The two boys stood and watched with awe the mighty conflagration they had started. The jungle was filled with dead and dying trees which flamed up like tinder at the fire's breath. Soon the flames were shooting up forty or fifty feet high and the roaring was like that of a mighty tempest. The heat quickly grew so intense that the boys were compelled to retreat slowly back to the machine. Even there the heat could be felt, although it was a thousand feet to the jungle and the wind was blowing the fire away from them. The engineer stopped the machine for a few minutes to give all hands a chance to view the wonderful sight. As the pillars of flame and smoke reared themselves skyward, the boys realized with astonishment that the jungle that had seemed so lifeless was really teeming with life. From both sides of the mighty blaze rose great flocks of blue and white cranes, egrets, whoopers, owls, parrots, great scarlet flamingoes, and dozens of strange birds the like of which the boys had never seen before. Nor was animal life lacking in either number or variety. Hundreds of hairy swamp rabbits, as big as a small dog, poured out from their doomed hiding places. Great big rats by the thousands swarmed by the machine. A couple of deer went by, covering the ground with great bounds. Wild cats, foxes, squirrels poured forth in great numbers. One huge, sprawling object emerged from the thicket and lumbered toward the machine, but before reaching it turned aside and sunk with a splash in a nearby lake. "Whew!" breathed the engineer, "that was the grandfather of all alligators. He must be all of twenty feet long." As the fire spread to either side the flow of animal life was diverted in other directions and their rushing by the machine ceased. "I believe that fire will kill every snake in the jungle," Charley declared with satisfaction. "I doubt it. They will just keep under water until it is all over," his chum replied. "That water is shoal and stagnant," Charley reminded him. "Burning branches and trees are dropping in it all the time. I'll bet it is actually boiling by now." CHAPTER XXVIII. SHOOTING TO KILL. WHEN night came Charley and Walter had to go on the picket line alone, for the two remaining Spanish guards would have to join the grading gang in the morning. They adopted the plan the first two Spanish guards had used of each one making a half circle of the camp. For several hours they paced wearily back and forth, but as midnight drew near they became more watchful and alert, for this was the hour that their enemies generally chose to make their attacks.