Changes in the Sun’s apparent Diameter. 275 
ephemeris, and the small figures below them show the number 
of observations upon which each number depends. 
In Wagner’s paper, above referred to, sufficient data are given 
to allow his work to be treated in a like way, and his observa- 
tions give when so treated the following results, which agree, in 
le. 
general, with the figures in the above table. 
8 
Pulkowa Class IV. 0055 Wash. Weight 2-3 -0-063 
V-Il. 0°020 = 
IlI-IV. —0-002 as 3 +0°027 
lL -+0-029 “ 3-4 +0180 
Although the weights of Washington observations were as- 
signed by as many as six or seven different observers, each by 
a different standard, the agreement between the resulting errors 
of ephemeris diameter at Washington and Pulkowa is evident, 
in regard to sign at least. : : 
o show how rough a division of sun observations accordin 
to state of image will exhibit the effect of good definition upon 
the deduced values of diameter, we further divided the Wash- 
2 comprises those made when the cloudiness ranged from 5 to 
10. (O0=clear sky, 10=all overcast.) These numbers 0-10 
Horizontal Diameter. Vi Diameter. 
Year. Cloud=0: Cloud 5-10. Cloud=0: Cloud 5-10. 
8 8 s 
1867 —0033 +0012 —0°45 +0°35 
1868 —0°047 +0.03: —1°45 +0°45 
1869 0°000 +0°039 +0°75 1 
1870 —0093 +0014 —0°70 —0°44 
The numbers in the various columns are again the mean ap- 
parent errors of ephemeris diameter (corrected). The cause of 
the periodicity in the monthly means being now understood, it 
remained to free the separate residuals from periodic error, 
Weights— 1. 2. 3. 4, 1-2. 2-3, 34, 
cee ine ae a ce SS ooo eee ees aE cea tar 
Year| H.D, | V.D. | H.D. | V.D.§ H.D. | V.D. | H.D. | V.D.§ H.D. | V.D. f H.D. | v.D. | H.D, | V.D, 
| 8 | “ 8. “ 8 4“ “ Ben 8. 4“ 8. 
1866) -0°130| -1-064~-0-024| -0:06]+0-008 | +0391+0-045|+0'6s 0°120| -1°80}+-0-180 -6+20 
RAY ae eoea Pe aie Fae 7 SO n 36 Oe ant Net pen Ln.An Pea nel Ne x I 
20un Ty UlYy Vo VVILV Vv VUVUeil TV VIETU Vie Vv Ad baMeinted HS ilies | VA OY OUR one sel wnene 
8 6 33 3 40 | 40 I I 4 
12a. )-H20 f) -29) Hpe gy Li.202! Ln. O-fMiN 1+7-on nnie ray 
peel UUS. Uo UU U Vv VUay Ti OV VVviv TF CO a ante ee | an to 
5 5 fay | 17 18 18 2 3 6 5 
a 0°100|+0°1 2. 2 047|+0 POLS 0 C0ne eo lo 
2 2 to | 9 12 Io | 6 7 
