With great caution the huge prowler came onward, raising his head a few
inches every now and then and listening. The black man's nostrils moved
feverishly. He was using them, as a dog would have done, to scent any
signs of alarm on the part of the human quarry that he was after.

At last Harry Hazelton turned sharply, for his own ears were attuned to
the stillnesses of the western forests and his hearing was unusually acute.
He had just heard a sound on the wall, not far away. Instantly the young
engineer was on the alert.

Then his eyes, piercing the darkness, made out the crawling, dark form,
which did not appear to be more than fifty feet away from him.

For a second or two Harry stared. But he knew there could be no snake as
broad as this crawling figure appeared to be.

"Who's there?" Hazelton called quickly.

The writhing mass became still, flattening itself against the bed of rock.
Hazelton was not to be deceived, however.

"Who's there?" Harry repeated. "You had better talk up, my man!"

Still no sound. Harry started forward to investigate. His foot touched
against a good sized fragment of rock left there by one of the masons.

Without delay Harry reached down, picking up the rock, which was rather
more than half as large as his head.

Holding this in his right hand Harry advanced with still more confidence,