W. G. Du 
Phil. Trans., A, vol. 208 , Plate G. 
Line 
dl d3 A 2 dl dO 
¥ f- 
Line. 
Wave-length. 
dO 
4325 19 
dl 
4315 -21 
d2 
4307 '96 
d 3 
4299 '42 
dl 
4294 26 
Group 
I. III. 
I. E. I. 
I.E 
Fig. 1. 
Negative 
O 
(enlarged). 
Line 
/2/1 
eA 
i Jl. : 
it. 
f:| '• : 
Group 
III. III.E. 
I.E 
Fig. : 
e3 el 
III.E. I.E. 
Negative (enlarged). 
Line. 
Wave-lengt 
el 
4271 -30 
e3 
4260 -64 
4250 '93 
n 
4236 -09 
f2 
4233 -76 
4200 
§ Ca ? 
w a 
( 
Liue. 
Wave-length 
i i 
Ca? 
4226 91 
1 'ill 
20 atmospheres. 
TIP! 
. . . _ 
1/0 
gl ? Sa 
liO 
4219 -47 
4210 -48 
4191 ‘57 
ko. 
3' go. 
Fig. 3. Original negative. 
