ugh the man-hole. At
first he thought it was his queer midnight visitor returning. Then the
head and shoulders of Jack appeared.

"I've come to relieve you," said Jack. "Your watch is up; it's two
o'clock. Here are the night glasses. I found them on the cabin table. I
thought you had them with you."

"I did," replied Mark.

"Then how did they get below?"

"I--I don't know," said Mark.

The mystery was deepening, yet he did not want to tell Jack just yet.

"Well, that's queer," remarked Jack. "Maybe the captain came up and got
them while you were asleep."

"I didn't go to sleep," answered Mark rather crossly.

Jack said nothing more, but took his place in the conning tower, while
Mark went below. Thinking to discover if the ghost might by any chance
have been one of the persons on the _Porpoise_, Mark looked into each
bunk. From the captain to Washington, all the inmates were peacefully
slumbering.

"Queer," murmured Jack, as he took a look into the engine room before
turning in. The engine needed no attention, as it worked automatically,
and all there was to do was to steer the ship. Even this needed little
care as the course was a straight one, and the wheel could be locked,
leaving the lookout little to do.

"Did you see anything during your watch?" asked Mark of Jack the next
morning.

"See anything? What do you mean?"

"I mean anything unusual."

"Nothing, only a school of porpoises went past and gave me a little
scare. They were like a lot of water kittens at play."

Mark concluded he would say nothing of the white visitor until he
ascertained whether any one else had seen it.

It was several nights later, when the ship was once more proceeding
slowly along the surface of the water, that the ghost again appeared.
This time Washington had the midnight watch.

But the colored man was not one to remain quiet when he had such a scary
visitor, and his yells aroused the ship.

"It's a ghostess! A big white ghostess!" yelled Washington. "I don seen
it wid my eyes, an' it waved his arms at me. I's goin' to die suah!"

"What's all this nonsense?" demanded the professor sternly. Then
Washington, more or less excitedly, told of what he had seen. It was
just as it had happened to Mark.

"You were dreaming," said the professor to Washington. "There are no
such things as ghosts."

Every one, from old Andy to Tom and Bill, had been roused by
Washington's cries, and listened to his story. At the close of