REPORT ON ASTRONOMY. 
137 
doubt remained as to the law of temperature in ascending in 
the atmosphere: this they attempted to remove by means of 
observations of horizontal refraction. On these grounds a table 
was calculated by Delambre (assisted partly by Piazzi’s and his 
own observations), and published in 1806 by the French Board 
of Longitude ; and this table has been always highly esteemed. 
In 1806 Carlini published (in the Milan Ephemeris ) his astro¬ 
nomical investigations of refraction. His object, besides giving 
a table of refractions generally, was to show that the refraction 
on the north side of the zenith at small altitudes was sensibly 
different from that on the south side. For refractions on the 
north side he used observations of circumpolar stars; as, the 
law of refraction as far as the pole being well known, the true 
zenith distances below the pole are immediately found. For 
refractions on the south side he referred to observations made 
at Palermo, where the same stars were seen with 7° greater 
elevation. In this manner a difference of a few seconds was 
found below 85° zenith distance. In the position of Milan this 
difference is quite conceivable: I know not whether the idea 
has been taken up by any other astronomer. 
In 1810 Mr. Groombridge published in the Phil. Trans, a 
table of refractions founded on observations of circumpolar 
stars. 
In 1813 and 1815 Mr. Pond published catalogues of the 
N.P.D. of the principal stars, determined by observations with 
the Greenwich circle. In reducing these, Bradley’s refractions 
were still used. 
In 1813 Bessel published (in the Berliner Jahrhuch for 1816,) 
the table of refractions obtained from Bradley’s observations. 
In 1818 he published the Fundamenta Astronomies pro Anno 
1756, deduced from Bradley’s observations. This work has 
always been considered one of the most valuable contributions 
to our Astronomy. It exhibits the result of all Bradley’s ob¬ 
servations of stars, reduced on a uniform system, and is always 
referred to by succeeding astronomers as the representative of 
Bradley’s observations. Various disquisitions on refraction 
and the mathematical theory of the other corrections are con¬ 
tained in it. From Kramp’s and Laplace’s theories and Brad¬ 
ley’s observations, a new table of refractions was formed. No 
alteration was made in the coefficient of nutation. 
In 1816 Lindenau announced in the Zeitschrift fur Astro- 
nomie, that by the discussion of 810 Greenwich observations 
of the right ascension of Polaris, he had found the coefficient 
of nutation to be rather less than No details of this in¬ 
vestigation were given, and none (I believe) have been pub- 
