MOTION OF THE SOLAR SYSTEM. 
89 
being entirely unknown, no account can be taken of it excepting upon some assump- 
tion more or less arbitrary. Argelander assumes as a probable hypothesis, that 
those stars which have the largest proper motions are the nearest to our system, and 
introduces the condition of relative proximity by dividing the stars upon which his 
calculation was made into three classes, and giving different weights to the equations 
belonging to the different classes, all the stars in the same class being assumed to be 
at the same mean distance. The first class contained twenty-one stars, having proper 
motions exceeding one second of arc annually ; the second contained fifty stars whose 
annual proper motions are between 1"’0 and 0" - 5 ; and the third the remaining 319 
stars, the annual proper motions of which were included between 0"‘5 and 0"*1. The 
partial results deduced from each class presented a nearer agreement than was, per- 
haps, to be anticipated from the nature of the question. In giving an account of his 
memoir in No. 363 of the Astronomische Nachrichten, Argelander corrects some 
errors of calculation which had escaped detection in the original paper, and states 
the most probable values (with their probable errors) of the right ascension and 
declination of Q, as resulting from the combination of the whole of the equations of 
condition, to be as follows : — 
A = 259° 47'-6±3° 18'*6, D =+32° 29'-5±2° 13'-5, 
for 1792'5 (the mean epoch of the catalogues), or 
A=259°5l'-8, D=+32° 29'T, 
when reduced to the beginning of 1800. 
This result differs very considerably from that which was obtained by Sir W. 
Herschel in his paper of 1805, viz. A=245° 52' 30", D= +49° 38', but approximates 
nearly to the determination in the paper of 1783 ; the difference from the latter being 
less than 3° in right ascension, and about 7|° in declination. 
In order to give an idea of the probable accuracy of this result, Argelander 
deduces the following conclusions. If with the point Q thus found as a centre, and 
a radius containing 3° 45'*7, a circle be described on the sphere, the wager is 1 to 
1 that the sun’s motion is directed to some point within this circle ; 14 to 3 that it 
is directed to some point within a circle having the same centre and a radius of 
7° 3l'*4 ; 89 to 4 that it is directed to a point within a circle having the same centre 
and a radius of 11° 1 7'* 1 ; 142 to 1 that the point will be within a circle having the 
same centre and a radius containing 15° 2' 8 ; and if we increase the radius to 
18° 48' # 5, the wager will be more than 1341 to 1 that the point Q will lie somewhere 
within that circle. 
In No. 398 of the Astronomische Nachrichten, Argelander returns to the subject 
a third time, and gives another determination of the direction of the solar motion, 
calculated by Lundahl from a different set of stars. The Abo catalogue does not 
contain the whole of Bradley’s stars given in the Fundamenta Astronomiae, and on 
comparing the latter work with Pond’s catalogue of 1 1 12 stars (reduced to the begin- 
MDCCCXLVII. N 
