SOLAR AND STELLAR PROPER MOTIONS. 
151 
analytical method of determining the direction of the solar 
motion. Employing the same data used by Herschel in 
1805, he found the results from the different stars so discord¬ 
ant that he concluded that the material then at hand was 
insufficient to fix the direction of the solar translation. 
In his Fundamenta Astronomise, published in 1818, Bes¬ 
sel 12 gave a portion of his discussion of alleged proper mo¬ 
tions, from which he inferred that the data did not warrant 
Herschel’s conclusions in regard to the position of the apex 
of the sun’s motion. It appeared to him that the variable 
apparent stellar motions could not be explained by any gen¬ 
eral law. 
In 1837, Argelander 13 presented to the Imperial Academy 
of Sciences of St. Petersburg, a very complete mathematical 
determination of the position of the apex of the solar motion. 
He used the proper motions derived from a larger number of 
stars than had been used by any of his predecessors, and divided 
them into three classes. In the first class he had 21 stars 
whose observed proper motions were greater than 1".0; in 
the second class 50 stars with proper motions between 0".5 
and 1".0; and in the third class 319 stars with proper mo¬ 
tions between 0".l and 0".5. 
He found the right ascension of the point towards which 
the solar motion is directed, to be 257° 47'.6 and its declina¬ 
tion + 32° 29'.5, or very near the sixth magnitude star 
Piazzi XVII, 143. 
This investigation settled beyond all doubt the reality of the 
motion of the solar system in space, and also attested the ac¬ 
curacy of the adopted direction of that motion. In 1840, Lun- 
dahl 14 published the results of his mathematical discussion 
based upon the proper motions derived from Pond’s catalogue 
of 1112 stars, from which he found the position of the solar 
apex to be in R. A. 260° 51' and in Dec. +31° 17'. Combining 
12 Bessel, F. W. Fundamenta Astronomise, 1818, sect. 12; 808. 
13 Argelander, F. 'W. A. Memoires presentes a PAcademie Imp. des 
Sciences de St. Petersbourg par divers savans. Tome III. 
14 Lundahl, G. Astronomische Nachrichten, 898; 209. 
17—Bull. Phil. Soc., Wash., Vol. 11. 
