236 SOLAtt MOTION. 



Investigation Aldebaran, which hare at negative sign prefixed to thoit* 

 »iotion of^the ^^"^^ motions when the solar motioti is I'^O are afl'ected 

 «un. differently from Arcturus, Siriiis, and Procyon, which 



have a positive sign ; and that even the motions of the 

 two last become negative when the solar motion is in- 

 creased beyond a certain point. It may be easily under- 

 stood that tlie motion of Arcturus itself would become 

 negative were -we to increase the solar motion till the 

 parallactic motion of this star should exceed its apparent 

 motion. 



From these considerations it appears, that a certain 

 equallization, or approach to equality may be obtained 

 between the motions of the stars, or between that of the 

 sun and any one of them, selected for the purpose; for 

 instance, the motions of Arcturus and Aldebaran being 

 contrary to each other, may be made perfectly equal by 

 supposing the sun's annual motion to be l'',S59^5. For 

 then we shall have the real annual motion of Arcturus 

 towards the parallactic centre l",09 1 , and that of Aldeba- 

 ran towards the opposite part of the heavens, in which 

 the solar apex is placed, will be l",091 likewise 5 the 

 first in a direction 550 29' 39" south-preceding, the latter 

 88<^ 16' 31" north-following their respective parallels; 

 and a composition of these motions with the parallactic 

 ones arising from the given solar motion, will produce 

 the apparent motions of these stars which have been es- 

 tablished by observation. But since Arcturus, by the 

 hypothesis which has been adopted in Table VIII. is a 

 nearer star than Aldebaran, the velocities of the real mo- 

 tions, describing these equal arches will be 1309109 in the 

 former and 1527780 in the latter. And it is not the 

 arches but these velocities that must be equalized. 

 Therefore, in order to have this required equality, let the 

 solar motion be 1",718865 then will a velocity of 1399478 

 in Arcturus, and 1399842 in Aldebaran, which are suf- 

 ficiently equal, occasion such angular real motions in the 

 two stars as will bring them, when compounded with 

 their parallactic motions, to the apparent places in which 

 we $nd them by observation. 



Before we proceed, it will be proper to obviate sL re- 

 mark that may be made against this way of equalization 



01' 



