142 
Lieut. Foster’s observations on the diurnal changes 
North end of Needle to the East. 
The axes of the magnets placed north and south of the needle, were on this occasion inclined to the 
magnetic meridian at an angle of 22 degrees ; the distance of the nearest ends of each, from the centre 
of the compass-box was 28 inches, and the time of performing one vibration by the needle was 16,4 
seconds, so that the directive power now, was to the undiminished force as 0,113 to 1. 
Date, 
1825. 
Feb 23rd. 
Mean 
Time of 
Obser- 
vation. 
h. 
I 
I 
3 
4 
5 
6 
6 
7 
7 
7 
7 
7 
7 
m. 
OO 
55 
00 
X 5 
3 ° 
OO 
40 
OO 
5 
20 
25 
3 ° 
32 
A. M. 
or 
P. M. 
A. M 
Reading of 
north end of 
Needle. 
1 00N 
2 00 S 
10 00 
8 00 
7 3 ° 
7 3 ° 
7 30 
4 4 ° 
10 00 
19 OO 
18 30 
19 40 
20 OO 
Temp. 
Fahren', 
Instr 
-26 
-27 
-27 
“27 
-27 
-27 
-27 
-2 6 \ 
-261 
-26 
-26 
-26 
-26 
Direction of 
north end of 
needle during 
westerly daily 
variation. 
Time that a ho- 
rizontal needle 
took to make 
60 vibrations. 
7 
35 
20 
10 
— 26 
7 
40 
19 
00 
— 26 
7 
42 
18 
5 ° 
—27 
8 
8 
10 
00 
—27 
8 
12 
9 
30 
—27 
9 
10 
4 
40 
—27 
9 
3 ° 
5 
00 
—27 
9 
40 
6 
10 
—27 
10 
10 
6 
5 ° 
—26^ 
10 
3 ° 
3 
00 
— 26 
10 
40 
4 
3 ° 
— 26 
1 1 
00 
4 
00 
— 26 
11 
3 ° 
East 
1 1 
33 
E 
1 
coN 
— 26 
1 1 
36 
0 
30 
— 26 
1 1 
40 
E 
East 
1 1 
45 
1 
00 S 
— 25 
Noon 
2 
00 
—25 
0 
10 
P. M. 
1 
30 
—25 
0 
5 ° 
E 
East 
25 g 
1 
00 
3 
0 
0 
2 
25 2 
I 
15 
4 
20 
—255 
I 
25 
5 
10 
— 25 J 
1 
30 
5 
10 
— 2 5 § 
l 
35 
5 
00 
— 25I 
1 
45 
5 
20 
—25 2 
2 
00 
5 
3 ° 
— 25J 
2 
10 
5 
20 
-255 
2 
3 ° 
4 
00 
—253 
3 
00 
4 
00 
-253 
3 
25 
4 
00 
—25 s 
3 
55 
4 
00 
—252 
5 
3 ° 
5 
00 
—25 h 
Winds. 
m. 
17 
18 
18 
18 
18 
18 
s. 
57-2 
3- 6 
5.2 
2,6 
3 >4 
9-5 
Eastward 
18 13,7 
18 
11, 1 
18 
I >5 
18 
2,3 
17 
59-3 
Easterly 
Fresh 
Weather. 
Clear 
Max. easterly var. 
Aurora bright 
to the north; 
at 4 11 brilliant 
from NW to 
NEby(com- 
pass.) 
Hazy 
17 59- 6 
East 
1 7 54-5 
17 5 1 >3 
17 54 
17 5C4 
17 50,1 
Fresh 
Hazy 
Clear over- 
head, much 
drift, wea- 
ther very 
cold. 
Remarks, &c. 
The max. westerly 
var. happened by 
the suspended 
needles at 10 h 
48“' nearly. The 
indications of this 
needle appear to 
be rather those of 
changes of intend 
than of direction, 
since the irregu- 
larities (by com- 
paring them with 
the times of vib. 
of a hor. needle), 
were found to fol- 
low that law. 
Very cold W. 
