of course, the shape of the circular land; and then, in the interior of
the circle, there is a pool of water, which is not very deep--probably
in this case not more than eight or nine fathoms--and which forms a
strange and beautiful contrast to the deep blue water outside. This
circular island, or atoll, with a lagoon in the middle, is not a
complete circle; upon one side of it there is a break, exactly like the
entrance into a dock; and, as a matter of course, these circular
islets, or atolls, form most efficient break-waters, for if you can only
get inside your ship is in perfect safety, with admirable anchorage in
the interior. If the ship were lying within a mile of that beach, the
water would be one or two thousand feet deep; therefore, a section of
that atoll, with the soundings as deep as this all round, would give
you the notion of a great cone, cut off at the top, and with a shallow
cup in the middle of it. Now, what a very singular fact this is, that
we should have rising from the bottom of the deep ocean a great pyramid,
beside which all human pyramids sink into the most utter
insignificance! These singular coral limestone structures are very
beautiful, especially when crowned with cocoa-nut trees. There you see
the long line of land, covered with vegetation--cocoa-nut trees--and you
have the sea upon the inner and outer sides, with a vessel very
comfortably riding at anchor. That is one of the remarkable forms of
reef in the Pacific. Another is a sort of half-way house, between the
atoll and the fringing reef; it is what is called an "encircling reef."
In this case you see an Island rising out of the sea, and at two or
three miles distance, or more, and separated by a deep channel, which
may be eight to twelve fathoms deep, there is a reef, which encircles
it like a great girdle; and outside that again the water is one or two
thousand feet deep. I spent three or four years of my life in cruising
about a modification of one of these encircling reefs, called a
"barrier reef," upon the east coast of Australia--one of the most