[ 495 ] 
more than io minutes of North latitude ; and will 
be fo favourably circumftanced, that, if the errors 
in obferving each contact do not exceed 4" or 5", 
the quantity of the Sun’s parallax may be deter- 
mined within lefs than part of the whole : 
as the total duration, or the interval between the two 
internal contacts, will be found to be about 18 mi- 
nutes longer at Tornea 0 than at Mexico. But the 
feveral circumftances of that tranfit mull: be the fub- 
je£t of a future paper. Let it fuffice at prefent to ob- 
ferve that it will in part be vilible to the inhabitants 
of this ifland, as Venus will be feen wholly entered 
upon the Sun’s difk more than half an hour before 
the time of fun-fet at Greenwich. 
SI! 2 
LVI. J 
