M. Struve and Prof. Amici’s Observations on Double Stars. 387 
8. y Virgin, R. Asc. 12^ 33'. Decl. 0° 27. 
3d Mag. and 3d Mag. 
1756.0 Angle of Position 
= 54° 22' N. Foil. Mayer. 
1781.9 
- 
40 44 
Herschel . 
1803.3 
- 
30 20 
Herschel. 
1820.2 
. 
15 15 
Struve . 
1819 
Diff. of R. Asc. 
0" ,239 
Struve. 
1820 
Distance, 
3 .56 
Struve. 
1780 
Distance, 
5 .7. 
Calculated from Mayer and 
1756 
Distance, 
6 .55 
, Herschel’s observations. 
Baron Zach and M. Struve propose to determine the distance 
of these stars from their occultation by the moon. 
9. 44 Bootes, R. Asc. I4 h 58'. Decl. 48° 21' N. 
6th Mag. and 7th, 8th Mag. 
Both these stars are white, and very difficult to be seen on ac- 
count of the smallness of their distance. 
In 1781.6 Angle of Position 30° N. Following. 
1819.0 - - 42 S. Preceding. 
1819 Diff. of R. Asc. 0".88 
Hence the angle of position has changed 168° or 192°. A third 
observation will shew if one of the stars has performed more 
than one revolution in 38 years. 
10. <r Northern Crown , R. Asc. 16 h 8'. Decl. 34° 20' N. 
4th, 5th Mag. and 7th Mag. 
The largest star is white, and the smallest dull. 
Their distance is 2".2, which is a little doubtful. The differ- 
ence of declination is 0".73. 
In 1781.8 the Angle of Fosition was 77° 32' N. preced. Herschel. 
1802.7 - - 78 36 Do . 
181.9.6 - - 40 0 Struve . 
11. £ Hercules , R. Asc. 16 h 34'. Decl. 31° 56' N. 
In 1781 SirW. Herschel saw the two stars very distinctly. Af- 
terwards he could only observe, with very high magnifying 
powers, one of them, which was of a conical form. M. Struve 
has never been able to see this star double ; but it will no doubt 
again appear so. 
12. 1 + Dragon, R. Asc. 17 h 45'. Decl. 72° 14'. 
It appears from the observations of 1815, that these stars 
vol. ix. no. 18. oct. 1823. 
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