^M, DE Zacii*s Afirtnomlcal Ohfervji'ioni, T'5'i. 



SIR, Lyons, >:f,y 4, i)3j. 



Lately 1 recelveJ from the Obfervatory at Marlllllcs.the 

 oblervatlon of the tranfit of Mercury, which happened the izrii 

 Nov. 1:82. The fkv not beuijr verv favourable, only the two in- 

 tcrnalcontafls were obferved ; the firfl: internal conta£l was oh- 

 iervcd by M. St. Jacques df, Sylvabelle, at 3 h. 18^ 30'^^ 

 apparent time ; the lafl internal contact by M. St. Jacques, at 

 4h. 33^ 16'"; by M. Bernard, his Adjunclns, at 4 h. 29' i^'\ 

 The neareH- diftances of Mercury's limb to that of the fun in. 

 the northern part of its diik were at 



h. 



parts of the micrometer. 



The apparent diameter of the fun was 2174 parts of this mi- 

 crometer : I fuppofe the before-mentioned 2174 parts— 32-^ 

 26^^,9. I conclude farther, by the obfervations, the middle of 

 the tranfit at 3 h. 54^ ''/\'^S-> ^^^J^r^^s I fix, by interpolation, 

 the diftances of the limbs at 3h. 54^ 7^^,2:5 = 35^'', 6 ; I have 

 therefore femi-diameter of the fun =: 16' 13^,4-35^^,6 =: 

 15^ 37'''?8 + femi-dlameter of Mercury = 6^^ := 15^ 43'^8 ^rtO'the 

 leaft diflance of centers of the fun and Mercury. By M. de. 

 la Lande's tables it is 15'' 42'',. only a ditFerence of \'\%. 



M. Wallgt at Paris has obferved this tranfit at the Royah 

 Obfervatory,. 



Firfl: external con ta:f): 2 56 28 



Firfl internal conta(ft 3 '^ 3. 



Second - - 4 ^7 18 



Second external - 4, 22 53. 

 5.^ lonl/- 



