49 



By Greenwich Obser. 1755 

 Palermo, . 1800 

 Dublin, . 1821 



N.P.D. ? Ursae 

 Maj. 



O I II 



34 47 18,7 

 34 1 34,2 

 34 8 12,5 



Diff. AR 



I 



172 25 



173 9 

 175 9 



These stars being nearly opposite in right ascension, much pre- 

 cision is not required in the difF. of right ascensions for investigating 

 the distances between these stars at the respective periods. 



With the above data ; ' i" -^ . [..,.:■ 



O I II 



The distance in 1755 = 35 46 37,6 

 1804 35 46 37,6 

 1821 35 46 58,2 



The near agreement of these distances in itself renders it highly 

 probable that both the Pole Star and ^ Ursse Majoris have no sen- 

 sible proper motion. This is much strengthened v^hen we consider 

 that the attendant of ^ Ursas Majoris has preserved its relative po- 

 sition to the larger star during the last forty years, in like manner 

 as the attendant of Polaris has preserved its position to Polaris. 



M. Struve, however, attributed a motion in right ascension to 

 this star, which probably arises from an inexactness in one of the 

 right ascensions which he used. • ' '•' ■' •' '•'•^ •■. 



From the right ascensions and declinations of Rigel, a Orionis, 

 and a Cygni above given, were deduced the distances of these 

 stars from each other as before given. As an addition to the argu- 

 ment thence deduced for the fixedness of these stars we may adduce 

 the observed and computed N. P. distances at different periods. On 

 account of the smallness of the cosines of the right ascensions of 

 Rigel and a Orionis, the computed precessions in north polar dis- 

 tances cannot be affected by any possible error in the quantity of 

 luni-solar precession, as deduced above from the Pole Star. The 



j2 



