Htftory of AJlronomy for the Year 1 800, 7 



formulae for a greater number of equations than are in the 

 tables above mentioned. He propoies publidiing a hiftory 

 of the integral calculus* 



De Laplace is employed alfo on the theory of the moon ; 

 and we have reafon to expe(Sl from him new and valuable 

 things. He has given a memoir on the fatellites of Saturn 

 and thofe of Herfchcl's planet. He has fhown that the laft 

 fatellite of Saturn has a conftant inclination, and he deter- 

 mines the motion of its nodes. New confiderations in regard 

 to thofe of Herfchel, induce him to think that ihis planet 

 may maintain in the fame plane its firit five fatellites ; but 

 that the cafe, in all probability, is not the fame in regard to 

 the fixth. 



Vidal continues to fend us rare observations on Mercury, 

 which he has made at Mirepoix. He is our valuable Her- 

 mophilus, who fees Mercury every day, and who fees him 

 even at the diftance of fome minutes from the fun. This 

 aftonifhing obferver has already fent me more than 500 ob- 

 fervations of Mercury. He has done more in this refpeiSt 

 than all the other atlronomers in the world. At Mirepoix, 

 perhaps, it is not known that fuch a man exifts in thai 

 fmall town, but we fliall proclaim it to the univerfe and to 

 pofterity. 



The minifter appointed him dire6lor of the national ob- 

 fervatory at Thouloufe on the 21ft of April laft, and a better 

 choice could not have been made. 



- Michel Le Fran9ai8-Lalande, my nephew, finding that' 

 Mars was the only planet the tables of which were ftill 

 liable to errors of one or two minutes, has re-calculatcd all 

 the obfervations of that planet. Burckhardt has re-calcu- 

 lated the perturbations which I formerly ^ave in the memoirs 

 of the Academy of Sciences, and which Schubert and Oriani 

 afterwards calculated ; and Le Fran^ais has prefented to the 

 Inftitute new tables of Mars in tenths of a fccond, and which 

 give us reafon to apprehend no more than a few feconds of 

 error. They are now printing in the ConnoiJJance dcs Temps 

 for the year 32 ; and the oppofition of the 8th of November 

 laft has confirmed the corre6lnefs of thefe tables. An exact 

 obfervation of the 13th, gave an error of only 15 feconds in 



lons.itude 



