The little plane slackened its speed, as it approached the tree, and then sailed by it at a moderate rate.  When it was opposite the flag a spurt of flame came from the pistol of the man in it, and John actually laughed.

“That was sheer spite,” he said.  “Did he think he could shoot our flag away with a single bullet from a pistol when a machine gun has just failed?  That’s right, turn about and make off as fast as you can, you poor little mono!”

The monoplane also curved around the tree, but did not make a series of circles.  Instead, when its prow was turned northward it darted off again in that direction, going even more swiftly than it had come, as if the aviator were ashamed of himself and wished to get away as soon as possible from the scene of his disgrace.  Away and away it flew, dwindling to a black speck and then to nothing.

John’s shoulders shook, and Weber, looking at him, was forced to smile too.

“Well, it was funny,” he said.  “Our flag is certainly making a stir in the heavens.”

“I wonder what will come next,” said John.  “It’s like bait drawing birds of prey.”

The heavens were now beautifully clear, a vault of blue velvet, against which anything would show.  Far away the cannon groaned and thundered, and the waves of air pulsed heavily, but John noticed neither now.  His whole attention was centered upon the flag, and what it might call from the air.

“In such a brilliant atmosphere we can certainly see our visitors from afar,” he said.

“So we can,” said Weber, “and lo! another appears out of the east!”

The dark speck showed on the horizon and grew fast, coming apparently straight in their direction.  John did not believe it had seen their flag at first, owing to the great distance, but was either a messenger or a scout.  As it soon began to descend from its great height in the air, although still preserving a straight course for the tree, he felt sure that the flag had now come into its view.  It grew very fast in size and was outlined with startling clearness against the burning blue of the sky.

The approaching machine consisted of two planes alike in shape and size, superimposed and about six feet apart, the whole with a stabilizing tail about ten feet long and six feet broad.  John saw as it approached that the aviator sat before the motor and screw, but that the elevating and steering rudders were placed in front of him.  There were three men besides the aviator in the machine.

“A biplane,” said John.

“Yes,” said Weber, “I recognize the type of the machine.  It’s originally a French model.”