698 
PROFESSOR J. N. LOCKYER ON THE PHOTOGRAPHIC 
(4.) Stjb-division S. 
Characteristics of the Spectra. 
In these stars the hydrogen lines are very broad, and the additional lines, as before 
remarked, are chiefly faint representatives of those which appear in the solar 
spectrum. There is a complete inversion of the intensities of the hydrogen and 
metallic lines as compared with the solar spectrum. The most strongly-marked hue, 
next to those of hydrogen, is generally the K line of calcium. A line of magnesium 
at 4481 is also usually easily distinguished. In the brighter stars, such as a L^T8e, 
a trace of the line at 4024 appears. In this case, however, it is accompanied by the 
lines of iron, whereas in Sub-division y no iron lines have been detected so far. 
It will be evident that no sharp line can be drawn between these stars and those 
of Sub-division yS. The difference lies only in the relative intensities of the hydrogen 
and metallic lines. When all the principal solar lines are easily seen in the photo¬ 
graphed spectrum the star has been classed in Sub-division y8, but when only a 
comparatively small number of lines is seen, it has been placed in Sub-division S. 
It has not been found desirable or, indeed, possible to further sub-divide the stars 
included in Sub-division S. 
VI.—DISCUSSION OF STARS IN TABLE B. 
In these stars there is a considerable amount of continuous absorption in the ultra¬ 
violet, and the spectra beyond K are very difficult to photograph with the instm- 
rnents employed, as compared with the stars of Table A. The thickness of the 
hydrogen lines does not greatly differ from that observed in the solar spectrum. 
(1.) Sub-division a . 
Characteristics of the Spectra. 
The only star of this sub-division which has yet been photographed at Kensington 
is y Cygni. The spectrum shows a large number of dark lines, but it presents a very 
different appearance from that of the Sun. The characteristic gi’ouping of lines 
about G is entirely absent, and many lines have very different intensities. The lines 
of calcium, including H and K, are only of moderate thickness. 
Among the more prominent lines are the following :— 
4383 
4372 
4351 
4340 (G) 
