onderful discovery!"

"And this accounts for all the strange noises we heard, and the
fellows we saw going through the woods with bundles on their backs,"
added Randy.

"Yes, and I guess it straightens out that story Jed Kessler told about
the two Germans in the wagon with stuff that rattled like hardware,"
said Jack.

"It's as plain as day," cried Fred. "Those two fellows must be
connected with this gang here who are working on the submarine. And
more than likely they were the same two Jed Kessler saw hanging around
the ammunition plant just before the explosion."

"If that's a German submarine, it must have come from the other side
of the Atlantic!" exclaimed Andy in a low, excited voice. And then he
added, his eyes snapping: "What do you suppose happened to it? Do you
think she ran afoul of some of our big warships or our submarine
chasers?"

"Either that, or in cruising up and down the coast here she may have
run afoul of some of the rocks and maybe knocked a hole in her bottom
or side," answered Jack. "And I guess it's true that all the pounding
and strange noises we have heard came either from this underground
place or from some overhead spot close by."

"What gets me is--how did that submarine get into this underground
place?" questioned Gif.

"There must be a much larger outlet than the one by which we entered,"
answered Jack. "More than likely those fellows don't know anything
about the way by which we got in. They must have a large entrance by
way of the water from the bay, and they must also have an entrance
from the forest--that place where the man disappeared."

"I guess you're right," said Fred. "Gee, this certainly is an
important discovery! I guess the best thing we can do is to hurry back
to camp as fast as possible and notify Captain Dale. He will probably
want to let the Secret Service men and the authorities at Rackville
know at once, so they can round up these fellows before they have a
chance to get away."

"I'd like to stay here awhile and watch these chaps," said Randy.
"Maybe we may learn something more that is worth while."

The matter was talked over by the cadets for fully ten minutes. At the
place to which they had withdrawn they could talk freely, because the
noises near the submarine continued, so there was little danger of
their being overheard. While they talked they peeped out from time to
time at the workmen, and saw that they were laboring over several
sheets of steel an