It was a regular noise.

It had the rhythm of a quick footfall, but in its nature it was more like the sound of a heavily beating pulse.

Randall Byrne sat up in his chair.

A faint creaking attested that it was, indeed, a footfall traversing the room to and fro, steadily.
The stranger, then, no longer leaned over the couch of the old cattleman.

He was walking up and down the floor with that characteristic, softly padding step.