68 
The Principles of Magnetism. 
[February, 
III. THE PRINCIPLES OF MAGNETISM. 
By Charles Morris. 
(Concluded from page 31.) 
t N this progress southward from the north pole it could 
not matter at what point we took the testing magnet 
beneath the surface, so that a sufficient distance south- 
ward was attained. A line of small magnets starting from 
the pole, proceeding southward over the surface to some 
point north of the equator, then curving inwards to the axis, 
and following this to the point of starting, must display a 
gradual variation in axial direction, until a complete revolu- 
tion upon the axial plane is effected. And in all such lines 
possible to form the same result must appear. If this be 
the case, then the earth, in its northern hemisphere, must 
form a magnetic vortex, of closed curves of the kind above 
indicated. These curves would become less in diameter as 
they were drawn in the interior, and become very small when 
confined to the region serving as the centre of their curva- 
tion. In the southern hemisphere a like magnetic vortex 
must exist, with the difference that its curves are opposite in 
direction to those of the northern vortex. These two vorti- 
ces are separated by the equatorial plane, into which the 
curves do not enter, but where the magnetic reversion takes 
place by a gradual weakening and dying out of magnetic 
energy in the intermediate zone. 
Each of these vortices must have its central zone of rota- 
tion, to which the north poles of all magnets display a ten- 
dency to point in the northern hemisphere, and the south 
poles in the southern. These central zones must lie between 
surface and axis, and between equator and pole, and their 
locality may be indicated by the surface localities at which 
the magnetic needle stands vertical to the axis, and thus, 
perhaps, points diredtly inwards to these interior zones of 
vortical rotation. If the magnet, in its southward move- 
ment, be carried inward at a point north of this locality, its 
dipping process could not continue, but must be exchanged 
for the opposite reversion, since it would meet the opposed 
curve of the vortex. Also if carried south of the equator 
the same opposition would result. But between the locality 
indicated and the equator the curvation would regularly 
