TOL. LH.] PHILOSOPHICAL TRANSACTIONS. SfiS 



round about Venus, which followed her like a luminous atmosphere, more or 

 less lively, according as the air was more or less clear : its extent altered in the 

 same manner; Nor was it well terminated, throwing out as it were some feeble 

 rays on all sides. 



As for the last contact, he would not be surprized if there was a difference of 

 10' or 12* between 2 observers, who had instruments and eyes of equal good- 

 ness, and made their observations by the same clock; so difficult a matter he 

 thinks it to determine the exact moment. But for the first, he certainly believes 

 that the difference could scarcely amount to more than 1" under the same cir- 

 cumstances. 



However, the following are greater differences for the first contact than were 

 expected. 

 Mr. Maraldi observed . . 1st contact at 8** 28"" 42' : 2d contact at 8*^46™ 54* 



L'Abbe de la Caille 8 28 37 : 



Mr. Messier observed 8 28 27 : 



Pere Noel 8 28 27 



Mr. Fouchy 



Mr. Ferner 8 28 29 : 



Mr. de la Lande 8 28 25 : 



Considering the quickness with which the luminous thread of the sun's limb 

 was broken, by the approach of Venus's limb, Mr. F. has sufficient foundation 

 for supposing that almost all the difference between these observations, for the 

 first contact, depends solely on the different goodness of the instruments, and 

 particularly the measuring the time. It seems to him that the observations of 

 the last contact agree, for the same reasons that the others differ from each 

 other. 



P. S. I hope Mons. Baudouin's pieces upon the satellite of Venus is come to 

 your hands. Notwithstanding all the care taken here to discover this satellite 

 on the disk of the sun, on the 6th past, we could see nothing of it. 



XLII. Observations on the same Transit of Venus made at Constantinople. By 

 James Porter , Esq., his Majesty^s Ambassador there, p. 226. 

 The sun rises at Stanbole, Constantinople, the 6th June, 4*" 32*". Venus 

 entered the sun much earlier, and is supposed to have entered its disk above an 

 hour and more, when seen at its rising here. Venus, at emerging out of the 

 sun's disk, touched the interior limb of the sun s.e. at lO'' 15™. Emerged to- 

 tally the point of contact, at its going out, at 10^ 32"* 20'. Observed with a 

 Hadley s reflector 18 inches only, and a good pendulum, with seconds. 



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