gh, 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
and air. This was done with the view of assisting to provide authentic
data, collected from all parts of the world, and ready for the use of
future labourers, whenever some accidental discovery, or the direction of
some powerful mind, should happily rescue that science from its present
neglected state. But those hours of entry greatly interfere with the
employments of such officers as are capable of registering those
instruments with the precision and delicacy which alone can render
meteorologic data useful, and their future utility is at present so
uncertain, that it does not appear necessary that you should do more than
record, twice a day, the height of the former, as well as the extremes of
the thermometer, unless, from some unforeseen cause, you should be long
detained in any one port, when a system of these observations might then
be advantageously undertaken. There are, however, some occasional
observations, which cannot fail of being extensively useful in future
investigations:

1. During the approach of the periodic changes of wind and weather, and
then the hygrometer, also, should find a place in the journal.