352 LORD WROTTESLEY ON THE PERIODICAL OBSERVATION OF STARS 
The eighth column contains the weight of the difference computed from the formula 
W"= 
WW' 
W + W' 
where W and W' are the weights of the two positions compared, and W" the weight 
of their difference : — from the value of W" so obtained, that of the probable error of 
the difference, inserted in the seventh column, is computed by the above equation. 
The ninth column contains the distance, taken from the third Table to the first 
place of decimals. 
All the computations have been very carefully examined. 
Table IV. 
Name. 
Epoch. 
Position. 
Probable 
error. 
Weight. 
Diifer- 
ence. 
Probable 
error of A. 
Weight 
of A. 
Distance. 
7 Arietis. 
1843. 
1844. 
1847. 
1847. 
•576 
•069 
•080 
•608 
179 
179 
178 
178 
10 
42 
14 
51 
7-33 
7-54 
5- 89 
6- 55 
19 
18 
29 
23 
- 32 
+ 37 
10-52 
8-81 
9 
13 
// 
8-9 
1843,7. 
1844, 5, 7. 
•592 
•077 
178 
179 
59 
29 
4-89 
3-65 
42 
75 
— 30 
6-10 
27 
32 Eridani. 
1843. 
1845, 6, 7, 9. 
•661 
•110 
345 
348 
50 
48 
4-59 
3-74 
48 
72 
+ 178 
5-92 
29 
6-8 
w Aurigse. 
1845. 
1846. 
•734 
•188 
351 
350 
16 
37 
10-60 
6-77 
9 
22 
- 39 
12-58 
6 
6-4 
1843, 4, 5. 
1846, 7, 8, 9. 
•729 
•213 
350 
351 
55 
13 
4-62 
4-28 
47 
55 
+ 18 
6-30 
25 
118 Tauri. 
1843. 
1844. 
1844. 
1845. 
1845. 
1846. 
•732 
•225 
•737 
•184 
•723 
•169 
196 
195 
194 
193 
193 
195 
38 
38 
45 
58 
23 
31 
4-93 
4*10 
6-10 
6-73 
13-62 
6-13 
41 
59 
27 
22 
5 
27 
+ 60 
- 53 
+ 47 
— 35 
-128 
6- 42 
7- 35 
9-08 
15-18 
14-93 
24 
19 
12 
4 
5 
5-0 
1843, 4, 5. 
1844, 5,6, 
•731 
•193 
195 
195 
42 
16 
3-69 
3-04 
73 
108 
+ 26 
4-78 
44 
41 Aurigse. 
1843. 
1843. 
•163 
•685 
353 
353 
54 
56 
7-69 
4-07 
17 
60 
— 2 
8-22 
15 
7-9 
1843, 5, 6, 7, 8. 
1843. 
•191 
•685 
352 
353 
45 
56 
2-53 
4-07 
156 
60 
- 71 
4-79 
44 
$ Geminorum. 
1845. 
1846. 
•846 
•268 
198 
198 
23 
42 
8- 14 
9- 19 
15 
12 
- 19 
12-29 
7 
7-4 
1843, 4, 6. 
1845. 
•268 
•846 
196 
198 
58 
23 
3-99 
8-14 
63 
15 
+ 85 
9-06 
12 
Anon. Cancri. 
1845. 
1845. 
•272 
•846 
353 
351 
30 
43 
6-19 
9-41 
26 
11 
+ 107 
11-26 
8 
3-7 
1843, 4, 5, 8. 
1845. 
•268 
•846 
353 
351 
26 
43 
3-00 
9-41 
111 
11 
+ 103 
9-88 
10 
