ator sent the call flashing through the air:

"Ventura! Ventura! Ventura!"

The instrument at Wilkins' side began to click.

"Ventura replying, sir," Wilkins reported.

"I hear him," said Jack briefly. "Let me get at that key, Wilkins."

The operator sprang up and Jack took his place and strapped the receiver
over his head.

"What's the trouble, Ventura?" he clicked.

"Held up by submarine," was the reply. "U-Boat due east of us. You can't
see her. We sighted you just after we were boarded."

"Then how does it come you are at the key?" Jack clicked.

"Broke away from captors on deck. They are pounding at the door now."

"Have they sighted us?"

"They hadn't. There goes the door, Good-bye."

The flashes from the Ventura ceased. Jack sprang up and turned the
receiver over to the operator.

"Keep calling," he said. "If you pick the Ventura up again, let me know.
I'll send a man so you can report to me through him."

Jack hurried on deck.

In the distance the Ventura was plainly visible now. Jack changed the
course of the ship slightly, and after the vessel had gone half a mile he
made out the form of a submarine lying close astern of the Ventura.

"By George! They must see us," he muttered. "If the lookout on the U-Boat
hasn't espied us, surely some of the Germans on the deck of the Ventura
must have done so. Wonder why the submarine captain doesn't sink the
steamer and submerge. Surely he is not going to risk an encounter with
me."

Nevertheless, it seemed that such must be the submarine commander's
intention, for the submarine showed no sign of submerging as the Essex
bore down on her.

Through his binoculars Frank was now able to ascertain the fact that a
struggle was in progress on the deck of the Ventura. A dozen or more
figures, closely interlocked, were scuffling to and fro across the bridge.
Frank gave an exclamation.

"I know what's wrong," he ejaculated.

"Well, what?" demanded Jack, turning to him.

"Why, the crew, or some of the crew, has jumped the commander of the
submarine and his escort. That's why the officer left on the U-Boat
doesn't dare sink the vessel. And the crew of the steamer is keeping the
German and his friends so busy aboard that they haven't had a chance to
jump overboard."

"By George! I guess you're right," declared Jack. "Now if they can hold
them fifteen minutes longer we'll get in the game ourselves."

Again Jack altered the course of the Essex and approached