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. 
94. In the following table is given the value of «, 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. 
TasLe IX. 
(1?s=12,.3”.) 
Values of d, e, a in revolutions 
Reference at 50’ distance. 
No. of eclipse plate. ean ie a ina epee: oaoibacal eae MEAN sun’s limb 
late! * é a in are. 
r T tT m 
ihe 2) ae Oe ee ee aR ERT eT es oe 184 a +0. 051 +0. 089 +0. 033 +1. 28 
Des deere ep tied. Scien atts eee 184 ll — .009 + .059 + .025 + .97 
Se ae ree ect nes Saree yer 184 8 — .074 + .101 + .028 +1. 09 
Ee AB ea cain te nie tare are estate eae 184 11 — .168 + .091 + .033 +1. 28 
i P tdee SESE. By. SU: Pe Be 113 10 + .094 + .076 + °.025 + .97 
Bice caret abs) Yo acai 113 ll + .186 + .082 + .021 + .82 
Va ceed hepish oats eat Ua, Aaiecore eee a 143 12 + .006 + .119 . 000 .00 
Mee eae cere Eee ce ree 183 7 — .054 + .166 . 060 . 00 
eS SS. LEP BERS Eee 143 10 + .093 + .064 + .021 + .82 
De ae Eoin em cRies Sa Ee 174 7 — .096 + .129 + .008 + .31 
HO ee a aise areas ela ke 17% 10 + .090 + .045 + .026 +1.01 
eee ee Oe Se OS eee 1h; 10 + .073 + .061 + .032 +1.24 
TORE A SE, EE Fass 1h; il — .009 + .102 + .049 +1. 91 
5 Ae EIR pe SAY SAO Ot Sy Rs 172 7 — .102 + .114 + .019 + .74 
Doe ise tec dacisiaae we macicee eases 153 6 + .111 + .036 + .018 “+ .70 
DBs en se ppaiu cise eins cee oe 153 7 — .002 + .037 + .018 + .70 
Die che sayeeh at och? bapeterd: sieetes = 172 8 — .022 + .109 + .012 + .47 
PBwer: swiibo ies th ele yess aka, 172 7 + .045 . 000 + .030 +1.17 
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