen in that far perspective, the 

 names of those who have revealed them will go down to pos- 

 terity with honour. 



That mysterious circlet, hung up, as it were, on high at 

 once to challenge and perplex our inquiries — whether it may 

 be a flat ring of suns, circular perhaps in reality, but presented 

 somewhat obliquely to our sight ; or a starry cylinder or funnel 

 seen endways, according to Chacornac's comparison; or a huge 

 perforated mass of luminous vapour — will henceforth be among 

 the most fascinating subjects of investigation for instruments 

 and apparatus of the highest class. It would be matter of 

 exceeding interest, too, if we could attain to even the most 

 vague idea of its distance and dimensions. Of these, however, 

 we know at present even less than of its constitution. There 

 is not the slightest indication to guide our conjectures. It 

 may be a body of stupendous magnitude at a corresponding- 

 remoteness ; or it may occupy a comparatively near position, 

 if anything can be called near in the vast expanse of the starry 

 heavens. Measures of parallax, which alone could solve the 

 question, have not as yet been undertaken, and they would no 

 doubt be difficult and uncertain from the want of a sharper 

 outline, though this might possibly be compensated in some 

 degree by an average taken from its four edges. The neigh- 

 bourhood is not barren in stars, some of which might serve 

 as standards of comparison ; and there is one little star very 

 near it, which, if sufficiently bright, might possibly be used 

 as a point of departure. Herschel II., who gives its position 

 measured from the centre of the nebula 9(>°--J., and its distance 

 from the edge rather more than the breadth of the ring, 

 assigns to it 11 mag. To me it now appears smaller. At 



