PACIFIC OCEAN. 
201 
of between two and three hundred yards ; coloured red. 
Pitcairn Island, in the immediate neighbourhood, according 
to the same authority, has no reefs of any kind, although 
numerous pieces of coral are thrown up on the beach ; the 
sea close to its shore is very deep (see Zool. of Beechey’s 
Voyage, p. 164) ; left uncoloured. Gambler Islands (see 
Plate I. fig. 8) are encircled by a barrier-reef ; the greatest 
depth within is 38 fathoms ; coloured pale blue. Metia or 
Aurora Island lies N.E. of Tahiti, close to the large space 
coloured dark blue in the map ; it has been already de- 
scribed as an upraised atoll ; as it is said by Captain Wilkes 
(Narrative of U.S. Exploring Expedition, vol. i. p. 337) to 
be surrounded by fringing-reefs, in one part 500 feet in 
width, it has been coloured red. But I must remind the 
reader of the discussion in the sixth chapter, showing that 
if an upraised atoll were to subside again, the reef would 
probably retain for a long time or for ever, its fringing 
character, owing to the steepness of the submarine flanks. 
The Society Abchipeeago is separated by a narrow 
space from the Low Archipelago ; and in their parallel 
direction they manifest some relation to each other. I 
have already described the general character of the reefs 
of these encircled islands. In the atlas of the Coquille’s 
Voyage there is a good general chart of the group, and 
separate plans of some of the islands. Tahiti , the largest 
island in the group, is almost surrounded, as seen in Cook’s 
chart, by a reef from half a mile to a mile and a half from 
the shore, with from 10 to 30 fathoms within it. Some 
considerable submerged reefs, lying parallel to the shore, 
with a broad and deep space within, have lately been dis- 
covered on the N.E. coast of the island, (Naut. Mag. 1836, 
p. 264,) where none are laid down by Cook. At Eimeo the 
reef, ‘ which like a ring surrounds it, is in some places one 
or two miles distant from the shore, in others united to 
the beach ’ (Ellis, Polynesian Researches, vol. i. p. 18, 12mo. 
