142 
SECOND REPORT — 1832 . 
motion towards the south. Dr. Brinkley found no traces of 
this, and in several volumes of the Phil. Trans, the reasons for 
and against this opinion are fully stated. This question, like 
the other, seems to be still in doubt. 
These discussions, while they have improved the accuracy 
of the places of the fixed stars, have naturally given rise to 
different fundamental catalogues. The thermometrical cor¬ 
rection of refraction affects the determination of the equinox, 
because the temperature of the two equinoxes is not the same. 
As Bradley’s refractions are still employed at Greenwich, the 
Greenwich right ascensions will differ from Brinkley’s or Bes¬ 
sel’s. The declinations are immediately affected by the re¬ 
fraction. Mr. Pond several years since found that the right 
ascensions of all the stars of Dr. Maskelyne’s catalogue ought 
to be increased 0 S *31 of time; but he has since thought that 
0 S *20 is sufficient: no investigations were published with these 
statements. Several catalogues have been published by him 
in the Greenwich Observations and in the Nautical Almanac : 
the last (included in the large catalogue published with the 
Greenwich Observations for 1829,) is undoubtedly excellent. 
Dr. Brinkley’s catalogue is in the Irish Transactions for 1828. 
Bessel’s catalogues are in various volumes of his Observations , 
and in the Berliner Jahrbuch. In the Astronomische Nach- 
richten, vol. v. and vi., are elaborate comparisons of the declina¬ 
tions of different observers by Mr. Pond ; and in the Berliner 
Jahrbuch , 1825, by Bessel. In Plana’s Observations ( Turin 
Memoirs , 1828), and in Schwerd’s Observations, there appear 
to be good catalogues of declinations. 
By comparing late declinations with those of Bradley, &c. 
the quantity of lunisolar precession is found from different stars, 
and the difference of each from the mean is held to be the pro¬ 
per motion of that star. In like manner, by comparing late 
right ascensions with those of Bradley, &c., the quantity of 
general precession is found. Different values of precession 
and proper motion are of course obtained by different cata¬ 
logues. Piazzi’s and Maskelyne’s depend sensibly on the nu¬ 
tation employed. In the Memorie delV Instituto nazionale 
Italiano, 1804, Piazzi gave the proper motion of 300 stars; in 
the Berlin Memoirs 1801, and the Phil. Trans. 1805 and 1806, 
Prevost, Maurice, and Sir W. Herschel explained some on the 
supposition that the sun was moving towards A Herculis : their 
calculations appear very plausible, but the result has not been 
generally received. Pond’s proper motions have been given 
with his catalogues ; Bessel’s precession in the Berlin Memoirs , 
1819 and 1825, and the Astronomische Nachrichten, No. 92; 
