154 
ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
out any change in the adjustments, the instrument had returned to 
focus when the comparison plates were taken in July. 
These changes must be attributed to the effect of the sun's heat on 
the mirror, but it is difficult to say whether this caused a real change 
of scale in the resulting photographs or merely blurred the images. 
The photographs were measured in the astrographic duplex mi- 
crometer, the eclipse photographs being directly compared with the 
comparison plates taken in July. All the stars shown were measured. 
They were reduced by the same method as that employed for the 
" 4-inch " photographs. With the exception of plates Nos. 15 and 16, 
taken through clouds, the stars numbered 3, 4, 5, 6, 10, 11, and 12 
are shown on all the plates; the fainter stars 2, 7, 8, and 9 are some- 
times shown, but No. 1, which is very near the sun, is always drowned 
in the corona. These plates were only measured in declination, as 
the right ascensions without No. 1 are of little weight. 
24. In the following table is given the value of a, the constant of 
the gravitational displacement, as calculated from the measures; 
the apparent difference of scale e between the eclipse and comparison 
plates; d^ the difference of orientation of the plates given by the 
measures of y and depending on the adjustment of the plates in the 
measuring machine. 
Table IX. 
(l'-==12.3".) 
No. of eclipse plate. 
Reference 
No. of 
comparison 
plate. 
Number of 
stars. 
Values of i, e, a in revolutions 
at 50' distance. 
a at 
sun's limb 
d. 
e. 
». 
in arc. 
1 
I84 
I84 
184 
184 
113 
113 
143 
183 
143 
174 
174 
111 
111 
172 
153 
153 
172 
172 
7 
11 
8 
11 
10 
11 
12 
7 
10 
7 
10 
10 
11 
7 
6 
7 
8 
7 
T 
+ 0.051 
- .009 
- .074 
- .168 
+ .094 
+ .186 
+ .006 
- .054 
+ .093 
- .096 
+ .090 
+ .073 
- .009 
- .102 
+ .111 
- .002 
- .022 
+ .045 
T 
+0. 089 
+ .059 
+ .101 
+ .091 
+ .076 
+ .082 
+ .119 
+ .166 
+ .064 
+ .129 
+ .045 
+ .061 
+ .102 
+ .114 
+ .036 
+ .037 
+ .109 
.000 
r 
+0.033 
+ .025 
+ .028 
+ .033 
+ .025 
+ .021 
.000 
.000 
+ .021 
+ .008 
+ .026 
+ .032 
+ .049 
+ .019 
+ .018 
+ .018 
+ .012 
+ .030 
+1.28 
2 
+ .97 
3 
+ 1.09 
4 
+1.28 
5 
+ .97 
6 
+ .82 
7 
.00 
7 . .. 
.00 
8 
+ 82 
9 
+ 31 
10 
+ 1.01 
n 
+ 1.24 
12 
+ 1.91 
12 
+ 74 
15 
+ .70 
16 
+ .70 
17 
+ .47 
18 
+ 1 17 
+ .082 
+ .022 
+0.86 
