1836.] STONES TRANSPORTED BY TREES. 335 



almost equalling in force those during a gale of wind in the temperate 

 regions, and which never cease to rage. It is impossible to behold 

 these waves without feeling a conviction that an island, though built of 

 the hardest rock, let it be porphyry, granite, or quartz, would ultimately 

 yield and be demolished by such an irresistible 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 symmetrical ' structure. Let the 

 hurricane tear up its thousand huge fragments ; 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 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 withdraw 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 ; after- 

 wards 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 

 contrary 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 death 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 found 

 embedded in the conglomerate on the outer coast, a well-rounded 

 fragment of greenstone, rather larger than a man's head : he and the 

 men with him were so much surprised at this, that they brought it 

 away and preserved it as a curiosity. The occurrence of this one stone, 

 where every other particle of matter is calcareous, certainly is very 



