230 Mr. Herschel’s and Mr. South’s observations of the apparent 
Mean. Position 8i° 51' sf ; Distance = 1' ^".539 ; 1821.35: 
Other measures are 
1781.81. 80 25 sf-, H. Catal. of 1782. 
1819.85. 82 54 sf; Struve, Dorpat Obs. ii. p. 166. Obs. 121. 
1821.78. 82 36 sf; D°. Dorpat Obs. iii. ; reported by Zach. Corr. Astron. 
1821.78. Distance = i' 48"-733 ; D°. D°. computed from A 
decl. == i'47".645. 
The relative positions of the large and small star appears 
then not to have varied (at least as far as angle is concerned) 
since 1781 . This is a point of some importance, as the rotation 
of the small star (which is itself a close double star) is es- 
tablished by this fact. On the other hand, if the proper 
motions assigned by Piazzi (-— o". 30 in R. A. and -J- o".i 6 
in declination) be correct, this fact would go to establish 
a connexion between the two stars ; for supposing the small 
star at rest, the space passed over in its path by the large 
one amounts, in 40 years, to i3"-5, which being inclined at 
an angle of 28° to the parallel in a np direction, would sub- 
tend at the small one an angle of 5 0 49', a quantity which 
could not have escaped measurement in so distant a star ; 
either therefore Piazzi’s proper motions are erroneous, or 
the two stars have a common proper motion. 
