Total ecliTse of the sun, January 22, i898. 
201 
Determination of Origins. 
Ill the report on the eclipse of 189S, to which reference has already been made, I 
pointed out, p. 557, that the chemical part of the investigation could not lie satis¬ 
factorily conducted until much more intpiiry liad lieen made, “ («) into the old 
observations, (6) into the spectra of stars and nebulae, and (c) into certain (piestions 
for which new observations are necessary.'’ Since 1896 great progress has been made 
in our knowledge of the sjiectra of the heavenly bodies, and of the changes in the 
spectra of chemical sulistances with different conditions of temperature, and the 
chemical part of the inquiry is now placed on a much firmer basis. 
The origins of the various lines have been determined partly by direct com])arison 
with the arc and spark spectra of the elements, photographed with the same 
instrument fitted with a collimator, as described above, and where such comparison 
spectra were not available by reference to existing records of the arc and spark lines 
of the elements. The list of chromospheric lines has also been compared with the 
lists (published and unpublished) of enhanced lines of many of the elements observed 
at Kensington. 
The Spectrum of the Chromosphere. 
Distribution o f Substances in the Chromosphere. 
I first deal with the determination of the heights of the various absorbing vapours 
so far as they can be gathered froin the photographs, which, of course, only record for 
us the brightest lower portions of tlie different arcs, and not their complete extension. 
The following table shows the results obtained in the case of some of the most 
typical lines :— 
Lines. 
Ca(K). 
Hyclroe:en. 
He 447H-2.o. 
He 4026-.3; Sr 4077-9, 4215-GG. 
Ca 422G-9 ; Sc 4247 . 
Mg ultra-violet triplet. 
Fe trijjlet (404.5). 
Strongest are lines (4307-96, 4325-92, Ac.) . . . . 
A1 3944-16 and 3961 67 . 
Fe enhanced lines 4584, 4233 . 
Mn quartet (4030 9, Ac.). 
Fe enhanced quartet (4523-0, &c.) and many other lines 
Carbon fluting and many lines, including some arc lines 
of iron. 
Length 
of arcs. 
Height. 
In miles. In secs, of arc. 
130° 
6000 
13-3 
112° 
4500 
10-0 
105° 
4000 
8-9 
86“ 
2700 
6-0 
72 r 
2000 
4-4 
60° 
1450 
3-2 
51° 
1100 
2-4 
40° 
650 
1-4 
35° 
475 
1-05 
2 D 
VOL. CXCVH.-A. 
