120 THEORY OF THE FORMATION Ch. V. 



flourish at a very limited depth, — and secondly, that 

 throughout areas of vast dimensions, none of the 

 coral-reefs and coral-islets rise to a greater height 

 above the level of the sea than that attained by matter 

 thrown up by the waves and winds. I do not make 

 this latter statement vaguely ; I have carefully sought 

 for descriptions of every island in the inter-tropical 

 seas; and my task has been in some degree facili- 

 tated by a map of the Pacific, corrected in 1834 by 

 MM. D'Urville and Lottin, in which the low islands 

 are distinguished from the high ones (even from those 

 much less than a hundred feet in height) by being 

 written without a capital letter. 1 I have also ascer- 

 tained, chiefly from the writings of Cook, Kotzebue, 

 Bellinghausen, Duperrey, Beechey, and Lutke regard- 

 ing the Pacific ; and from Moresby 2 with respect to the 

 Indian Ocean, that in the following cases the term 

 ' low island ' strictly means land of the height com- 

 monly attained by matter thrown up by the winds 

 and the waves of an open sea. If we draw a line 

 joining the external atolls of that part of the Low 



1 I have detected a few errors in this map, respecting the heights of 

 some of the islands, which will be noticed in the Appendix, where I 

 treat of coral -formations in geographical order. To the Appendix, also, 

 I must refer for a more particular account of the data on which the 

 following statements are grounded. 



2 See also Captain Owen's and Lieut. Wood's papers in the Geogra- 

 phical Journal, on the Maldiva and Laccadive Archipelagoes. These 

 officers particularly refer to the lowness of the islets; but I chiefly 

 ground my assertion respecting these two groups, and the Chagos 

 group, from information communicated to me by Captain Moresby. 



