346 
rOrULAR SCIENCE REVIEW. 
drawings which will give the appearance of two or three such 
stars. Each star has a different series of lines in its spectrum ; 
but each is found to contain several of the chemical elements 
which are met with upon the earth. Fig. 13 represents the 
spectrum of the bright star Aldebaran, in the constellation 
Taurus ; tig. 14 that of Betelgeus, the bright star in the shoulder 
of Orion, and fig. 7 on the Plate that of Sirius, the most 
brilliant of the stars visible to us in this country. Many 
of the metals found in these stars are of comparatively rare 
occurrence, while others are abundant. For instance, in Aide- 
baran, sodium, magnesium, calcium, iron, bismuth, hydrogen, 
tellurium, antimony, mercury ; in Betelgeus, sodium, magne- 
sium, calcium, iron, bismuth, thallium ; in Sirius, sodium, 
magnesium, hydrogen, and iron. 
Several of the substances found in these stars appear to be 
absent from our sun. 
The fixed stars vary in colour, and they each have their own 
peculiar spectrum, yet they are formed upon a plan which these 
observations show is analogous to that of our sun, viz., an 
intensely heated nucleus or kernel surrounded by a less hot, but 
still prodigiously heated atmosphere, containing various metallic 
and other vapours, many of which are identical with the ele- 
ments which occur in the earth. In the spectra, both of the sun 
and of the fixed stars, there are, however, numerous lines which 
we have not as yet been able to refer to their constituent mate- 
rials. This arises, probably, in a great measure from our im- 
perfect acquaintance with the spectra of the elements at present 
known. It arises in part also from our ignorance of some of the 
elements which compose our earth itself. Within the last eight 
years no fewer than four elementary bodies, viz., caesium, rubi- 
dium, thallium, and indium have been discovered by the special 
character of their spectra. Thallium, for instance, produces a 
magnificent green line unlike that of any other element, shown 
at Plate L., fig. 5. Indium shows two remarkable bands in the 
blue, fig. 6. 
Another reason why we have not yet interpreted all these 
lines is, probably, that many of them are the results of com- 
pounds formed in the outer and less heated part of the sun’s 
atmosjdierc, wliere ordinary chemical attraction again exerts 
itself. In the intense focus of the nucleus of the sun the heat 
is so fierce that all chemical combinations are destroyed, and 
the elements occur in a state of mixture with each other, as they 
do in the intense heat of the voltaic arc. 
Hut the revelations of the spectroscope do not end here. 
From time to time stars blaze forth in the heavens with great 
brilliancy, and then as s[)oedily fade and dwindle awa}% Mar- 
vellous changes are seen in such civses to be going on. In 
