90 
MR. GALLOWAY ON THE PROPER 
ning of 1830), Lundahl found 147 not included in Argelander’s investigation, whose 
proper motions appeared to be not less than 0"-09 of space annually. Having first 
recomputed the places of those stars with a more exact value of the precession, and 
applied to Pond’s observations the correction necessary to render them strictly com- 
parable with those of Argelander, Lundahl assumed the apex of the sun’s motion 
to be situated at the point indicated by Argelander’s investigation, and calculated 
the value of for each star on this assumption. Comparing the directions thus 
obtained with those of the apparent motions, and forming the equations of condition 
according to the method of Argelander, the resulting values of the right ascension 
and declination of Q were found to be 
A = 252° 24'-4±5° 25'*3 ; D= + 14° 26'- 1 +4° 29'-3. 
This result differs from that of Argelander more than 8° in right ascension, and 
about 17 ° in declination; and the corrections of the assumed values are far beyond 
the limits of the probable errors assigned by Argelander. By reason, however, of 
its smaller weight, it does not, when combined with the former determinations, 
materially alter the probable situation of the point Q. Combining it with the results 
of each of his three classes, with due regard to their relative weights, Argelander 
gives the following values of the coordinates of Q as the most probable result of the 
whole of the observations : — 
A=257° 49'7±2° 49'-2 ; D=+28° 49'7+l° 59'-8. 
A still more recent attempt to assign the position of the apex of the sun’s proper 
motion has been made by Otto Struve, the results of which are given in a paper 
published in the Petersburg Memoirs (tome 5) for 1842. This investigation is 
grounded on the proper motions of about 400 stars, as determined by a comparison 
of their mean places in 1735, according to Bessel’s catalogue, with their positions in 
1825 deduced from observations made at the Borpat Observatory. Of the whole 
number of stars employed, only 134 are included among those from which Argelan- 
der’s result was deduced, so that about 260 additional proper motions are brought 
to bear on the hypothesis. The mode of investigation is different in several respects 
from that which has been described. Assuming the direction of the sun’s proper 
motion to be determined, the proper motions indicated by the comparison of the 
catalogues are manifestly functions of the constant of precession used in reducing 
Bradley’s places to 1825, and of the quantity of the solar motion. From the equa- 
tions of condition furnished by the observed variations of right ascension and decli- 
nation, be determines the precession and the angular motion of the sun (which, as 
seen from the mean distance of stars of the first magnitude, he finds to be 0"'339 in 
a year, with a probable error of 0"*025), and having substituted these values in the 
equations of condition, be employs the residual errors in forming a new system of 
equations which serve to determine dA and dD, the corrections in right ascension 
and declination of the assumed direction of the solar motion. The directions of the 
