Free The Human Edge by Gordon R. Dickson Page B

way back to the door leading to the chamber where the prospecting machines were parked. To his surprise, it opened as he approached it. He slipped through into darkness.
    Immediately, the door closed behind him; and sudden panic grabbed him, when he found he could not open it from this side. Then, self-possession returned to him.
    By touch, smell, and memory, he made his way among the parked machines and down the corridor to the outside door. To his gratification, this also opened when he came close. He slipped through into cool, fresh outer air and a sky already graying with dawn. A few moments later, wet but free, he was back in the woods again.
    From then on, each night he returned. He found it was not necessary to do more than put any sizable object before the returning machine. It would stop to clear the path, and he could enter ahead of it. Then, shortly after he was inside, a box-collecting machine would open the inner door.
    Gradually, his fear of the machines faded. He came to hold them in a certain contempt. They always did the same thing in the same situation, and it was easy to trick or outmaneuver them.
    But the two inner doors of the machine area with the steps would not open to him; and he knew the upper parts of the pyramid were still unexplored by him. He sniffed at the cracks of these doors, and a scent came through—not of lubricating medium and metal alone, but of a different, musky odor that raised the hairs on the back of his neck again. He snarled at the doors.
    * * *
    He went back to exploring minutely the machine level. The sample boxes from the prospecting machines, he found, were put on conveyor-beltlike strips that floated up on thin air through openings in the ceiling—but the openings were too small for him to pass through. But he discovered something else. One day he came upon one of the machines taking a grille off the face of one of the immobile devices. It carried the grille away, and he explored the opening that had been revealed. It was the entrance to a tunnel or duct leading upward; and it was large enough to let him enter it. Air blew silently from it; and the air was heavy with the musky odor he had smelled around the doors that did not open.
    The duct tempted him, but fear held him back. The machine came back and replaced the grille; and he noticed that it fitted into place with a little pressure from the outside, top and bottom. After the machine had left he pressed, and the grille fell out into his hands.
    After a long wait, he ventured timorously into the tube—but a sudden sound like heavy breathing mixed with a wave of a strong, musky odor came at him. He backed out in panic, fled the pyramid, and did not come back for two days.
    When he came back, the grille was again neatly in place. He removed it and sat a long time getting his courage up. Finally, he put the grille up high out of reach of the machine which had originally removed it and crawled into the duct.
    He crept up the tube at an angle into darkness. His eyes were useless, but the musky odor came strongly at him. Soon, he heard sounds.
    There was an occasional ticking, then a thumping or shuffling sound. Finally, after he had crawled a long way up through the tube, there was a sound like a heavy puffing or hoarse breathing. It was the sound that had accompanied the strengthening of the musky odor once before; and this time the scent came strong again.
    He lay, almost paralyzed with terror in the tube, as the odor grew in his nostrils. He could not move until sound and scent had retreated. As soon as they had, he wormed his way backward down to the lower level and freedom, replaced the grille, and fled for the outside air, once again.
    But once more, in time he came back. Eventually he returned to explore the whole network of tubes to which the one he had entered connected. Many of the branching tubes were too small for him to enter, and the biggest tube he could find led to another grille from which the musky-smelling