whom it will be so essential to be on friendly terms. Such a person will
greatly assist in that object; but you will keep him on board no longer
than absolutely necessary, and you will take care to provide for his
return if the Beagle should not be able to carry him back.

GENERAL INFORMATION.

In such an extensive and distant survey, numerous subjects of inquiry,
though not strictly nautical, will suggest themselves to your active
mind; and though, from your transient stay at any other place, you will
often experience the mortification of leaving them incomplete, yet that
should not discourage you in the collection of every useful fact within
your reach. Your example in this respect will stimulate the efforts of
the younger officers under your command, and through them may even have a
beneficial influence on the future character of the navy.

It has been suggested by some geologists, that the coral insect, instead
of raising its superstructure directly from the bottom of the sea, works
only on the summits of submarine mountains, which have been projected
upwards by volcanic action. They account, therefore, for the basin-like
form so generally observed in coral islands, by supposing that they exist
on the circular lip of extinct volcanic craters; and as much of your work
will lie among islands and cays of coral formation, you should collect
every fact which can throw any light on the subject.

Hitherto it has been made a part of the duty of all the surveying vessels
to keep an exact register of the height of the barometer, at its two
maxima of 9, and its two minima of 3 o'clock, as well as that of the
thermometer at the above periods, and at its own day and night maximum
and minimum, as well as the continual comparative temperature of the sea