72 History of Astronomy for the Year 1S0(?. 



in this atlas SCO stars which M. Messier had occasion to 

 determine, which are in the various volumes of the Academy 

 where there are any details of his observations upon comets; 

 but several of them have not yet been published. 



The Transactions ot the Royal Society of London for 1804 

 contain experiments upon the measurement of small angles, 

 and upon the size of Harding's planet, by Mr. Herschel : 

 he finds a fourth of a second for it, but does not decide 

 whether it is a real diameter or not. 



M. Pigot gives the changes of the star of the fifth magni- 

 tude in Sobieski's Buckler from 61 and -^ to 62 and J- days, 

 which is sometimes scarcely visible. He discovered it in 

 1795 : its position was in right ascension 279° 94-', declina- 

 tion 5" 5G' A, June 179S: its smallest lustre 1796, 17th of 

 September and 13th of November ; J 797, 14th of May and 

 7th of August; 1798, 29th of July and 15th of September ; 

 1799, 7th of August and 11th of October; 1800, 14th of 

 July and 24th of September ; 1801, 9th of August. Ninth 

 magnitude, or invisible. 



Part of these observations were made at Fontainebleau in 

 1803, before the National Institute had procured M. Pigot 

 liberty to return to England. 



Mr. Herschel examines the effect which the displacing of 

 the solar system should produce: he reduces to 1"3" the 

 proper annual movement of six principal stars, supposing 

 that the sun was directed towards 243° 52' of right ascen- 

 sion and 49° 38' of declination. Maskelyne had 5\" for the 

 sum of the six annual movements of these six stars; the 

 surplus is the efiect of the displacement of the sun. 



Mr. Herschel has given some observations upon the sin- 

 gular figure of Saturn. On the 12th of April 1805, with a 

 7-foot telescope which gave an ordinary distinctness, and 

 which magnified 570 times, he found the ring whiter, and 

 Saturn yellowish. 



With a 10-foot telescope, which magnified 527 times, 

 he found the four points of the greatest curvature at 43°; 

 he compares it to a parallelogram, the four corners of which 

 are rounded. 



With 



