Being unprovided with floats like those fitted to naval seaplanes the machine took the water clumsily. The sudden resistance of the girders carrying the landing-wheels as they encountered the water, caused the body to tilt nose downwards. With solid water well over her forepart, the battleplane shook herself free, bobbed violently several times and finally rocked easily upon the placid waters of the Baltic.
Leaving Athol to keep watch all remaining hands set to work. First the contents of the carburettors were strained. Globules too heavy to pass through the fine meshed gauze confirmed Dick's suspicions. The petrol had been heavily "doctored" with water.
It was a lengthy and disagreeable task draining each of the tanks and refiltering the liquid fuel. The atmosphere of the confined space reeked of petrol fumes; the unusual motion of the hull as it pitched and rocked to the action of the sullen waves added to the discomforts of the highly necessary work. Sergeant O'Rafferty, almost overcome with nausea, stuck gamely to his job, while both Dick and Desmond Blake felt their heads whirling under the powerful influence of the volatile gas.
Suddenly Athol perceived two pole-like objects forging slowly through the water at a distance of nearly a quarter of a mile. Only the feather of spray caused by the resistance of the vertical objects betrayed their presence. They were the twin periscopes of a submarine.
At his shout of alarm Blake and the rest of the crew left their task and hurried to their respective flying-stations. Anxiously they awaited developments. Was the submarine a friend or foe?
Flight, under present conditions, was impossible.
Until the whole of the petrol in the tank nearest the carburettors was completely strained, it would be impossible to get the motors to fire.
Quietly Athol and the sergeant fitted ammunition belts to the two automatic guns. Although the bullets did not possess sufficient penetrative powers to perforate the shell of a submarine the hail of projectiles would be sufficient to prevent any attempt on the part of the vessel's gunners from using their quick-firers—provided they kept within range. Nor could the submarine make use of a torpedo, for the lightness of the battleplane's draught—floating she drew but four or six inches—offered no target to an under-water missile unless the weapon struck the girder-work of the landing-wheels which projected several feet underneath the surface.
Nevertheless the situation was a perplexing one. Should the submarine prove to be German, she could either shell the battleplane from a distance or else summon, by means of wireless, Zeppelins and seaplanes to finish off the helpless aircraft by means of bombs.
Several long-drawn-out minutes passed. The eyes of the periscopes were steadily fixed upon the battleplane as the invisible submarine slowly approached. At length, apparently satisfied with her investigations, the submerged craft housed her periscopes and made off, leaving a tell-tale swirl upon the surface of the water.