426 THE BEAUTIES OF NATURE CHAP. 



such a nebula as that in Andromeda, which 

 with our most powerful instruments appears 

 only as a mere cloud, is really a vast cluster 

 of stellar points. 



This, however, by no means applies to all 

 the nebulas. The spectrum of a star is a 

 bright band of colour crossed by dark lines ; 

 that of a gaseous nebula consists of bright 

 lines. This test has been made use of, and 

 indicates that some of the nebulae are really 

 immense masses of incandescent and very 

 attenuated gas ; very possibly, however, in a 

 condition of which we have no experience, and 

 arranged in discs, bands, rings, chains, wisps, 

 knots, rays, curves, ovals, spirals, loops, 

 wreaths, fans, brushes, sprays, lace, waves, 

 and clouds. Huggins has shown that many 

 of them are really stupendous masses of 

 glowing gas, especially of hydrogen, and 

 perhaps of nitrogen, while the spectrum also 

 shows other lines which perhaps may indicate 

 some of the elements which, so far as our 

 Earth is concerned, appear to be missing 

 between hydrogen and lithium. Many of 

 the nebulae are exquisitely beautiful, and 

 their colour very varied. 



