21*2 ON eORAL ISLANDS. 



The animalcules forming these reefs, went to shel- 

 ter their habitation from the impetuosity of the winds* 

 and the power and rage of the ocean ; but as, within the 

 tropics, the winds blow commonly from one quarter, 

 they, by instinct, endeavour to stretch only a ledge, with- 

 in which is a lagoon, which is certainly entirely screen- 

 ed against the power of both : this therefore might ac- 

 count for the method employed by the animalcules in 

 building only narrow ledges of coral roclss, to secure m 

 their middle a calm and sheltered place : and this seems 

 to me to be the most probable cause of THE ORIGIN of 

 all THE TROPICAL LOW ISLES, over the whole South 

 Sea. 



That excellent navigator, the late Captain Flinders, 

 gives the- following interesting account of the formation 

 of Coral Islands, particularly of Half-way Island on the 

 north coast of Terra Australis :* 



This little island, or rather the surrounding reef, 

 which is three of four miles long, affords shelter from 

 the southeast winds ; and being at a moderate day's run 

 from Murray's Isles, it forms a convenient anchorage for 

 the night to a ship passing through Torres' Strait: I 

 named it Half-way Island. It is scarcely more than a 

 mile in circumference, but appears to be increasing both 

 in elevation and extent. At no very distant period of 

 time, it was one of those banks produced by the wash- 

 ing up of sand and broken coral, of which most reefs af- 

 ford instances, and those of Torres' Strait a great many. 

 These banks are in different stages of progress : some, 

 like this, are become islands, but not yet habitable ; 



some are above high water mark, but destitute of vege- 

 ^ 



* Vol. II. p. 114, 115, 116. 





