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to the exa&nefs of -1th of a fecond of time j as were 
alio the inftants of the moon’s enlightened limb 
pading the fame wires. It is manifeil that the 
difference of time, obferved by the clock, between 
the ftar and the moon’s limb paffing the horary 
wires, reduced to fidereal time, and from thence into 
parts of the equator, is the apparent difference of 
right afcenfion between the ftar and the moon’s limb 
palling the horary wires. The fame obfervations re- 
peated after an interval of fome hours gave the pre- 
fent difference of right afcenfion between the ftar and 
the moon’s limb; whence the moon’s apparent mo- 
tion in right afcenfion, or the difference of thefe dif- 
ferences is known ; which fubftra£ted from the 
moon’s motion in right afcenfion, in the given inter- 
val of time, owing to her proper motion in her 
orbit, computed, in the moft exadt manner, from 
the beft tables, leaves the remainder for the change 
of the moon’s parallax in right afcenfion between 
the two times of obfervation ; the ratio of which to 
the horizontal parallax at that time being alfo com- 
puted, the horizontal parallax of the moon is known : 
and confequently, by the help of a proportion bor- 
rowed from the tables, the mean horizontal paral- 
lax of the moon in the latitude where the obferva- 
tions are made. The mean horizontal parallax be- 
ing deduced in this manner from a great many ob- 
fervations on different nights, the mean of all the 
refults may be taken, as approaching very near to 
the truth : for the advantage is fo great from taking 
a mean of a great number of aftronomical obferva- 
tions, that any degree of exa&nefs required, may 
