Hour followed hour while the gray New England coast slid back like a great map beneath him, the sun sinking ever to the horizon westward as he roared on. Hardly conscious of more than the steady, even song of the motor and the rush of wind about him, Ralton checked his progress automatically by the natural features of the coast below him, and at last was flying northward over the tangle of deeply indented bays and islands that forms the Maine coast, veering outward from it over the gray waters to the east, and peering intently for Cone Island. The sun had dipped to the horizon, by then, but he knew from Mallett's account that the island should be clearly discernible by reason of the gigantic squat cone of rock that rose from its level sands. Dusk was dropping upon the world, though, and Ralton had become slightly anxious before he glimpsed it at last, a huge, dark, squat cone, its broad summit flattened as though by some giant hand, that seemed to rise directly out of the gray waters miles from the coast. It was with a feeling of some relief that he sent his plane circling down toward the place, and as it loomed larger beneath him in the failing light he scanned it closely. The island itself, he saw, was roughly circular, perhaps a dozen miles across, a barren, level stretch of sands from whose center the great squat cone of rock arose, a curious formation frequent on such islands and carved out by the wind-driven sands. The cone's steep sides of rock, almost vertical, could not be more than a few hundred feet in height, Ralton estimated, but its broad, flat summit was several times that in diameter. And now, as he wheeled down toward that summit, he saw that upon it were the laboratories of the men he sought, long, low buildings of white concrete grouped in a rough circle about the summit. The circle enclosed by the buildings, though, save for some great looming object at the center which he could but vaguely make out, was clear and flat, and seemed to Ralton of sufficient extent to permit the landing of his little plane. Carefully wheeling again over the place, he spiraled slowly down toward it. Even through the dusk he could see that no human figures were visible beneath, though from one of the buildings came a white spark of light. Downward still he circled, therefore, until at last he was dipping gently into the open clearing at the summit's center, running along over its smooth rock surface for a few seconds and then coming to a stop just before one of the encircling buildings. A moment more and Ralton had clambered forth and stood gazing into the dusk about him.