SIR WILLIAM HERSCHEL 117 



magnitude, visibly affected with a very faint nebulosity of little 

 extent, all around. A power of 300 showed the nebulosity of 

 greater extent (d). The connection is not to be doubted. 



March 19, 1790. A very bright nucleus, with a small, very faint 

 chevelure, exactly round. ' In a low situation, where the chevelure 

 could hardly be seen, this object would put on the appearance of an 

 ill-defined, planetary nebula, of 6, 8 or 10'' diameter (e). 



November 13, 1790. A most singular phenomenon! A star of 

 about the 8th magnitude, with a faint luminous atmosphere, of a 

 circular form, and of about 3' in diameter. The star is perfectly in 

 the centre, and the atmosphere is so diluted, faint, and equal through- 

 out, that there can be no surmise of its consisting of stars ; nor can 

 there be a doubt of the evident connection between the atmosphere 

 and the star. Another star not much less in brightness, and in the 

 same field with the above, was perfectly free from any such ap- 

 pearance. This last object is so decisive in every particular. Dr. H. 

 says, that we need not hesitate to admit it as a pattern, from which we 

 are authorised to draw the following important consequences : 



Supposing the connection between the star and its surrounding 

 nebulosity to be allowed, we argue, that one of the two following 

 cases must necessarily be admitted : In the first place, if the nebu- 

 losity consist of stars that are very remote, which appear nebulous on 

 account of the small angles their mutual distances subtend at the eye, 

 by which they will not only, as it were, run into each other, but also 

 appear extremely faint and diluted ; then, what must be the enormous 

 size of the central point, which outshines all the rest in so superlative 

 a degree as to admit of no comparison ! In the next place, if the 

 star be larger than common, how very small and compressed must 

 be those other luminous points that are the occasion of the nebulosity 

 which surrounds the central one ! As, by the former supposition, the 

 luminous central point must far exceed the standard of what we call 

 a star, so, in the latter, the shining matter about the centre will be 

 much too small to come under the same denomination; we therefore 

 either have a central body which is not a star, or have a star which is 

 involved in a shining fluid, of a nature totally unknown to us. Dr. 

 H. can adopt no other sentiment than the latter, since the probability 

 is certainly not for the existence of so enormous a body as would 



