of the lithophytes to fresh water is not singular, as, independent of its
not being the natural element of those animals, it probably supplies no
materials with which they can work.
It has been suggested, that these openings being opposite to valleys,
the continuation of them under water is the cause of the break in the
reef. But when we consider the narrowness of these openings, compared
with the width of the valleys, and that the latter are already filled
up to the surface and furnished with a smooth sandy beach, many
obstacles will be found to the confirmation of such an opinion ; and
it appears to me more reasonable to attribute it to the nature of the
element. The depth of these channels rarely exceeds twenty-five feet,
the greatest limit probably to which the influence of fresh water would
be felt.
Henderson Island, one of the exceptions mentioned in the early
part of this discussion, is among the rare instances of its kind iu these
seas. It is an island composed of dead coral, about eighty feet above
the sea, with perpendicular cliffs nearly all the way round it, as if after
being formed in the ocean it had been pushed up by a subterraneous
convulsion. These cliffs are undermined at the base, as though the sea
had beaten against them a considerable time in their present po.sition.
There are no marks upon them indicative of the island having risen
by degrees ; but, on the contrary, a plain surface indicating its ascent by
one great effort of nature. On examining the volcanic islands near
Henderson Island, no traces appeared of the sea having retired ; and we
may, therefore, presume it to have risen as described. Its length is five
miles, and breadth one mile ; it is nearly encompassed by a reef of living
coral, so wide that the cliffs, which were at first subjected to the whole
force of the waves, are now beyond the reach even of their spray.
The navigation of this archipelago was made at a period of the
year when the westerly monsoon was about to commence, and toward the
end of which it had actually begun, and materially retarded our operations;
but previous to that time, or about the beginning of March, the
trade was fresh and steady, blowing between S. E. by E. and E. N. E.,
which is more northerly than the direction of the same trade between
corresponding parallels in the Atlantic. In consequence of this opposition
to the trade wind the currents were very variable, sometimes
setting to the eastward, and at others in the opposite direction ; and
on the whole, the body of water at that period is not drifted to the
westward with the same rapidity that it is in other parts of the ocean
within the influence of the tropica! winds. The mean temperature
for the above-mentioned period, the weight and humidity of the atmosphere,
with other meteorological observations, are given in the Appendix
under their respective heads.
For the information of persons who may traverse this arclupelago,
it is evident from the account of Tuw'anl, that there is a small island
situated about halfw'ay between Byam Martin and Barrow Islands,
which was not seen by us ; and hence it is possible that there are other
low islands lying between the tracks of the Blossom which were not seen;
and ships ought in consequence to keep a vigilant look-out during the
night, or adopt the precaution of lying to when the weather is dark or
thick. The lead is no guide whatever in these seas, and the islands are so
low that in the night the white line of the surf or the roar of the breakers
w'ould give the first warning. Fallacious as the appearance of birds is
generally considered, and in some parts of the globe justly so, in this
archipelago, wlieii seen in flocks, it is an almost certain indication of
land. They range about forty miles from the islands, and consist principally
of black and white tern. This, however, applies particularly to
uninhabited islands; for when they become peopled, the birds generally
quit them, and resort to those where they are less molested.
At day-light on the 15th the island of Maitea was seen in the
north west, and soon afterwards the mountains of Otaheite appeared
five minutes above the horizon at the distance of ninety miles, from
which its height may be roughly estimated at 7000 feet. As we passed
Maitea we had an opportunity of verifying its position and ascertaining
its height to be 1432 feet. Baffling winds prevented us from reaching
our port until the evening of the 18th, when, at the suggestion of Captain
Charlton, his majesty's consul for the Society and Sandwicli Islands,
from whom w e liad the pleasure of receiving a visit, we anchored in the
outer harbour of Toanoa, about four miles to the westward of Matavai
Bay.
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