[ 357 ] 
have been feen, but which I could not dif- 
cover. 
It had been thought by fome, that Venus’s cir- 
cumference might probably be feen, in part at lead:, 
before (he entered at all upon the Sun, by means of 
the illumination of her atmofphere by the Sun 5 I 
therefore looked out diligently for fuch an appearance, 
but could fee no fuch thing. 
I was alfo attentive to fee if any penumbra or 
dufky fhade preceded Venus’s firft impreffion on the 
Sun at the external contact, fuch a phenomenon 
having been obferved by the Rev. Mr. Hirft, F. R. S. 
at the former tranfit of Venus, in 1761, which he 
obferved with much care and diligence at Madrafs, in 
the Eaft-Indies; but I could not difeern the leaf! ap- 
pearance of that kind. I would not, however, be 
therefore thought to call in queftion either Mr. 
Hirft’s difeernment or fidelity; as I am fendble that 
the tremors of the limbs of the Sun and Venus, oc- 
cafioned by the vapours at the altitude of y°, might 
eadly obfeure a faint objedt. 
When Venus was a little more than half im- 
merged into the Sun’s dife, I faw her whole circum- 
ference completed, by means of a vivid, but narrow- 
and ill-defined border of light, whi'eh illuminated 
that part of her circumference which was off the 
Sun, and would otherwife have been invifible. This 
I might, probably, have feen fooner, if I had at- 
tended to it. I continued to fee it till within a few 
minutes of the internal contadf, and grew apprehen- 
five that it would prevent the appearance of the 
thread of light, when it came to be formed ; but it 
difappeared about two or three minutes before, as 
