316 tt;iK F. W. DYSON, PKOF. A. S. EDDINGTON AND Mil. C. DAVIDSON ON A 
Eclipse Field (R.A. 4h. 19m. 30s., Decimation +21° 43') 
Ref. 
Place. 
Date. 
Loc. Sid. 
T. 
Exp. 
Approx. 
Z.D. 
Bar. 
Tlier. 
Plate. 
1919. 
h. 
m. 
s. 
s. 
0 
m. 
O 
Oxford 
January 16 
3 
58 
1 
5 
30 
29-65 
39-0 
S. 
G, 
?) 
January 22 
4 
4 
39 
5 
30 
30-30 
31-0 
s. 
Hi 
55 
55 
4 
34 
28 
5 
30 
30-30 
31-0 
s. 
k 
55 
4 
48 
46 
10 
31 
30-30 
31-0 
s. 
Ik 
55 
February 9 
4 
45 
24 
10 
30 
30-48 
24-5 
s. 
G.M.T 
K' 
Principe 
May 29 
2 
13 
9 
5 
46 
29-45 
77-0 
S.R. 
L 
55 
2 
13 
28 
10 
46 
29-45 
77-0 
S.R. 
M 
55 
55 
2 
13 
46 
3 
46 
29-45 
77-0 
S.R. 
N 
55 
5 5 
2 
14 
1 
5 
46 
29-45 
77-0 
E. 
0 
55 
55 
2 
14 
20 
10 
46 
29-45 
77-0 
S.S. 
p 
55 
5 5 
2 
14 
44 
15 
46 
29-45 
77-0 
s.s. 
Q 
55 
55 
2 
15 
6 
5 
46 
29-45 
77-0 
S.R. 
R 
55 
55 
2 
15 
30 
20 
46 
29-45 
77-0 
S.R. 
S 
5 5 
55 
2 
15 
53 
3 
46 
29-45 
77-0 
S.S. 
T 
55 
2 
16 
13 
15 
46 
29-45 
77-0 
E. 
U 
55 
55 
2 
16 
37 
10 
46 
29-45 
77-0 
S.R. 
V 
55 
55 
2 
16 
56 
5 
■ 46 
29-45 
77-0 
S.S. 
w 
55 
2 
17 
15 
10 
46 
29-45 
77-0 
s. 
X 
55 
55 
2 
17 
33 
3 
46 
29-45 
77-0 
S.R. 
Y 
55 
2 
17 
47 
2 
46 
29-45 
77-0 
S.R. 
Z 
55 
5 
2 
18 
1 
2 
46 
29-45 
77-0 
S.R. 
Notes. 
Columns 1 to 9. See previous page. 
Tlie large proportion of Ilford Special Rapid plates used at the eclipse was due to 
the fact that experience in developing the check plates showed that these suffered less 
than the others from the high temperature of the water (78° F.). Ice was generally 
available for the check plates through the kindness of Sr. Grageira ; but the supply 
failed after the eclipse, and formalin was used to harden the films. This was un¬ 
satisfactory except for the I.S.R. plates, and so plates P, S, T, W were brought home 
undeveloped. The developing at Principe was done at night, and the drying was 
accelerated by use of alcohol. 
The use of an 8-inch stop in front of the object-glass was suggested to us by 
IVIr. Davidson, who showed that a great improvement of the images resulted ; it was 
originally intended, however, to use the full aperture for part of totality. Early 
measures of check plates made at Principe soon convinced us that the results from the 
full aperture were greatly inferior, and we decided to rely entirely on the 8-inch 
aperture. 
