APPENDIX II 
277 
| A/ao, from R. A., 
from decl., 
+ ''046 — ''oi 5 
2 X .796 
— "002 + "020 
2 X .605 
+ '.'0194 
+ " OI 55 
The mean is +"0174, which chances to agree very closely with that derived from the equa¬ 
tions (B). We may, therefore, adopt as the perspective effect observed in the meridian-observa¬ 
tions: A — + "034, with a probable error of perhaps ± "020. 
Vo may also be computed according to the formula of Seeliger (A.N., Bd. 154, s. 67. See also 
previous note on Groomb 1830). For this purpose let us assume: /x 0 = 5"2o; n = "34; l = — 62 km. 
The latter quantity is the result for motion in the line of sight derived at the Yerkes Observatory, in 
kind compliance with the author’s request. This will give us A/xo = + /022, in very fair agreement 
with that derived from meridian-observations. We may assume that this result is entitled to twice 
the weight of A/**, from meridian-observations, and this leads to the value of A/x 0 (the perspective 
effect) finally adopted: 
A/io = + "026 A fj. = + "021 Aju,' = -f "016 
This means that the proper-motion of 61 Cygni is now increasing at about this rate (+ '.'026) per 
century, due to the perspective effect of approach upon the angular motion in a great circle of the 
projected uniform rectilinear motion of the point midway between the two stars. Combining 
this with the effect of orbital motion as determined by Dr. Bergstrand, on the assumption that 
one-half the effect is applicable to each star (and remembering that the effect on “secular variation” 
is twice this amount), we have: 
An 
61 1 Cygni, effect of perspective term -f ''0206 
61 1 Cygni, effect of orbital term -f .0460 
+ '.'067 = + *0056 
61 2 Cygni, effect of perspective term + "0206 
61 2 Cygni, effect of orbital motion — .0460 
— .025 = — *0022 
An' 
+ '.'0158 
~ -QI34 
+ .002 
+ "0158 
+ .0134 
+ .029 
It will be remembered that these quantities were determined directly from the meridian-observa¬ 
tions at the outset (equations A giving one-half these terms). We therefore have the following 
comparison between the values directly determined from the meridian-observations and those 
resulting from adjustment, as above, and adopted: 
Direct 
Adjusted 
61 1 Cygni. 
V = 
+ ''092 
+ ''067 
61 1 Cygni. 
V- 
- .003 
+ .002 
61 2 Cygni. 
A/x = 
- .030 
- .025 
61 2 Cygni. 
A/x' = 
+ .041 
+ .029 
The agreement appears to be fairly satisfactory, and the secular variations and values of A/x and 
A/x', as they would have otherwise appeared in the Catalogue, are corrected for perspective and 
orbital effects as herein adopted. 
Nos. 5832 and 5833. 2 2922. 
For 1900 we have 5^9—6^7, 22", 185° for 2 2922. There is a companion of B, io M 28” 155 0 . 
The two principal stars differ little in right-ascension. The meridian difference agrees badly with 
the result from micrometrical measures. In order to produce better agreement, the solution of the 
equations in right-ascension for No. 5832 (the fainter star, which is of 6^7) has been somewhat 
forced by the rejection of Br’y., Pi., Tay., and Paris«. 
