344 Dr. Brinkley's observations for investigating 
If this should turn out, as I believe it will, more exact 
than the former, it will occasion no difference of results as 
to parallax and the constant of aberration. 
The solar nutation I used was — o", 48 Sin (iR — 20 ), not 
regarding the smaller term. With my lunar nutation, the 
solar nutation will be = — o", 52 Sin (Tt — 20) — o,02Sin 
(iR + 20). That which I used, therefore, is sufficiently 
exact. 
The small terms depending on 2 long, moon, have not 
been noticed on account both of their smallness and of the 
quickness of their period. The principal term of the nuta- 
tion in North Polar distance depending on 2 long, of moon 
= — o", 08 Sin (iR — 2 > ),* which going through its period 
in the short space of a fortnight, can occasion no error in the 
results that I have obtained. 
To the stars above given, for which the constants of aber- 
ration have been investigated, may be added a Cassiopeas, 
a and (3 Cephei. The observations relative to parallax for 
these stars have not been sufficiently numerous to use the 
method of least squares. 
* This term was stated in my paper in the Philosophical Transactions, 1818, as 
being — — o,o4Sin(Tt — 25). I had adopted the numbers in the Mec. Cel. Tom. 2, 
p. 350, for the coefficients of Sin 2 / and cos 2 v ‘ , but on examination I found that 
M. Laplace had omitted to multiply by x ( 3). 
I may also remark, that in my two former papers on this subject, I unnecessarily, 
and in the first erroneously, introduced the effect of the elliptical motion of the 
earth in computing the aberration. The aberration in N. P. D. computed by the 
formula m cos ( © ~K) differs from the true quantity by the constant quantity ^ m 
cos (9 s . 9 °.~k) and therefore the mean place of the star needs only to be regarded. 
