S20 
POPULAR SCIENCE REVIEW. 
as Olir Sun^ and are composed of matter identical,, at least in 
part^ witli tlie materials of our system There is,, there- 
fore,, a probability that these starSj which are analogous to our 
Sun in structure,, fulfil an analogous purpose, and are, like our 
Sun, surrounded by planets, which they by their attraction 
uphold, and by their radiation illuminate and energize 
On the whole, we believe that the foregoing spectrum obser- 
vations on the stars contribute something towards an experi- 
mental basis, on which a conclusion, hitherto but a pure 
speculation, may rest ; viz., that at least the Iwighter stars are, 
like our Sun, upholding and energizing centres of systems of 
worlds adapted to he the abode of living beings (Miller and 
Huggins.) 
Having advanced thus far in this inquiry, which is in every 
way attractive to the thoughtful observer, Mr. Huggins 
naturally thought it an object of great importance, in reference 
to our knowledge of the visible universe, to ascertain whether 
this similarity of plan observable among the stars, and uniting 
them with our sun in one great group, extended to the distinct 
and remarkable class of bodies of which we have spoken in 
introducing the subject of this paper, known as nebulce. 
Analysis by means of the prism was the means by which 
remarkable facts had been discovered in relation to the Sun 
and the stars. Why, therefore, should not the prismatic 
spectra of even the faint lights of the nebulse inform us 
of their constitution ? Selecting that class which has been 
grouped by Sir William Herschel as planetary nebulse, Mr. 
Huggins has brought them to the test of spectrum analysis. 
It is not necessary, even did our space admit of it, that we 
should describe the results of each observation; a selection 
wilfsuffice.* On the 29th August, 1864, the telescope, armed 
with its spectrum apparatus, was turned to a planetary nebula 
in Draco, described as ^‘^very bright, pretty small, suddenly 
bright in the middle, very small nucleus.''^ The spectrum given 
(fig. 6) in our plate was obtained. The strongest line cor- 
responding with the line always obtained in the air spectrum., 
and indicating Nitrogen, the well-known and remarkable con- 
stituent of our atmosphere. The faintest fine agreeing in posi- 
tion with that of Hydrogen, and the other bright line in all 
probability belonging to some new element, since it does not 
correspond with the Barium line, to which it is nearest, or 
any other. The nebula which we have shown (fig. 1), the 
colour of which is greenish-blue, exhibited the two bright 
We must premise, that, upon examining some of the bright clusters of 
stars — “ clustering collections ” of Herschel — they were found to give a con- 
tinuous spectrum, indicative of solid matter ; not so the true nebulae. 
