250 Mr. Herschei/s and Mr, South's observations of the apparent 
a- Coronae continued. 
The observations of this star, arranged in order of 
time, are 
1781.79. Position 77 0 32' np ; H. Catal. of 1782. 
1804.74. 78 3 6 nf\ H. Account of the changes, &c. 
1819.60. 40 o nf\ Struve. Additamenta. p. 179. 
1821.30. 24 45 nf\ H. and S. observed in 1821. 
1822.83. 18 27 nf\ Dist. i". 455.H. and S. ut supra. 
1823.47. 17 4 nf\ H. and S. Meanof Obs. of 1823. 
We have here an instance of a great and almost sudden 
acceleration in the angular velocity of the small star. In the 
interval of 20.95 years elapsed, between 1781 and 1802, the 
angle described was 23°.8 6, giving a mean velocity of 
i0 .!39 per annum. In tiie next interval of 16.86 years the 
angle described was 38°.6o, or 2°.298 a year ; while from 
1819.6 to 1823.83 the angle described amounted to 22°.55. 
in 3.23 years, or 6°.982 per annum. This rapid increase of 
angular velocity has been accompanied with a very sensible 
diminution of distance. In the catalogue of 1782, the inter- 
val between the two stars is described as being full 1J 
diameter of the large star, with a power of 227 ; while, with 
the same power, M. Struve observed them only ■§• di- 
ameter asunder ; and the same assiduous observer remarks, 
that the stars J Ursae and 17 Draconis, both of which are 
set down in the catalogues as closer than <r, are now farther 
asunder. Our observations corroborate this diminution of 
distance ; <r Corona is now a very difficult star to separate, 
almost equally so with vj, and requiring the most favorable 
