hat
have to put in. Now, for some time the Army engineer officers have been
perfecting a system of submarine mines for the bay. The engineers have
a problem on hand as to whether an enemy's submarine boats could sneak
into the bay and blow up the submarine mines before the Army woke up
to the danger."

"There's a chance that _that_ could be done," nodded Jack, musingly.

"Jest so," nodded Mr. Farnum. "So I want you to go up in one of the
boats. To-morrow the engineer officers at that station will test it out
with you whether a submarine can destroy the mines, or the mines could
be made to destroy the submarine boats."

"Then the Army engineer officers will use dummy submarine mines, I hope,"
broke in Eph.

"Oh, of course," nodded Mr. Farnum. "Now, the trip to Craven's Bay is
only an eight-hour sail at a good gait, so you won't really need to
start until after dark to-night."

"I believe I'd rather start now, though, and go at less speed," suggested
Jack, thoughtfully.

"That's just as you please, of course," nodded the shipbuilder.

"It will take us out on the water, for one thing," Captain Jack
continued, "and we've been growing stale on shore, of late." Then he
added, whimsically: "Besides, if the agents of any more foreign
governments show up, they won't find us here."

"And there's a Jap just about due now," grimaced Eph.

"Take Williamson with you, for use in the engine room," advised Mr.
Farnum. "That will allow you to take the boat through with two watches
above and below. Which boat will you take?"

"The 'Spitfire,' unless you'd rather have us take the other one," young
Benson replied.

"Take the 'Spitfire,' by all means," nodded the owner.

Twenty minutes later, Williamson having been found, the crew was all
ready for the start for Craven's Bay.

Eph and Williamson cast off from moorings while Hal Hastings, down below
at the gasoline motors, started the twin propellers as soon as Jack
Benson, at the deck wheel, signaled for speed ahead.

Right after the start, Williamson, a grown man and machinist, dropped
below. Eph Somers stood beside the young submarine captain.

For some minutes both boys gazed out over the waters. Then Eph remarked:

"Well, we got away without being overhauled by a Jap or a Russian,
didn't we?"

"I don't know," smiled Jack, unsuspectingly. "See that launch over to
port? Hanged if she doesn't seem to be putting toward us."

"She does," admitted Eph, solemn