■33 • ^ Schtittfc NewSy ^c, 



« 

 number of known genera. The fecond work of Vauquelin coiififts of a feries of experl- 



inents, made in order to analyfe the fap of the elm, the beech, the maple, the birch, and the 



chefnut-trce. 



The fame chemifl: has alfo publifhed a work, entitled, Manuel de I'EfTayeur, or a treatife 

 on the art of affaying gold and filver by the cupel, and the proccfs of parting ; containing 

 every thing which is abfolutely nec^ffary to be known in the praitifing that art. Cit. De- 

 lambre has publifhed his roethad. of computing the arc of the meridian from the late meafure- 

 ments in France. 



The tranllt of Mercury over the fun's difc, which happened on the i8th of Flcreal, year 

 7 (29 May, 1798)5 and lafted fjven hours twenty-four minutes and fifty feconds, 'was ob- 

 ferved by Cir. Meffier, during the whole time of the paflage. The great number of accurate 

 obfervations wlixh this aflronomer made, are recorded in a memoir read at one of the or- 

 <jinary fittings. Mercury appeared perfedtly round, and furrounded by a very fenfibl; at- 

 mofphere, when the light of the ilm was moderated by flight clouds. Cit. Jeaurat obferved 

 the fame phenomenon, and read a memoir containing his obfervations. 



Cit. Caffini, afiociated member, gave a defcription of a new compafs for determining the 

 declination of the magnetic needle \\ ith the greateft preciflon. The needle of his compafies is 

 fufperided by wire or thread according to the method of Coulomb ; and Cit. Caffini, by adapt- 

 ing a telefcope, and an entire movable circle, obtains an inftrument with which an angle 

 may be meafured with the fame degree of cxadtnefs, as by the repeating circle of Borda. 

 According to the obfervations made with this compafs on the platform of the National Ob- 

 fcrvatory, it is proved that the bars of iron, which enter inio the conftruSion of the edifice, 

 render all the obfervations of the needle defeitive : and by other experiments made at Mont- 

 martre, far from all foreign influence, Cit. CaflJini has fettled the declination of the magnetic 

 needle at 22" 49' on the 5th Prairial, in the year i. 



Van Swinden gave an account to the clafs of mathematical and phyfical fciences, of the 

 operations for determining the length of the meridian, and that of the -metre. Cit. Tralles 

 made a report of the operations relative to fixing the unity of weight. 



The ftandards, in platina, of the metre and kilogramme, and the general r 'port of the whole 

 operation by Van Swinden, were prefented to the Icgiflative body, and depofiied among the 

 national archives. 



Note concerning the Devahk, or Cubit of the Nihmetre. 



This meafure, which is of the higheft antiquity, is valued at 20,544 inches, in the Hif- 

 tory of Modern Aftronomy, tome II. p. 146 (I fuppofe of Lalandc), which amounts to 

 0,5559 metres. Cit. Di Ion, examiner of weights and meafures, having procured a new 

 copy of the cubit of the nilometre, very carefully made in the worklhop of the widow Len- 

 nel, after another copy, taken immediately upon the fpot by ^a learned Englifhman, found it 

 coirtfpond with 0,5355 metres, a refalt falling fhort of the fBrmer determination by 0,0004 



only. 



