128 THEORY OF THE FORMATION Ch. V. 



considerable changes have taken place recently in some 

 of the atolls in the Low Archipelago, appears certain 

 from the case of Matilda Island given in the last chapter. 

 With respect to Whitsunday and Gloucester Islands in 

 this same group, we must either attribute great inac- 

 curacy to their discoverer, the famous circumnavigator 

 Wallis, or believe that they have undergone a consider- 

 able change in the period of fifty-nine years between his 

 vo} 7 age and that of Captain Beechey's. Whitsunday 

 Island is described by Wallis as ' about four miles long, 

 and three wide,' now it is only one mile and a-half 

 long. The appearance of Gloucester Island, in Captain 

 Beechey's words, 1 c has been accurately described by its 

 discoverer, but its present form and extent differ mate- 

 rially.' Blenheim reef in the Chagos group, consists of a 

 water-washed annular reef thirteen miles in circumfer- 

 ence, surrounding a lagoon ten fathoms deep ; on its sur- 

 face there are a few worn patches of conglomerate coral- 

 rock of about the size of hovels ; and these Captain 

 Moresby considers as being, without doubt, the last 

 remnants of islets ; so that here an atoll has been con- 

 verted into an atoll-formed reef. The inhabitants of 

 the Maldiva Archipelago, as long ago as 1605, declared, 

 ' that the high tides and violent currents were always 

 diminishing the number of the islands : ' 2 and I have 

 already shown, on the authority of Captain Moresby, that 



1 Beechey's Voyage to the Pacific, chap, vii., and "Wallis's Voyage in 

 the Dolphin, chap. iv. 



2 See an extract from Pyrard's Voyage in Captain Owen's paper on 

 the Maldiva Archipelago, in the Geographical Journal, vol. ii. p. 84. 



