THE PHYSICAL PHENOMENA OE OTHER WORLDS. 319 
The more refrangible portions of its spectrum are very bright^ 
in consequence of the absence of any strong bands. The 
yellow and the orange are crossed by several groups of lines. 
The diversity in the colours of the stars has been remarked 
through all ages, but it is only of late years that the subject 
has been carefully examined. Ptolemy calls Arcturus, Alde- 
baran, Sirius, and three other fixed stars fiery red,^^ and 
Cleomedes compares Antares with the red hue of the planet 
Mars. Tycho Brahe especially notices the colours of the 
stars, and quotes the case of Sirius — in his time as in ours a 
white star — to prove that they change in colour. The 
Grecian astronomers,^^ says Humboldt,* knew only red stars ; 
while, by the aid of the telescope, the moderns have dis- 
covered in the starry vault — in the celestial fields which light 
traverses, as in the corollas of our flowering plants, and in 
the metallic oxides — almost every gradation of prismatic colour 
between the two extremes of refrangibility, or between the 
violet and the red rays."’^ Sir David Brewster observes, that 
in the spectrum of every coloured star certain rays are wanting 
which exist in the solar spectrum. He shows that the 
orange-coloured star, of the double star Z Herculis, gave a 
spectrum, wanting a band in the red space, and two or more 
bands in the blue space. t An argument drawn from this 
was that the chemical constitution of the star, or of its atmo- 
sphere, varied in each case where a variety of colour was 
observed. Dr. George Wilson, whose fine mind is lost to us, 
and who adorned every subject to which his thoughts were 
ever applied, asks, What forms of the primary matter are 
likely to occur in different globes Answering his own 
question, he refers to some of the rarer terrestrial elements, 
which are not known to be of service in our globe and 
then says, These seemingly useless and sparingly distri- 
buted bodies in our earth, may be the prevailing and most 
important constituents of other globes, and may perform func- 
tions there of which we have no conception.'’^ J 
The results which have been obtained by spectrum analysis 
instruct us thus far. The speculations, based upon imperfect 
data, to which we have referred, approach very near the truth. 
It has become evident to us that a similar unity of operation ex- 
tends through the universe as far as light enables us to have 
cognizance of material objects. For we may infer that the 
stars, while differing the one from the other in the kinds of matter 
of which they consist, are all constructed upon the same plan 
“ Cosmos,” vol. iii., p. 111. 
t “ Speculum HartweUianum,” 1860, p. 315. 
J “ The Chemistry of the Stars : an argument touching the Stars and 
their inhabitants.” By George Wilson, M.I)., F.R.S.E. 
