ITS PROPERTIES A.ND DIVISIONS. 299 



neraliy long and narrow, they are formed by a narrow bar of 

 laud, inclosing the sea within it; generally, perhaps always, with 

 some iJian.iel of ingress at least to llie tide, commonly with an 

 opening capable of receiving a cauoe, and frequently sufficient to 

 admit even larger vessels. 



The origin of these islands will explain their nature. What led 

 Mi. Diilryinjxe first to tin's deduction, was an observation of Abdul 

 Roohiu, a Sooloo pilot; that all the islands, King off the N. E. 

 coast of Borneo, had shoals to the eastward of them. These islands 

 being covered to the westward by Borneo, the winds from that quar- 

 ter do not attack them with violence. But the N. E. winds, turn, 

 bling iu the billows from a wide ocean, heap up the coral with which 

 those seas are filled. This, obvious after storms, is perhaps at all 

 other times in-perctptibly effected. The coral banks, raised in the 

 ^ame manner, become dry. These banks are found at all depths 

 at all distances from shore, entirely unconnected with the land, and 

 detached from each otner : though it often happens that they arc 

 divided by a narrow gut, without bottom. 



Coral banks also grow, by a quick progression, towards the sur- 

 face ; but the winds, heaping up the coral from deeper water, 

 chiefly accelerate the formation of the.se into shoals and islands. 

 They become gradually shallower, and when once the sea meets 

 with resistance, the coral is quickly thrown up by the force of the 

 waves breaking against (he bank; and hence it is that, in the open 

 sea there is scarcely an instance of a coral bank having so little water 

 that a large ship cannot pa?s over, but it is also so shallow that a 

 boat would ground on it, Mr. D. has seen these coral banks in all 

 the stages; some in deep water, others with a tew rocks appearing 

 above the surlace, some just formed into islands, without the least 

 appearance of vegetation, and others, from such as have a few 

 weeds on the highest part to those which are covered with large 

 timber, with a bottomless sea at a pistol-shot distance. 



The loo>-e coral, roiled inward by the billows in large pieces, will 

 ground, and the reflux, beitig unaolq to carry them away, they be- 

 come a bar to coagulate the sand, always found intermixed with 

 coral; which sanU, being easiest raised, will be lodged At .top. 

 When the sand bank is raised by violent storms, beyond the reach 

 of common uaves, it becomes a resting place to vagrant birds, 

 whom the search of prey draws thither. The dung, feathers, c. 



