220 CORALS AND CORAL ISLANDS. 
sixteen miles southwest of the same southern reef, giving a 
slope of 1:5°4. The soundings are too few for a decision as 
to the maximum slope. 
The emerged land, about fifteen miles long, is confined 
to the side facing southeast, excepting a single isolated rock, 
or group of rocks, on the north side (between ¢ and d on the 
map) called North Rock. It is broken into a hundred and 
fifty or more islets, and the surface is made up of hills and 
low basins. The highest point, Sears’ Hill (E), is, according 
to Lieutenant Nelson, two hundred and sixty feet in eleva- 
tion above the sea, and Gibbs Hill (D), the site of the light- 
house, two hundred and forty-five feet. Wreck Hill (F), near 
the western point of the principal island, is about one hundred 
and fifty feet high, and North Rock 1s sixteen feet high, above 
mean tide. H is the position of Hamilton, the seat of Govern- 
ment, and G, of St. George’s, the other principal town. A 
(Castle Harbor), B (Harrington Sound), and C (Great Sound) 
are three encircled bays, looking as if once the lagoons of sub- 
atolls in a Maldive-like compound atoll. The surface, about 
half way between the sounds A and B, is low. Most of the 
land is covered with cedars where not cultivated or given 
over to loose sand. The last island of the southern hook is 
Ireland Island. 
The greater part of the old atoll is still a submerged reef. 
But it is of the typical form, in having a large lagoon-like 
depression enclosed within a relatively narrow border. Its 
border is mostly from one to three fathoms under water at 
low tide, though in some parts laid bare at the ebb. It has 
open channels at a, called the Chub cut; b, Blue cut, shallow; 
ce, N. W. Channel; d, N. E. Channel ; e, Mills’ Breaker Chan- 
nel ; f, the channels affording the nearest routes to Murray 
Anchorage and St. George’s Harbor; g, Channel by St. 
