There was a rapid rat-a-tat, not so clear and distinct as it would have been at the same distance on ground, and a stream of bullets poured from the machine gun.  But they passed between the Arrow and the Omnibus, and only cut the unoffending air.  Meanwhile Wharton was watching.  A wrath, cold but consuming, had taken hold of him.  The fact that he was high above the earth, perched in a swaying unstable seat was forgotten.  He had eyes and thought only for the murderous machine gun and the man who worked it.  An instinctive marksman, he and his rifle were now as one, and of all the birds of prey in the air at that moment Wharton was the most dangerous.

The machine gun was silent for a minute.  The riflemen in the Taubes on the wings of the attacking force fired a few shots, but all of them went wild.  John, tense and silent, sat with his own rifle raised, but half of the time he watched Wharton.

The two forces came a little nearer.  Again the machine gun poured forth its stream of bullets.  Two glanced off the sides of the Omnibus, and then John saw Wharton’s rifle leap to his shoulder.  The movement and the flash of the weapon were so near together that be seemed to take no aim.  Yet his bullet sped true.  The man at the machine gun, who was standing in a stooped position, threw up his hands, fell backward and out of the plane.  A thrill of horror shot through John, and he shut his eyes a moment to keep from seeing that falling body.

“What has happened?” asked Lannes, who had not looked around.

“Wharton has shot the man at the machine gun clean out of the aeroplane.  He must be falling yet.”

“Ghastly, but necessary.  Has anybody taken the slain man’s place?”

“Yes, another has sprung to the gun!  But he’s gone!  Wharton has shot him too!  He’s fallen on the floor of the car, and he lies quite still.”

“Your friend is indeed a sharpshooter.  How many men are left in the plane?”

“Only one!  No, good God, there’s none!  Wharton has shot the third man also, and now the machine goes whirling and falling through space!”

“I said that friend of yours must be a sharpshooter,” said Lannes, in a tone of awe, “but he must be more!  He must be the king of all riflemen.  It’s evident that the Omnibus knows how to defend herself.  I’ll swing in a little, and you can take a shot or two.”

John fired once, without hitting anything but the air, which made no complaint, but the battle was over.  Horrified by the fate that had overtaken their comrades and seeing help for their enemy at hand the Taubes withdrew.

The Arrow and the Omnibus flew on toward the French lines, whence other machines were coming to meet them.

CHAPTER XI

THE CONTINUING BATTLE

The Arrow bore in toward the Omnibus.  Wharton had put his rifle aside and was staring downward as if he would see the wreck that he had made.  Lannes called to him loudly: