timber.
Had the morning proved windy, instead of calm, the flames would have gone
racing into the big timber, with the chances good for a disastrous
crown-fire, when the flames would have gone leaping from tree top to tree
top, utterly consuming the forest, as the previous fires had destroyed the
timber on Old Ironsides. A lucky combination of circumstances alone had
prevented a holocaust.

Climbing upon a high rock, the forester searched for the point at which
the fire had originated. Prom his pocket he drew some powerful
field-glasses, and again and again swept his vision over the farther edge
of the burned area. Presently he closed his glasses and leaped to the
ground.

"Come on," he said, and headed diagonally across the burned tract.

In a few minutes the three stood on the unburned forest floor on the
farther side of the strip of black.

"We must get our aerial up at once, Lew," said Charley. "It's been
three-fourths of an hour since we talked to Willie."

They glanced about, selected two suitable trees, and had the supporting
wires attached to them in no time, with the aerial dangling aloft between
the trees. It took only a moment more to couple up the instruments.

"CBWC--CBWC--CBWC--CBC," rapped out Charley, as soon as the outfit was in
readiness.

Almost instantly Willie replied to the signal.

"Any message for us from Oakdale?" inquired Charley.

"Not a word. What are you doing?"

"We are investigating the cause of the fire. Have moved our aerial down
past the burned area. Forester and Lew and I alone. Fire crew on way back
to Oakdale."

"Have you found cause of fire?"

"No. Just got here. Haven't investigated yet. Will listen in every quarter
hour, beginning with the hour."

"All right. I'll be here. Good-bye."

The minute Charley finished talking with Willie, the three investigators
set about their work.

"We'll walk along the edge of the burned area," said the forester, "and
try to find the point of origin."

He went ahead, the two boys following. They were facing toward the brook.
The line was irregular, like a huge saw-blade, with little jutting, black
teeth here and there, where the flames had crept out in advance of the
main line. The wind that had come up when the boys were fighting the fire
had driven the flames back upon the area they had already consumed and the
blaze had died out of itself. It could not eat its way to windward out
here in the open, as it could have done in th