OF ARTS AND SCIENCES: MARCH 8, 1864. 249 



Obs. — Bessel. 



Montojo — 1M2 

 Hoy OS -f .7G 



Marquez -|- 1 .49 



+ 0.38 •• 



has been added to the place of the Tabute Regiomontanse for 1835. 



1840, 1850. — Paris. Annales de I'Observatoire Imperial de Paris. 

 Observations, Tome II. p. xxxv. The observations from 1837 to 

 1845 were reduced to 1840, and those for 1846-1854 to 1850. 



1840, 1845. — Berlin. The series in Vol. II. of the Berlin Obser- 

 vations, by Encke and Galle, gives for 1843 A « = -j- 0^06 (corrected 



for A )'), 



A'M = -|-0^03, A"a=-f 0M8. 



1842, 1845. — Oxford. Mr. Lucas observed with the old transit 

 instrument, and Mr. Johnson with the new one. 



1843. — Doellen. I have not been able to find a copy of the Dor- 

 pat observations for 1841 and 1842, which also contain observations 

 by this eminent astronomer. • 



1848. — Washington. The transit instrument gives, by thirty-seven 

 double transits, 1^ 4^ 25^81, and the meridian circle by forty-nine, 

 jh ^.m 26\92. I have simply taken the mean. The instruments seem 

 both to be affected by temperature. 



1855. — Carrington. Double transits alone. Redhill Catalogue, 

 p. xxii. 



1858. — Greenwich. Mr. Airy's new Catalogue of 2020 stars gives 

 I'' B'" 3'.05, reduced to 1860. This would give Aa = — 0'.26; this 

 does not include the result for 1861. 



In order to justify the course which has been pursued, in determin- 

 ing the correction to Bessel's A. P., it is necessary to show that Bes- 

 sel's declination is not largely erroneous. (See my paper in the Me- 

 moirs of this Academy, Vol. VIII. pp. 541 et seqq.) 



The declination was computed from the place for 1755 in the Fun- 

 damenta, compared with Bessel's own for 1820. The correction for 

 1830 was -j- 0".03 ( Argelander in "VVolfers's Tabulae Reductionura, p. 

 liii.) by seven series of observations; that for 1843 is — 0".06 (Pe- 

 ters in Struve's Recueil des Memoires, I. p. 201), and for 1850 and 

 1860 the Greenwich and Paris observations give, as compared with 

 Bessel, 



