STRUCTURE OF CORAL ISLANDS. 197 
four in diameter. The shore platform was much intersected 
by channels. 
Captain Hudson obtained soundings half a mile off in two 
hundred fathoms; the lead struck upon a sandy bottom, but 
was indented by coral. | 
Hull’s Island. — Lat. 4° 20’ 8. Long. 171° 15’ W. 
Trends northeast and southwest. Well wooded nearly all 
round ; but on leeward side the forest in patches, with breaks 
of bare coral. Lagoon narrow, without entrance. Width of 
island from sea to lagoon, one hundred to four hundred yards: 
width greatest at south end. Beach ten feet high. The soil 
of the island consisted of coral fragments and sand. Shore 
platform fifty to eighty feet wide; five or six feet of water 
over it at high tide. Cut up very irregularly by channels 
three to eight or ten feet wide. Observed small corals grow- 
ing on the bottom outside of the platform. Shores of lagoon 
shallow for fifty yards, and consisting of coral sand. Beyond 
this a slope covered with growing corals; the corals rather 
tender species of Madrepores. In the interior of the lagoon 
many knolls and large patches of coral. 
Swain’s. — (Fig. 8, page 168.) Lat. 11° 10’ S. Long. 
170° 52’ W. 1:3 miles by 2; shape nearly rectangular; 
trends east and west. No lagoon, but the centre a little 
lower than the sides. Surface covered with shrubbery and 
large trees, among the latter many cocoanuts; the centre 
more sparsely wooded. Height fifteen to eighteen feet, ex- 
_cepting on the middle of the western side, where the surface 
is covered with loose fragments of coral of small size; there 
appears to have been a former entrance to the lagoon at this 
place. Shore reef, or platform, one hundred yards in average 
width, and one hundred and fifty yards at the place where 
we landed. Beach high, ten to twelve feet. At lower part 
