ON THE MAGNETIC INTENSITY OF THE EARTH. 73 
geographical pole would have also two maxima and two minima. 
The New Holland curves inclose larger areas than the South 
American, indicating that the centre to which they more espe- 
cially belong is more powerful than the other. We have another 
indication of the same fact in the appearance in Van Diemen’s 
Land of an intensity exceeding 1°8, which in the other hemi- 
sphere we have seen to characterise distinctively the centre of 
primary influence. The coincidence in this respect in the two 
hemispheres is very striking ; not only is the highest intensity . 
yet observed in the one, (1°80 at New York,) matched by the 
nearly identical value of 1°82 at Hobart Town, but the geogra- 
phical latitudes of the two observations are also nearly identical, 
New York being in 40° 43' N. and Hobart Town in 42° 53'S. ; 
both being unexpectedly low latitudes in which to find such 
high intensities. 
With regard to the geographical positions of the centres in 
the southern hemisphere, the observations are yet too few 
and too distant from them to admit of their localities being 
assigned with any fair degree of approximation ; but by com- 
paring the observations in Southern Africa, and on the east 
coast of South America, with those of the corresponding paral- 
lels in the better known hemisphere, we are able to infer with 
considerable probability, that the southern centres are not only 
not in opposite points of the hemisphere,—that is to say, distant 
180 degrees of longitude from each other, measured both 
ways,—but that they are nearer to each other in the one diree- 
tion, and more distant in the other, than is the case with the 
centres of the northern hemisphere. We have seen that in 
the meridians of Europe, where the northern centres are widest 
apart, the lower intensities extend. greatly northward, occupy- 
ing latitudes which in all other parts of the hemisphere possess 
a higher intensity. In the southern the same thing takes place, 
but in greater degree. ‘The line of unity, once thought to 
be the minimum intensity on the globe, is found on either side 
the Atlantic in south latitudes exceeding 30°; whence we may 
conclude that in the higher latitudes of the southern Atlantic, 
a much lower intensity prevails generally than the lowest inten- 
sities in the same latitudes in the northern hemisphere; eviden- 
cing that the space between the influential centres is wider in that 
quarter of the southern, than in the corresponding quarter of 
the northern hemisphere. 
The converse of this should be found in the Pacific section. 
As the southerly inflection of the lines of low intensity in the 
South Atlantic is the greatest, so should their southerly in- 
flexion in the opposite section of the hemisphere be the least, 
of the inflections which these lines undergo in either hemi- 
