362 Dr. Herschel’s Account of the Changes that have happened 
several angles of position I have taken at different times, and 
show that they agree perfectly well with the appearances which 
must arise from the revolution of a small star round Castor. A 
calculation of these angles may be had, by finding the annual 
motion of the small star, from the change of 21 0 54', which has 
been shown to have taken place in 23 years and 142 days. 
Accordingly, I have given, in the 1st column of the following 
Table, the time when the angles were taken. In the 2d, are 
the angles as they were found by measure ; they are all in the 
north -preceding quadrant. The 3d column contains a calculation 
from the annual motion of 56', 18, obtained as before mentioned : 
it shows what these angles should have been, according to our 
present supposition of a revolving star. And the last column 
gives the difference between the observed and calculated angles. 
Times of the observations. 
Observed 
angles. 
Calculated 
angles. 
Differences. 
Nov. 5, 1779 
32 0 
47 ' 
32 0 
47 ' 
o° 
o' 
Feb. 23, 1791 
22 
57 
22 
1 1 
+ O 
46 
Feb. 2 6, 1792 
27 
16 
21 
i6‘ 
4 - « 
0 
Dec. 15. 1795 - 
13 
52 
17 
42 
~3 
50 
March 26, 1800 - 
18 
8 
J 3 
4 1 
-f- 4 
27 
April 23, 1800 
IO 
30 
13 
37 
- 3 
7 
Dec. 31, 1801 
7 
58 
12 
2 
-4 
4 
Jan. 10, 1802 
10 
53 
12 
1 
— 1 
8 
Jan. 23, 1802 - 
10 
28 
1 1 
59 
. — 1 
31 
Feb. 28, 1802 - 
13 
0 
1 1 
53 
+ 1 
7 
Feb. n, 1803 
7 
53 
1 1 * 
0 
— 3 
7 
March 23, 1803 - 
13 
23 
IO 
54 
+ 2 
2 9 
March 27, 1803 
10 
53 
IO 
53 
0 
0 
