176 
THE OCEAN WORLD. 
repose granted ; the long swell caused by the gentle hut steady action 
of the trade-winds, always blowing in one direction over a wide area, 
causes breakers almost equalling in force those during a gale of wind 
in the temperate regions, and which never cease to rage. It is impos- 
sible to behold these waves without, feeling a conviction that an island, 
though built of the hardest rocks- — let it be porphyry, granite, or 
quartz — would ultimately yield and be demolished by such an irre- 
sistible power. Yet these low, insignificant coral islets stand, and are 
victorious ; for here another power, as an antagonist, takes part in the 
contest. The organic forces separate the atoms of carbonate of lime, 
one by one, from the foaming breakers, and unite them into a symme- 
trical structure. Let the hurricane tear up its thousand huge frag- 
ments, yet what will that tell against the accumulated labour of 
myriads of architects at work night and day, month after month ? 
Thus do we see the soft and gelatinous body of a polypus, through 
the agency of the vital laws, conquering the great mechanical power 
of the waves of an ocean which neither the art of man nor the 
inanimate works of Nature could successfully resist.” 
We have said that madreporic or coralline formations affect three 
forms, to which the names of atolls, barrier reefs, and fringing reefs 
have been applied. We have spoken of atolls ; we shall now say a few 
words on barrier and fringing reefs. 
Barrier reefs are formations which surround the ordinary islands, or 
stretch along their banks. They have the form and general structure 
of atolls. Like atolls, the barrier reefs appear placed on the edge of a 
marine precipice. They rise on the edge of a plateau which looks 
down on a bottomless sea. On the coast of New Caledonia, ouly two 
lengths of his ship from the reef, Captain Kent found no bottom in 
a hundred and fifty fathoms. This was verified at G-ambior Island in 
the Pacific Ocean, in Qualem Island, and at many others. 
According to Mr. Darwin, the barrier reef situated on the western 
coast of New' Caledonia is four hundred miles long ; that along the 
eastern coast of Australia extends almost without interruption for a 
thousand miles, ranging from twenty or thirty to fifty or sixty miles 
from the coast. As to the elevation of the islands thus surrounded 
with reefs, it varies considerably. The Isle of Tahiti rises six thousand 
eight hundred feet above the level of the sea ; the Isle of Maurua to 
