While Kirkwood was letting loose a drum of ammunition from the Lewis gun Barcroft employed his usual tactics. He steered straight for his antagonist. If the gun failed to do its work in time, and if the Hun pilot's nerves did not desert him, the result would be a rending crash in mid-air as the two swift-moving craft collided. The interlocked wreckage, a mass of flame, would drop like a firebrand to earth--a swift yet terrible death for friend and foe alike. But Billy knew how the odds were against such a mutual catastrophe. The Hun, if he managed to avoid the stream of bullets, was not likely to "stand up" to the resistless onrush of the British seaplane. Suddenly the double-fuselaged biplane nosedived. Only just in time did Barcroft tilt the ailerons, for the seaplane literally scraped the tail of his vertically-descending foe. For nearly a thousand feet the machine "plumbed," then like a silvery dart it flattened out. "Old trick, Fritz," muttered Barcroft. "Well, you've lost your altitude advantage. I'll renew your acquaintance later." The flight-sub knew that some minutes must elapse before the double-fuselaged machine could climb to renew the encounter. During that interval he had time to devote his attention to the remaining Fokker that, following Fuller with deadly persistence, was firing the while but receiving no reply from the British craft. Already Fuller was a couple of miles away. His antagonist was gaining slightly. It seemed remarkable that with such a prodigious outlay of ammunition the Huns had not succeeded in strafing their quarry. Suddenly Fuller's seaplane dipped. Barcroft gave vent to an involuntary groan, but the next instant he wanted to cheer, for his chum had looped the loop two or three times and was now heading in the opposite direction. "I see the move," thought Barcroft. "He's luring Fritz towards us." The two seaplanes passed one another at less than a hundred yards. Fuller raised his arm by way of greeting as they swept by. As he did so shreds of canvas flew from the lower plane, and dipping abruptly the crippled machine dropped, lurching hideously as it did so. Almost simultaneously the Hun pilot of the Fokker collapsed across the decking of the fuselage. The machine, no longer under control, swayed through a distance of nearly a quarter of a mile, and then, tilting obliquely, began a terrific tail spin that ended in a jumble of wreckage on the unsympathetic soil of Belgium. "Now for the double bus," muttered Billy. "The Huns will pay dearly for strafing poor old John." But the remaining aeroplane of the two had had enough, for, seeing the British seaplane swooping down to engage upon round two, she promptly sought safety in flight.