C 337 ] 
of the obfervations of the ingrefs and egrefs, both in 
contrary directions ; the fum of the errors, therefore, 
in each comparifon, will amount to 24" of time ; 
this will produce an error of 1" of fpace in the ap- 
parent leaft diftance of the centers by computation, 
but this error of 1' cannot produce an error of fo 
much as half a fecond in the determination of the 
Sun’s parallax. It therefore follows, on the above 
fuppofition of an error of 24' of time in the obfer- 
vation, that though we had no other obfervations of 
the tranlit of Venus than two of the above total du- 
rations, (luppofe that of Cajaneburg and Madrafs) 
yet we fhouid have been abfolutely certain of the pa- 
rallax of the Sun within lefs than an error of half a 
fecond, and therefore of courfe it follows, that the 
mean of fo great a number of refults muft be very 
near the truth. 
This determination of the Sun’s parallax, by the 
leaft diftance of the centers, is alfo a convincing proof 
that there is no miltake in the obfervation of Mr. Ma- 
fon at the Cape, as alledged by M. Pingre, and that 
there muft be a miftake of 1' in fetting down the 
time of the internal contact at the egrels at Rodrigues, 
notwithftanding M. Pingre, in the aforelaid memoir, 
prefers his obfervation to that of Mr. Malon, be- 
caufe, as he fays, that after a ftridt examination of 
ail the circumftances attending his obfervation, he 
could not find any miflake in it , but alfo becaufe he has 
proved that no miflake could pojjibly be committed. In 
this. determination of the parallax by the apparent 
leaft diftance ot the centers, we are not embarrafted 
with an exadf knowledge oi the difference of longi- 
tude between the places compared, which therefore 
in • 
