"Here, take the helm," said Blake, handing over the steering wheel to the lad. "Let her volplane in spirals. I must see what this game is."
It did not take Blake long to form a pretty accurate idea of the situation. The sea was fairly calm, showing that here, at least, the gale had blown itself out. The water, too, was clear and comparatively shallow, the bed consisting chiefly of white sand. Visible against the bottom of the sea was a long grey object, sufficiently distinct to enable Blake to decide that it was a submarine.
Less than three hundred feet above it hovered the Zeppelin, flying slowly dead into the eye of the light breeze and thus endeavouring to keep almost stationary over the submerged craft.
On her part the submarine was creeping over the sandy bottom, sometimes backing astern and striving to hide herself in the disturbed water from the watchers on the Zeppelin.
The airship, intent upon the destruction of the submarine, had now descended to within two hundred feet and was dropping specially shaped bombs resembling aerial torpedoes. On striking the surface of the water these diabolical contrivances would plunge to the bottom under their own weight and momentum, then exploding with sufficient force to destroy any craft within fifty feet. Up to the present, however, the Zepp had not scored, although the crew were getting nearer their objective with each missile they dropped.
A sharp order and Athol and the sergeant manned the two automatic guns. Although the weapon did not fire shells, the peculiar nature of the bullets would enable them to rip up the airship's envelope like a jagged knife once the gun could be brought to bear.
All intent upon the destruction of the submarine the crew of the gas-bag had no inkling of the presence of the battleplane until a regular sheaf of bullets struck the Zeppelin well for'ard. In a couple of seconds the pilot's gondola was completely wrecked; but the ballonets came off comparatively lightly. There was a rush on the part of the Zeppelin's crew to man their guns, while with a bound the airship shot vertically upwards, intent upon gaining a greater altitude than that of her attacker.
But for once the commander of the airship had underrated the climbing capacity of a "heavier-than-air" machine; for, anticipating the manoeuvre, Blake set the battleplane to climb at her maximum speed.
With her fuselage pointing almost vertically the battleplane rose under the powerful beats of her wings. Thanks to the balanced gear of the seats, all four of her crew felt no inconvenience. Athol and Sergeant O'Rafferty were pumping in hundreds of nickel bullets, until it seemed as if the Zeppelin must be riddled through and through.
Still the gas-bag rose. Two of her guns were replying to those of the battleplane, firing a sort of combined high explosive and shrapnel three-pounder shell.