But lumber and iron were necessary for our water supply, and while the natives were busy with their housebuilding, we set to work to build a long low shed, with a gutter along the lower edge of the roof, from which tin piping would conduct the rain water to a series of large connected tanks. The drinking-nuts would never suffice for such a gathering, and fresh water was the one important thing the islet lacked. We relied on the rains to furnish our supply, and the shed was to serve as a store, and as a warehouse for our shells when that had been cleaned and sacked. The building was finished on a Saturday, and that night the men went out in their canoes to fish. They were all Christians and they kept the Sabbath more religiously than most of us at home. The missionaries who had converted them were of the strict old Calvinist school, which taught that it was sinful to fish, or plant, or to do any kind of work on the day of rest. My uncle respected the divers' beliefs, but he had communicated his own restless energy to the members of the Tara's crew, and on that Sunday, while the Paumotans dozed in the shade of their new houses, we took the whaleboat on an excursion to explore the diving-grounds. When we returned at sunset the others shook their heads--in their eyes we had reaped the reward of sacrilege, for our boating-party had come near to ending tragically. The lagoon was calm that morning, calm as an inland lake, its surface ruffled at intervals by faint catspaws from the north. Looking back toward the pass, there was no land in sight--the blue water met the sky in an unbroken line. Ahead of us, at the northern end of the atoll, the seabeach was little more than a mile away, and the thunder of the breakers was borne to our ears, now loud, now soft, on flaws of air. My uncle stood in the stern and I sat beside him; Fatu was in the bow, Ivi and Ofai at the oars. Once or twice Fatu motioned my uncle to change his course, to avoid the coral mushrooms rising to within a few inches of the surface, but in general the depth of the lagoon varied from six to twenty fathoms. Gazing down through the blue translucent water, I could see the strange forms of growing coral far beneath us; and sometimes, as the bottom turned sandy and the water shoaled, the lagoon shaded to purest emerald green. Clad only in a scarlet pareu, with his bronzed back and shoulders bare, Uncle Harry was leaning over the side, gazing intently at the bottom through a water glass. He had given the word to go slowly, and the men were resting on their oars. "This is the place," he said; "we'll anchor here and let Ofai go down for a look."