FIFTH REPORT- 1835. 
meridians of America, and the variation will have become, first 
zero, and then easterly. 
. As a moved south-westward in the Pacific, it must have been 
followed by the lines of easterly variation in the Southern Atlan¬ 
tic ; and the westerly variation shown in the Indian Ocean in 
the map of 1600, must have progressed to the westward as a re¬ 
ceded, and A advanced. 
The motion of the small system of westerly variation from 
North-east Asia in 1770 and 17^7} towards Corea and Japan 
where it was found in 1805, is explained by the eastern progress 
of h > 
Our knowledge of the lines of variation in the Pacific is con¬ 
fined to recent dates : the phenomena, however, as represented 
in the map of 1787 and in subsequent maps, are in all particulars 
accordant with the explanation of them afforded by the hypothesis 
of two magnetic axes. 
Viewing next the phenomena of the dip, we may infer that 
the south dip in South America decreases, because a is moving 
further into the Pacific; and the north dip in Europe decreases, 
because h is moving further eastward in Siberia. The great dips 
(from 844° to 89^-°) observed by Hudson at and near the North 
Cape and Nova Zembla in 1608 were occasioned by the vicinity 
of b , which was, at that epoch, to the north-east of Spitzbergen. 
In Europe the dip will shortly again increase as B approaches 
our part of the world. The north dip in China increases, and 
the south dip in the same longitudes decreases, because h ap¬ 
proaches the meridians of that quarter;' and for the same reason 
the line of no dip, which was observed by Cunningham in the 
Chinese Sea in 20° north latitude in 1700, is now found con¬ 
siderably to the south of that parallel. 
Proceeding next to consider the intensity of the magnetic force 
at different parts of the earth’s surface corresponding to the two 
magnetic axes, we must first remember that the axes are supposed 
to be chords, and that in their present position they are both nearer 
to the surface of the Pacific than to that of the opposite hemi¬ 
sphere, i. e. than to the continents of Europe and Africa. Aline 
drawn from the centre of the earth perpendicularly on the axis A 
B, and prolonged, wouldmeet the earth’s surfaceat a point inabout 
197 c E., and near the equator. This would be the nearest point 
on the earth’s surface to the middle of the stronger axis; and a 
point 180° from it, i. e. about 17° E., (on the continent of Africa, 
not far from the Bight of Benin,) would be the point on the earth’s 
surface most distant from the middle of that axis ; and here ne¬ 
cessarily would be the minimum of intensity if this axis were 
the only one. But a line drawn from the earth’s centre perpen- 
