APPENDIX II 
265 
Position of brighter star minus position of center of gravity. 
Date. 
Aa. 
AS. 
Date. 
Aa. 
AS. 
s 
// 
S 
Iff 
1800 
-.362 
-1.78 
1885 
— .018 
+ 2.19 
1810 
-•369 
—1.27 
1890 
-f .026 
+ 2.16 
1820 
-•364 
— 0.72 
1895 
+ .070 
+ 2.04 
1830 
-•347 
- i 5 
1900 
+ .110 
+1.82 
1840 
-.316 
+ .42 
1905 
+ .144 
+ 1.51 
1850 
-•273 
+ .98 
1910 
+ .170 
+ 1.11 
i860 
—.216 
+ 1.49 
191S 
+ .186 
+ .64 
1870 
-•145 
+1.90 
1920 
+ .190 
+ .14 
i 875 
1880 
-.105 
—.062 
+ 2.05 
+ 2.15 
1925 
+ •183 
- -38 
Nos. 376-377. L 495. 3 G Eridani, p. Dunlop 5. 
This is probably a binary of long period, though the material of observation is, as yet, insuffi¬ 
cient for the computation of a reliable orbit. Under the circumstances, no very marked error is 
likely to result from the computation of position and motion for each of the components in the 
usual manner, without taking into account possible curvature of orbital motion. 
No. 1732. a Canis Majoris (Sirius). 
The annual parallax of this star is about o'.'4. The catalogue-position is for the center of gravity. 
In deriving the orbit of the bright star about this center of gravity the orbit of the faint companion 
is adopted from the computation of Zwiers, as quoted in the Bulletin of the Lick Observatory, 
No. 84, thus: 
P = 48.84 years T = 1894.09 6 = 0.588 a — 77594 
0=147.89° 0 = 44.50° *’ = 46.03° log p = 0.86752 
The ratio of the masses results thus: from residuals in right-ascension, .284 to .716; from 
residuals in declination, .279 to .721; adopted, .282 to .718. Or calling the mass of the bright 
star 1.0, that of the companion becomes .393. Thus the mass of the bright star is only about two 
and one-half times that of the companion. This result seems to be entitled to confidence. The 
following table gives the quantities that must be added to positions computed from the catalogue- 
place and motion of the center of gravity in order to get the predicted position of the bright star 
at the corresponding dates. In order to get the corresponding positions of the faint star, multiply 
the tabular quantities by — 2.55 and add to the position computed for the center of gravity. The 
nominal epochs and probable errors for this star are: 
in R. A., 1871; p.e. at epoch ±''023; at 1910 ±'' 0 5 > of c.v.±"n; 
in Deck, the epoch is 1869; p.e. at epoch ±''028; at 1910, ±"06; of c.v. ±'.'13. 
But the p.e. of orbital motion adds to and complicates these numbers so that they do not apply. 
They simply serve to indicate the weight of observation which this star has received. 
