Mr. Gilpin's Observations on the Variation , 
4i& 
Table III. 
Mean monthly tme Variation , and mean monthly diurnal Alteration of Variation of 
the magnetic Needle. 
True 
Variation, 
Diurnal 
Alteration 
of 
Variation. 
True 
Variation. 
Diurnal 
Alteration 
of 
Variation. 
True 
Variation. 
Diurnal 
Alteration 
of 
Variation. 
True 
Variation. 
Diurnal 
Alteration 
of 
Variation. 
True 
Variation. 
Diurnal 
Alteration 
of 
Variation. 
True 
Variation. 
Diurnal 
Alteration 
of 
Variation. 
January. 
February. 
March. 
April. 
May. 
June. 
O / 
O , 
0 
0 / 
O / 
0 
1786 
1787 
2 3 ! 9 ’ 2 
10, Z 
23 19,8 
10,4 
2 3 
20,3 
15,0 
2 3 18,5 
1 7 > 4 
23 17,0 
ON 
OO 
2 3 
18,3 
19,6 
1788 
2 3 2 5 > 6 
8,7 
2 3 
23,9 
18,8 
1789 
2 3 
34 - 2 
17-1 
1790 
2 3 3 8 -9 
8,4 
1791 
2 3 35 - 6 
6,8 
23 36,0 
15,0 
» 79 2 
23 4 1 - 1 
5-4 
23 41,9 
”-5 
• 
. • 
. . . 
1 793 
23 46,9 
4-3 
23 48,3 
4-6 
2 3 
00 
00 
rh 
8-5 
23 46,2 
”-7 
2 3 47-3 
10,4 
2 3 
48-5 
12,6 
I 794 
2 3 54 > 2 
4-5 
1795 
2 3 
57-5 
9 -§ 
2 3 
57 »i 
9-4 
1796 
2 4 
1, 1 
7 -o 
2 3 
58,7 
9,8 
1 797 
24 
1-5 
7-4 
24 
0,2 
1 1,6 
i 79 8 
24 
o ; 6 
7 - 2 
2 3 
59-4 
1 1,2 
1799 
24 
1, 1 
7-5 
2 4 
0,6 
10,8 
1 800 
2 4 
3 > 6 
6,9 
2 4 
1,8 
10,9 
1 801 
2 4 
5,2 
8,8 
2 4 
2,8 
10,8 
1802 
24 
6,9 
9-5 
2 4 
5-3 
10,7 
1803 
2 4 
8,o 
1 1,8 
2 4 
7-o 
12,6 
1 804 
... 
2 4 
9-4 
10,0 
. . . 
24 
6,0 
ii -3 
1805 
— — 
2 4 
8 -7 
8,1 
24 
7-8 
12,5 
