[ 3^7 ] 
‘‘ motion, which might arife from the growing den- 
‘ hty of the atmofphere, as it pufhes forward on the 
‘‘ Sun, varying the refraftion of the rays. If fuch an 
^ atmofphere be allowed, then it probably gives the 
^ fame tremulous motion, at the internal contadt, to 
‘‘ the thread of light creeping round Venus j and 
“ prevents its doling quietly till the atmofphere (^or 
“ at lead; its denfeft part) be wholly on the Sun ^ and 
“ confequently the true coincidence of the limbs be 
pad:. For though the atmofphere of Venus can- 
“ not be feen on the Sun, yet that part which isfur- 
“ rounding, or jud: entering on the Sun’s limb, hav- 
ing, as it were, a darker ground behind it, may be 
‘‘ vifible. But thefe are only little conjedures fnb- 
“ rnitted to others j though if they have any founda- 
“ tion, it would make fome difference in the time 
‘‘ eftimated between the contads.” 
Gener^ 
