Blood beat against the back of his eyes. He heard drumming in his temples and straightened suddenly, thinking it the footsteps of Redhelms. Then, grinning sardonically, he bent to his work again, and this time the handle moved. Beneath him the door slid down and swung aside, and the darkness below gave place to soft light. He saw a long tube stretching down vertically, with pegs protruding from the metal walls at regular intervals. It made a ladder. The bottom of the shaft was thirty feet below; its diameter was little more than the breadth of a big man's shoulders. * * * * * He stood still for a moment, looking down, his mind almost swimming with wonder and surmise. Old, very old it must be, for the stream had cut its own bed out of the rock whose walls rose above him now. Old--and yet these metal surfaces gleamed as brightly as they must have gleamed on the day they were put together--for what purpose? The wind sighed again down the canyon, and Dantan remembered the Redhelms on his track. He looked around once more and then lowered himself onto the ladder of metal pegs, testing them doubtfully before he let his full weight come down. They held. There might be danger down below; there might not. There was certain danger coming after him among the twisting canyons. He reached up, investigated briefly, and swung the door back into place. There was a lock, he saw, and after a moment discovered how to manipulate it. So far, the results were satisfactory. He was temporarily safe from the Redhelms, provided he did not suffocate. There was no air intake here that he could see, but he breathed easily enough so far. He would worry about that when the need arose. There might be other things to worry about before lack of air began to distress him. He descended. At the bottom of the shaft was another door. Its handle yielded with no resistance this time, and Dantan stepped across the threshold into a large, square underground chamber, lit with pale radiance that came from the floor itself, as though light had been poured into the molten metal when it had first been made. The room-- Faintly he heard a distant humming, like the after-resonance of a bell, but it died away almost instantly. The room was large, and empty except for some sort of machine standing against the farther wall. Dantan was not a technician. He knew guns and ships; that was enough. But the smooth, sleek functionalism of this machine gave him an almost sensuous feeling of pleasure. How long had it been here? Who had built it? And for what purpose? He could not even guess. There was a great oval screen on the wall above what seemed to be a control board, and there were other, more enigmatic devices. And the screen was black--dead black, with a darkness that ate up the light in the room and gave back nothing. Yet there was something-- "_Sanfel_," a voice said. "_Sanfel. Coth dr'gchang. Sanfel--sthan!_