SPECTRA OF SOME OF THE BRIGHTER STARS. 
719 
deal with successive combinations rendered possible by the :^11 of temperature in a 
gaseous mass. Hence difterences in the spectra are to be expected. 
(Stage 3.)—The phenomena which would be expected on the hypothesis, at this 
stage, are fully satisfied by the stars of Table A, Sub-division a. In these stars there 
is no continuous absorption in the violet or ultra-violet, and the spectrum is one with 
simple line absorptions, the iron lines quite disappearing after such a star as a Cygni 
is passed. The new lines which now make their appearance include the chromospheric 
line at X 4471, and possibly a few others. It is important to note that the photo¬ 
graphic region of the spectrum of the chromosphere has not yet been fully investigated, 
and hence a fair comparison with the spectra of these stars in the region F to K is 
not yet possible. M. Deslandres and Professor Hale have photographed the 
chromospheric spectrum in the region more refrangible than H, but have not as yet 
published any account of the spectrum.in the region now under discussion. 
The Hottest Stars. 
The conditions required by the hypothesis with regard to the stars at this stage 
are satisfied by the stars of d’able A, Sub-division y. 
In these stars we have— 
[a.) Broad lines of hydrogen, and 
(6.) Other absorption lines agreeing in position with some of the bright lines 
which appear in nebulae. This will be seen from the following Table, 
showing the coincidences of the lines which appear in a Andromedae with 
the lines of the Orion Nebula :— 
cc Anclromedce. 
Orion Hebnla. 
3933 (K) 
3933 
3968 (H) 
3968 
402.5 
4025 
4066 
4068 
4101 (7ij 
4101 
4130 
4130 
4143 
4142 
4152 
4155 
4168 
4167 
4187 
4188 
4202 
4200 
4268 
4268 
4340 (G) 
4340 
4471 
4471 
Professor Pickering’s photographs have shown that in the spectrum of Pleione 
there are bright lines down the middle of the broad dark lines of hydrogen, and we 
know from the photographs taken by Mr. Roberts and others that this star is 
