A sudden gleam came into the youth's eyes, for he saw that his chance had come.

"Let me have all the spare petrol from the other machine, and let me get up above the clouds in that new No. 7 Bristol Fighter which you brought over, sir."

"I'm afraid it means certain death for you, my lad," replied the chief, after a pause, unwilling to permit the youth to take such unknown risks, and yet still more unwilling to deny him his request. "This Scorpion, according to Captain Watson, must be some stunting machine."

"I am willing to take the risks, sir," replied Keane. "It is not my first fight with a Hun."

"Don't I know it, boy!" replied the other, gazing with fond admiration into the frank and pleasing face of the pilot. "The ribbons which you gained speak for themselves, but they don't tell half the story. Don't I remember the morning when you went over the line by yourself, and encountered seven enemy machines, how you fought with them for an hour and brought five of them down, chased the others till your machine threatened to break up, then turned and staggered home with your wings shot to ribbons?" and the colonel fondly patted the youth's shoulder.

"Then let me go, sir. The brigand will be not a little confounded to find himself attacked both from the ground and the air at the same time."

"You shall go!" said the colonel after another pause. "Will you take a gunner with you?"

"No, sir. I would rather go alone."

And while the petrol was drawn off from the other machine, No. 7 was brought out, filled up, and tested, ready to start at a moment's notice. The Vickers gun, fixed forward to fire through the propeller, was carefully examined, and several drums of the new armour-piercing bullets placed in position. Another moment was given to the alignment of the gun-sight, a matter of supreme importance in an aerial duel like this one promised to be, for the slightest error in this respect would be like courting disaster.

Ten minutes later the signal was given to stand clear, the colonel himself swung the propeller, and, instantly, the powerful 350 H.P. Rolls-Royce burst into life with a crackle and a roar, and, when the chocks were withdrawn, the Bristol dashed across the ground, leapt into the air at sixty yards, and by a steep climb just cleared the tops of the trees on the edge of the forest.