a dozen sacks of salt and a
few other supplies, such as a sailing craft of the kind usually carries.

In four days' time Frank had every movable article out of her, yet the
dreaded squall had not come nor a drop of rain fallen.

There lay the Sea Eagle, blistering under the sun by day and gauntly
outlined under the stars by night, changed in no way since she stranded,
except that she had settled quite two feet in the sand and was aground
so firmly that it looked as if it would take a pretty strong gale to
blow her to pieces.

So far, Frank had been too busy and too much engrossed by the novelty of
his situation to devote much time to thinking; but now, when the
excitement and hurry was over and he had leisure to turn his attention
to other matters, second only in importance to securing all there was of
value in the schooner, he concluded to make a thorough exploration of
the island and the grim, conical-shaped ledge of rocks that formed its
upper, or southern part.

So, the fifth day of his landing on the island, he got ready the small
boat, placed in it a bottle of water and a good supply of food, and set
out to row around the reefs.

He made a complete circuit of the island, and found it to be one of the
many results of volcanic eruption common throughout the Pacific Ocean
and the Caribbean Sea.

At low tide, a long, black reef showed its frowning edge above the
restless surf, connecting with the higher point of rocks overlooking the
narrow strip of fertile land lying between it and the sandy beach, where
the Sea Eagle had stranded, and still maintained the strange and lonely
anchorage she had made for herself.

Frank, curious and venturesome as he might be, was yet keenly alive to
hidden dangers, and, as he rowed around among the rocks, kept a sharp
lookout for treacherous currents and submerged ledges.

The meridian sun was pouring down its fiercest rays, and he was thinking
of returning to his tent and the grateful shade of the palm-trees, when,
just as he had rounded the jagged spur of a particularly ugly-looking
coral reef, he suddenly saw before him a deep, dark line of perfectly
smooth water, over-arched by a natural bridge of grayish-white
limestone, and flowing, as it seemed to him, directly under the island.

The entrance to this odd underground water-way was not more than four
feet in height by six wide, but he unhesitatingly entered the narrow
channel, bent upon seeing what there was of it and w