On the Diminution of the Obliquity of the Ecliptic. 48 
Year. 
Obliquity. 
Diff. 
Year. 
Obliquity. 
Diff. 
| Y ear. 
Obliquity. 
Diff. 
o III 
0 / // 
// 
j 
o / // 
// 
400 
23 43 8.8 
// 
900 
23 34 18.4 
41.9 
2200 
23 24 56.0 
42.8 
300 
23 42 29.3 
39.5 
1000 
23 33 36.4 
42.0 
| 2300 
23 24 13.2 
42.8 
200 
23 41 49.6 
39.7 
1100 
23 32 54.3 
42.1 
1 2400 
23 23 30.4 
42.8 
100 
23 41 9.6 
40.0 
1200 
23 32 12.1 
42.2 
2500 
23 22 47.6 
42.8 
0 
23 40 29.4 
40.2 
11300 
23 31 29.8 
42.3 
| 2600 
23 22 4.9 
42.7 
100 
23 39 49.0 
40.4 
1400 
23 30 47.4 
42.4 
j 2700 
23 21 22.2 
42.7 
200 
23 39 8.3 
40.7 
1500 
23 30 4.9 
42.5 
j 2800 
23 20 39.5 
42.7 
300 
23 38 27.4 
40.9 
1600 
23 29 22.3 
42.6 
J 2900 
23 19 56.9 
42.6 
400 
23 37 46.4 
41.0 
1700 
23 28 39.7 
42.6 
3000 
23 19 14.3 
42.6 
500 
23 37 5,2 
41.2 
§1800 
23 27 57.0 
42.7 
3100 
23 18 31.7 
42.6 ] 
600 
700 
23 36 23*7 
23 35 42.1 
41.5 
41.6 
1900 
2000 
23 27 14.3 
23 26 21.6 
42.7 
42.7 
3200 
23 17 49.2 
42.5 
800 
23 35 0.3 
41.8 
2100 
23 25 38.8 
42.8 
!. 
J 
Observed. 
Table. 
818, 
Almamon, (according to Golius), 
23 
i i 
35 
// 
0 
23 
> / 
35 
// 
7.8 
1437, 
Uleigh Beigh, 
23 
30 
27 
23 
30 
31.7 
1587, 
Tycho Brahe, 
23 
29 
30 
23 
29 
28.0 
1653, 
Hevelius, (see Long’s Astronomy), 
23 
29 
0 
23 
28 
59.7 
1672, 
Cassini, (Vince’s Astron. vol. i.), 
23 
28 
54 
23 
28 
51.7 
1672, 
Richers, Rees’ Encyclopaedia, 
23 
28 
51.5 
23 
28 
51.7 
1736, 
Condamine, 
( De la Caille, "j 
23 
28 
24 
23 
28 
24.5 
1750, 
-< Bradley, v mean of their results, 
( Mayer, j 
23 
28 
18.33 
23 
28 
18.35 
1755, 
Bradley, - 
23 
28 
15.5 
23 
28 
16.2 
1769, 
Maskelyne, 
23 
28 
10 
23 
28 
10.2 
1769, 
Cerstners, 
23 
28 
11 
23 
28 
10.2 
1772, 
Maskelyxe, (Phil. Tr. 1773, p, 93.) 
23 
28 
8.7 
23 
28 
8.95 
1786, 
Lalande, 
23 
28 
0 
23 
28 
2.99 
1800, 
Delambre, 
23 
27 
57.0 
23 
27 
57.00 
1811, 
Groombridge, (these are reduced to 
Jan. 1.), 
23 
27 
51.15 
23 
27 
52.30 
1812, 
— 
23 
27 
51.42 
23 
27 
51*88 
1818, 
Pond, 
23 
27 
52.01 
23 
27 
51.88 
Brinkley, 
23 
27 
51.00 
23 
27 
51.45 
1821, 
(Dublin Magazine), 
23 
27 
48.45 
23 
27 
48.47 
The error in the above seldom amounts to a second ; and 
when it does amount to more, the greatness of the error can 
easily be accounted for. The following Tables were calculated 
to find the apparent obliquity from the mean at any time. The 
first contains the mean diminution for any number of years. 
The second contains the correction for days of the year, from 
the formula — + 0".4345 cos 2 © ; and the last con- 
tains the Lunar Nutation ; the greater axis being 9".64, which 
is the number Gauss and Delambre used, (see the Table at the 
end of Woodhouse\> Astronomy, voh i. 
