"All right, then," said Billy, "in we go!" And, suiting the action to the word, the four friends swarmed into the airplane, filling the cramped passenger carrying space to overflowing. Meantime, the Germans, having found cover, had opened up a brisk rifle fire against the aeroplane, and bullets began to sing through the framework. One of the observers leaped to the ground, gave the propeller a vigorous twist, and as the motor began to roar clambered aboard as the big plane started over the rough ground, bumping and jolting, but rapidly gaining speed. The Germans broke from their shelter in pursuit, firing wildly as they ran, but although some of their shots came close, none came near enough to do any real damage. In a few seconds, in answer to a quick movement from Dick Lever, the big bombing machine left the ground, and amid a parting rain of bullets from the Germans, started to ascend in long, sweeping spirals. The friends were about to congratulate themselves on their safe escape, when suddenly one of the observers, who had been scanning the horizon closely, pointed behind them, and exclaimed: "Just as I thought! Those two Boche planes that we saw getting ready to come after us just after we dropped our last bomb are coming up fast. Look!" All twisted about, and saw that it was as the observer had said. High up in the sky two swift, darting objects were coming in pursuit. The American machine was built more for carrying capacity than for speed, and in addition was heavily loaded. Every advantage was with the swift German machines. Their pilots no doubt realized this, for now they headed directly for the Americans, descending in a long slant that gave them tremendous speed. "All right," said Lever, coolly, "if they're going to come down, it may be a good idea for us to go up," and, suiting the action to the word, he elevated the nose of the big plane skyward, and they started to climb steeply. The American machine was equipped with a tremendously powerful motor, and this, combined with its great wing spread, enabled it to climb with great rapidity, in spite of the heavy load it was carrying. The Germans had not counted on this, and the result was that they miscalculated their distances, passing beneath the American flyer instead of above it, as they had intended. They both turned quickly and started to climb, but by this time the American aviators had trained their two machine guns on the Germans, and opened fire.