[ 57 2 ] 
obferved is lefs than computed, it is weft of ac- 
count. 
The horary motion of the Moon in the ecliptic 
may be thus made out very expeditioufly from Mayer's 
equations, by the help of the principal arguments ufed 
in the computation of the Moon’s place. Call A, B, 
C, and D, the differences of the equations of the 
center, evedtion, and variation, and redu&ion to the 
ecliptic, for i° addition to their arguments; where it 
muft be noted, that they muft have the fame fign as 
the equation, if it is increafing; but a contrary fign, 
if it is decreafing. Compute the value of 32' 56" 
4* A x 4.4. X -iVo- + B x 4. X 44 , which put“H; and 
the true horary motion of the Moon in her orbit = H 
C x — — P ut == ^ 5 anc ^ horary 
D x K' 
motion of the Moon in the ecliptic is K -| ^7— • 
The horary motion of the Moon in latitude, calling 
the difference, anfwering to i° increafe of the argu- 
E x K' 
ment of latitude E, is ■ 
The moft difficult part in the above computations, 
and in which a perfon is moft liable to make miftakes, 
is the computation of the Moon’s place ; but if this 
be done at land for every twelve hours at leaft, and 
the diftance of a proper ftar, or of two ftars, one to 
the eaft, and the other to the weft, from the Moon’s 
enlightened limb, be computed for every fix hours 
at leaft, according to Monf. De la Caille’s propofal, 
the reft of the computation, which will remain to be 
done at fea, will be very plain and concife. 
Here 
