stepped cautiously into the bushes.

"Yes; there were just two of them here, apparently," replied Jack, after
studying the prints, and discovering the marks of only two different
sizes or kinds of shoes.

"Here's the imprint of a box," added Foster. "Good heavens, the
scoundrels had a regular magneto battery, insulated wire and all, for
firing that mine from the shore. Mr. Benson, they meant to blow your
boat into Kingdom Come!"

"It looks that way," replied Jack Benson, composedly.

On hearing that voice, so even and unaffected in its utterance,
Lieutenant Foster looked at the submarine boy keenly.

"By Jove, Benson, you're cool enough to be an admiral," muttered the
marine officer, admiringly.

"Why, this doesn't seem to be a joke on me," replied Captain, Jack,
smiling back at the lieutenant.

"A joke!"

"It's one on the Secret Service," laughed Jack, quietly. "They are the
ones who are supposed to have the job of keeping off spies and all of
their kind."

"Yes; this certainly came from the spies, or their friends," muttered
Lieutenant Foster. "Jove, but we have a desperate crowd to deal with
when they'll go to such a length as this in time of peace!"

"Oh, it may all turn out to be a joke," put Hal, quietly. "Some one
may have been doing this to try us out. That metal cylinder may prove
to have been loaded with ginger-bread or peanuts. If anyone has been
trying a joke on us, then I'm mighty glad we didn't get rattled."

"I reckon we shall soon know just what that cylinder did contain,"
muttered Lieutenant Foster. "Here's another cutter coming from the
'Waverly,' and I think I make out Lieutenant Commander Kimball in the
stern-sheets."

It was, indeed, the lieutenant commander. As he stepped ashore, his
face coming into the circle of light cast by the lantern, his features
were seen to be white with anxiety.

"We have just looked into the cylinder," he announced, in a low voice.
"We found there enough gun-cotton to blow the 'Benson' into inch pieces.
It was a fearful crime to plan."

Jack Benson and Hal Hastings heard, but did not change color. There was
no sense in losing nerve over a disaster that had been averted in time.

"The first thing to do, of course," continued Lieutenant Commander
Kimball, "is to send instant word to Messrs. Trotter and Packwood.
They have a heap of work ahead of them."

"As to our own boat's crew," replied Jack, "I fancy the best thing we
can do is to go ba