708 
PROFESSOR J. K LOCKYER ON THE PHOTOGRAPHIC 
Typical stars. 
a Cygni . 
7 Cygni . . . 
a Taui’i 
Andromedse . 
a Orionis ... I 
/3 Pegasi . . . ' 
a Herculis 
Sub-divisions. 
Table A, sub-division a 
j, B ,, ct 
C /3 
1 
J) 
C 
a 
Reference to Plate 29. 
a 
a 
rx 
a 
a 
(X 
a 
Typical stars. 
Andromedse 
Canis Majoris 
Geininorum 
Persei . 
Canis Alinoris 
Aurigse 
Bootis . . , 
Sub-divisions. 
Table A, sub-division y 2 
; ? 
8 
; J 
5 ? 9 ? 
/3 2 
„ 3 
yS 1 
9 
(2.) Variations Obseryed. 
It will be seen, on reference to Plates 2G and 27, that, starting with a Herculis, we 
have a mixed spectrum of lines and flutings, the latter gradually disappearing in 
/3 Pegasi, a Orionis, and f Andromedre, until, in a Tauri, nothing but lines remain. 
At the same time the continuity of the lines is unbroken, so that if we were to 
arrange the stars according to the thicknesses of, say, the lines of calcium, the same 
order would be deduced. 
Next in the series is y Cygni, the spectrum of which has much in common with that 
of a Tauri, but there is less continuous absorption, and many of the lines of a Tauri 
thin out. 
The next step, to a Cygni, is rather a long one, but it seems very probable that, if 
more photographs were available, intermediate spectra would be found. It will be 
seen, however, that in a Cygni the hydrogen lines are intensified as compared with 
7 Cygni, and that all the important lines of a Cygni agree in position with promineut 
lines in y Cygni. 
At this stage there is a great diminution in the number of lines, as will be seen on 
referring to the spectrum of Bigel (/3 Orionis), which is the next star in the series. 
In passing to Bigel, the more important lines of a Cygni are retained, and a few new 
lines make their appearance. 
