256 
DR. T. R. MERTON AND PROF. J. W. NICHOLSON ON 
Neon. 
A. 
\ ( ord 0- 
\ (bulb). 
Photographic 
intensity 
(ord.). 
Photographic 
intensity 
(bulb). 
Ratio 
(bulb/ord.). 
Tabular intensity 
(Watson and 
Baly). 
7032-6 
6-7 
4-2 
4-35 
2-51 
0-578 
3, - 
6929-8 
9-2 
5-8 
7-52 
3-57 
0-474 
6, — 
6717-2 
17-6 
12-2 
47-4 
14-5 
0-306 
h i 
6678-5 
20-5 
12-5 
100-3 
16-6 
0-166 
9, — 
6599-2 
17-6 
13-5 
52-2 
20-8 
0-398 
9, 4 
6533-1 
15-0 
11-2 
31-6 
12-9 
0-417 
6, 4 
6506-7 
27-3 
17-0 
537 • 0 
50-1 
0-093 
9, 6 
6402-4 
27-3 
17-9 
537 • 0 
61-7 
0-115 
10, 10 
6383-1 
19-4 
15-0 
87-1 
31-6 
0-363 
9, 8 
6334-6 
20-6 
16-7 
114-9 
46-8 
0-407 
9, - 
6305-0 
15-0 
12-1 
31-6 
16-2 
0-513 
6, 8 
6266-7 
20-0 
14-4 
111-5 
29-8 
0-267 
6, 10 
6217-4 
13-8 
10-6 
25-9 
12-2 
0-470 
6, 8 
6163-7 
15-5 
11-0 
38-6 
13-4 
0-346 
6, 10 
6143-3 
21-6 
19-0 
162-6 
88 * 1 
0-542 
7, 10 
6096-4 
19-4 
15-7 
96-8 
40-5 
. 0-418 
6, 10 
6074-5 
16-0 
14-8 
47-4 
35-5 
0-749 
6, 10 
6030-2 
11-0 
9-0 
14-2 
8-77 
0-618 
5, 10 
5975-* 
9-5 
9-0 
9-89 
8-77 
0-887 
5, 7 
5945-0 
16-3 
13-7 
51-0 
27 ■ 2 
0-534 
6, 10 
5902-6 
8-0 
5-7 
7-04 
4-02 
0-571 
5, 4 
5882-0 
13-7 
10-8 
28-3 
13-9 
0-493 
5, 8 
5852-6 
24-5 
16-0 
421-7 
51-8 
0-123 
10, 20 
5820-3 
5-8 
6-0 
4-18 
4-40 
1-050 
5, 4 
5764-5 
8-0 
10-0 
7-19 
11-78 
1-638 
7, 8 
* A doublet, AA5974-8 and 5975-8. 
the corresponding region of the secondary spectrum of Hydrogen, the table contains 
the necessary information as to the variations of energy in the individual lines of such 
spectra. It is in any case noteworthy that the relative behaviour of the lines is 
very varied—and not comparatively uniform, as a mere visual inspection might 
suggest. 
(X.) Photographic Intensities in the Carbon Arc. 
An inspection of Plate 1a, which contains a wedge-photograph of the Carbon arc, 
indicates the irregular behaviour of the photographic plate through the visible region. 
We have calculated already the absolute relative intensities in the Carbon arc when 
corrected for the dispersion adopted. Below are given the measurements and 
subsequent determination of the photographic intensities in the arc, as registered on 
a plate which contains the ordinary Helium spectrum examined in an individual case, 
through the wedge. On the arc is also superposed the ordinary Helium spectrum 
without the wedge, in order to identify positions of given wave-lengths, and to 
facilitate the measurements of the heights to which the arc photograph extends at 
