am burst.

He had been seen getting off the train at Elmvale that evening. But he
had disappeared immediately after. He had not returned to the munition
factory, where the manager, Mr. Santley, was waiting for him; nor had he
been observed at all after leaving the railroad station.

Later it was proved that he had obtained his position at the factory by
the aid of forged credentials. It was believed that he was rather a
famous German inventor who had been living in the United States for some
years. He had an almost uncanny knowledge of mechanics, as well as of
chemistry.

The ingenious little water wheel Whistler had seen at the foot of the
dam had probably furnished power for some machine that had been fixed
on the face of the dam with a charge of dynamite. This invention had
been rigged to explode the dynamite after a certain length of time--time
enough, without doubt, to enable the inventor to get well away from the
vicinity of the dam.

"If Linder is his name," Whistler said, when the boys were afterward
talking it over among themselves, "I hope I'll see him again some time.
He was never blown up with the dam, that is sure."

"You don't think he was 'hoist with his own petard, then?" suggested
Torry.

"Hear the high-brow!" sniffed Frenchy.

"Oi, oi!" cried Ikey. "He means was he blown up, too? I bet not!"

"I ought to have told somebody about him before," sighed Whistler.
"I had a feeling he wasn't using his real name."

"Say! why should you worry? That Mr. Santley didn't think anything wrong
of him until he found the letter in German in Blake's locker. And we did
set Mr. MacMasters and the S. P. Eight-eighty-eight after him and the
oil boat, didn't we?"

"By the way," Whistler suddenly observed, drawing an official looking
letter from his pocket. "Did I tell you I got this?"

"No," said Torry. "What is it?"

"Hurray!" yelled Frenchy, the quick-witted. "It's our assignment to the
_Kennebunk_, I bet you!"

"Is that right, Whistler?" asked Torry.

"That's what it is," admitted Morgan. "We're to report, however, to Mr.
MacMasters at Rivermouth day after to-morrow. But our ultimate
destination is the _Kennebunk_, superdreadnaught, just built and fitted
out for her first cruise. You know, she was only christened a month
ago."

Even the Elmvale disaster and the mystery regarding the German spy,
Franz Linder, were at once ousted from the minds of the Navy boys. Their
first cruise in a superdreadnaught w