THE SPECTRA OF SOME OF THE FIXED STARS. 
429 
19. The following stars have also been observed: numerous lines are seen in the 
spectrum of each ; and in some, several of the lines were measured ; but we have not 
instituted any comparisons with the metallic spectra as yet. 
Castor ; s, and t] Ur see majoris ; a, and s Pegasi ; cs, (3, and y Andromedce, the last 
an interesting spectrum ; Bigel, a spectrum full of fine lines ; n Ononis ; a Trianguli ; 
y and g Cygni ; a, (3, y, s, and fj Cassiopeice; y Geminorum; (3 Canis majoris ; (3 Canis 
minoris ; Spica ; y, <5, and g Virginis ; a Aquilce ; Cor Caroli ; [3 Aurigce ; Begulus ; (3 , y, 
h, s, £, and n Leonis. 
§ Y. General Observations. 
20. On the Colours of the Stars. — From the earliest ages it has been remarked that 
certain of the stars, instead of appearing to be white, shine with special tints ; and in 
countries where the atmosphere is less humid and hazy than our own, this contrast 
in the colour of the light of the stars is said to be much more striking. Various 
explanations of the contrast of colours, by Sestint and others, founded chiefly on the 
difference of the wave-lengths corresponding to the different colours, have been at- 
tempted, but as yet without success. Probably in the constitution of the stars as 
revealed by spectrum analysis, we shall find the origin of the differences in the colour 
of stellar light*. 
Since spectrum analysis shows that certain of the laws of terrestrial physics prevail in 
the sun and stars, there can be little doubt that the immediate source of solar and stellar 
light must be solid or liquid matter maintained in an intensely incandescent state, the 
result of an exceedingly high temperature. For it is from such a source alone that we 
can produce light even in a feeble degree comparable with that of the sun. 
The light from incandescent solid and liquid bodies affords an unbroken spectrum 
containing rays of light of every refrangibility within the portion of the spectrum which 
is visible. As this condition of the light is connected with the state of solidity or 
liquidity, and not with the chemical nature of the body, it is highly probable that the 
light when first emitted from the photosphere, or light-giving surface of the sun and 
of the stars, would be in all cases identical. 
The source of the difference of colour, therefore, is to be sought in the difference of 
the constituents of the investing atmospheresf . The atmosphere of each star must 
* In connexion -with this subject we quote the following passage from Smyth’s ‘ Speculum Hartwellianum,’ 
4to, I860, p. 315: — “Sir David Brewster observes that there can he no doubt that in the spectrum of every 
coloured star certain rays are wanting which exist in the solar spectrum ; hut we have no reason to believe that 
these defective rays are absorbed by any atmosphere through which they pass. And in recording the only 
observation perhaps yet made to analyze the light of the coloured stars, he says, ‘ In the orange-coloured star of 
the double star £ Herculis, I have observed that there are several defective hands. By applying a fine rock- 
salt prism, with the largest possible refracting angle, to this orange star, as seen in Sir James South’s great 
achromatic refractor, its spectrum had the annexed appearance [in the Campden Hill Journal], clearly showing 
that there was one defective hand in the red space, and two or more in the blue space. Hence the colour of 
the star was orange, because there was a greater defect of blue than of red rays.’ ” 
t The presence in the atmospheres of Aldeharan and a Orionis of metals, such as iron, which require an 
