diurnal variation of the magnetic needle^ ^c. 
325 
Table of the Deviations of the Needle when the plane of the Plate was horizontal, and 
the centre of the Needle vertically above or below the outer edge of the Copper. 
Angular distance of the 
place of Heat from the 
centre of the Compass. 
The centre of the Needle being in the plane of the 
meridian passing through the Plate’s centre. 
The centre of the Needle in the vertical plane at 
right angles to the meridian and passing through 
the Plate’s centre. 
To the North of the Plate’s 
centre. 
fo the South of the Plate’s 
centre. 
To the East of the Plate’s 
centre. 
To the West of the Plate’s 
centre. 
1'3 inch 
above its 
surface. 
1'3inch 
below its 
surface. 
1‘3inch 
above its 
surface. 
I’S inch 
below its 
surface. 
1'3 inch 
above its 
surface. 
1-3 inch 
below its 
surface. 
1-3 inch 
above its 
surface. 
1-3 inch 
below its 
surface. 
0 
0 
45 
90 
180 
270 
315 
5 45 E 
0 38 E 
2 30 W 
3 CO W 
4 00 W 
0 52 E 
0 f 
11 30 w 
5 00 W 
5 00 E 
3 15 E 
2 30 E 
3 15 W 
0 / 
9 00 W 
3 45 w 
3 00 E 
2 00 E 
2 30 E 
I 20 W 
0 ! 
8 45 E 
1 30 E 
2 15 W 
3 30 W 
c 30 W 
3 08 E 
0 / 
5 45 W 
18 15 E 
14 00 E 
4 22 W 
22 30 W 
25 30 W 
0 / 
2 22 E 
25 45 W 
23 1 c W 
I 15 w 
21 45 E 
22 00 E 
0 / 
I 00 E 
16 15 E 
15 30 W 
0 38 E 
15 30 E 
17 00 E 
0 / 
2 15 W 
24 30 E 
22 15 E 
0 08 E 
21 00 W 
|27 00 W 
Table of the corresponding Deviations of the Needle when its centre was vertically 
above or below the line of junction of the Copper and Bismuth. 
0 
45 
90 
180 
270 
315 
11 00 E 
I 15 E 
4 00 W 
5 00 W 
6 15 W 
I 30 E 
18 00 W* 
8 00 W 
6 45 E 
6 30 E 
4 30 E 
5 00 W 
16 00 W 
6 00 W 
4 45 E 
4 00 E 
5 00 E 
3 30 W 
12 45 E* 
2 45 E 
3 15 W 
6 00 W 
8 30 W 
3 30 E 
0 30 E 
20 15 E 
16 00 E 
0 00 
17 00 W 
18 45 W 
Observations could 
not be made in 
this position of the 
compass. 
1 30 E 
11 30 W 
14 30 w 
I 00 w 
15 00 E 
14 00 E 
Observations could 
not be made in 
this position of the 
compass. 
The character of these deviations perfectly accords with 
the position which I have assigned to the poles in the plate, 
but when the centre of the needle was in the plane of the 
meridian, and the heated point directly under or over it, the 
extent of the deviations, compared with others, was greater 
than would arise from this position of the poles, supposing 
* These observations were made with the centre of the compass vertically below 
a point ’35 inch from the line of junction towards the outer edge, the extremity of 
the needle not being visible when nearer to the centre of the plate. 
