250 NEW STARS IN ANDROMEDA AND ORION. 
At the risk of going over familiar ground I will review 
briefly the spectra of stars as now classified by astrono- 
mers. Secchi who was among the first to apply spectro- 
scopic investigation to the stars, divided the numerous 
Spectra examined by him into four classes. The first 
includes white stars mainly, like Sirius, which give 
spectra with a marked predominance of hydrogen lines, 
all others being comparatively inconspicuous. The 
second includes mainly yellow stars and give spectra 
like that of our sun, such as Capella and Pollux. The 
third includes mainly red and orange-red stars, like 
Betelgeuse, which give spectra with several prominent 
absorption ,bands 7.e. they are bands, not lines like the 
ordinary solar spectrum lines. These bands are sharply 
defined toward the violet end and shade off toward the 
red end. The fourth class comprises small red stars, 
none brighter than the fifth magnitude, which also give 
banded spectra. But the bands are in this case fewer in 
number, (three) broader, and sharply defined toward 
the red end, shading off toward the violet ; in this last 
respect just the reverse of the Betelgeuse spectrum. <A 
representative star of the fourth class is a 5.5 magnitude 
star in the Great Bear, called by Secchi Za Superba 
from the brilliancy of its prismatic colors. 
Prof. Vogel, of Potsdam, who has devoted careful 
study to this subject, has decided to put Secchi’s classes 
III and IV into one, which he calls III, and Ill, He 
believes they denote the same stage of development in 
order of time. He holds that the first type belongs to 
bodies at a maximum temperature, having few elements 
except hydrogen in their atmosphere at a sufficiently 
low temperature to produce absorption lines. The sec- 
ond type implies a lower temperature, which has pro- 
duced an atmosphere in the condition of that sur- 
rounding our sun. The third comprises bodies whose 
atmospheres have become heavily absorptive; and II], 
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