( *3 l ) 
with the Meridian, being in this Place 73° z^', the 
vifible Way of Mercury , made an Angle of 6 $ 0 5' 
with the Meridian palling through the Center of the Sun, 
whence the Horary Change of Declination becomes 
exa&ly 2' 30". 
Thefe Data I choofe rather to take from the The- 
ory, than from immediate Obfervation •, becaufe there 
is always an unavoidable, tho’ fmall Uncertainty, in 
what we obferve, yet greater than there can be in the 
Computation for fo fmall a Space of Time, efpecially 
now the Theory is, as I faid before, fo very near the 
Truth. 
This premifed, let us now enquire the true Time 
of the central Ingrefs, and the Latitude of the Planet 
at that Time. And hr ft, by my own Account, Mer- 
cury was gotten into the Parallel of the Sun s Center, 
zii Minutes after the central Ingrefs, in which Time 
he afcended to the Northward of 54", and fo much, 
therefore, was he more Southerly than the Suns Cen- 
ter at his Ingrefs. Mr. Bradly , 74 . Minutes after the 
faid Ingrefs, in which the Planet afcended o' 19", found 
his Declination o' 45" South, and therefore at the Ingrefs, 
his Declination was 1 ' 4" South. And by by Mx. Gra- 
ham's Obfervation, Mercury was more northerly than 
the Suns Center 1 ' 1 1 ", 53 / zo" after the central In- 
grefs • but in that Time, Mercury afcended z 1 13//, 
wherefore, according to him, at the Ingrefs the Planet had 
1 / 2 77 South Declination. We (hall not therefore erra- 
bove a Semidiameter of Mercury , if we alfume his De- 
clination, at thatTime, to have been precifely one Minute. 
Now the Suns Semidiameter being then 16/ 15 
one Minute is the Sine of 3 0 %zi in the Arch of the 
Sun's Limb and consequently, the Point of this Ingrefs 
was 1 3 0 4/ more northerly than the Ecliptick • whence 
the Latitude of Mercury was then 3 / 40// North, and 
Dif- 
