448 PROF. F. W. DYSON: DETERMINATIONS OF WAVE-LENGTH FROM SPECTRA 
Tantalum. 
The strongest spark lines are possibly shown. 
Lead. 
The strongest arc lines appear to be faintly shown, but not the enhanced lines. 
The following table gives all the strongest lines in Exner and Haschek :— 
Spark. 
Chromosphere. 
Wave¬ 
length. 
Sun. 
Arc. 
Wave¬ 
length. 
Intensity. 
Wave¬ 
length. 
No. of 
photos. 
Intensity. 
3572-95 
20 
3573-19 
1 
0 1 
_ 
8r 
3639-72 
20 
3639-66 
1 
1 
3639-66 
Pb 1 
lOr 
3683-60 
20 
3683-70 
3 
0 
3683-62 
Pb 000 
lOr 
_ 
_ 
— 
— 
— 
3683-76 
Fe 2 
— 
3740-10 
20 
3740-19 
2 
0 
— 
— 
8r 
3786-37 
20 
3786-29 
1 
1 
3786-31 
Fe 4d ? 
—■ 
3854-05 
20 
Not shown 
4058-05 
20 
4058-02 
2 
1 
4058-04 
Pb 0 
lOr 
4245-2 
20 
Not shown 
4387-0 
20 
4387-01 
2 
1 
4387-01 
Ti 1 1 
The evidence, such as it is, is in favour of the presence in the chromosphere of the 
three lines of intensity 10 in the arc, though the line at 4058'05 may just as well be 
a spark line of tantalum. 
Europium. 
1 Watts’ Dictionary of Spectra’ (Appendix M.) gives the intensities in the spark 
and arc of the strongest lines. 
Wave¬ 
length. 
Intensity. 
Chromosphere. 
Spark. 
Arc. 
Wave¬ 
length. 
No. of 
photos. 
In¬ 
tensity. 
4662-1 
50 
5 
4662-32 
1 
0 
4627-4 
100 
8 
— 
— 
— 
4522-8 
20 
15 
4522-80 
5 
5 
Enh. Fe. 
4435-7 
50 
30 
4435-53 
2 
2 
4205•2 
100 
50 
4205-21 
5 
4 
4129-9 
100 
100 
4129-87 
5 
4 
In sun 29 - 88, intensity 1. 
3972-2 
50 
50 
3972-02 
5 
2 
In sun 72’13, intensity 0 1 
3930-7 
50 
50 
3930-46 
5 
4 
Fe. 
3907-3 
30 
30 
3907-28 
6 
2 
3819-8 
50 
50 
3819-73 
3 
1 
He. 
3725-1 
30 
20 
3724-97 
3 
1 
3688-6 
20 
10 
— 
The strongest spark lines, 4205'2 and 4129'9, are strongly shown. 
