t 35 8 ] 
Received February 8, 1770. 
XXX. ExtraSl of a Letter from John 
Winthrop, Efq\ F. R. S. Hollifian Pro - 
feffor of Mathematics and Natural Phi - 
lofophy , at Cambridge, N. England ; to 
B. Franklin, LL. D. F . R. S. Dated 
Sept . 6. 1769. 
Read April FIND that Mr. Blifs and Mr. 
Hornfby, in their calculations in the 
Philofophical Tranfa£tions, fuppofe the phafes of the 
tranlit of Venus, to be accelerated by the equation 
for the aberration of light, which amounts to 55" 
of time. According to my idea of aberration, I 
fhould think the tranlit would be retarded by it. I 
can very ealily fuppofe that I am in an error ; and 
that I may more readily be led out of it, I beg leave 
to lay before you the feveral fteps by which I have 
been led into it. And I think it will be belt to 
take fome fimilar inftance, rather than to confider 
the thing in a general abftradt manner. 
1. Let 
