188 
VOYAGE TO THE 
greatly altered by circumstances, and 
the growth or age of the island. Those parts of the strip which are 
is?(i. ^®yond the reach of the waves are no longer inhabited by the animals 
that reared them, but have their cells filled with a hard calcareous 
substance, and present a brown rugged appearance. The parts which 
are still immersed, or are dry at low water only, are intersected by small 
channels and are so full of hollows, that the tide as it recedes leaves 
small lakes of water upon them . The width of the plain or strip of dead 
coral, in the islands which fell under our observation, in no instance ex- 
ceeded half a mile from the usual wash of the sea to the edge of the 
lagoon, and in general was only about three or four hundred yards. 
Beyond these limits, on the lagoon side in particular, where the coral was 
less mutilated by the waves, there was frequently a ledge, two or three 
feet under water at high tide*, thirty to fifty yards in width ; after which 
the sides of the island descended rapidly, apparently by a succession of 
inclined ledges formed by numerous columns united at their capitals, 
with spaces between them in which the sounding-lead descended several 
fathoms. This formation, though not clearly established as applying to 
all the islands, was so conspicuous in some as to justify the concluSon 
with regard to others. At Bow and Matilda Islands, I have been 
tolerably minute in ray descriptions of them, and it will be unnecessary 
here to repeat what has been said there ; but these two, as also Hen- 
derson’s Island, afford good examples of what I have been describino-. 
To enable the reader more readily to comprehend the nature of these 
singular formations, I subjoin a sketch and a section of a coral island, 
with the slope of the sides of several of them, laid down according to 
the soundings and the depths at which attempts were made to reach 
the bottom. 
REFERENCES. 
Fig. 1. 
AB Section of one side of the strip of coral inclosing the lagoon. 
C, C The lagoon, protracted according to the depth found at Gambler Island. 
DD Coralline in it. 
Z The Pacific. 
* At Bow Island, on the sea side, it was more. 
