82 PEOCEEDINGS OF THE AMERICAN ACADEMY 



IV. 



ON THE SOLAR MOTION IN SPACE. 



By Tkuman Henrt Safford. 



Presented, Nov. 11, 1874. 



I. It was first suggested by Sir W. Herschel that the sun with its 

 phxnets is moving towards the constellation Hercules. That the sun 

 moves seems to be a necessary consequence of the law of universal 

 gravitation ; but in what direction was not noticed until Herschel 

 pointed it out, upon rather imperfect evidence. 



Bessel doubted that the evidence proved any thing certain with refer- 

 ence to this motion of the sun, but began the collection of more facts. 

 This was continued by Argelander, who first fairly solved the problem, 

 by Pond, the Struves, and others ; and discussions by Lundahl, O. 

 Struve, Galloway, and Miidler agreed in method with Argelander, 

 and their results were substantially in accordance with his and with 

 Herschel's. 



The following are the various right ascensions and declinations of the 

 points towards which the solar motion is directed, according to these 

 various authorities : — 



Herschel .... ^ = 257° i) = + 25° ) 



= 245 52'.5 4- 49 38' ) 



Argelander ... = 259 51. 8 + 32 29.1 



Lundahl .... =25224.4 4-1426.1 



O. Struve .... = 261 28. 1 +37 35.7 



Galloway .... = 257 4. 4 +34 18.1 



Of the four latest determinations, that of Argelander is based upon 

 the most stars. It is true that he finally employed but 390 ; but these 

 are selected from a larger list of 560, and these again from the 3,222 

 of the Fundamenta Astronomias, as giving certain evidence of proper 

 motion: while .0. Struve employed 392 in all. 



