322 
Mr, Christie’s theory of the 
the lamp was applied to the point marked o, as before. They 
are contained in the following Table. 
Table of the Deviations of the Needle when the plane of the Plate was in the plane of the 
Meridian, and the centre of the Needle opposite to 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 vertical plane at 
right angles to the plate and passing through its centre. 
The centre of the Needle in the horizontal plane 
passuig through the Plate’s centre. 
Above the Plate’s 
centre, and 
Below the Plate’s centre, and 
To the North of the 
Plate’s centre, and 
To the South of the 
Plate’s centre, and 
1’3 inch 
East of its 
surface. 
1*3 inch 
West of its 
surface. 
1‘3 inch East 
of its surface. 
1'3 inch West 
of its surface. 
1*3 inch 
East of its 
surface. 
1‘3 inch 
West of its 
surface. 
1‘3 irich 
East of its 
surface. 
1'3 inch 
West of its 
surface. 
0 
o 
45 
90 
180 
270 
315 
0 / 
2 15 E 
13 00 W 
10 00 W 
0 15 W 
9 15 E 
12 45 E 
0 ' 
2 15 E 
14 00 W 
9 00 w 
0 15 w 
7 00 E 
12 15 E 
0 ! 
ill 00 E 
1 I 00 E 
14 15 W 
8 45 W 
0 00 
9 15 E 
10 45 E 
0 1 
2 52 E I * 
0 15 E k 
17 00 W 
11 30 w 
0 15 w 
10 45 E 
13 00 E 
0 / 
4 45 E 
37 15 W 
36 30 w 
0 30 E 
15 37 E 
20 30 E 
0 / 
3 15 E 
13 30 W 
10 30 w 
I 15 E 
16 00 E 
22 00 E 
0 / 
2 45 E 
16 30 W 
11 07 W 
0 30 W 
17 45 E 
21 45 E 
0 / 
1 30 E 
30 00 W 
24 15 w 
0 52 w 
12 15 E 
14 30 E 
Table of the corresponding Deviations of the Needle when its centre was opposite to the 
line of junction of the Copper and Bismuth. 
0 
45 
90 
180 
270 
3'5 
i 
6 00 E 
34 30 W 
39 00 W 
0 22 E 
40 00 E 
36 30 E 
9 CO E 
43 00 w 
29 45 W 
I 15 w 
29 00 E 
44 00 E 
f 10 00 E 
1 0 37 w 
34 00 W 
25 45 w 
1 07 E 
25 15 E 
30 00 E 
7 45 E K 
0 15 w] 
40 00 w 
36 00 w 
0 15 E 
36 30 E 
31 00 E 
12 00 E 
77 00 w 
74 00 w 
0 00 
30 15 E 
38 30 E 
15 15 E 
38 45 w 
29 00 w 
0 37 W 
65 30 E 
72 00 E 
3 >5 E 
36 30 W 
27 45 W 
2 00 W 
51 00 E 
58 30 E 
5 30 E 
6i 00 W 
59 *5 W 
2 00 W 
28 30 E 
34 30 E 
* It will be remembered, that, in all cases, the first observation of the deviation 
was made, after removing the lamp, when the point to which the lamp had been 
applied was the lowest, and the deviation was again observed when this point was 
brought into the same situation, by the plate having been turned on its axis, in 
order to observe the deviations due to other positions of the heated point; and 
likewise, that similar observations were made when the plate was turned in the con¬ 
trary direction. In each of these four positions, then, of the compass, there were 
four observations corresponding to the angular distance o°; the upper numbers 
are the means of the deviations first observed on removing the lamp; and the 
lower, the means of those when the plate was again brought round into its original 
position. In the position of the needle opposite to the line of junction of the 
copper and bismuth, and to the east of the plate, during the time that the lamp 
