Mark nodded his head, and the mate cried:

"I knew I could fetch 'em. I have hypnotic power. This boy will raise
the ship for us. Loosen his bonds, some of you."

Satisfied that they were now on the way to experiencing a new
sensation, the sailors took the ropes off Mark's arms and legs, and he
was allowed to rise. With a reassuring nod toward the professor he led
the way to the engine room, followed by half the men. He resolved to
start the gas machine slowly, so as to make the upward trip last
longer, thinking before it had gone far, some way of escape from the
mutineers might be found.

While a crowd of the sailors stood near him, Mark operated the
machinery in the engine room that started the gas generating, and set
the negative gravity apparatus working.

"You'd better not try any tricks on us," said one of the men in an
ugly tone of voice.

"I'm not going to," replied Mark. "If you go out on deck you will soon
see the ship leaving the water and mounting into the air."

"Some of you go," ordered a man with a big bushy red beard. "See if
the ship rises. When she begins to go up sing out. I'm going to stay
here and see how the young cub does it so I can work it myself."

Obeying the red-bearded man, who seemed to be a leader, several of the
sailors went out on the deck. It was quite dark, but there was a