

XIV.] 



TYPICAL STELLAR SPECTRA. 



189 



magnesium, calcium, iron, bismuth, tellurium, antimony, and 

 mercury. 



In the last class of stars to which I have referred, the fourth, 

 the lines have given place to fluted bands, at the same time that 

 the light and colour of the star indicate that we have almost 

 reached the stage of extinction. 



Here are some typical stellar spectra (Fig. 74), which show us 

 at once the very considerable difference in the phenomena ob- 

 served. In the upper part of this diagram we have a star, of 

 Type I, remarkable for the fewness of lines in its spectrum. 



S / R / US 



^- GA 



SUN 



POLL U X 



III 



FIG. 74. Three chief types of stellar spectra. 



From one end of the spectrum to the other there are not above 

 half-a-dozen prominent lines. In the next part however we have 

 a star of Type II, which is remarkably like our own sun, both as 

 regards the number of lines and their arrangement. In the 

 lower part of the diagram we have, on the other hand, a star in 

 which we get flutings instead of lines ; so that we get not only 

 a difference of degree, but a fundamental spectroscopic difference 

 of kind. 



Now there is a circumstance connected with stars of the first 

 type those with the simple spectrum very striking to any one 

 in the habit of observing the sun, and it is this : those lines 



