THE SUN'S MOTION IN SPACE. 153 



system, this group round still another centre, and so on. How- 

 ever wild such surmises may now appear they were efficient in 

 stimulating inquiry as to the nature of the evidence of general 

 stellar movement, and of course cannot even now be proved to be 

 utterly false. 



(10) Michell. 1767. — Six years later, an "inquiry into the 

 probable parallax and magnitude of the fixed stars, from the 

 quantity of light which they afford us, and the particular circum- 

 stances of their situation," was sent forth by Michell. 1 In this it 

 was argued that the apparent change of place might be due to 

 either solar or stellar motion, or to both combined, 2 and Michell 

 observed that if the annual parallax of a few of the stars should 

 at any time be ascertained, it might serve as a basis for the calcu- 

 lation of the distances of others. He regarded the sun as merely 

 one member of a great system of stars. 



(11) Lalande, 1776. — Lalande 3 in 1776, applied, to the theory 

 of the sun's motion, the somewhat fanciful doctrine, that a force, 

 causing a revolution of a body about its centre, impelled the body 

 onwards through space. He did not however, contribute anything 

 of moment to the question. 



(12) Prevost, 1781. — The first attempt to definitely calculate 

 the direction of the solar motion was, I believe, made in Germany 

 by Prevost, and published in the Nouveaux Memoires of the Berlin 

 Academy for 1781. 4 Prevost's investigation, based upon the 

 proper motions in Tobias Mayer's table, led him to an opposite 

 conclusion to that drawn by Mayer himself; for he, Prevost, was 

 satisfied, contrary to Mayer's view, that the table afforded distinct 

 indication of motion, and selecting 26 stars for discussion; he fixed 

 the coordinates of the point towards which the sun must, from 

 their apparent motions, be supposed to really move, as 



R.A. = 230°, D. = +25° 



1 Rev, John Michell, b.d., f.r.s. — Phil. Trans. Reprint Vol. xn., pp. 

 423 - 440, 1767. 2 p. 433. 

 3 Mem. l'Acad. Sc, Paris 1776. 

 i p. 418. See also Berl. Astr. Jahrb. 1786, 259. 



