440 PROF. F. W. DYSON: DETERMINATIONS OF WAVE-LENGTH FROM SPECTRA 
A good deal of caution is necessary in establishing the identical origin of the weak 
lines, but the cumulative evidence of the close agreement of the wave-lengths of the 
lines 3862, 3905, 4103, 4128, 4131, and 4552 gives a fair degree of probability for 
the existence of Si in the chromosphere. 
Calcium. 
The calcium lines are very strongly shown, and the intensities follow closely those 
given by Exner and Haschek for the spark spectrum. 
Chromosphere. 
Intensity in—- 
Chromosphere. 
Intensity in— 
Wave¬ 
length. 
No. of 
photos. 
Intensity. 
Spark. 
-A.TC 
(Iv. and R.). 
Wave¬ 
length. 
No. of 
photos. 
Intensity. 
Spark. 
A rC 
(K. and R.). 
3706-18 
11 
5* 
10 
4 
4302-68 
2 
1 1 
6 
10 
3737-08 
11 
8* 
15 
4 
4307-92 
4 
4* 
2 
8 
3933-84 
13 
100 
100 
10 
4318-79 
— 
— 
3 
8 
3968-63 
13 
80 
80 
10 
4425-62 
— 
— 
3 
10 
4226-91 
4 
5 
10 
10 
4435-12 
\ 2 
2 
4 
10 
4435-84 
J 
3 
8 
4454-93 
2 
1 
5 
10 
* Compound lines. 
Comparison of the two sides of the above table shows the relative behaviour of 
enhanced and unenhanced lines, the 7 strong arc lines on the right being only 
just shown, if at all, in the chromosphere spectrum. 
Scandium. 
Scandium is very strong in the chromospheric spectrum. Exner and Haschek 
give 23 lines of intensity 10 or greater. The only one of these not found in the 
chromospheric spectrum is 355872, intensity 20. The intensities agree well with 
the spark. All the lines are present in the solar spectrum. 
Titanium. 
Titanium is very strong in the chromospheric spectrum. Analysing the results, 
taking Exner and Haschek’s spark spectrum as argument, it is found that : (i) lhe 
7 lines of intensity 50 are all strongly shown. These are all fairly strong aic lines, 
but two of them, 3383-91 and 3505-06, are weak in the solar spectrum, (ii) The 
5 lines of intensity 30 are well shown. They are all strong in the solar spectium. 
The lines 3741 and 3913 are decidedly “ enhanced.” (iii) Of the lines of intensity 
20 the weakest in the chromosphere is 3989"91, a line strong in the arc and the sun. 
(iv) The lines of intensity 15 are strongly shown, with three exceptions, viz. 3653 64 
and 3998*79 very strong in the arc and strong in the sun, and 3456"53 of intensity 
3 in the sun and outside the limit of Hasselberg’s arc spectrum, (v) The lines of 
