Commencing with the eastern part; the encircling reef round UALEN appears to be only about half a mile from the shore; but as the land is low and covered with mangroves ("Voyage autour du Monde," par F. Lutke, volume i., page 339), the real margin has not probably been ascertained. The extreme depth in one of the harbours within the reef is thirty-three fathoms (see charts in "Atlas of 'Coquille's' Voyage"), and outside at half a mile distant from the reef, no bottom was obtained with two hundred and fifty fathoms. The reef is surmounted by many islets, and the lagoon-like channel within is mostly shallow, and appears to have been much encroached on by the low land surrounding the central mountains; these facts show that time has allowed much detritus to accumulate; coloured pale blue.--POUYNIPETE, or Seniavine. In the greater part of the circumference of this island, the reef is about one mile and three quarters distant; on the north side it is five miles off the included high islets. The reef is broken in several places; and just within it, the depth in one place is thirty fathoms, and in another, twenty-eight, beyond which, to all appearance, there was "un porte vaste et sur" (Lutke, volume ii., page 4); coloured pale blue.--HOGOLEU or ROUG. This wonderful group contains at least sixty-two islands, and its reef is one hundred and thirty-five miles in circuit. Of the islands, only a few, about six or eight (see "Hydrog.
Descrip." page 428, of the "Voyage of the 'Astrolabe'," and the large accompanying chart taken chiefly from that given by Duperrey) are high, and the rest are all small, low, and formed on the reef. The depth of the great interior lake has not been ascertained; but Captain D'Urville appears to have entertained no doubt about the possibility of taking in a frigate. The reef lies no less than fourteen miles distant from the northern coasts of the interior high islands, seven from their western sides, and twenty from the southern; the sea is deep outside. This island is a likeness on a grand scale to the Gambier group in the Low Archipelago. Of the groups of low (In D'Urville and Lottin's chart, Peserare is written with capital letters; but this evidently is an error, for it is one of the low islets on the reef of Namonouyto (see Lutke's charts)--a regular atoll.) islands forming the chief part of the Caroline Archipelago, all those of larger size, have the true atoll-structure (as may be seen in the "Atlas" by Captain Lutke), and some even of the very small ones, as MACASKILL and DUPERREY, of which plans are given in the "Atlas of the 'Coquille's' Voyage." There are, however, some low small islands of coral-formation, namely OLLAP, TAMATAM, BIGALI, SATAHOUAL, which do not contain lagoons; but it is probable that lagoons originally existed, but have since filled up:
Lutke (volume ii., page 304) seems to have thought that all the low islands, with only one exception, contained lagoons. From the sketches, and from the manner in which the margins of these islands are engraved in the "Atlas of the Voyage of the 'Coquille'," it might have been thought that they were not low; but by a comparison with the remarks of Lutke (volume ii., page 107, regarding Bigali) and of Freycinet ("Hydrog. Memoir 'L'Uranie' Voyage," page 188, regarding Tamatam, Ollap, etc.), it will be seen that the artist must have represented the land incorrectly. The most southern island in the group, namely PIGUIRAM, is not coloured, because I have found no account of it. NOUGOUOR, or MONTE VERDISON, which was not visited by Lutke, is described and figured by Mr. Bennett ("United Service Journal," January 1832) as an atoll. All the above-mentioned islands have been coloured blue.
WESTERN PART OF THE CAROLINE ARCHIPELAGO.
FAIS Island is ninety feet high, and is surrounded, as I have been informed by Admiral Lutke, by a narrow reef of living coral, of which the broadest part, as represented in the charts, is only 150 yards; coloured red.--PHILIP Island., I believe, is low; but Hunter, in his "Historical Journal," gives no clear account of it; uncoloured.--ELIVI; from the manner in which the islets on the reefs are engraved, in the "Atlas of the 'Astrolabe's' Voyage," I should have thought they were above the ordinary height, but Admiral Lutke assures me this is not the case: they form a regular atoll; coloured blue.--GOUAP (EAP of Chamisso), is a high island with a reef (see chart in "Voyage of the 'Astrolabe'"), more than a mile distant in most parts from the shore, and two miles in one part. Captain D'Urville thinks that there would be anchorage ("Hydrog. Descript. 'Astrolabe' Voyage," page 436) for ships within the reef, if a passage could be found; coloured pale blue.--GOULOU, from the chart in the "'Astrolabe's' Atlas," appears to be an atoll. D'Urville ("Hydrog. Descript." page 437) speaks of the low islets on the reef; coloured dark blue.
PELEW ISLANDS.
Krusenstern speaks of some of the islands being mountainous; the reefs are distant from the shore, and there are spaces within them, and not opposite valleys, with from ten to fifteen fathoms. According to a MS. chart of the group by Lieutenant Elmer in the Admiralty, there is a large space within the reef with deepish water; although the high land does not hold a central position with respect to the reefs, as is generally the case, I have little doubt that the reefs of the Pelew Islands ought to be ranked with the barrier class, and I have coloured them pale blue. In Lieutenant Elmer's chart there is a horseshoe-formed shoal, laid down thirteen miles N.W. of Pelew, with fifteen fathoms within the reef, and some dry banks on it; coloured dark blue.--SPANISH, MARTIRES, SANSEROT, PULO ANNA and MARIERE Islands are not coloured, because I know nothing about them, excepting that according to Krusenstern, the second, third, and fourth mentioned, are low, placed on coral-reefs, and therefore, perhaps, contain lagoons; but Pulo Mariere is a little higher.
