e other valley, where no one
lives, and where it can escape into the big river there, the amount
that will flow down this valley will be so small that only a little
damage will be done."

"That's right!" declared the steel foreman, as he caught Tom's idea.
"It's the only way it could be done, too, for there won't be time to
make the necessary excavation any other way. Is the gun swung around
far enough, Mr. Swift?"

"No, a little more toward me," answered Tom, as he peered through the
telescope sights. "There, that will do. Now to get the proper
elevation," and he began to work the other apparatus, having estimated
the range as well as he could.

In a few seconds the giant cannon was properly trained on the white
rock. Meanwhile the horseman, with his red flag, had continued on down
the valley. In spite of his warning of the night before, it developed
that a number had disregarded it, and had remained in their homes. Most
of the inhabitants, however, had fled to the hills, to stay in tents,
or with such neighbors as could accommodate them. Some lingered to move
their household goods, while others fled with what they could carry.

It was to see that the town was deserted by these late-stayers that the
messenger rode, crying his warning as did the messenger at the bursting
of the Johnstown dam twenty-odd years ago.

"The projectile!" cried Tom, as he saw that all was in readiness.
"Lively now! I can see the top of the dam beginning to crumble," and he
laid aside the telescope he had been using.

The projectile, with a heavy charge of bursting powder, was slung into
the breech of the gun.

"Now the powder, Koku!" called Tom. "Be quick; but not so fast that you
drop any of it."

"Me fetch," responded the giant, as he hastened toward the small cave
where the explosive was kept. As the big man brought the first lot, and
Ned was about to insert it in the breech of the gun, behind the
projectile, Tom exclaimed:

"Just let me have a look at that. It's some that I first made, and I
want to be sure it hasn't gone stale."

Critically he looked at the powerful explosive. As he did so a change
came over his face.

"Here, Koku!" the young inventor said. "Where did you get this?"

"In cave, Master."

"Is there any more left?"

"Only enough for this one shoot."

"By Jove!" muttered Tom. "There's been some trick played here!" and he
set off on a run toward the bomb-proof.

"What's the matter?" cried Ned, as he notic