"Now, what on earth does the 'Old Man' want?" wondered Runkle, as he started away on this errand. "But never mind. Even if I can't guess what he wants it's a cinch that he knows. The stupidest one, eh? I wonder why any Fritz wouldn't do, then!"

Runkle found his man within five minutes, detached him from the other prisoners, and led him to the chart-room. Darrin tried his own German on the fellow, asking:

"Your craft had just arrived from the base port?"

The man stared, then slowly nodded.

"How many mines did you have on board when you left the base port?"

"Thirty, I heard."

"You planted some on the way?"

"A few, so I heard."

"Most of the mines you were to deliver here tonight?"

"Yes."

"How many trips a week has your craft been making between here and the base port?"

"Usually about four."

"Did you always deliver, here, to the same mine-layer?"

"No; that was as it happened. Sometimes to one boat, sometimes to another."

"How many mines could your craft carry?"

"Thirty."

As this agreed with the information supplied by Ensign Andrews, Dave believed that the seaman was telling the truth.

"Did your craft always come to these same waters to deliver mines to mine-layers?"

"Always, since I have been aboard, to some one of the shoals in this stretch of them," replied the sailor.

"Do you know how many mine-layers wait over here on the English side to have mines delivered to them?"

"No, but they are not so many."

"A few, supplied four times a week, can plant a lot of mines," quizzed Darrin.

"Oh, yes."

"And the craft you were aboard was one of the smaller ones that brought cargoes of mines. Your people have some that carry much larger numbers of mines?"

"Yes, and the larger boats that bring mines over to the real mine-layers travel faster under water than our boat did."

"So that these larger boats can make at least five round trips a week?"

Dave asked.

"Oh, yes."

"You have not told me the name of your base port," Darrin went on.

"And I don't intend to," retorted the seaman. "You are asking me too many questions. I should not have said as much as I did, and I shall not answer any more questions."

"You do not need to," Dave a.s.sured him. "I already know the answers to a lot of questions that I might have asked you. But you look like a reasonable fellow, and also like a fellow fond of some of the good things of life. Had I found you more ready to talk I might have arranged for you to have a pleasanter time in the English prison than your mates will have."

"A pleasanter time until the hangman called for us?" demanded the German, 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 a.s.sured him. "You will be well fed. You will have some amus.e.m.e.nts. 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 sh.o.r.e, and in an English prison camp, and then you will know that you have been lied to. You will enjoy finding yourself on sh.o.r.e, for you were not often allowed to go ash.o.r.e 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 ash.o.r.e 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, to make sure that I understand just what you propose to do."

On the map Darrin traced the course that he felt sure the German underseas craft pursued when bringing cargoes of mines to the other submarines that were laying mines in British waters.