mbered over two hundred," Omar
answered.

But even as he had been speaking the water of the lake had so drained
away that its clean stony bottom was now revealed, the pebbles being
exposed in large patches here and there, while the deeper pools remaining
were alive with water-snakes and fish of all kinds. There seemed but
little mud, yet in the very centre of the great basin was a patch of
pebbles and rock higher than the remainder, standing like a small island
that, before the lever had been touched, had been submerged. Leading the
way, Omar descended to the edge of the lake, skirted it for some little
distance, until he came to a long row of flat stones placed together,
forming stepping-stones to the miniature island.

"Come," he said. "Follow me," and starting off we were soon crossing the
bed of the lake, being compelled to advance cautiously owing to the
slippery nature of the weeds and water-plants that overgrew the stones.
On gaining the island, however, a fresh surprise awaited me, for Omar,
halting amid the mud in the centre, exclaimed:

"Watch carefully, Scars. You may some day desire to act as I am acting;
but always remember that here any undue hurry means inevitable death."

"Death! What do you mean?"

"Wait, and you shall see," he replied, as stooping suddenly he turned up
the sleeves of his royal robe and groping with his hand in the mud, at
last discovered an iron ring, green with slime, which, grasping with both
hands, he slowly twisted many times. A hissing sound was emitted, as if
the action of untwisting the ring relieved some heavy pressure, admitting
air to a chamber that had been hermetically sealed. This surmise was, I
afterwards learned, correct. The unscrewing of this ring caused the sides
of a plate embedded in the mud to contract, and air, so long excluded,
entered the mysterious place below.

In a few moments, having paused to wipe the perspiration from his brow,
Omar, again grasping the slippery ring, gave it a sudden jerk and by that
means lifted the covering from a circular hole descending into an
impenetrable darkness, but bricked round like a cottage well in England,
and having projecting pieces of iron, forming steps.

"Now," exclaimed Omar, as together we peered into the mysterious opening.
"To descend at once would mean certain death."

"How? Is the air below foul?"

"Not at all. The ingenuity of my ancestor who constructed this place made
arrangements to avoid all that. Th