and we mean to keep her. You'll have to run her or show us how."

"Never!" cried the professor.

"I guess he will when he feels this," said one of the men, as he
dragged from a recess two wires. "I happen to know something of
electricity, and when he feels these perhaps he'll change his mind.
I'll start the dynamo."

The sailor showed that he was acquainted with machinery, for soon the
hum of the electric apparatus was heard.

"Now to make him tell!" the man with the wires exclaimed, advancing
toward the professor, who turned pale.

"Stop! You must not torture the old man!" cried a voice, and the mate
of the Good Hope stepped in front of the sailor with the electrified
wires.

"Who's going to stop me?" asked the man.

"I will. It's not necessary," the mate went on quickly. "If we make
him weak we may kill him, and he can not tell us what we want to know.
One of the boys can tell us how to run the ship."

The mate came quickly over to where Mark lay, and whispered:

"Consent to tell. It is the only way of saving his life. Tell 'em how
to raise the craft. Then leave all to me. I will save you all and the
ship, too, if I can. But consent."