"Been having a look at Rangiroa, eh," he remarked. "There's a kind of beauty about the atolls, especially on a moonlight night. Iriatai is the same sort of place, though on a much smaller scale. There's no other group in the world like the Paumotus: eighty lagoon islands, some of them of immense size, strung out northwest and south-east in a cluster a thousand miles long. Darwin believed that they were the peaks of a submerged mountain-range, on which the coral polyps have built, as the mountains sank little by little beneath the sea. The lagoons are accounted for on the ground that the polyps tend to die in calm water, and thrive best in the froth and spray of breaking seas. As time went on, you see, the ones on the outside would build higher and higher, while the ones inside would die. Then, as the island continued gradually to sink, with the live polyps all working in the wash of the sea along the outer run, a deepening lagoon would form inside--and there you have your atoll. The passes are believed to be caused by fresh water, the heavy rainfall of these latitudes, finding an outlet to the sea. Running out at low tide over the lowest portion of the reef, it kills the coral-builders and causes the slow formation of a pass, often deep enough to allow large vessels to enter the lagoon. "There was a day, perhaps, two thousand years ago, when the Paumotus lay lonely and uninhabited, spread out like a vast net, a thousand miles long and four hundred miles across, to catch the canoes of wanderers who had missed the higher and richer islands to the west. The Polynesians were daring seamen, but their methods of navigation were of the most primitive sort--by the stars, the clouds, the trade wind, and the flight of birds. Hundreds of their great double canoes with clumsy sails of matting must have left Samoa for the eastern groups, and some of them, missing the Cook Islands or Tahiti, of which they had only half-legendary accounts, fetched up along this chain of atolls. The Paumotan people of to-day are their descendants. The names of the islands still show the wonder of those ancient wanderers at the strange sea in which they found themselves, and the joy and relief the landfalls brought--'The Spread-out Heavens'; 'The Place of Rejoicing'; 'The Windward Rainbow'; 'The Land of Great Beacon-Fires.' But perhaps this doesn't interest you very much--I have a way of preaching when I start on the subject of the islands!" My uncle tilted his chair and smiled at me through a cloud of smoke.