The lieutenant drew a deep breath. "We knew we were owing him a lot," he said. "But it seems we were owing even more than we thought." "And I'm beginning to think," said the C.O., "that all of us here on the ground are owing more than we've known to those fellows in the air." II BRING HOME THE 'BUS For ten minutes past the observer had been alternately studying his map and the ground 20,000 feet below, and now he leaned forward out of his cockpit, touched the pilot on the shoulder, and made a slight signal with his hand. Immediately the machine began to swing in a wide curve, while the observer busied himself with his camera and exposed plate after plate. He looked up and out a moment as there came to his ear, dully but unmistakably above the roar of the engine, the hoarse "_woof_" of a bursting anti-aircraft shell. The black smoke of the burst showed a good hundred yards out to their left and some hundreds of feet above them, and the observer returned to his photographing. "_Woof_" came another shell, and then in quick succession another and another, the last one dead ahead and with such correct elevation that, a second later, the machine flashed through the streaming black smoke of the burst. The pilot looked back inquiringly, and the observer made a sign which meant "Do what you please," and sat back to wait until the pilot took such steps as he thought fit to disarrange the aim of the gunners below. The harsh rending cough of another shell came so close beneath the machine that both men felt her distinctly jolt upward, twisting from the wind shock. The pilot waited no more. He jammed the controls hard over and flung the machine out in a vicious side-slip, caught her at the end of it, tipped her nose over and plunged straight down with the engine full on for a thousand feet, banked sharply, pivoting fairly on his wing-tip, and shot off at right angles to his former course for a quarter of a mile; then, climbing slightly as he went, swung hard round again, dipped a little to gather speed, hoicked hard up, and in a few seconds was back somewhere about the position at which he had first departed from the course.