14ti COSMOS. 



of the animal motion of the fixed stars due to the translation 

 of the whole solar system in universal space, and to the true 

 proper motion of thu stars. The difficult problem of numer- 

 ically separating these two elements, the true and the appar- 

 ent motion, has been effected by the careful study of the di 

 rection of the motion of certain individual stars, and by the 

 consideration of the fact that, if all the stars were in a state 

 of absolute rest, they would appear perspectively to recede 

 from the point in space toward which the Sun was directing 

 its course. But the ultimate result of this investigation, con- 

 firmed by the calculus of probabilities, is, that our solar sys- 

 tem and the stars both change their places in space. Accord- 

 ing to the admirable 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 direc- 

 tion of the constellation Hercules, and probably, from the 

 combination of the observations made of 537 stars, toward a 

 point lying (at the equinox of 1792-5) at 257 49'-7 R.A., and 

 28 49' 4 7 N.D. It is extremely difficult, in investigations of 

 this nature, to separate the absolute from the relative motion, 

 and to determine 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 rnind to investigate ultimate and highest causes cer- 

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

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

 Stagirite proclaimed that " every thing which is moved must 

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



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

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

 the Annuaire, 1842, p. 388-399 ; Argelander, in Schum., Astron. Nadir., 

 No. 363, 364, 398, and in the treatise Von der eigenen Bewegung dea 

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

 respecting Perseus as the central body of the whole stellar stratum, 

 likewise Otho Struve, in the Bull, de I' Acad.de St. Ptlersb., 1842, t. x., 

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

 recent combination, 261 23' R.A.-J-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 79) stars, the formula 251> a 

 9' R. A. + 34 36' Decl 



