On the Motion of the Sun and Solar System. 23/ 



arm of Hercules, by Lyra and a. Arletis. The lOtli in the 

 tbilowing lea" of Hercules, bv Aklebaran and ,3 Tauri. The 

 lllh in the following leg of Hercules, by Aldebaran and a, 

 Andromedae. The 12th in t^e head of Hercules, by Alde- 

 baran and a Arietis. The 13th in the foliowina; arm of 

 Hercules, by Procyon and /3 Tauri. The 14th in the back 

 of Hercules, by Procyon and a Andromedae. And the ] 5th 

 near the following arm of Hercules, is made by Procyon 

 and a Arietis. 



An ari;ument like this, founded upon the most authentic 

 observations, and supported by the strictest calculations, 

 can hardly fail of being convincing. And though only the 

 ten principal apices of the twenty-five that are given have 

 been calculated, the other fifteen may nevertheless be de- 

 pended upon as true to less than one degree of the sphere. 



Changes in the Position of doiMe Stars. 



Wc have lately seen that the alterations in the relative 

 situation of a great number of double stars may be ac- 

 counted for by a parallactic motion. Among the 56 stars 

 which I have given, the changes of more than half of them 

 appear to be of this nature ; and it will certainly be more 

 eligible to ascribe them to the effect of parallax than to ad- 

 mit so many separate motions in the diiTerent stars; espe- 

 cially when it is considered, that if the alterations of the 

 angle of position were owing to a motion of the largest 

 star of each set, the direction of such motions must, in 

 contradiction to all probability, lend nearly to one particu- 

 lar part of the heavens. 



This argument, drawn from the change of the position 

 of double stars, may be considered as deiiving its validity 

 from the same source with the former, namely, the paral- 

 lactic motions of at least 28 more stars, pointing out the 

 same apex of a solar motion by their direction to its oppo- 

 site parallactic centre. 



Incongruity of proper Motions. 



It may be remarked that the proper niolions of the stars, 

 if they were in reality such as they appear to be, would con- 

 lain a certain incongruous mixture of great velocity and 

 extreme slowness. Arcturus alone describes annually an 

 arch of more than two seconds : Aklebaran liardly one-tenth 

 and a quarter of a second : Rigcl little more than one-tenth 

 and a half; even Lyra moves barely three and a ([jarter 

 tenths of a second, while Procyon has almost four times 

 that velocity. Out of 3C stars, wl.ose proper motion vve 

 ~ - ■ * 7 have 



