"Drive on, kid," said Marta Lami. "The boojums are going to get us if we wait."
"Stop, look, listen, watch out for the cars," he quoted as they leaped down and both laughed.
The roadbed was as smooth as glass, the rail set flush with it. Judging that the best route was the one taking them upward Sherman turned to the right and they began climbing, hand in metal hand.
The track was on a curve as well as an ascent. After a few steps they were in complete darkness and could only feel their way along, running into the wall every few minutes. They climbed for what seemed hours. The tunnel continued dark, without branches, simply winding on and on. Finally, so quickly that Sherman missed his step, they reached a level place, rounded one more curve, and saw ahead of them a band of light across the track from some side-tunnel.
"Shall we try it?" he asked as they reached the opening.
"Might be another machine room," she said, "but let's go. This track is terrible. If I wasn't made of iron I'd have bruises all over."
He vaulted over the sill, reached down and hauled her after him. From behind them came the roar, sunk to a vague purring by the distance. They were in another granite-lined passage; one that went straight ahead for a few yards, then branched sharply. The right hand fork seemed to lead downward; automatically they took the other turn. A diffused radiance from somewhere high in the walls, as though the granite had been rendered transparent here and there, filled the whole place with shadowless light. For a time the passage ran level, then it climbed again, with another fork to the right, which dipped away from their level and which they again avoided. Of any other living being there was thus far no sign.
The passage began climbing again, in a tight spiral, this time.
"Good thing we're in training," remarked Marta Lami. "This is worse than the stairs in the Statue of Liberty."
"Oh, did you fall for climbing that, too?" asked Sherman.