TOTAL ECLIPSE OF THE SUN, APRIL 16, 1893. 
573 
No. 
Kind of plate. 
Exposure. 
Interval of 
change. 
Remarks. 
1 
Mawson 
Inst. 
\ miD. 
2 
1 1 
2 secs. 
2 secs. 
Commencement of totality 
3 
11 
8 „ 
2 „ 
4 
,, (Stellar) 
Inst. 
2 „ 
5 
11 11 
11 
2 „ 
6 
5 secs. 
o 
7 
11 
30 „ 
2 „ 
8 
11 
15 „ 
2 „ 
9 
11 11 
Inst. 
2 „ 
10 
Isochromatic (Edwards) 
5 secs. 
2 „ 
11 
11 11 
30 „ 
2 
ii 
12 
J? 5> 
60 „ 
2 „ 
Middle of eclipse 
13 
11 11 
Inst. 
2 „ 
14 
11 H 
30 secs. 
2 
^ ii 
15 
11 11 
5 „ 
2 „ 
16 
Mawson 
30 „ 
10 „ 
17 
11 
15 „ 
2 „ 
18 
,, (Stellar) 
Inst. 
2 „ 
Last photo, in totality 
19 
11 11 
5 secs. 
2 „ 
After totality 
20 
1) 11 
Inst. 
5 „ 
11 11 
21 
11 
11 
10 „ 
11 11 
22 
11 
8 secs. 
20 „ 
23 
Inst. 
o 
u 11 
24 
” 
11 
11 Ii 
IV. Description of the African Photographs. 
Photographs near Beginning of Totality. 
From what has been stated with respect to the conditions of eclipse, it is clear 
that at the commencement of totality an arc of chromosphere and its associated 
prominences would be visible in the north-east quadrant. In other parts of the 
sun’s edge, the chromosphere was hidden by the moon, but several prominences were 
large enough to show their outlying parts, with the result that the photographs 
exhibit nearly complete rings in the radiations common to chromosphere and 
prominences. Negative No. 7, taken with an instantaneous exposure about 10 
seconds after the commencement of totality, is reproduced in Plate 11 ; as the photo¬ 
graphic plate was not isochromatic, the spectrum only extends to F at the less 
refrangible end. The principal lines, or rather portions of rings, are obviously due 
to the H and K radiations of calcium and hydrogen radiations. The bright arc on 
the right is H s , and the two very prominent rings near the violet end are II and K. 
The photograph shows very distinctly the variation of spectrum in passing from 
one prominence or chromospheric region to another. One small prominence is 
specially remarkable for its complex spectrum, and there is nearly every gradation 
between this and prominences which show practically nothing but H and K. The 
