unknown land, will not
soon again present itself.

SAIL FROM TENERIFE.

Having completed the necessary magnetic observations, and rated the
chronometers, we sailed from Tenerife, on the evening of the 23rd. It
should be noticed that the results obtained from our observations for the
dip of the needle, differed very materially from those given by former
observers: the experiments made by Lieutenant Grey in different parts of
the island, satisfied us that the variation could not be imputed to
merely local causes.

As in obedience to our instructions we had to examine and determine the
hitherto doubtful position of certain rocks near the Equator, about the
meridian of 20 degrees West longitude, we were obliged to take a course
that carried us far to the eastward of the Cape de Verd Islands; for this
reason we had the North-East trade wind very light; we finally lost it on
the 30th, in latitude 13 degrees 0 minutes North, and longitude 14
degrees 40 minutes West; it had been for the two previous days scarcely
perceptible.

The South-East trade reached us on the 8th of August, latitude 3 degrees
30 minutes North longitude 17 degrees 40 minutes West, and on the morning
of the 10th we crossed the Equator in longitude 22 degrees 0 minutes
West: when sundry of our crew and passengers underwent the usual
ceremonies in honour of old Father Neptune. A close and careful search
within the limits specified in our instructions justified us in
certifying the non-existence of the rocks therein alluded to: but before
we presume to pass any censure upon those who preceded us in the honours
of maritime discovery, and the labours of maritime survey, it will be
proper to bear in mind the ceaseless changes to which the earth's surface
is subject, and that, though our knowledge is but limited of the
phenomena connected with subterranean and volcanic agency, still, in the
sudden upheaval and subsidence of Sabrina and Graham Islands, we have
sufficient evidence of their vast disturbing power, to warrant the
supposition that such might have been the case with the rocks for which
our search proved fruitless. Nor are these the only causes that may be
assigned to reconcile the conflicting testimonies of various Navigators
upon the existence of such dangers; the origin of which may be ascribed
to drift timber--reflected light discolouring the sea, and causing the
appearance of broken water--or to the floating carcass of a whale, by
which I have m