( 133 > 
at io h 28' mane. The fecond was, Otfob. 28° 1 677, 
when myfelf had the good Fortune to obferve both the 
Ingrefs and Egrefs of the Planet in the Ifland of St. He- 
lena ; the middle Time, when he was neareft to the 
Sun' s Center, being there but 3' 5*0" paft Noon, and 
the vifible Duration of the Tranfit of the Center of the 
Planet 5 h 14' 20"; which was fome fmall matter 
con traded by Parallax, and mod likely might have been 
5h 15' 00" without it. Nowin* h i$\Mercury^t- 
fcrib’d the Chord of 1 46° £2' in the Sun's Limb, be- 
ing 3 1* 9", and confequently the neareft Diftance to 
the Center was 4' 38", or the Sine of 1 6° 34' the 
Sun's Semidiameter being Radius ; that is, 1' 18" lefs 
than we found it in 1723. Hence alfo it follows, 
that the true Conjundion in Longitude was 7 min. of 
Time later than the neareft Approach of the Centers, 
viz. at o h 10' 50" at St. Helena , or at o h 35' paft Noon 
at Greenwich : and, that the North Latitude of the 
Planet, at that Time, was 4' 4 1 ". 
Suppoftng, therefore, the neareft Diftance of the Cen- 
ters in the Tranfit of 1631, to have been 3' 20", that 
is, i' 18" Jefs than in 1677, we (hall find that Mer- 
cury then defcrib’d a Chord of 156° 2c', traverfing the 
Disk of the Sun in 5 h 21' 30''; fo that fuppofing his 
Exit at io h 28' at Taris, that is io h 18' 4c" at Green- 
wich, he enter’d on the Sun at 4 11 57' 10" in the Morn- 
ing:, and was neareft his Center at 7 11 38' T. app. but 
in the fame Longitude with him at y h 43', or Oclob. 
2 7 0 i9 h 43' T. app. having then 3' 22" North Lati- 
tude. 
And here, I think I may, without Vanity, advertife 
the Reader, that above thirty Years fince, viz, in 
\ Thilofoph . Tranf. N° 193, for the Month of 
March , &c. 1 69®, I predided, by Help of the two 
former, this laft Tranfit, with a furprifing Exadnefs, 
V o L. XXXIII# L 1 even 
