Rorden was speaking, rather quickly and jerkily.

“You’ll have no difficulty in controlling the machine,” he said. “Did you see how it obeyed that thought of mine? I should get inside quickly in case the time delay is fixed.”

Alvin stepped aboard, placing his belongings on the nearest seat. He turned to face Rorden, who was standing in the barely visible frame of the doorway. For a moment there was a strained silence while each waited for the other to speak.

The decision was made for them. There was a faint flicker of translucence, and the walls of the machine had closed again. Even as Rorden began to wave farewell, the long cylinder started to ease itself forward. Before it had entered the tunnel, it was already moving faster than a man could run.

Slowly Rorden made his way back to the chamber of the moving ways with its great central pillar. Sunlight was streaming down the open shaft as he rose to the surface. When he emerged again into the Tomb of Yarlan Zey, he was disconcerted, though not surprised, to find a group of curious onlookers gathered around him.

“There’s no need to be alarmed,” he said gravely. “Someone has to do this every few thousand years, though it hardly seems necessary. The foundations of the city are perfectly stable-they haven’t shifted a micron since the Park was built.”

He walked briskly away, and as he left the tomb a quick backward glance showed him that the spectators were already dispersing. Rorden knew his fellow citizens well enough to be sure that they would think no more about the incident.

* * *

Alvin settled back on the upholstery and let his eyes wander round the interior of the machine. For the first time he noticed the indicator board that formed part of the forward wall. It carried the simple message:…

lys 35 minutes