MAGNITUDES AND DISTANCES OF STARS. 247 



lately Leon shown, the almost invisible star Gl Cygni has a 

 greater parallax than a Cygni, though, according to an es 

 timate based on Sir W. Ilerschel s assumption, it should be 

 about twelve times more distant if, as it turns out, there 

 exist telescopic stars which are nearer to us than Sirius ; ol 

 what worth is the conclusion that the nebula) are very re 

 mote, because their component luminous masses are made 

 visible only by high telescopic powers ? Clearly, if the 

 most brilliant star in the heavens and a star that cannot be 

 seen by the naked eye, prove to be equidistant, relative* 

 distances cannot be in the least inferred from relative visi 

 bilities. And if so, nebula) may be comparatively near, 

 though the starlets of which they are made up appear ex 

 tremely minute. 



On the other hatu. what follows if the truth of the as 

 sumption be granted ( The arguments used to justify this 

 assumption in the case of the stars, equally justify it in the 

 case of the nebula). It cannot be contended that, on the 

 average, the apparent sizes of the stars indicate their dis 

 tances, without its being admitted that, on the average, the 

 apparent sizes of the nebula) indicate their distances that, 

 generally speaking, the larger are the nearer, and the 

 smaller are the more distant. Mark, now, the necessary 

 inference respecting their resolvability. The largest or 

 nearest nebula) will be most easily resolved into stars ; the 

 successively smaller will be successively more difiicult of 

 resolution ; and the irresolvable ones will be the smallest 

 ones. This, however, is exactly the reverse of the fact. 

 The largest nebula) arc either wholly irresolvable, or but 

 partially resolvable under the highest telescopic powers ; 

 while a great proportion of quite small nebula), are easily 

 resolved by far less powerful telescopes. An instrument 

 through which the great nebula in Andromeda, two and a 

 half degrees long and one degree broad, appears merely a* 

 a diffused light, decomposes a nebula of fifteen minutes di- 



