154 G. H. KNIBBS. 



a result nearly agreeing with the deduction of Herschel two years 

 afterwards} Prevost raised the question as to whether, assuming 

 comets to enter our system from without, more ought not to appear 

 from the advancing than from the opposite quarter. 



(13) Herschel, 1783.— In 1783 Herschel's paper "On the proper 

 motion of the sun and solar system etc.," appeared in the 

 Philosophical Transactions of the Royal Society. 2 Using Dr. 

 Maskelyne's account of the proper motions of a number of stars, 

 he formed two tables, one containing 32 stars; the other 12. He 

 concluded that the solar motion cannot be less than that which 

 the earth has in her annual orbit, and assigned a point near A 

 Herculis, with the coordinates, according to Galloway, (1847), 



R.A. = 257°, D. = +25° 

 as the positive direction of the motion at that date. In the post- 

 script to his paper he says, that out of 44 stars, the apparent 

 movement of which were examined, 32 agree with the hypothesis, 

 and the remaining 12 cannot be accounted for by it. This "must 

 therefore be ascribed to a real motion of the stars themselves, or 

 to some more hidden cause of a still remoter parallax." Herschel's 

 method of solution depended upon the direction of the proper 

 motion of the stars, the intersections of which on the celestial 



1 The Encyclopaedia Britannica 9° Edit, xi., p. 767, the article being 

 by Prof. Pritchard, by implication rather than specific statement credits 

 Herschel with being the author of the idea of solar motion. Although 

 he, Herschel, made no acknowledgments, Prevost's work was probably 

 widely known. Proctor also fails to recognise Prevost's result, see Encyc. 

 Brit, ii., p. 819. It may be mentioned that Galloway writing on 4th 

 March, 1847 says, (Phil. Trans. Reprint, Vol. lxv., p. 83): — '* In the same 

 year (i.e., 1783) in which Sir W. Herschel's paper appeared in the Trans- 

 actions, Prevost communicated the results of a similar inquiry to the 

 Berlin Academy in a memoir which was published in the Nouveaux 

 Memoires of that Society for 1781." It may be further remarked that in 

 1894 in the Abh. d. k. Leop.-Carol. Akad., Bd. 64, p. 215, Kobold says, 

 "William Herschel im Jahre 1783 zuerst das Vorhandensein einer fort- 

 schreitenden Bewegung unseres Sonnensystems darlegte und die Richtung 

 dieser Bewegung bestimmte . . ." ■ That is to say Kobold has failed 

 to notice Prevost's claim to priority. 



2 William Herschel— Phil. Trans. Eeprint, Vol. xv., pp. 397-409. The 

 remainder of the title is: — "With an account of several changes that 

 have happened among the fixed stars since the time of Mr. Flamsteed. 

 See also Berl. Astr, Jahrb. 1787, p. 224. 



