399 
iron arising from its rotation. 
of the plate was in latitude 54° 45', the rotation produced 
so little effect, that only in one instance did the mean values 
of and differ by a minute ; and therefore cannot but con- 
clude that 54® 45 is, as nearly as can be ascertained by obser- 
vation, the true value of x when and that the value 
of X as determined by the theory differs from its value derived 
from observation by or 
Let us now compare the values of and — 6^, deduced 
from the equations (5J, (6j, (5^) (6^), for different values of 
X, with those actually observed. This comparison is made • 
in the following tables, where I have computed the values of 
and to- seconds, not that either the observed or computed 
values can be determined to such a degree of accuracy, but 
because the omission of the seconds might in some cases 
affect the value of by more than a minute. 
Table of the values of 0 ^ and 9 ' — 0 ^, computed from the equations ( 5 ^), ( 6 ^) 
compared with their mean observed values in Table A. 
X 
9 ' 
9 ' — fi, 
Observed. 
Computed. 
Difference. 
Observed. 
Computed. 
Difference. 
Observed. 
Computed. 
Difference. 
0 
0 
/ 
// 
0 
/ 
// 
/ 
// 
0 
// 
0 
! 
// 
/ 
// 
0 
> n 
0 / II 
/ 
// 
0 
+ 
47 
55 
+ 
49 
10 
+ 
1 
15 
— 
47 
55 
— 
49 
10 
+ 
1 
15 
I 
35 50 
I 38 50 
4 - 
2 
30 
10 
3 
57 
20 
4 
22 
35 
+ 
25 
*5 
2 
26 
40 
2 
49 
57 
+ 
23 
^7 
I 
30 40 
I 32 28 
+ 
1 
58 
20 
6 
57 
00 
7 
*9 
21 
+ 
22 
21 
5 
40 
00 
6 
02 
21 
+ 
22 
21 
I 
17 00 
1 17 00 
0 
00 
30 
9 
03 
25 
9 
»7 
07 
+ 
13 
18 
8 
03 
45 
8 
22 
06 
+ 
18 
2 1 
59 40 
55 
— 
4 
39 
40 
9 56 
20 
10 
04 49 
+ 
8 
29 
9 
*9 
30 
9 
34 
*3 
+ 
H 
3 * 
36 50 
30 48 
— 
6 
02 
50 
9 
31 
20 
9 4 * 
19 
+ 
9 
59 
9 
21 
25 
9 
34 
25 
+ 
13 
00 
09 55 
06 54 
— 
3 
01 
60 
8 
05 
15 
8 
13 
00 
+ 
7 
45 
8 
16 
»5 
8 
26 
5 ° 
+ 
10 
35 
— 
11 00 
— 13 50 
— 
2 
50 
70 
5 
5 * 
35 
5 
51 
44 
+ 
0 
09 
6 
19 40 
6 
21 
41 
+ 
2 
01 
28 05 
— 29 57 
— 
I 
52 
80 
2 
25 
2 
53 
40 
+ 
2 
*5 
3 
31 
30 
3 
33 
52 
+ 
2 
22 
— 
40 05 
— 40 12 
— 
0 
07 
90 
22 
25 
2 1 
51 
+ 
0 
34 
+ 
22 
15 
+ 
21 
51 
0 
34 
44 50 
— 43 42 
+ 
I 
08 
