returned to call off the rear. All repaired to
the scene of obstruction.

Bob noticed the slack water a mile or so above the jam. The river was
quite covered with logs pressed tight against each other by the force of
the interrupted current, but still floating. A little farther along the
increasing pressure had lifted some of them clear of the water. They
upended slightly, or lay in hollows between the others. Still farther
downstream the salient features of a jam multiplied. More timbers stuck
out at angles from the surface; some were even lifted bodily. An abattis
formed, menacing and formidable, against which even the mighty dynamics
of the river pushed in vain. Then at last the little group arrived at
the "breast" itself--a sullen and fearful tangle like a gigantic pile of
jackstraws. Beneath it the diminished river boiled out angrily. By the
very fact of its lessened volume Bob could guess at the pressure above.
Immediately the rivermen ran out on this tangle, and, after a moment
devoted to inspection, set to work with their peavies. Bob started to
follow, but Welton held him back.

"It's dangerous for a man not used to it. The jam may go out at any
time, and when she goes, she goes sky-hooting."

But in the event his precaution turned out useless. All day the men
rolled logs into the current below the dam. The _click!_ clank! clank!
of their peavies sounded like the valves of some great engine, so
regular was the periodicity of their metallic recurrence. They made
quite a hole in the breast; and several times the jam shrugged, creaked
and settled, but always to a more solid look. Billy, the teamster,
brought down his horses. By means of long blocks and tackle they set to
yanking out logs from certain places specified by Roaring Dick. Still
the jam proved obstinate.

"I hate to do it," said Roaring Dick to Welton; "but it's a case of
powder."

"Tie into it," agreed Welton. "What's a few smashed logs compared to
hanging the drive?"

Dick nodded. He picked up a little canvas lunch bag from a stump where,
earlier in the day, he had hung it, and from it extracted several sticks
of giant powder, a length of fuse and several caps. These he prepared.
Then he and Welton walked out over the jam, examining it carefully, and
consulting together at length. Finally Roaring Dick placed his charge
far down in the interstices, lit the fuse and walked calmly ashore. The
men leisurely placed themselves out of harm's way. Welt