444 
ME. W. HUGGINS ON THE SPECTEA OE SOME OF THE NEBUL2E. 
character of the brightest of the lines of nitrogen, that with which the line in the nebulae 
coincides, differs from that of the two double lines next in brilliancy. This line is more 
nebulous at the edges, even when the slit is narrow and the other lines are thin and 
sharp. The same phenomenon was observed with some of the other elements* *. We 
do not yet know the origin of this difference of character observable among lines of 
the same element. May it not indicate a physical difference in the atoms, in connexion 
with the vibrations of which the lines are probably produced 1 The speculation pre- 
sents itself, whether the occurrence of this one line only in the nebulae may not indi- 
cate a form of matter more elementary than nitrogen, and which our analysis has not 
yet enabled us to detect. 
Observations on other nebulae which I hope to make, may throw light upon these 
and other considerations connected with these wonderful objects. 
tion of the two gases to each other easily regulated. With this apparatus the fading out of the bright lines of 
nitrogen, as the proportion of this gas to hydrogen was diminished, and again their increase in brilliancy when 
the current of nitrogen was made stronger, were carefully observed, hut without detecting any marked variation 
in the relative brightness of the lines. 
* Philosophical Transactions, 1864, pp. 143, 150. 
