"She's off, sir," exclaimed O'Rafferty.
"Yes, for the present," replied Blake. "She'll be at it again, I fancy. Come on, lads, let's carry on. Another half hour will see us straight."
Leaving Athol still on watch the rest of the crew resumed their labours, but before they had been at work for another five or ten minutes the submarine appeared upon the surface at a distance of nearly two miles.
"The brutes!" ejaculated Blake. "They've spotted our automatic guns. We'll be having some three pounder shells this way before long."
Bringing their glasses to bear upon the low-lying hull of the submarine the airmen found that their fears were realised. The vessel was a large unterseeboot flying the Black Cross ensign of Germany. She was lying broad-side on and forging ahead at a rate of about five knots. The two quick-firing guns were already raised from their respective "houses" or watertight troughs, and were being served by their gunners.
A flash followed by a dull crack announced that the submarine had opened the ball.
"You'll have to do better than that, old sport!" exclaimed O'Rafferty disdainfully, as the projectile struck the water at a hundred yards beyond the target, and ricochetting with a tremendous splash, finally disappeared a mile and a half away.
Again and again the Huns fired, each shell approaching with uncanny and methodical exactness nearer and nearer the crippled battleplane. They were blazing away with plugged shell, and that fact, combined with the evident reluctance of the submarine's crew to score a direct hit, told the airmen pretty plainly that the Germans wished particularly for their surrender and the capture of the battleplane intact.
From time to time Athol and the sergeant let loose a few rounds of ammunition, but in spite of the extreme elevation of the sights of the automatic weapons the bullets all fell short.
Suddenly Athol ducked his head as a projectile hurtled through the air less than ten feet above him. He could distinctly feel the windage of the missile, while the screech was appalling. The Huns, getting out of patience with the resistance of the British battleplane, were trying to shell it in grim earnest.