136 ASTRONOMICAL AND 
Mercury' sgeo. hor. mot. from the fun in theeclipitc, 5'53”, 52 
Mercury's geo. hor..motion in latitude increafing, |... 51,96 
The fun's femi-diameter, — IÓ 12, 2 
Mercury’ sfemi-diameter, . 55-4 
Mercury's horizontal parallax from de fun, 3» 94 
The obliquity of the ecliptic, 33°28 12 
The lat. of Cambridge reduced to thecenter, 42 8 37 
~ Hence, 
The altitude of the nonagefimal degree, 44 24 32 
‘The longitude of the nonagefimal degree, 5% 26 45 44 
Mercury's parallax in latitude.from the fan, 2, 805 
Mercury’s parallax in longitude from the fun, 2, 224 
— At the fecond external contact, at 11» 29* 3025 A.M, 
Apparent time ; by. calculation, 
Mercury’s parallax in latitude from the fun, 3, 169 
Mercury's parallax in longitude from the fun, 1, 280 
The longitude of the nonagefimal degree, at the time both 
"m the firft and fecond external contact, being lefs than the 
longitude of Mercury, ‘the parallax in longitude is to be added 
to Mercury’s longitude, in each, to give the vifible; and as 
Mercury’s.motion in tranfits is retrogade, and the: parallax at 
the time of the fecond external contact was greater than at the 
time of the firft, the length of the vifible tranfit-line was 
greater than the true, by the difference of the parallaxes. 
.The true latitude, at each contact, was diminithed by the 
parallax in latitude ; and as the geocentric latitude was increaf- 
ud aid the parallax, at the time of the cond external: contact, 
greater than at the time of the firft, the vifible motion in lati- 
elici was s lef than. the truc, by the. differencerof the. parallaxes, 
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