a cunning look coming into his eyes.

"The hangman?" Darrin repeated.

"Oh, yes! I know! We all know. The English hang the crews of German
submarines. Our officers have told us all about it. You are wrong, too,
to hang us, for it is the knowledge that the English will hang us that
makes us fight more desperately when we are attacked."

"But the English will not hang you. You and your mates will be treated as
prisoners of war," Darrin assured him. "You will be well fed. You will
have some amusements. When spring comes you will have gardens to work in
and the flowers or vegetables that you raise will belong to you. It is a
stupid lie to tell you that the English hang you all. You will soon be on
shore, and in an English prison camp, and then you will know that you
have been lied to. You will enjoy finding yourself on shore, for you were
not often allowed to go ashore when you got back from these trips to take
on your next mine cargo at--"

It was a simple trap, but as Darrin paused, the seaman replied:

"No, we were not often allowed ashore in ----," naming the port.

The port that the seaman mentioned was the one Darrin had been trying to
get him to name. The German had unwittingly allowed himself to name the
base port from which the mines were shipped. As soon as the German
realized his blunder he used some bad language.

"That is all," said Dave Darrin. "You may go back to your mates, and by
daylight you will know that an English military prison is not at all a
bad place."

CHAPTER XVII

TRYING OUT THE BIG, NEW PLAN

"YOU see," Dave nodded to his brother officers, "the theory we had worked
out about the method of supplying mines to the submarine layers was the
right one. I think that we shall be able to show some results to the
admiral."

Dan was then instructed to remain to keep watch over the shoals, while
the "Grigsby" soon afterwards started for port, escorting the two prizes.

Before daylight the captured under-sea boats were duly turned over to the
British authorities. Darrin then sought the admiral, and, despite the
lateness of the hour, he was soon admitted.

"What do you need for your enterprise?" inquired the admiral after
listening attentively to the plan Dave had unfolded to him.

"Nothing but a dirigible, commanded by the right man," Dave explained.

"That ought not to be difficult," declared the British officer. "You
shall have what you want. Now, suppose we go over the chart, t