feet. Those of the second class
are of crystallised limestone, and vary in height from one hundred to
five hundred feet. The hills on these are not so wild or broken as
those of the first class, but are richly clothed with vegetation, and
very beautiful. I have no doubt that the Coral Island on which you were
wrecked was one of this class. They are supposed to have been upheaved
from the bottom of the sea by volcanic agency; but they are not
themselves volcanic in their nature, neither are they of coral
formation. Those of the third class are the low coralline islands,
usually having lagoons of water in their midst. They are very numerous.

"As to the manner in which coral islands and reefs are formed, there are
various opinions on this point. I will give you what seems to me the
most probable theory--a theory, I may add, which is held by some of the
good and scientific missionaries. It is well known that there is much
lime in salt water; it is also known that coral is composed of lime. It
is supposed that the polypes, or coral insects, have the power of
attracting this lime to their bodies, and with this material they build
their little cells or habitations. They choose the summit of a volcano,
or the top of a submarine mountain, as a foundation on which to build,
for it is found that they never work at any great depth below the
surface. On this they work. The polypes on the mountain-top, of
course, reach the surface first; then those at the outer edges reach the
top sooner than the others between them and the centre, thus forming the
coral reef surrounding the lagoon of water and the central island.
After that, the insects within the lagoon cease working. When the
surface of the water is reached, these myriads of wonderful creatures
die. Then birds visit the spot, and seeds are thus conveyed thither,
which take root and spring up and flourish. Thus are commenced those
coralline islets of which you have seen so many in these seas. The
reefs round the large islands are formed in a similar manner. When we
consider," added the missionary, "the smallness of the architects used
by our heavenly Father in order to form those lovely and innumerable
islands, we are filled with much of that feeling which induced the
ancient king to exclaim, `How manifold, O Lord, are Thy works! in wisdom
hast Thou made them all.'"

We all heartily agreed with the missionary in this sentiment, and felt
not a little gratified to