C 230 ] 
'Isroke ofF from the upper edge of tlie Sun, but Ve- 
nus did not affume its circular form till it had de- 
fcendcd into the folar difc, at lead to the diftance, by 
edimation, from the upper edge of the Sun, as de- 
■feribed in fig. 7 . 
Although at the time of the contadls the atmo- 
fphere v/as remarkably clear, yet, as the Sun defend- 
ed towards the horizon, the atmofphere grew more 
and more hazey, fo that the edge of the Sun, as well 
as' the edge of the Planet, began to grow more and 
more tremulous, and caufed the Planet to aflume, in 
appearance, different configurations, refembling fome- 
times a prolate and fometimes an oblate fpheroid, till 
we lod light of the Sun by its being intercepted by a 
dark cloud, or rather fog-bank, fome time before the 
calculated time of Sun-fet. Although thefe lad 
phaenomena are entirely optical deceptions, owing to 
the date of the air at that particular time, or to ho- 
rizontal vapours, yet I beg it may be here very care- 
fully remarked, that, at the times of the contafts, the 
air, as you can bear me witnefs, was perfectly clear and 
favourable, fo that our obfervations were then cer- 
tain, and not fubjedled to any fallacy in vifion. The 
following circumdance is a proof of this affertion. 
The fird warning which I had of the near approach 
of Venus to the Sun’s external edge was, as I have be- 
fore faid, by the fudden appearance of a violent cor- 
rufeation, ebullition, or agitation of the upper edge of 
the Sun, five or fix feconds before the edge of Venus 
broke in upon the Sun ; where alone I obferved the 
violent agitation, the edge on each fide remaining per- 
fedlly quiefeent, as^, 2, fig. i. If this appearance 
had been owing to the date of oiir atmofphere only, 
then 
