Dr. Brinkley on the 
tides at the port of Brest. Laplace* afterwards modified this 
quantity, in consequence of the determination of Delambre, as 
to the lunar equation of the solar tables ; of the determination 
of Dr. Maskelyne, as to the nutation itself from Bradley’s 
observations ; and of the determination of M. Burg, as to the 
parallax of the moon. These three determinations agree in 
deducing nearly the same mass of the moon, and induced 
Laplace to adopt and then the nutation will be nearly 
that in formula (2), which is nearly the same as that of 
Delambre, “ t 
Laplace has farther considered this subject, J and finds, 
according to a high degree of probability, that the maximum 
is between 9", 31, and g,‘ "94. 
From the above there is evidently room for some uncer- 
tainty, which uncertainty may be doubled, by taking two 
stars differing 180° in right ascension. 
M. Delambre, although he thinks the maximum in aber- 
ration is settled, supposes the mass of the moon still subject 
to some uncertainty. § 
6 . As to s, or the semiannual equation as it is called. This 
= o /# ,48 Sin. (2 o —if l). Here, on account of the smallness 
of the quantity of this equation, there is no room for any 
material uncertainty. 
There is also another equation omitted by astronomers, 
viz. o", 04 Sin. (2 3) — iR). This cannot occasion a greater 
difference than o",o8, and therefore scarcely need be noticed 
even among the minute objects of this enquiry. 
* Mec. Cel. Tom. 3, p. 159. 
4 Astr. Tom. 3, p. 156. 
% Conn, des Temps. 1818, p. 361 
§ Conn, des Temps. 1810, p. 462. 
