700 
PROFESSOR J. N. LOCKYER ON THE PHOTOGRAPHIC 
Further Division into Two Sub-Classes. 
(!•} 
Stars Avith spectra whicli cannot be 
distinguisbed fi’om that of the 
Sun. 
(2.) 
Stars with spectra which differ 
from the Sun in having some of the 
lines, especially those of calcium, 
slightly intensified. The lines of 
hydrogen are somewhat thinner 
than in (1). 
a Cassiopeia? 
ji Ceti 
a Ursfe Minoris 
K Persei 
cc Arietis 
f Hydrge 
a Aurigge (Capella) 
a Bootis (Arcturus) 
/3 Geminorum (Pollux) 
/3 Bootis 
6 Hydr® 
TT Herculis 
6 Leonis 
7 Leonis 
a Ursa? Majoris 
6 Virginis 
?/ Bootis 
6 Bootis 
e Ophiuchi 
/I Herculis 
^ Herculis 
1 ] Herculis 
/i Ophiuchi 
/I Herculis 
V Ophiuchi 
70 Ophiuchi 
f Cygni 
7 Pegasi 
fi Pegasi 
7 Aquilse 
It will be evident that these two sub-divisions must be placed in juxtaposition 
whatever classification may be finally adopted. The spectra of Capella and Arcturus, 
which may be taken as types, are reproduced in Plate 29. 
Carbon A bsorption. 
A question of considerable interest, as will appear later, is, whether in these stars 
there is any evidence of carbon absorption. In a communication to the Eoyal 
Society in 1878,* I showed that in the solar spectrum there is a dark fluting of carbon 
commencing at wave-length 3883. This has since been confirmed by Messrs. 
Trowbridge and Hitchins,! who also found that this fluting was the only one which 
remained visible when a complicated metallic spectrum was added to that of carbon. 
It is therefore to be expected that indications of carbon absorption will be found in 
the spectra of the stars under discussion. 
* ‘ Roy. Soc. Proc.,’ vol. 27, p. 308. 
t ‘ Phil. Mag.,’ series 5, vol. 24, p. 148. 
