Celestial Chemistry. 403 



57 M. Lyras, the •well-known ring nebula, was a most 

 interesting object. Its light is very pale, and the brightest of 

 the three lines was the only one distinctly seen, the others 

 being, perhaps, glimpsed, but no faint continuous spectrum 

 whatever could be detected. The bright line was remarkable, 

 consisting of two bright spots corresponding to sections of 

 the ring, with a very faint connecting line. Lord Rosse had 

 previously seen much more nebulosity in the centre of the 

 ring than had been drawn by other observers; and the 

 spectrum shows that it is full of rare nebulous matter. 

 Another planetary nebula, 18 H. IV., but which under a 

 power of 600 is distinctly annular, gave a fourth excessively 

 faint line, more refrangible than the one agreeing with F. 

 The last object which has been examined was the celebrated 

 Dumb-Bell Nebula, 27 M. Vulpeculge. The light of this body 

 after prismatic analysis remained concentrated in the strong 

 bright line corresponding to that of nitrogen, no others being- 

 visible, nor was there any trace of a faint continuous spectrum. 

 Various portions of this large nebula were tried, but the 

 light, although different in intensity, was always the same in 

 refrangibility. 



So much for the positive evidence of the different con- 

 stitution of these nebulae to anything like stars, or clusters of 

 stars ; and this testimony is corroborated by the negative 

 evidence obtained in the examination of a number of other 

 bodies which are palpably of the class of clusters. For 

 example, 92 M. Herculis, and 26 IV. Eridani, both fine clusters, 

 gave continuous spectra as the stars do. 50 H. IV. Herculis 

 though nebulous in the telescope, still produces a starry 

 spectrum, showing its true character. 55 Andromedas, which 

 Herschel describes as a star with a nebulous atmosphere, gave 

 a star spectrum, but no bright lines ; and Lord Rosse notes that 

 he has looked at it eight times and seen no such atmosphere, 

 so that it is probably not a nebulous star at all. The 

 examination of the great nebula in Andromeda is of much 

 interest. The brightest part gave a continuous spectrum from 

 about D to F, the light ceasing abruptly in the orange, and 

 the companion 32 M. gave a similar spectrum. It would 

 appear, therefore, that these are really clusters at the enormous 

 and almost inconceivable distances which must be necessary 

 so to blend the light of their constituent stars. It is, how- 

 ever, also possible that they may be gaseous matter so full of 

 condensed and opaque portions as to give a continuous spectrum. 



Mr. Huggins remarks, "It is obvious that the nebulae, 37 



H. IV., 6 %, 73 H. IV., 51 H. IV., 1 H. IV., 57 M., 18 H. 



IV., and 27 M., can no longer be regarded as aggregations of 



suns after the order to which our own sun and the fixed stars 



vol. vi. — NO. VI. d d 



