362 French Kational Institute. 



remains some doubt. The observations of Lacaille, Brad- 

 ley, and Mayer, compared with those which we have men- 

 tioned, and those of the most celebrated modern observers, 

 furnish quantities the extremes of which are 44" and 36" 

 for the present century; theory gives 52"; and this result 

 has been adopted in the solar tables now printing. 



The observation of the equinoxes furnishes the most na- 

 tural and most exact means of knowing the length of the 

 year, the apparent motion of the sun, and the point of the 

 heavens from which the motion of all the stars is reckoned. 

 The five last equinoxes, and more particularly those of the 

 year 13, have fully confirmed the correction of from 4" 

 to 5", made some years ago, in the right ascensions of the 

 stars, which serve as a foundation to all our calculations. 



M. Pictct, correspondent, has communicated to us the 

 observation of an occultation of the Pleiades by the moon, 

 made at the observatory of Geneva. 



An occultation of tt of Scorpio, observed on the 28th of 

 Messidor, year 12, on the sunnnit of Casuelta, a mountain 

 in the kingdom of Valencia, has been found among the 

 papers of M. Mechain, and will appear in the 6th volume 

 of the Memoirs of the Class. This is the last observation 

 made by an astronomer whose premature loss the Institute 

 will long regret. 



There was found also among his papers a series of ob- 

 servations of the comet which he discovered at Barcelona 

 in 1793; it is also printed in the 6th volume of the Me- 

 moirs, and will soon appear. 



M. Humboldt read in one of our sittings a memoir on 

 the longitude of Mexico, the capital of the kingdom of the 

 same name. 



Geographers were little agreed in regard to the position 

 of that important point. The considerable dift'erence which 

 M. Humboldt found between his first observations and the 

 last which were made by htm, induced him to repeat them 

 as often as he could, and bv different methods. The di- 

 stance of the moon from the stars, and the eclipses of se- 

 veral satellites of Jupiter, constantly gave him the same re- 

 sult ; which is incontcstably preferable to all those which 

 had appeared bef(;rc. 



[To be continued.] 



LV. In- 



