Frefioh National hiJlUuie^ 187 



Toufid, fhows us at prefent, by cooti.i?ucd obfervation of her 

 -motion, the fmall .elliptic,ity pf the terreftrial meridian. But 

 we muft okierve that this ellipticitv, which is below y{-^, 

 is too little tp be perceptible -to our fenfcs even if we had an 

 opportunity pf feeing the whole (Ladow of the earth. We 

 l;now, however, that we fee only a very inconfiucrable part 

 ■of it disfigured by the penumbra and inequalities of the lunar 

 diflc ; fo that it would be inipoffible for the nioft accurate eye 

 to difcover, in fo fmall an arc, the leaft diil'erence between 

 Xhe circular curve and that of an eUipfe fo little flattened. 



The obliquity of the ecliptics, wJiich caufes llie different 

 feafons and the difference in the length of the days, is one 

 of the meft interefting ek-mcnts in theoretic and praflical 

 aftronomy. Every year the aftronomcrs examine it with 

 care, by deterwmiiig the fp! 11 iti,al altitude of the fun. Me- 

 chain and Delambi:e, the one at the national and the other 

 at his private obfervatory, have employed in thefe nice ob- 

 servations the fame inftruments which fliey ufed in mea- 

 fpring the magnitude of the earth. Lalande the nephew, 

 and Burckhardt, have made fimilar and iimultanepus ohferv- 

 at,lons at the College de France with inftrumcnts of the like 

 Jcind, but a little larger. Thefe obfervations, whatever may 

 jbe the caufe, do yol feem to be fufceptible of the fame pre- 

 cifion as thoCe which have given the rncafyrc of the meridian 

 by means of the ftar^, but by taking the geceral refuit of 

 more than 600 obfervations, made at Paris both this year 

 and at the fumrncr folftice of the year 7, there \vill jcarcely 

 be a fecond of uncertainty in regard to the real quantity of 

 ;this efleptiaJ element which enters into all our calculations. 



Since ^ve have had occafion to mention the pieafurement 

 ,of the meridian, we fliall here add, that the aftronomers by 

 whom it was performed are now employed in priiatiijg their 

 obfervations, that they may fubmit, to the examination of 

 !the learned in a^ll countries, the prpofs of a laboyr which has 

 already received the fan»^\ion of the deputies of different na- 

 tions affemblcd at Paris laft year. 



We have received a letter from Cifcar and Pedrayes, the 

 Spanifh members of the commiHion of weights and mea- 

 Xures^, by which it appears that his Spanifli majefty has re- 

 ceived 



