e been waiting for him to show up here," cried Mr.
Santley. "To tell the truth, young man, I have discovered some things
here that I want him to explain. For one thing, I have picked up a
letter in his locker which is addressed to him, it is evident, but not
by the name of Blake. It is written in German and I want it explained."

"Oh, Mr. Santley!" cried Whistler, "I believe there is something wrong.
He told that Captain Braun, of the _Sarah Coville_, that his work was
finished here. He was only returning for a particular thing to Elmvale."

"But he hasn't come here!" exclaimed Mr. Santley. "And he has some
private property in the office."

"Maybe he isn't coming here," breathed the boy. "Maybe he is only going
up to the dam!"

"To the dam?"

"That water-wheel business! It perplexes me," explained Whistler Morgan.

"We'll go up there and take a look!" exclaimed Mr. Santley, grabbing his
hat and banging down the roll top of his desk and locking it. "You've
got me all stirred up now, boy."

They hurried out of the office. Mr. Santley spoke in a low voice to the
armed guard on the front steps.

"If Blake comes here, hold him till I return," he said. "Do you
understand? _Hold him_--even if you have to knock him down and sit on
him."

"All right, sir," said the man, nodding grimly.

Mr. Santley started down the steps after the excited Whistler, who was
already getting into the automobile, the engine of which was still
running. At that instant the night was as peaceful as could be. The
valley below the high dam lay quietly under the light of the stars, and
a pale moon was just rising above the treetops.

Then, with a shock which electrified the atmosphere and seemed to make
heaven and earth tremble, a burst of flame rose at the foot of the dam,
not more than half a mile away!

The glare of it blinded them; the reverberating explosion that followed
almost immediately well nigh stunned them. It was Ikey, standing in the
tonneau of the car, and pointing a trembling arm toward the dimly
distinguished wall of masonry, whose voice was first heard:

"Look! Look! The dam's broke!"

A balloon-shaped cloud of smoke had risen above the wall of masonry.
Beneath it the dam crumbled, dissolved, and poured away into the bed of
the river like the changing picture in a kaleidoscope.

CHAPTER X

AHEAD OF THE FLOOD

Each one in the little group at the main entrance to the munition
factory had cried out--no doubt of