136 COSMOS. 



able researches of Argelander, at Abo, who has extended and 

 more perfectly developed the work begun by William Herschel 

 and Prevost, the Sun moves in the direction of the constella- 

 tion Hercules, and probably, from the combination of the 

 observations made of 537 stars, towards a point lying (at tha 

 equinox of 1792-5) at 257 49', 7 R.A., and 28' 49'-7N.D. 

 It is extremely difficult, -in investigations of this nature, to 

 separate the absolute from the relative motion, and to deter- 

 mine what is alone owing to the solar system. 



If we consider the proper, and not the perspective motions 

 of the stars, we shall find many that appear to be distributed 

 in groups, having an opposite direction ; and facts hitherto 

 observed, do not at any rate render it a necessary assumption, 

 that all parts of our starry stratum, or the whole of the stellar 

 islands filling space, should move round one large unknown, 

 luminous or non-luminous central body. The tendency of the 

 human mind to investigate ultimate and highest causes, cer- 

 tainly inclines the intellectual activity, no less than the imagi- 

 nation of mankind, to adopt such an hypothesis. Even the 

 Stagyrite proclaimed that " everything which is moved must 

 be referable to a motor, and that there would be no end to 

 the concatenation of causes, if there were not one primordial 

 immoveable motor."* 



The manifold translatory changes of the stars, not those 

 produced by the parallaxes at which they are seen from the 

 changing position of the spectator, but the true changes 

 constantly going on in the regions of space, afford us incon- 

 trovertible evidence of the dominion of the laivs of attraction, 

 in the remotest regions of space, beyond the limits of our 



* Regarding the motion of the solar system, according to Bradley, 

 Tobias Mayer, Lambert, Lalande, and William Herschel, see Arago, in the 

 Annuaire, 1842, pp. 388-399 ; Argelander, in Schum. Astron. Nachr*, 

 Nr. 363, 364, 398. and in the treatise Von der eigenen Beweyung des 

 Sonnensystems (On the proper motion of the Solar System), 1837, s. 43, 

 respecting Perseus as the central body of the whole stellar stratum ; like- 

 wise, Otho Struve, in the Bull, de I'Acad. de St. Petersb., 1842, t. x. 

 No. 9, pp. 137-139. The last-named astronomer has found, by a more 

 recent combination, 261 23' R.A. + 37 36' Decl. for the direction of 

 the Sun's motion, and taking the mean of his own results with that of 

 Argelander, we have, by a combination of 797 stars, the formula, 259 9' 

 R.A. -f 34 36' Decl. 



t Aristot., de Ccelo, iii. 2, p. 301, Bekker; Pnys., viii. 5, p. 256. 



