aid in the handling of the boat. You need none of you feel any
uneasiness."

Both Miss Peddensen and the Englishman ceased their objections. But
Jack, remembering the glance that had passed between the pair on deck,
remained behind the curtain, too, as he dropped it.

"Go ahead, Hal!" he called. "Fifty feet under the surface. Dive
gently."

"O-o-o-oh!" came in little screams of alarm as the guests felt the floor
on which they stood inclining at a sloping angle.

"We're going below the surface now," young Benson informed them. "We'll
soon be running on an even keel."

"All below," called Hal Hastings in a few moments.

"And all clear?" asked Jack.

"All clear, Captain."

"Jack Benson threw aside the heavy curtain, come forward, slowly ladies
and gentlemen, and take seats," was Jack's invitation. "I am sorry I
shall have to ask you all to remain seated, but we cannot have any
serious shifting of weight while we are running under the water."

Though Eph was at the tower wheel Hal Hastings was now virtually in
command of the boat, by previous arrangement, for young Benson meant to
keep a sharp, though covert, eye on passengers.

The young skipper noted, swiftly, that Miss Peddensen had taken the seat
furthest aft in the cabin, while the young Englishman was seated at the
forward end of the party of guests.

"Oh, I say, Captain Benson," called the Englishman, "are you permitted
to show me how you know just how far below the surface you are?"

"The gauge tells that," replied Jack. "But I will ask you to excuse
me from describing it, as I wish to keep my mind on the running of the
boat. Mr. Hastings will oblige you; or, I don't doubt, one of the
naval officers will."

Even this momentary distraction, however, had given Miss Peddensen time
to slip something out of one of her wide sleeves into her lap. And now
the young Swedish woman sat so that the object taken from her sleeve was
concealed behind the woman who sat next to her.

It wasn't many moments ere Jack noted some thing about the young Swedish
woman that caused the young skipper to turn, every now and then, for a
swift though hidden glance in her direction.

"What on earth is Miss Peddensen doing?" wondered the submarine boy.
"Hang it, I believe she's up to something that she ought not to be
doing!"

Through he did not turn and walk in her direction, Jack, thereafter,
kept the young Swedish woman much more under secret observation.

"By