DR. W. HUGGINS ON THE PHOTOGRAPHIC SPECTRA OF STARS. 
681 
conditions corresponding to these variations in the line K,'“ nor to many important 
suggestions which naturally present themselves when we study the modifications of 
what it is convenient to regard as the most typical form of spectrum. Do these modi¬ 
fications not represent some of the stages through which our sun has passed ? I hope 
travels a millimetre in air). In fact, taking their wave frequencies in air I find as follows, the differences 
being wholly insensible. 
n by calculation. 
n by Angstrom’s observations. 
For line near G 
32x72-003=2304-096 
2304-09 
„ „ H 
35x72-003=2o20-105 
2520-10 
The remaining typical lines do not belong to either this series or that of which 0, F, and h are mem- 
bers; and to include them we must suppose two other motions at least to exist 
in hydrogen. 
Possibly six of these lines may be harmonics of - - 7 - 
J J 9-0572 
for I find: 
Calculated. 
Observed. 
Outstanding 
differences. 
lZ 
284 
X 
9-0572 = 2572-2 
2572-3 
+o-i 
ft 
288 
X 
„ = 2608-5 
2608-2 
-0-3 
7 
291 
X 
„ = 2635 - 6 
2635-05 
-0-55 
b 
293 
X 
„ = 2653-8 
2654-3 
+ 0-5 
s 
296 
X 
„ = 2680-9 
2681-0 
+ 0-1 
V 
297 
X 
„ = 2690-0 
2690-0 
0 
and possibly the others 
, viz.: 6, 
0, and 1 may be harmonics 
01 6-845 £ ° r 
Calculated. 
Observed . 
Outstanding 
differences. 
€ 
390 
X 
6*845 = 2669"6 
2669"9 
+ 3 
0 
394 
X 
„ = 2696-9 
2697-2 
+ 3 
i 
395 
X 
„ = 2703-8 
2703-4 
-4 
I do not attribute much weight to the last two series, for I fancy the computed positions of 7 and 5 are 
too divergent from your observed positions. The calculation puts these lines 1 degree of wave frequency 
O 
scale (=1-4 degree of Angstrom’s scale) nearer together than your determination.” 
Mr. Lockyer, in a “Note on the Spectrum of Hydrogen” (Proceedings Royal Society, December 17, 
1879), describes a line in his photographs of hydrogen coincident with H in the solar spectrum. 
In many of my own photographs this line and also fine lines coincident with most of the typical lines 
are seen, but I reserve for the present any further description of my experiments. The line H in such 
stars as Yega must be ascribed, chiefly at least, to hydrogen. To what extent in cooler stars this line 
may be due also to calcium we do not know.—March 10, 1880.] 
[Messrs. Dewar and Liveing state that the calcium hue K is more easily reversed than the calcium line 
at H (Proceedings Royal Society, February 20, 1879). This fact should be considered in connexion 
with the presence of a line of hydrogen at H in any explanation that may be attempted of the phenomena 
presented in the stars.—March 30, 1880.] 
* Professors Dewar and Liveing have permitted me to witness some of their experiments in which 
analogous changes of relative intensity of K to H occur in the emission spectrum of calcium. They are 
of opinion that these variations and similar changes in the absorption spectrum, such as those shown in 
the stars, naturally follow from the known laws of emission and absorption. They state that the line of 
calcium K is more easily reversed than the line at the position of H. 
