Puff passed over him at eight hundred feet, and Ball dropped one bomb.
It was a long slim bomb, with an armour-piercing nose, and weighed two hundred and thirty pounds.
Ball leaned out of the cockpit and watched it all the way down. Unconsciously he held his breath, and time seemed to stop. And then he saw it crash into the stern of the submarine.
On the explosion the stern went down and the bow rose out of the water. It smacked down a moment later with a wide-flung splash.
Close behind the leading boat came Young. Barker dropped two one hundred pound bombs. They detonated just in front of the submarine. He saw that the bow hydroplanes were damaged.
The U-B 20 was now out of control.
She did figure eights.
She dived and came up again.
And then, after seven minutes of such evolutions, her twin propellers stopped, and she began to sink by the stern.
The pilots were now circling above their quarry at a height of four hundred feet. Puff and Ball obtained a second direct hit just in front of the conning-tower, and Young and Barker straddled her with two bombs.