254 KEELING ISLAND. 



force of the wind. Hence it is observed that the 

 tide near the head of the higoon does not rise so 

 higli during a strong breeze as it does when it is 

 cahii. This diflereuce of level, although no doubt 

 very small, has, 1 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 occunence 

 of this one stone, where every other particle of 

 matter is calcareous, certainly is very puzzling. 

 The island has scarcely ever been visited, nor is it 

 probable that a ship had been wrecked there. 

 From the absence of any better explanation, I came 

 to the conclusion that it must have come entangled 

 in the roots of some large tree ; when, however, I 

 considered the great distance from the nearest 

 land, the combination of chances against a stone 

 thus being entangled, the tree washed into the sea, 

 floated so far, then landed safely, and the stone, 

 finally, so embedded as to allow of its discovery, I 

 was almost afraid of imagining a means of transport 

 apparently so improbable. It was therefore with 

 great interest that I found Chamisso, the justly dis- 

 tinguished naturalist who accompanied Kotzebue, 

 stating that the inhabitants of the Radack Archi- 

 pelago, a group of lagoon-islands in the midst of 

 the Pacific, obtained stones for shar[:)ening their in- 

 struments by searching the roots of trees which are 

 cast upon the beach. It will be evident that this 



