THE SUN'S MOTION IN SPACE. 157 



of the solar motion." 1 He gave — p. 233 — its value calculated for 

 the distance of Sirius as 1*"117, and remarked on the possibility 

 of the sun forming a unit in a very extensive stellar system. He 

 also pointed out that it could not possibly be one member of a 

 binary combination, as for example, with Arcturus. It may be 

 mentioned further, that he assigned the following values for the 

 relative distances of Sirius, Arcturus, Oapella, a Lyrse, Aldebaran 

 and Procyon, viz., 1, 1-2, 1-25, 1*3, 14 and 1*4. 



(21) Prevost, 1808.— In 1808 a further attempt of Prevost's to 

 deduce the solar motion appeared in the Bibliotheque brittanique. 2 



(22) Burkhardt, 1809. — Herschel's scheme for deducing the 

 solar motion in space was objected to by Burkhardt in a memoir 

 published in the Oonnaissance des Temps of 1809. Burkhardt 

 gave formulae for the solution of this problem, and applied these 

 to several of the stars in Maskelyne's catalogue. The discrepancy 

 among the results led him to conclude that we were not in pos- 

 session of sufficient information to justify any deduction. His 

 contention that the Herschelian method of solution, based on the 

 assumption that the sum of the true proper motions of the stars 

 must be a minimum, was equivalent to supposing that the stars 

 are inclined to rest rather than to motion, shews a singular mis- 

 apprehension of the nature of the problem. 



(22a) Gauss, 1810? — According to Ludwig Struve, 3 Gauss 

 assigned the values 



RA. = 259'°2, D.= +30-°8 

 for the direction of the solar motion. No reference is given so 

 that the date is uncertain. 



(23) Bessel, 1818. — In 1818 it was again, this time more 

 elaborately, investigated by Bessel in the 12th section of the 

 Fundamenla astronomice. After discussing the proper motions of 

 71 stars, each being not less than 0*"5 annually, and finding that 



1 Phil. Trans. Reprint Vol. xxiv., pp. 205 - 237. 



2 t. xxxix., pp. 192-210, 1808. 



3 Mem. Acad. St. Petersb., 7me serie, t. xxxv., (3). 



