DETP]RMINATION OF 1)P:FLP:CTI0N OF LIGHT BY TIH: .SUN’S GRAVITATIONAL FIIH.D. 3 I 5 
results. Of the other series, only the exposures actually used in the reductions are 
given. 
List of Plates. 
Check Field (R.A. 14h. 12m. 47s., Declination -)-20° 30') 
Ref. 
Place. 
Date. 
Loc 
Sid. 
T. 
Exjn 
Approx. 
Z.D. 
Bar. 
Ther. 
Plate. 
1919. 
h. 
m. 
S. 
s. 
0 
m. 
O 
Oxford 
January 16 
12 
55 
10 
60 
35 
29-64 
37-0 
S. 
L 
> 
January 17 
13 
10 
40 
60 
34 
29-83 
35-3 
s. 
G 
> J 
J 5 
13 
54 
55 
60 
31 
29-83 
35-3 
s. 
? J 
>5 
14 
9 
25 
60 
31 
29-83 
35-3 
s. 
G 
)> 
January 23 
13 
13 
30 
60 
33 
30-45 
29-0 
s. 
G.M.T. 
Principe 
May 22 
12 
25 
40 
40 
43 
29-45 
76-5 
S.R. 
G 
J5 
J J 
12 
31 
20 
40 
45 
29-45 
76-5 
S.R. 
> > 
3? 
12 
37 
50 
80 
46 
29-45 
76-5 
S.R. 
G 
?5 
May 25 
12 
22 
20 
40 
45 
29-45 
76-5 
S.S. 
J 5 
33 
12 
26 
20 
40 
46 
29-45 
76-5 
S.S. 
Notes. 
Column 1.—The letter is marked on the original plates (preserved at Cambridge Observatory). The 
number refers to the exposure, disregarding exposures taken without the S-inch stop. 
Column 2.—The co-ordinates of Oxford Observatory are 5m. -3s. W., 51° 46' N., and of the site at 
Principe, 29m. 32s. B., 1° 40' N. 
Column 4.—The mid-instant of the exposure is given. Times for check plates at Principe were only 
noted roughly. Times for the eclipse plates are deduced from the calculated time of totality, the interval 
from the end of one exposure to the beginning of the next being assumed uniform. 
Column 7.—Readings at Principe were taken with an aneroid recording instrument, and therefore 
automatically reduced to the latitude of England. The barometer during our visit was practically constant 
except for a regular semi-diurnal wave of amplitude about 0-05 in. 
Column 9.—Brand of Plate ; S. = Imperial Sovereign, S.S. = Imperial Special Sensitive, S.R. = Ilford 
Special Rapid, E. Ilford Empress. Backed plates were used at Principe. 
VOL. CCXX.-A. 
2 X 
