Roger threw a leg over the branch and unslung his glasses. He was above the tops of the other trees on the bank, and mud, water and mangrove swamp lay well below. A patch of white far to the eastward in the swamp had caught his attention even before he raised the glasses to his eyes. Through the powerful lenses the phenomenon seemed at first to be composed of snow-white flowers growing upon the mangrove tops, but presently he saw that the patch was moving. Out of the sun-shot sky a cloud of tiny specks, white as the driven snow, were fluttering downward and settling upon the dark tops of the trees. Fascinated he watched the spectacle until the white patch had doubled in area and only a scatter of specks continued to add their mite to the countless number which had preceded them. "Egrets!" he cried aloud. "Millions of them. What a sight!" He was looking at one of the rarest sights beheld by men, a great egret rookery with its countless beautiful birds settling upon their nests for the night. He was about to turn his glasses elsewhere when an interruption seemed to take place in the snow-white patch. A cloud of gray smoke belched explosively up through its center. Another and another followed swiftly until six of the blasts had occurred. The dense mass of birds rose in fluttering flight and flew wildly up into the sky where the setting sun turned their spotless white to pink and gold. Only there remained upon the dark tops of the mangroves six small, ragged patches of white, the limp bodies of scores of the beautiful birds in each, where the strange smoke blasts had wrought their deadly work. "What's the good word; found a way out?" called Higgins from below. "Not yet." Payne dismissed the tragedy he had witnessed and moved his glasses in a slow arc to the north and east. "Look for running water," shouted Higgins. "That's our bet." "I know." Roger was scanning the mud field to the northward. "There must be high ground some place beyond," continued the engineer. "And if there is, there'll be a creek running into that mud. That would mean fresh water." "I see something that looks like high ground, all right," said Payne, studying a smudge of blue against the northern horizon. "But I don't see anything like running water." "It's got to be there," maintained Higgins. "In this soft mud it may be underground and you'd never see it."