246 



On a new Calculation of the 



former period, we may adopt a mode of calculation in which 

 these several errors are no longer involved confusedly. We 

 have only to take the declination of the star from modern cata- 

 logues, the precision of which we can thoroughly rely upon, 

 and apply it directly to the corrected zenith distances. 



The declinations of a and ^ Ursa Minoris, employed by M. 

 M^chain, are so nearly the same as those of our present cata- 

 logues, that I have left them unaltered. But it is not so with 

 respect to the other stars. The sources, therefore, from which 

 I have sought to correct them are the following : — 



First, Bradley's catalogue, reduced afresh, and compared with 

 Piazzi's by Bessel, gives the declinations in 1755. These 

 brought up to the 1st January, 1794, make as follows : — 



Capella 

 /3 Tauri 

 Pollux 



o / // 



45 46 09,86 

 28 25 02,50 

 28 30 33,41 



a Draconis 



? Ursse Majoris 



O J 11 



65 21 52,46 

 56 00 19,96 



I then take the declinations of the same stars ; First, in Bes- 

 sePs catalogue of 1820, drawn from his own observations, in 

 Zach's Corr. Astro., 1822, cah. 3 ; second, in Pond's Cata- 

 logue for 1826, from the Greenwich observations made with 

 the two mural circles, Schumacher's Astro. Nach. No. ] 19 ; 

 third, in Brinkley's Catalogue of 1813, also in Schumacher's 

 Astro. Nach. ; fourth, and lastly, I have myself calculated 

 them from a great number of observations made by my col- 

 leagues and myself at the observatory at Paris with the 

 mural circle of Fortin. 



These declinations referred to the 1st January, 1820, by ap- 

 plying the annual variation of the respective stars, give the 

 following results ; the agreement of which attests the great pre- 

 cision with which such astronomical elements are obtained at 

 the present period : — 



DECLINATIONS FOR JANUARY 1, 1820. 



