PHILOSOPHICAL TRANSACTIONS. 



405 



Etoiles. chan S- d ' arc - Chang, de 



VOL. LXXIII.] 



on too slight a foundation, he observes, that the concurrence of those 7 princi- 

 pal stars cannot but give some value to an hypothesis that will simplify the celestial 

 motions in general. We know that the sun, at the distance of a fixed star, 

 would appear like one of them ; and from analogy we conclude the stars to be 

 suns. Now, since the apparent motions of these 7 stars may be accounted for, 

 either by supposing them to move just in the manner they appear to do, or else 

 by supposing the sun alone to have a motion in a direction, somehow not far 

 from that above assigned to it, we are no more authorized to suppose the 

 sun at rest, than we should be to deny the diurnal motion of the earth, except in 

 this respect, that the proofs of the latter are very numerous, whereas the former 

 rests only on a few though capital testimonies. But to proceed : I have only 

 mentioned the motions of those 7 principal stars, says Mr. H. as being the most 

 noticed and best ascertained of all ; I will now adduce a further confirmation of 

 the same from other stars. 



M. de la Lande gives the annexed table of the 

 proper motion of 12 stars, both in right ascen- 

 sion and declination, in 50 years, in his Astron. 

 torn. 4, p. 685. Fig. 11 represents them pro- 

 jected on the plane of the equator. They are 

 all in the northern hemisphere, except Sirius, 

 which must be supposed to be viewed in the con- 

 cave part of the opposite half of the globe, while 

 the rest are drawn on the convex surface. Re- 

 gulus being added to that number, and Castor 

 being double, we have 14 stars. Every star's 

 motion, except Regulus, is assigned in declination as well as in right ascension, 

 so that we have no less than 27 motions given to account for. Now, by as- 

 suming a point somewhere near A Herculis, and supposing the sun to have a pro- 

 per motion towards that part of the heaven, we shall satisfy 22 of these motions. 

 For (3 Cygni, * Aquilae, c Cygni, y Piscium, y Arietis, and Aldebaran, ought on 

 the supposed motion of the sun, to have an apparent progression, according to 

 the hour circle 18, 1Q, 20, &c. or to increase in right ascension, while Arcturus, 

 Regulus, the two stars of « Geminorum, Pollux, Procyon, Sirius, and y Ge- 

 minorum, should apparently go back in the order l6, 15, \A, &c. of the hour 

 circle, so as to decrease in right ascension ; but according to M. de la Lande's 

 table, excepting (3 Cygni and y Arietis, all these motions really take place. With 

 regard to the change of declination, we see that every star in the table should go 

 towards the south , and here we find but 3 exceptions, in (3 and f Cygni, and y 

 Piscium ; so that on the whole we have onlv 5 deviations out of 27 known mo- 



