Ch. II. 
BARRIER REEFS. 
65 
in the large published charts. It has long been 
remarked, even from the time of Dampier, that a 
considerable degree of relation subsists between the 
inclination of that part of the land which is beneath 
water and that above it : hence the dotted line in the 
three sections is probably a moderately accurate repre- 
sentation of the actual submarine prolongation of the 
land. If we now look at the outer edge of the reef 
No. 4. 
South. North, 
1 — Vanikoro, from the Atlas of the Voyage of the Astrolabe, by 
D. D’Urville. 
2 — Gambier Island, from Beechey. 
3— Maurua, from the Atlas of the Voyage of the Coquille, by 
Duperrey. 
The horizontal line is the level of the sea, from which on the 
right hand a plummet descends, representing a depth of 200 fathoms, 
or 1,200 feet. The vertical shading shows the section of the land, 
and the horizontal shading that of the encircling barrier-reef ; from 
the smallness of the scale, the lagoon-channel could not be repre- 
sented. 
A A — Outer edge of the coral-reefs, where the sea breaks. 
B B — The shore of the encircled islands. 
