104 SAND BANKS IN REEFS. 



fathoms, or between twenty and thirty feet. At this 

 depth the white sandy patches at the bottom could 

 be distinctly seen among the large dark masses of 

 living coral. Immediately beyond this the lead 

 sank to ten fathoms, where nothing could be seen 

 but the deep blue of the water. The outline of this 

 inner edge of the reef was irregularly indented by 

 spaces and narrow crevices, as it were, of blue water, 

 sometimes only a foot or two wide, and penetrating 

 several yards into the body of the reef, as if this 

 were an overhanging ledge, and you could see 

 through it into deeper water below. 



June 21. — In going out of the reefs this morning 

 by the opening we came in at last night, we sounded 

 immediately at its mouth, as soon as we could do so 

 with safety, but got no bottom with 280 fathoms of 

 line. In the afternoon we ran in and anchored 

 under a reef with another sand bank on it. These 

 sand banks are invariably on the lee side of the 

 reef they are upon, which shows the nature of their 

 origin. They are composed of the washings of 

 the broken coral swept by the tides and winds 

 towards the lee side of the reef, until that is made 

 the shallowest, then, when this is dry at low water, 

 the sand is piled up by the wind into a heap with a 

 sloping bank, till it is at last reared above high 

 water mark. 



June 24. — The Bramble being despatched to the 

 mainland in order to measure a meridian distance 

 between the Barrier and Cape Direction, I seized 



