true north and south points of the horizon. It appears clearly, from
what has been said, that in order to arrive at the certain knowledge of
the variation, and of the variation of that variation of the compass, it
is absolutely requisite to have from time to time distinct accounts of
the variation as it is observed in different places: whence the
importance of Captain Tasman's remarks, in this respect, sufficiently
appears. It is true that the learned and ingenious Dr. Halley has given
a very probable account of this matter; but as the probability of that
account arises only from its agreement with observations, it follows
those are as necessary and as important as ever, in order to strengthen
and confirm it.



CHAPTER III: REMARKS ON THE VARIATION OF THE NEEDLE.


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.