442 KEELING ISLAND. [CHAP. xx. 



nificant 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 symmetrical structure. 

 Let the hurricane tear up its thousand huge fragments ; yet what 

 will that tell against the accumulated labour of myriads of archi- 

 tects 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 did not return on board till late in the evening, for we stayed 

 a long time in the lagoon, examining the fields of coral and the 

 gigantic shells of the chama, into which, if a man were to put his 

 hand, he would not, as long as the animal lived, be able to with- 

 draw it. Near the head of the lagoon, I was much surprised to 

 find a wide area, considerably more than a mile square, covered 

 with a forest of delicately branching corals, which, though standing 

 upright, were all dead and rotten. At first I was quite at a loss to 

 understand the cause ; afterwards it occurred to me that it was 

 owing to the following rather curious combination of circumstances. 

 It should, however, first be stated, that corals are not able to 

 survive even a short exposure in the air to the sun's rays, so that 

 their upward limit of growth is determined by that of lowest water 

 at spring tides. It appears, from some old charts, that the long 

 island to windward was formerly separated by wide channels into 

 several islets; this fact is likewise indicated by the trees being 

 younger on these portions. Under the former condition of the reef, 

 a strong breeze, by throwing more water over the barrier, would 

 tend to raise the level of the lagoon. Now it acts in a directly con- 

 trary manner; for the water within the lagoon not only is not 

 increased by currents from the outside, but is itself blown outwards 

 by the force of the wind. Hence it is observed, that the tide near 

 the head of the lagoon does not rise so high during a strong breeze 

 as it does when it is calm. This difference of level, although no 

 doubt very small, has, I believe, caused the deatli of those coral- 

 groves, which under the former and more open condition of the 

 outer reef had attained the utmost possible limit of upward growth. 

 A few miles north of Keeling there is another small atoll, the 

 lagoon of which is nearly filled up with coral-mud. Captain Ross 



