On the Spectra of some of the Fixed Stars. 515 



N.B. I need scarcely mention that the values arrived at 

 only possess a relative worth with respect to the instruments used. 

 An apparatus measuring* terrestrial radiation absolutely and in 

 a manner which renders it practical, is, I think, yet to be con- 

 trived. 



LXXI V. On the Spectra of some of the Fixed Stars. By William 

 Huggins, F.R.A.S., andW. A. Miller, M.D., LL.D., Treas. 

 andV.P.R.S., Professor of Chemistry, King's College, London, 



[Concluded from p. 425.] 



§ V. General Observations. 



20. (~)N the Colours of the Stars. — From the earliest ages it has 

 been remarked that certain of the stars, instead of appear- 

 ing 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 

 Sestini 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 constitu- 

 tion 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 ter- 

 restrial 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 



* In connexion with this subject we quote the following passage from 

 Smith's Speculum Hartwellianum, 4 to, I860, p. 315 : — "Sir David Brewster 

 observes that there can be no doubt that in the spectrum of every coloured 

 star certain rays are wanting which exist in the solar spectrum ; but we have 

 no reason to believe that these defective rays are absorbed by any atmo- 

 sphere 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 bands. 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 

 appearanc [in the Campden Hill Journal], clearly showing that there was 

 one defective band 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.' " 



