Then his eye fell to the ridge opposite, across the blue canon.  From one point on it a straight column of smoke rolled upward, to mushroom out and hang motionless above the top of the ridge.  Its base was shot by half-seen, half-guessed flaming streaks.

Bob had vaguely expected to see a whole country-side ablaze.  This single, slender column was almost absurd.  It looked like a camp-fire, magnified to fit the setting, of course.

“There’s the fire, all right,” said Jack.  “We got to get across to it somehow.  Trail ends here.”

“Why, that doesn’t amount to much!” cried Bob.

“Don’t it?” said Jack.  “Well, I’d call that some shakes of a fire myself.  It’s covered mighty nigh three hundred acres by now.”

“Three hundred acres!  Better say ten.”

“You’re wrong,” said Jack; “I’ve rode all that country with cattle.”

“You’ll find it fire enough, when you get there,” put in Amy.  “It’s right in good timber, too.”

“All right,” agreed Bob; “I’ll believe anything—­after this.”  He waved his hand abroad.  “Jack,” he called, as that young man led the way off the edge, “can you see where Jack Main’s Canon is from here?”

“Jack Main’s!” repeated young Pollock.  “Why, if you was on the top of the farthest mountain in sight, you couldn’t see any place you could see it from.”

“Good Lord!” said Bob.

The way zigzagged down the slope of the mountain.  As Jack had said, there was no trail, but the tracks left by the four rangers were plainly to be discerned.  Bob, following the pack horses, had leisure to observe how skilfully this way had been picked out.  Always it held to the easy footing, but always it was evident that if certain turns had not been made some distance back this easy footing would have lacked.  At times the tracks led far to the left at nearly the same level until one, two or three little streams had been crossed.  Then without apparent reason they turned directly down the backbone of a steep ridge exactly like a half-dozen others they had passed over.  But later Bob saw that this ridge was the only one of the lot that dipped over gently to lower levels; all the rest broke off abruptly in precipitous rocks.  Bob was a good woodsman, but this was his first experience in that mountaineering skill which noses its way by the “lay of the country.”

In the meantime they were steadily descending.  The trees hemmed them closer.  Thickets of willows and alders had to be crossed.  Dimly through the tree-tops they seemed to see the sky darkening by degrees as they worked their way down.  At first Bob thought it the lateness of the afternoon; then he concluded it must be the smoke of the fire; finally, through a clear opening, he saw this apparent darkening of the horizon was in reality the blue of the canon wall opposite, rising as they descended.  But, too, as they drew nearer, the heavy smoke of the conflagration began to spread over them.  In time it usurped the heavens, and Bob had difficulty in believing that it could appear to any one anywhere as so simple a mushroom-head over a slender smoke column.