Ashton-Kirk examined the ring keenly; then the rays of the torch flashed over the wall, all about it. As it approached the floor once more he suddenly exclaimed: “Ah!” And down he went on his knees in the dust.
Scanlon, bending forward, saw a place at the edge of a great block of stone where a thick, greenish fluid had apparently oozed through.
“From the river, I guess,” he said. “We’re pretty close to it, you know.”
Ashton-Kirk touched the fluid with a finger tip; then he held out his hand toward his friend.
“Is the odour at all familiar?” he asked.
Scanlon sniffed, gingerly.
“By George!” exclaimed he. “Crude oil.” He stared at the other. “What’s it doing here?”
Ashton-Kirk arose to his feet.
“Take hold of the ring,” directed he. Bat did so. “Now pull.”
As Scanlon put his weight to the pull, he felt something give; to his astonishment the whole mass of stone before him turned smoothly upon an invisible pivot; before him was a dark opening bricked, and extending apparently for a long distance underground. For a moment or two Bat was too dumbfounded to speak, but at length he thrust his hands deep into his pocket and said: