INTRODUCTION AND RESULTS. 
253 
ably greater in amount than at the northern, and that its position is in a somewhat 
higher geographical latitude than the corresponding point in the north ; as is also 
apparently the southern point of 90° of Inclination ; and probably also the position of 
the minor maximum of Force. If however we take a general view of the isodynamic 
lines in the two hemispheres, we see reason to believe that the difference under notice 
is rather a consequence of a different distribution of Force, than of an actual disparity 
in the magnetic charge of the two hemispheres. The two points of maximum in the 
south being nearer together at the present epoch (i. e. their shortest distance apart 
being less) than in the north, the intensity of the Force at both is raised, and a greater 
inequality is produced in the intensity on opposite sides of the southern hemisphere, 
than is the case in the northern hemisphere. 
The progress of secular change, as it may be inferred from the comparison of the 
earlier and more recent observations of the Declination and Inclination, is tending to 
bring the two points of maximum in each hemisphere nearer to each other ; whilst this 
progressive approximation continues, we may expect that the Force in each hemi- 
sphere will become more and more unequally distributed, and that the intensity at 
each of the four points of maximum will augment. The increase or decrease of the 
distance in geographical longitude between the two points of maximum in a hemi- 
sphere appears to be chiefly occasioned by the rapid secular change in respect to 
locality (or the rapid movement in translation) which the phenomena of the minor 
system undergo. The minor maximum was probably at its greatest elongation (180° 
of geographical longitude) from the major maximum in the northern hemisphere, some 
time in the last century. At that epoch therefore the distribution of Force in that hemi- 
sphere made its nearest approach to equality ; the opposite geographical longitudes 
had the minimum of dissimilarity in their respective intensities, and the values of the 
Force at the major and minor maxima were respectively lower than at any other epoch. 
In this conclusion I have omitted the subordinate consideration of the influence which 
the distribution of the Force in the southern hemisphere exercises on the northern in- 
tensities, which is distinctly perceptible even in the middle magnetic latitudes, and 
adds to the complication of the phenomena of progressive motion occasioned by 
secular change. The influence of the one hemisphere becomes of course more and 
more effective on the phenomena of the other, as the line which separates the mag- 
netic hemispheres is approached : it is this circumstance which renders the pheno- 
mena in the equatorial regions of the globe so much more complicated than else- 
where, so much more difficult to disentangle, and consequently so much less suited 
to conduct readily to a comprehension of laws. It has been justly said that meteoro- 
logical phenomena should be studied, in the first instance, in the tropical rather 
than in the temperate zones, because they present themselves under a simpler aspect: 
the contrary is true in respect to the magnetical phenomena, both in the distribution 
of the Force at a particular epoch, and in the order and succession of secular changes, 
which nowhere appear so complicated as in the lower magnetic latitudes, where they 
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