SPECTRUM ANALYSIS OF THE HEAVENLY BODIES. aS) | 
These numbers represent not the apparent brightness only, but the true 
brightness of these luminous masses, except so far as it may have been 
diminished by a possible power of extinction existing in cosmical space, and 
by the absorption of our atmosphere. It is obvious that similar observations, 
made at considerable intervals of time, may show whether the light of these 
objects is undergoing increase or diminution, or is subject to a periodic vari- 
ation. If the dumb-bell nebula, the feeble light of which is not more than 
one twenty-thousandth part of that of a candle, be in accordance with popular 
theory a sun-germ, then it is scarcely possible to put in an intelligble form 
the enormous number of times by which its light must increase before this 
faint nebula, feebler now in its glimmering than a rushlight, can rival the 
dazzling splendour of our sun. 
Measvres or tHE NEsuL. 
Some of the nebule are sufficiently defined in outline to admit of accurate 
measurement. By means of a series of micrometric observations, it will be 
possible to ascertain whether any considerable alteration in size takes place 
in nebule. 
Merrors. 
Mr. Alexander Herschel has recently succeeded in subjecting another order 
of the heavenly bodies to prismatic analysis. He has obtained the spectrum 
of a bright meteor, and also the spectra of some of the trains which meteors 
leave behind them. A remarkable result of his observations appears to be 
that sodium in the state of luminous vapour is present in the trains of most 
meteors. 
Conciuston, 
In conclusion, the new knowledge that has been gained from these obser- 
vations with the prism may be summed up as follows :— 
1. All the brighter stars, at least, have a structure analogous to that of the 
sun. 
2. The stars contain material elements common to the sun and earth. 
3. The colours of the stars have their origin in the chemical constitution of 
the atmospheres which surround them. 
4, The changes in brightness of some of the variable stars are attended 
with changes in the lines of absorption of their spectra. 
5. The phenomena of the star in Corona appear to show that in this object 
at least great physical changes are in operation. 
6. There exist in the heavens true nebule. These objects consist of 
luminous gas. 
7. A part of the light of comets is self-luminous. 
8. The bright points of the star-clusters may not be in all cases stars of 
the same order as the separate bright stars. 
It may be asked what cosmical theory of the origin and relations of the 
heavenly bodies do these new facts suggest? It would be easy to speculate, 
but it appears to me that it would not be philosophical to dogmatize at present 
on a subject of which we know so very little. Our views of the universe are 
undergoing important changes ; let us wait for more facts with minds un- 
fettered by any dogmatic theory, and therefore free to receive the obvious 
teaching, whatever it may be, of new observations. 
Star differs from star in glory, each nebula and each cluster has its own 
special features, doubtless in wisdom and for high and important purposes 
the Creator has made them all. 
