BIBLIOGRAPHY OF IIERSCHEL's WRITINGS. 531 



Herschel, W.: Synopsis of the Writings of— Continued. 



A. D. Yol. P. 



1783 73 247 On the proper motion of the Sun and Solar System; with an account of 

 several changes that have happened among the fixed stars since the time 

 of Mr. Flamsteed. By William Hekschel, Esq., F. R. S. 

 Read March G, 1783. 



247 Several of the fixed stars have a proper motion. 



248 We may strongly suspect that there is not, in strictness of speaking, 



one fixed star in the heavens, and reasons which I shall adduce 

 wiU render this so obvious that there can hardly remain a doubt of 

 the general motion of all the starry systems, and, consequently, of 

 the solar one among the rest. 



248 Reasons drawn from the theory of attraction evidently oppose every 



idea of absolute rest in any one of the stars, when once it is known 

 that some of thena are in motion. 



249 I will give a general account of the most striking changes which I 



have found to have happened in the heavens since Flamsteed's 

 time. I have now almost finished my third review. 

 249 The first review was made with a Newtonian telescope something less 

 than 7 feet focal length, a power of 222, and an aperture of 4| inches. 

 It extended only to stars of the first, second, third, and fourth mag- 

 nitudes. 



249 Of my second review I have given some account in Phil. Trans., vols. 



LXX, LXXI, LXXII. It was made with an instrument much supe- 

 rior to the other of 85.2 inches focus, 6.2 inches aperture, and 

 power 227. It extended to all the stars of Harris's maps, and the 

 telescopic ones near them as far as the eighth magnitude. The 

 Catalogue of Double Stars and the discovery of the Georgium Sidut 

 were the results of that review. 

 My third review was with the same instrument and aperture, but 



250 with a power of 460. This extended to all the stars of Flam- 

 steed's catalogue, together with every small star about them, to 

 the amount of a great many thousands of stars. 



250 It may be proper to mention that I have many a night, in the course 

 of 11 or 12 hours of observation, carefully and singly examined not 

 less than 400 celestial objects, besides taking measures, and some- 

 times viewing a particular star for half an hour together, with all 

 the various powers. 



250 The particularities attended to in this [third] review were— 



1. The existence of the star itself, sucli as it is given by Flam- 

 steed. 



2. To observe well whether it was single or double, well defined 

 or hazy. 



3. To view and mark dovm its particular color. 



4. To examine all the small stars in the neighborhood as far, at 

 least, as the twelfth magnitude. 



The results of these observations I shall collect under a few general 

 heads, as follows : 

 250 I. Stars that are lost or have undergone some capital change 



since Flamsteed's time. 

 254 II. Stars that have changed their magnitude since Flamsteed's 



time. 

 257 III. Stars newly come to be visible. 



[Several red and garnet stars in this list. ] 



