The door was round, about four feet in diameter, and set in a flattened part of the wall with its lower edge tangent with the floor. Rods about two inches thick projected a hand's breadth at four, eight, and twelve o'clock. The markings around them suggested that each could be rotated to three different positions. Barnsley squatted on his heels to study these.
Noting that all the rods were set at the position he had learned to think of as "one," he reached out to touch the door. It felt slightly warm, so he allowed his fingertips to slide over the upper handle. A tentative tug produced no