by the ringing of a bell and felt the vessel was coming to a
stop. They were still far beneath the surface; indeed, the boat
was resting on the bottom, for in the light of two or three
powerful search-lights they saw a wide succession of submerged
hills, vales, and rugged cliffs. Before them was a great
mountain-side and in it they saw the mouth of a dark tunnel. They
had scarcely noticed it before the vessel rose a little and
glided toward the tunnel and entered it. Through the glass walls
they could see that it was narrow, and that the ragged sides and
roof were barely far enough apart to admit them.

Suddenly one of the men came in and drew a curtain down behind
them, and, with a vexed look on his face retired.

When he was gone Johnston put his lips close to Thorndyke's ear
and whispered:

"Did you see that?"

"See what?"

"Just as he drew the curtain down I saw what looked to me like a
cliff of solid gold. It had been dug out into a cavern in which I
saw a vessel like this, and men in diving suits digging and
loading it."

This took the Englishman's breath away for a moment, then he
remarked: "That accounts for the heel-tap we found; who knows,
these people may be possessors of the richest gold and silver
mines on earth."