. f 474 j 
1 obolird in Siberia is fo fituated, that the interval be- 
tween tne two contacts was perhaps as fliort as could 
poffibly be obferved on any part of the earth’s fur- 
face; to this place was fent the Abbe Chappe d’Au- 
teroches, one ot the French aftronomers. Near Hud- 
Ion s Bay and in '6o J ot latitude the duration would 
have been 5 minutes longer, fuppofing the Sun’s par- 
allax — 9 ". xAt Eencoolen, where it was firft propofed 
to fend Mels. Malon and Dixon, the difference 
would have been about 4 4 minutes. At the ifland 
of Rodrigues, where Mr. Pingre could onlyobferve 
the lad internal contact, the difference would have 
been about 7 4 minutes. On the fouthern coafl of 
New-Holland, it would have been fomewhat more 
than 10 minutes. And in the great Indian Ocean, 
under 1154 of abfolute longitude from the I lie of 
Ferro and in 57° of fouth latitude, where the begin- 
ing of the tranfit would happen foon after Sun-rif- 
ing, and the end juft before Sun-fet, the difference 
would amount to 13 4 minutes. The greateft differ- 
ence between the interval of the two internal contacts, 
as determined by actual obfervation on the 6th of 
June, was 2h 49", 75, a quantity hardly fufficient to 
determine the Sun’s parallax agreeably to the method 
propofed by Dr. Halley. 
I have however made the neceffary calculations, 
and compared the duration of the tranfit obferved at 
feveral places with the duration as obferved at To- 
bolfki. The parallax refulting from each obfervation 
is contained in the following table, in which the 3d 
column contains the obferved duration, the 4th the 
difference of each obferved duration; the next con- 
tains that difference as deduced by computation upon 
a fuppofition that the Sun’s parallax is 9 ". In the 
laft 
