[ 2 3S ] 
leave to lay before you, both the obfervations them- 
felves, and the feveral refults deducible from them 
by calculation. 
The method of determining the right afcenfion 
and declination of the center of Venus from that of 
the fun, was the fame which Dr. Bradley ufed, in 
obferving a former tranfit of Mercury. The planet 
was made to run down the fixed wire of the mi- 
crometer, and the difference of the time of paffage 
was obferved between it, and that part of the fun’s 
limb, which was cut by that wire ; and the moveable 
wire was brought to touch the fun’s lower limb. If 
the fun’s lower limb had been made to run down the 
fixed wire, and the moveable wire brought to the 
planet, and the difference of the time of paffage 
had been obferved between it and the fun’s confe- 
quent limb, on the fuppofition, that the wire was not 
exactly parallel to the diurnal motion, it would have 
caufed a confiderable error in the difference of right 
afcenfion, obferved at the diftance of the fun’s femi- 
diameter. But the method we made ufe of requires 
fome calculation, to determine the pofition of Venus 
on the fun’s difk. 
Hh 2 
Fig. 
