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XXXV. Some Obfervations of the Planet 
Venus, on the Dijk of the Sun, June 6 th> 
1761 ; with a preceding Account of the 
Method taken for verifying the Time of 
that Phenomenon ; and certain Reafons for 
an Atmofphere about Venus : By Samuel 
Dunn. 
Read Nov. S» A S foon as I heard, that feveral ma- 
J \ thematicians were to go abroad, 
and obferve the tranfit of Venus over the difk of the 
fun, from foreign parts, I purpoled to obferve the 
fame at Chelfea, and to compare my obfervation 
with the more accurate ones, which I expeCted 
would be made at the Royal Obfervatory at Green- 
wich. Suppofing, that if my obfervation at Chelfea 
was made with equal care, and as good inftruments 
for afeertaining time, as the inftruments to be ufed 
by the obfervers abroad, it might be ufeful, as a kind 
of proof, how exaCt the obfervations had been made 
abroad, where the obfervers had lefs conveniences 
fqr afeertaining time, than at the Royal Obfervatory. 
Mr. Dollond (a member of the Society) had, 
fome time before, newly ground, and fitted up for 
me, a Newtonian reflecting telefcope, fix feet in 
length ; which fo far exceeded expectation, that by 
it the Reverend Mr. Mafkelyne (who is now at St. 
Helena) and myfelf, had feveral times obferved how 
long Jupiter’s fatellites dwell on the limb of Jupiter, 
entering on the body. And I was provided with an 
