[ S&8 ] 
the oblervation, cleared of refra<ftion and parallax. 
For this purpofe, it is necefiary to compute the 
Moon’s longitude and latitude, and horary motion 
both in longitude and latitude, from the moft exadt 
tables for the time under the known meridian, 
which is judged to correfpond nearly to the given 
time of obfervation under the unknown meridian. 
The mean motions of the Sun and Moon I took 
from very exa<ft tables, which I received as a prefent 
from the ingenious Mr. Gael Morris, compofed by 
himfelf, from the comparifon of a great number of 
Dr. Bradley’s obfervations j to which I applied the 
lunar equations, as they ftand in the learned Mr. 
Mayer’s printed tables. After finding the mean lon- 
gitude of the ftar at the prefent time, I always allowed 
for its aberration in longitude, which will fometimes 
amount to 20", without confidering the aberration 
in latitude, which can be of no confequence in a zo- 
diacal ftar, fuch as thofe are which are always to be 
ufed in thefe obfervations. The diftance of the ftar 
from the Moon I computed from their longitudes and 
latitude, by the two following rules : 
Rule L 
Add together the logarithmic cofine of the dif- 
ference of the computed longitudes of the Moon and 
ftar, and logarithmic cofine of the difference of their 
latitudes; if they are of the fame denomination ; or 
fum, if they are of different denominations ; the fum, 
abating 1 o from the index, is the cofine of the appro- 
ximate diftance. 
N. B. This gives the abfolute diftance of the Moon 
from the Sun, without any further calculation. 
1 But 
