Progress of Astronomy during the Year 1879. 467 
A new determination of the parallax of 61 Cygni, by Dr. Ball, 
forms the subject of the next paper. This determination differs 
from others of the same object in one particular, viz., that the 
preceding star instead of the following one has been observed. 
The method of observation used is that of differences of declina- 
tion, and the observations furnished thirty-six equations of con- 
dition for the determination of the four unknown quantities on 
which the apparent difference of declination depends, these contain 
the results of observations made on thirty-five different nights 
between July 3, 1877, and June 1, 1878. A detailed account is 
given of the operations by which the observations were cleared 
from the effects of refraction, precession, aberration, nutation, and 
proper motion. The resulting parallax is 0-465, in pretty good 
accordance with the results of Bessel (last three months 0°54), 
Struve (0°51), and Auwers (0'"56). 
A third paper, also by Dr. Ball, describes the first results of a 
series of reconnoitring observations in search of stars with a large 
annual parallax. These observations are only intended to reveal 
large parallaxes (07 or more), and each object is only observed 
twice a year with six months interval, when it is 90° from the 
sun, and at the two extremities of the major axis of the paral- 
lactic ellipse. The paper contains the discussion of the observations 
of forty-two objects, chiefly red and variable stars. The result is 
that in almost every case is the parallax certainly less than 1”, and 
most probably does not exceed 05. These objects will therefore 
not be observed any further, but it is Dr. Ball’s intention to 
continue this kind of observations until about 1200 objects have 
been examined ; his working list contains red and variable stars, 
stars with a large proper motion, and others chosen for various 
reasons, nearly all north of the 30° parallel. 
According to Herr Geelmuyden, of Christiania, the star Arg. 
Oeltzen, 11677, has a perceptible parallax (A.N. 2287). This star 
of the ninth magnitude has a propermotion of -- 0°507 and + 0°21. 
The resulting parallax, 0-27 from measures of Aa and 0'"24 from 
measures of Aé with a star preceding, is only considered provisional, 
but the subject seems worth followiag up. 
Scien. Proc, R.D.S, Vou. 1., Pr. vi 4 5 OP 
