382 ON THE GROWTH OF 



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 or four miles long, affords shelter from the 

 south-east 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 1 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 1 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 vegetation ; 

 whilst others are overflowed with every returning tide. 



" It seems to me, that, when the animalcules which 

 form the corals at the bottom of the ocean cease to live, 

 their structures adhere to each other, by virtue either of 

 the glutinous remains within, or of some property in salt 

 water ; and the interstices being gradually filled up with 

 sand and broken pieces of coral washed by the sea, which 

 also adhere, a mass of rock is at length formed. Future 

 races of these animalcules erect their habitations upon 

 the rising bank, and die in their turn, to increase, but 

 principally to elevate, this monument of their wonderful 

 labours. The care taken to work perpendicularly in the 

 early stages, would mark a surprising instinct in these 

 diminutive creatures. Their wall of coral, for the most 



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



