Herb shot a second time, just grazing his mark, picking off some of the feathers on the monster's back. At this time the crouching shape sprang upward with a sharp cry of anger, almost completely hiding the top of the tower from view, so enormous was the spread of its wings.
"There it is! There it is," exclaimed several of the party on the back of the ravine.
"An eagle," gasped Fred.
"The Thunder Bird," panted Carl.
"But what's the matter with him?" cried Dunk. At the same moment, the boys, staring upward with fascinated eyes, gave a cry of alarm.
The great creature seemed flying about wildly, furiously, without sense of, or regard for direction, beating its immense wings against the air, and, instead of attempting to escape, flew straight for the plane, almost colliding with it.
Fly, who had anticipated a chase, now found himself on the defensive, and was obliged to dodge, circle, swoop and whirl in a manner that made his head swim. Although almost near enough to touch the bird at times, the motion of the machine and the strange uncertain course of their antagonist made accurate aim impossible.
Above them it flew, passing like a dark cloud over the machine, then veering down so suddenly that Fly was obliged to concentrate all his energies to get out of its way. It was an equal conflict between nature's great king of the air, and the supreme handicraft of mechanical skill which had been made to conquer it in its own element.
"It must be blind," said Herb, remembering that Carl had told them the Thunder Bird was sightless in the daylight. "If I could only get a line on it!"
The boys below dared not shoot, lest their bullets go astray and strike their friends. The monster seemed possessed by an insane rage, throwing itself about in the air with blind recklessness.