On the 6th of November, I was in 49 degrees 4 minutes south latitude, and
in the longitude of 114 degrees 56 minutes; the variation was at this
time 26 degrees westward; and, as the weather was foggy, with hard gales,
and a rolling sea from the south-west and from the south, I concluded
from thence that it was not at all probable there should be any land
between those two points. On November 15th I was in the latitude of 44
degrees 33 minutes south, and in the longitude of 140 degrees 32 minutes.
The variation was then 18 degrees 30 minutes west, which variation
decreased every day, in such a manner, that, on the 21st of the same
month, being in the longitude of 158 degrees, I observed the variation to
be no more than 4 degrees. On the 22nd of that month, the needle was in
continual agitation, without resting in any of the eight points; which
led me to conjecture that we were near some mine of loadstone.
This may, at first sight, seem to contradict what has been before laid
down, as to the variation, and the causes of it: but, when strictly
considered, they will be found to agree very well; for when it is
asserted that veins of loadstone have nothing to do with the variation of
the compass, it is to be understood of the constant variation of a few
degrees to the east, or to the west: but in cases of this nature, where
the variation is absolutely irregular, and the needle plays quite round
the compass, our author's conjecture may very well find place: yet it
must be owned that it is a point far enough from being clear, that mines
of loadstone affect the compass at a distance; which, however, might be
very easily determined, since there are large mines of loadstone in the
island of Elba, on the coast of Tuscany.