THE PHYSICAL PHEHOHENA OP OTHEE WOELDS. 317 
sures US that metals such as we know on this Earth exist in 
that great orb — and that to their combustion we owe the light_, 
and the heat^ which we receive from him. The observer turns 
his spectroscope apparatus_, attached to the eye end of a 
refracting telescope^ first to the moon and the planets^ where^ 
of course^ we have to examine solar fight after it has under- 
gone reflexion^ and secondly to the stars^ shining with self- 
emitted fight. If either the moon or the planets are sur- 
rounded with atmospheres_, we might expect that the fight 
having to pass through them_, would suffer similar absorption 
to that which takes place in the Earth-’s atmosphere^ and that 
the spectra would show fines dependent on absorptive action. 
As it regards the moon — the fight of which we know is 
reflected from the surface — no change in the fines of the 
spectrum could be detected_, no variation in intensity^ or the 
addition or disappearance of any fines. The result of this 
spectrum analysis of the fight reflected by the moon is wholly 
negative as to the existence of any considerable lunar atmo- 
sphere.'’"’* The observers to whom we are more especially 
indebted for our knowledge on this subject, Dr. Miller and 
Mr. Huggins, examined the spectra of the planets Menus, 
Mars, Jupiter, and Saturn. Many curious and interesting con- 
ditions are noticed by those observers, but for these we must 
refer the interested reader to the original paper. Their con- 
clusions we give in their own words : The imperfect evidence 
which analysis by the prism affords of the existence of atmo- 
spheres around "those planets, notwithstanding the high pro- 
bability, amounting almost to certainty in the case of Jupiter^ 
that such atmospheres do exist, may receive an explanation 
in the supposition that the fight is chiefly reflected not from 
the planetary surfaces, but from masses of cloud in the upper 
strata of their atmospheres."’^ 
Adapting their spectroscope, and the telescope to which it 
was attached, to the necessities of their delicate inquiry. Dr. 
Miller and Mr. Huggins have examined about 50 stars, but 
they have concentrated their efforts upon three or four of the 
brighter stars, and of these they have mapped the spectra of 
two of them with much accuracy. Those, the spectra of Alde- 
baran and a Orionis are figs. 8 and 9 of our engraving 
(Plate XIII.), fig. 7 being a typical solar spectrum, sufficiently 
shown to enable any one to discover the positions of the lines. 
In the admirable arrangements made by those observers, the 
spectra of terrestrial elements could be observed simultaneously 
* “ On the Spectra of some of the Fixed Stars.” By William Huggins, . 
F.E.A.S., and W. A. Miller, F.K.S. “ Philosophical Transactions,” voL 154, 
p. 413. 
