But Tom had the start of them, and he was also on a higher level, so that the Germans must climb at an oblique angle to reach him.
And, thanks to this, Tom saw that, if nothing else happened, he would soon be in comparative safety with the unconscious form of Jack. The anti-aircraft batteries were firing in vain, as he was beyond their range, and, far away, he could see the lines of the French armies, behind which he soon hoped to be.
And then the unexpected happened, or, rather, it had taken place some time since, but it was only then brought to Tom's attention. His engine began missing, and when he sought for a cause he speedily found it. Nearly all the gasoline had leaked out of the main tank. As he knew that there had been plenty for the return flight, there was but one explanation of this. A Hun bullet had pierced the petrol reservoir, letting the precious fluid leak away.
“Now if the auxiliary tank has any in it, I'm fairly all right,” thought Tom. “If it hasn't, I'm all in.”
His worst fears were confirmed, for the auxiliary tank had suffered a like fate with the main one. Both were pierced. There were only a few drops left, besides those even then being vaporized in the carburetor.
With despair in his heart, Tom looked back. If the Hun plane chose to rush him now all would be over with him and Jack. He had only enough fuel for another thousand meters or so, and then he must volplane.
He saw a burst of flame and smoke from the enemy plane, and realized that he was being shot at again. But the distance was still too far for effective aim.
And then, to his joy, Tom saw the pursuer turn and start back toward the German territory. The firing had been a last, desperate attempt to end his career, and it had failed. Either the Huns were almost out of petrol themselves, or they did not relish getting too close to the French lines.
“And now, if I can volplane down the rest of the way, I'll be in a fair position to save myself,” mused Tom, as he made a calculation of the distance he had yet to go. It was far, but he was at a good height and believed he could do it.
Suddenly his engine stopped, as though with a sigh of regret that it could no longer serve him, and Tom knew that volplaning alone would save him now. He was still over the enemy country, and had his plight been guessed at by the Germans, undoubtedly they would have sent a machine up to attack him. But they were in ignorance.