They swerved east on Randolph Street. For a minute or two the yellow cab did not appear. It must have been caught behind some car or truck. But presently it rounded the corner and sprinted till it was again within about thirty yards of them, when it slowed down to their own pace.
Rockwell spoke through the tube to the chauffeur:
"That yellow cab!"
"I'll lose 'em!" the man replied, with reassuring confidence.
At the second corner he turned north again and sped across the Clark Street Bridge. The yellow cab also had business north of the river.
Their subsequent maneuvers were at first decidedly puzzling to Merriam and his fellow passengers, with the possible exception of Simpson. They sped around and around a rectangle of streets enclosing half a dozen squares, with one of its sides only one block from the River. On the shorter sides they sometimes lost the yellow cab, but on the longer stretches it always appeared in full and open chase behind them.
"What the devil!" cried Rockwell as their driver turned west for the fourth time on the southern, side of the rectangle--the street nearest the River.
Simpson spoke: "He's all right. It's the bridge trick."
No further explanation was necessary. Their chauffeur suddenly swerved south on Dearborn Street, making in a burst of speed for the River. The bridge bell was jangling its warning that traffic must stop for the opening of the bridge to let a steamer pass. Theirs was the last vehicle on the bridge. The bars dropped behind them. Looking back through the peephole window, our passengers had the satisfaction of seeing the yellow cab caught behind the bars, unable to follow them, unable even, because of other vehicles crowding behind, to turn out and make a detour to another bridge.
Rockwell excitedly seized the tube. "Good work!" he called. "I'll give you another ten for that."