tun 



272 SOLAR MOTION; 



Investigation ^^^ causc, which renders at least some part of their real 

 of the proper rnotion inyisible to us. But when a solar motion is intro- 

 mo ion o duced, tlie parallax arising from that cause will com- 

 pletely account for the singularity of these slow motions. 

 If the foregoing argument proves the expediency of a 

 solar motion, its direction is no less evidently pointed 

 out by it. For if the parallax occasioned by the motion 

 of the sun is to explain the appearances that have been 

 remarked, it will follow, that a direction in opposition to 

 the motion of Arcturus, will answer that end in the most 

 satisfactory martner. That compression, for instance, 

 which has been remarked in the motions of the stars 

 moving toward the solar apex in Fig. 3, and which is so % 

 completely accounted for by a parallactic motion arising 

 from the motion of the sun, points out the direction in 

 which the sun should move, in order to produce this re- 

 quired parallactic motion. The expansion of the mo- 

 tions that are in opposition to the former is evidently 

 owing to the same parallactic motions, which in this di- 

 rection unite with the real motions of the stars ; and as, 

 in the former case, the observed motions are the differ- 

 ences between the parallactic and real motions, so here 

 they are the sum o" them. 



The remark that stars having a side motion, are not 

 affected by the cause of the compression or expansion, 

 which acts upon the rest, is perfectly explained ; for a 

 parallactic motion, in the direction of the motion of Arc- 

 turus, can have no effect in lengthening or shortening the 

 perpendicular distance to which a star may move in a 

 side direction. 



I have only to add, that the small velocities of Rigel, ^ 

 a Orionis, Spica, and Antares, in Fig. 4, as well as the 

 great velocities of Arcturus, Procyon, and Sirius, point 

 out the same apex which in the first part of this Paper 

 has already been established by more extended compu- 

 tations. 



The case of Aldebaran, though seemingly contrary to 

 what has been shown, confirms the same conclusions. , 

 This will appear by considering that a star, moving to- 

 ward the solar apex with a greater real motion than its 

 parallactic one^ must continue apparently to move in its 



real 



