Inquiries concerning the Magnetism cf the Earth IIT 
points from east to west, also obliquely : and, according to a; 
great, though avowedly not a sulEcient number of observations, 
Mr Hansteen calculates, that the point B will accomplish its 
circuit round the north pole in 1740 years; b in 860; A round 
the south pole in 4609 years ; a in 1804 * 
These four points of convergence, the author supposes to ori- 
ginate in two magnetic axes, a stronger and a weaker, in the in- 
terior of the earth. No competent data exist for estimating 
their position, magnitude, or relative force : a variety of approxi- 
mations are attempted, however ; and a method, incapable of 
abridgment, and much too long for insertion, here, is exhibited 
for computing the variation, dip, and intensity, at any point of. 
the earth’s surface, — ^by giving to the unknown quantities such 
values as lead to the most accurate conclusions. The calculated 
results coincide pretty exactly with those of observation ; and 
the general hypothesis appears to represent the phenomena with 
a degree of fidelity hardly to be expected, when thg simplicity 
of the former is contrasted with the intricacy of the latter. A 
far stricter and more extensive scrutiny will, of course, be re- 
quired to establish the theory on firm foundations ; yet the facts 
it actually embraces are numerous, and in some cases explained 
with considerable elegance and success. 
The circumstances attending the intensity and dip are none 
of them inconsistent with the supposition of two magnetic axes, 
having their extremities severally directed to the stronger points 
• The following Table exhibits their respective positions, calculated from the 
above data, for the first half of this century. The latitudes are most dubious. 
Year. 
Point B. 
Strongest Pole in 
North Hemisphere. 
Point A. 
Strongest Pole in 
South Hemisphere. 
Points. 
Weakest Pole in 
North Hemisphere. 
Point a . 
Weakest Pole in 
South Hemisphere. 
Distance 
from the 
Pole. 
Longi- 
tude from 
Green- 
wich. 
Distance 
from the 
Pole. 
Longi- 
tude from 
Green- 
wich. 
Distance 
from the 
Pole. 
Longi- 
tude from 
Green- 
wich. 
Pistance 
from the 
Pole, 
Longi- 
tude from 
Green- 
wich. 
1800, 
1810, 
1820, 
1830, 
1840, 
1850, 
20*" r' 
20 15 
20 22 
20 30 
20 38 
20 46 
266 ° 27 ‘ 
268 32 
270 36 
272 41 
274 45- 
276 50 . 
20^53 
21 1 
21 8 
21 16 
21 23 
21 31 
o / 
134 8 
133 21 
132 35 
131 47 
131 1 
130 14 
o / 
4 35 
4 42 
4 48 
4 54 
5 0 
5 6 
13l''43' 
135 54 
140 6 
144 17 
148 28 
152 40 
O / 
12 10 
11 57 
11 44 
11 31 
11 19 
11 6 
229'*32' 
226 46 
224 1 
222 15 
219 29 
216 44 
