206 
SIR XORMAN LOCKYER AND MR. F. E. BAXANDALL 
is little doubt, were taken; lines which were suspected, however slightly, of havino; a 
double or complex origin were rejected. A list of the lines used is here given ;_ 
A. 
Origin. 
A. 
Origin. 
3900-68 
p Ti 
4501-45 
p Ti 
4012-54 
p Ti 
4584-02 
p Fe 
4215-70 
p Sr i 
4657-38 
pTi 
4415-29 
Fe 1 
1 
1 
4780-20 
p Ti 
Tlie result of a previous reduction of the spectrum of a Cygni, already published, 
serves as a valuable check on the accuracy of the reduced wave-lengths, as there are 
many lines common to the two spectra, and there can he no doubt as to the identity 
of most of the stronger a Cygni lines with enhanced lines of some of the metals, as 
has been shown in a jDrevious paper. ^ 
In the table at the end of the paper the y Cygni lines are compared with those 
reduced at Kensington from tlie spectrum of a Cygni and that of the chromosphere, 
and also with those recorded by PickerixgI in the spectrum of 8 Canis Majoris. The 
latter star is selected by Pickerixg as typical of Grouji XIIIc. in his classification, in 
which group he also includes y Cygni. In the case of the chromosphere, in order to 
keep the table within moderate limits, only those lines which agree with y Cygni 
lines have been inserted, but of the chromosjiheric lines omitted none are prominent 
except those of helium. 
Comparison of y Cygni and Chromospiliere. 
Iteference to the table will show that the metallic and protometallic lines have, 
speaking broadly, about the same relative intensities in the spectra of y Cygni and 
the chromosphere. It would thus appear that the temperature and electrical 
conditions prevailing in the chromospheric vapours which furnish the metallic lines 
are nearly identical with those appertaining to the absorbing atmosphere of y Cvgni. 
To arrive at any conclusion as to which of the two light sources in question represents 
the liigher temperature, it is necessary to study in detail the comparative intensities 
of well-known lines. For this purpose, two sets of lines have been considered : (1) the 
strongest unenhanced lines of the metals represented; (2) the most marked enhanced 
lines of the metals. In the following table a comparison is given of the intensities of 
the strongest lines of iron, manganese, chromium, cobalt, barium, calcium, aluminium, 
and titanium, as they occur in y Cygni and the chromosphere, 
* ‘Roy. Soc. Proc.,’ vol. G4, p. 321. 
t ‘Annals Harv. Coll. Obs.,’ vol. 28, Part I., p. 7y. 
