C 623 ] 
ferved= lB' 31", and if we fuppofe the diameter 
of Venus = 58 // , and the diameter of the Sun 
= 3 1 ', 33", the duration of the egrefs at Rome will 
be found — 18' 18", which duration being lefs than 
the oblerved duration, it, therefore, follows that the 
diameter of Venus was more than 58'' on the day of 
the tranfit, and the duration of the egrefs at Paris, 
obferved by M. de la Lande and P. Clouet, by Mr. 
Mallet and Mr. Bergman at Upfal, by M. Chappe at 
Tobolfk, and by myfelf at Savile-Houfe, prove the 
fame thing. 
Obfervations of the tranfit of Venus and Mercury 
over the Sun have been reckoned by aftronomers 
(if the Sun’s parallax is known) as very proper to 
determine the differences of the longitudes of the 
places of obfervation, even in many refpeds prefera- 
ble to the obfervations of Jupiter’s Satellites. I fhall 
therefore fet down in the following table the longi- 
tudes from Greenwich obfervatory of the different 
places, where the late tranfit of Venus was obferved, 
drawn from the Said obfervations. 
£ ‘ t 
: vol.lii. 4 l 
Places. 
