MANGROVE ISLETS. 151 



is called in the chart Middle Island. The well is on 

 the south point, and the water, which is very good, 

 rises and falls with the tide. Doubtless this must 

 have been the island on which the crew of Pelsart's 

 ship found water, though for some time they were de- 

 terred from tasting it by observing its ebb and flow, 

 from which they inferred it would prove salt. The 

 north point of Gun Island, which our observations 

 placed in lat. 28" 53' 10" S., long. 1" 53' 35" W. of 

 Swan River, is fronted for half a mile by a reef. 



The ship was now moved to the north-east ex- 

 treme of the lagoon, to which we crossed in 17 

 fathoms, — the depth we anchored in, a mile north- 

 west from a cluster of islets covered in places with 

 mangroves, from which they receive their name. 

 To the southward the depth in the lagoon, as far as 

 a square looking island, was 15 and 16 fathoms. 

 The north extreme of the south island lay three 

 miles to the south east of the Mangrove Islets, 

 by which we found that its length was nearly ten 

 miles, with a general width of about a tenth of a 

 mile. 



One of the eastern Mangrove Islets was a mere 

 cay, formed of large flat pieces of dead coral, of the 

 same kind as that of which I have before spoken as 

 resembling a fan, strewed over a limestone founda- 

 tion one foot above the level of the sea, in the 

 greatest possible confusion, to the height of five 

 feet. In walking over them they yielded a metallic 

 sound. Pelsart, like Easter Group, is marked by 



