"It may be buried deep."
A far-off sound caught Frank's ear. He started violently, because his nerves were already tautened by suspense.
"Did you hear that?" he asked.
Joe rested on the shovel.
"I heard something," he said doubtfully.
They listened, but the sound was not repeated.
"It might have been a fall of rock," said Frank. "It sounded like rocks striking against the walls of the shaft."
"It's just like my thinking I heard voices a while ago. This place is so silent and creepy it gets your nerves all unstrung."
"Maybe."
Joe resumed his shoveling.