Bob gazed at the wall of flame with some dismay.
"How we going to get through?" he asked.
"We got to find a rock outcrop somewheres up the ridge," explained Jack, "where there'll be a break in the fire."
He turned up the side of the mountain again, leading the way. After a time they came to an outcrop of the sort described, which, with some difficulty and stumbling, they succeeded in crossing.
Ahead, in the darkness, showed a tiny licking little fire, only a few inches high.
"The fire has jumped!" cried Bob.
"No, that's their backfire," Pollock corrected him.
They found this to be true. The rangers had hastily hoed and raked out a narrow path. Over this a very small fire could not pass; but there could be no doubt that the larger conflagration would take the slight obstacle in its stride. Therefore the rangers had themselves ignited the small fire. This would eat away the fuel, and automatically widen the path. Between the main fire and the back fire were still several hundred yards of good, unburned country. To Bob's expression of surprise Amy added to the two principles of fire-fighting he had learned from Pollock.
"It doesn't do to try to stop a fire anywhere and everywhere," said she. "A good man knows his country, and he takes advantage of it. This fire line probably runs along the line of natural defence."
They followed it down the mountain for a long distance through the eddying smoke. The flames to their right shot up and died and crept. The shadows to their left—their own among the number—leaped and fell. After a while, down through the mists, they made out a small figure, very busy at something. When they approached, they found this to be Charley Morton. The fire had leaped the cleared path and was greedily eating in all directions through the short, pitchy growth of tarweed. It was as yet only a tiny leak, but once let it get started, the whole forest beyond the fire line would be ablaze. The ranger had started to cut around this a half-circle connected at both ends with the main fire line. With short, quick jabs of his hoe, he was tearing away at the tough tarweed.