On the Motion of the Sun and Solar Si/stem. 235 



per motions of the principal stars ; for these, if the sun is 

 not at rest, must either be entirely parallactic, or at least 

 composed of real and parallactic motions ; in the latter case 

 they will fall under the denomination of one of the three 

 motions we have defined, namely s a, the apparent motion 

 of the star. 



In consequence of this principle I have delineated the 

 meeting of the arches arising from a calculation of the 

 proper motions of the 36 stars in Dr. Maskelyne's cata- 

 logue, on a celestial globe; and, as all great circles of a 

 sphere intersect each other in two opposite points, it will be 

 necessary to distinguish them both : for, if the sun moves 

 to one of them, it may be called the apex of its motion; 

 and as the stars will thcii have a parallactic motion to the 

 opposite one, the appellation of a parallactic centre may 

 very properly be given to it. Thn latter falling into the 

 southern hemisphere, among constellations not visible to 

 us, I shall onlv mention their opposite intersections ; and 

 of these I find no less than ten that are made by stars of the 

 first ma2;nitude, in a very limited part of the heavens, about 

 the constellation of Hercules. Upon all the remaining sur- 

 face of the same globe there is not the least appearance of 

 tiny other than a promiscuous situation of intersections ; and 

 of these only a single one is made by arches of principal 

 stars. 



The ten intersecting points made by the brightest stars 

 are as follows : The 1st is by Sirius and Arcturus, in the 

 mouth of the Dragon.- The 2d by Sirius and Capella, near 

 the following hand of Hercules. The 3d by Sirius and 

 Lyra, between the hand and knee of Hercules. The 4th 

 by Sirius and Aldebaran, in the following leg of Hercules. 

 The 3th by Arcturus and Capella, north of the preceding 

 wing of the Swan. The 0th by Arcturus and Aldebaran, 

 in the neck of the Dragon. The 7th by Arcturus and 

 Procvon, in the preceding foot of Hercules. The 8th by 

 Capella and Procyon, south of the following hand of Her- 

 cules. The 9th by Lvra and Procyon, preceding the fol- 

 lowing shoulder of Hercules. And the 10th is made by 

 Aldebaran and Procyon^ in the breast of Hercules. 



The 



