ith a start and realized
that he had been dozing.

"Come, come," he remarked to himself, "this will not do at all. This is
a fine way to watch for a ghost."

He remained wide awake for perhaps five minutes. Then he was off to the
land of nod again. He was just dreaming that he was skating on a pond
and was playing snap the whip with a lot of boys, when he awoke with a
start.

He felt something pressing on his chest and to his horror, as he looked
up, he saw a big towering white object standing over him. A second
glance showed him it was a man, or the semblance of one, and the thing's
foot was on his chest.

With a terrified scream Jack sprang up, upsetting the ghost, which, the
boy thought at the time, seemed rather heavy for an unearthly spirit.

"Did you catch it?" cried the professor.

"No! Yes! I don't know!" yelled Jack, struggling to his feet in time to
see the white object glide down the stairs that led from the conning
tower into the forward cabin.

"Run after it! We must solve the mystery!" cried Mr. Henderson springing
from the companionway up on deck.

But at that moment the ship began to whirl about in a circle slowly at
first, but with increasing speed until Jack and the professor felt sick
and dizzy. All about the water seemed to be bubbling and boiling, while,
at the same time, there arose on the air a mournful howl.

The professor jumped to the rail and looked over the side. What he saw
made him recoil with horror.

"Quick! Close the man-hole hatch!" he cried. "Shut the door of the
conning tower!"

"What is it?" Jack managed to ask.

"We are caught in a whirlpool!" Mr. Henderson yelled as he leaped down
the companionway and pulled the heavy steel cover after him.

Stricken with a nameless dread, Jack closed the water-tight door of the
conning tower and made his way to the cabin. He could hardly get down
the stairs, so swiftly was the ship whirling about.

He found the captain busy in the engine room and, in response to calls,
Washington and Mark came hurrying in. They had been awakened by the
commotion and the strange movements of the _Porpoise_.

"Turn on all the lights," ordered the inventor. "We must prepare for the
worst."

The incandescents were soon glowing and in the glare the frightened
adventurers gathered about Mr. Henderson, wondering what new terror had
befallen them.

"See!" exclaimed the inventor. "We are going comparatively slow now, but
we are on the outer edge. Wai