CHAPTER XVIII
THE DERELICT OBSERVATION BALLOON
"Well done, old man!" exclaimed Tressidar as he climbed back into the basket car. "That was a brilliant idea of yours. Look here, you know something of aeronautical work; I don't, so you had better pilot this contraption."
Fuller shook his head.
"This isn't a clinking little biplane," he said, "It is completely at the mercy of the wind. But we mustn't grumble; we're leaving Sylt a long way beneath us."
Looking over the edge of the car, Tressidar could discern practically the whole of the long, narrow island, which is twenty miles in length and averaging two miles in breadth. Owing to the fact that it was dead low water the island appeared to be a vast peninsula, joined to the Schleswig shore by a broad belt of sand. North and south of the island and running respectively south-east and north-east were two extensive estuaries that almost met at the causeway connecting Sylt with the mainland.
"Which way are we drifting?" asked Tressidar anxiously.
"Hanged if I can make out," replied Fuller. "We've apparently struck a calm patch. The wind was certainly sou'sou'west when we kicked off. See—the smoke from those buildings: it had a decided drift towards the Danish frontier."
"A good easterly gale would be more my mark," said Tressidar. "We would then stand a chance of getting picked up by our patrol craft."
"Unless they started to shell us with the most amiable intention of sending a couple of supposed Huns to blazes," added the flight sub. "So, in the circumstances, Denmark is good enough for me, even if we are lucky enough to fetch it."
For some moments there was silence, broken only by the barking of a dog some thousands of feet below Then Fuller, who had been leaning over the side, shrugged his shoulders.
"We're dropping, I'm afraid," he announced. "It's close on sunset, and with the fall of temperature the buoyancy of the gas-bag suffers. See what you can chuck overboard."
The balloon, being hitherto used as a captive observation machine, was unprovided with an aneroid, or indeed any instrument for measuring the altitude. During the last ten minutes it had drifted steadily in a north-easterly direction, so that, unless the wind changed, the aeronauts were faced with the possibility of "landing" somewhere in the North Sea instead of the shores of Jutland.
Overboard went the rifle, two hundred rounds of ammunition, the telephone, and other miscellaneous articles, all of which stood a good chance of doing a certain amount of damage to the German torpedo-boats at the mouth of Lister Deep. A revolver and fifty small cartridges Tressidar retained, arguing with himself that they might be useful.
"There's a fog coming up," he said, after studying the panoramic view through a pair of binoculars. "A night mist, I suppose. It will make things jolly awkward when we do land."
"It will be a jolly good thing for us very soon," corrected Fuller. "Look, what do you make of that?" And he pointed in the direction of the now distant fortress of Sylt.
"Taubes," exclaimed Tressidar laconically.
"Or Fokkers," added the flight-sub. "Two of the brutes; they'll be hard after us in a brace of shakes. In fact I think they are heading in our direction already."
"Thank heaven it's getting dark," said the sub. fervently, for already the land was shrouded in the gloom of twilight. "And it's getting fairly thick up here. I can hardly discern the aeroplanes."
"They have a bigger object to look for than we have," said Fuller. "We'll have to do one thing or the other—go up or down. Going down means irreparable loss of hydrogen."
"There's nothing left in the way of ballast to sling overboard."
"Yes, in due course," remarked the flight sub. "I see a couple of straps round the basket. We'll have to strap ourselves to the netting and cut the car adrift. It's our only chance."
Tressidar realised the gravity of the situation. The balloon, by no means fully inflated when they boarded her, was appreciably losing lifting power both by the minute yet none the less certain porosity of the envelope and by the fall of temperature. He shuddered, strong-minded though he was, at the idea of having to literally hang in the air with the prospect of a terrific drop to earth should the thin cordage of the netting give way.
Presumably the German airmen were reluctant to plunge into the mist, that was now spreading far and wide and increasing in height. They were still climbing spirally, evidently with the idea of gaining an immense altitude before swooping down upon the derelict balloon.
And every moment's delay meant that their chances decreased and that the odds against the fugitives diminished.
The balloon, still falling, was now swallowed up in the fog. To descend prematurely meant either falling upon the German island of Rom, or else into the German territorial waters. In either case recapture was a foregone conclusion.
The low drone of an air propeller announced the disconcerting fact that one of the Fokkers was approaching. Quickly the noise increased, but in which direction—whether above or below—neither of the British officers could determine.
Then, with a rush of displaced air that caused the balloon to sway violently, the aeroplane swept beneath it at the rate of an express train. Too late had the Huns spotted their quarry. To attempt to rise would result in collision with disastrous results to friend and foe. All the Huns could do was to depress the horizontal steering-rudders and dip sharply underneath the balloon before describing a curve and approaching it at an altitude that would enable them to use their weapons of offence. In this case the Germans hoped to recapture the two officers alive, and with that object in view they were endeavouring to perforate the envelope of the balloon sufficiently to send it with comparative slowness to the ground.
"Now!" exclaimed Fuller.
Both men hacked desperately with their knives they had found in the car. The basket dropped and was lost to sight in the darkness. Tressidar and his companion, clinging to the network, were almost unaware of any change of altitude, although there was a slight downdraught of air, until the balloon emerged from the bank of mist into the gathering darkness.
Tressidar gave a sigh of relief. There were no signs of the second German aeroplane. Evidently it was engaged, as was its consort, in hunting for the balloon in the fog, which was very much like looking for the proverbial needle in a bottle of hay—with the grave risk of an aerial collision thrown in.
By degrees the drone of the propellers died away and complete silence reigned. It was becoming bitterly cold. The two men, ill-clad for a night in the clouds, shivered violently. Their hands lost all sense of touch. Had it not been for the leather straps that encircled their bodies they would have been compelled to drop—to be dashed into unrecognisability upon the ground six thousand feet below.
Half an hour passed. Overhead the stars were shining brightly. Obliquely beneath them a dull blurr of light was visible. It was the searchlights of Sylt. Further away, and in the opposite direction, lights of varying intensity glimmered through the now dispersing fog.
"Hurrah!" exclaimed the flight sub. "The coastwise lights of Denmark. They can't be German, for the bounders are as cautious about showing as much as a candle-light as we are. That patch of luminosity must be the town of Esbjerg."
"We're getting nearer," declared Tressidar after another interval, during which the balloon had revolved half a dozen times on its own axis, for in the absence of the cable connecting it with the earth the supplementary gas-bag failed to serve its purpose of keeping the balloon steady.
"And falling," added Fuller. "We'll have to stand by for a jolly good old bump, I fancy."
They had now good reasons for supposing that they were over Danish territory, for beneath them numerous lights were twinkling. It was as yet only nine o'clock, and the villagers had not yet retired to rest. To the southward—for the aeronauts were now able to determine the cardinal points of the compass by means of the Pole Star—the lights ended abruptly, indicating the frontier line between a nation at peace and a nation at war.
"Rub your hands well," cautioned Fuller. "You'll have to be slippy getting that buckle unfastened. Directly we touch we must cast off simultaneously, or one of us will have another voyage through the air. We are now less than a thousand feet up, I think."
The balloon was again falling, although its descent was by no means rapid. The chums could now hear sounds coming from the country beneath them; even a horse trotting and a man whistling. Yet, with the exception of the lights, nothing was visible. Even the nature of the country, whether flat or hilly, open or wooded, was veiled by the darkness.
"What's that?" asked Tressidar, as a number of dark conical projections seemed to flit past only a few feet beneath them.
"Tree tops," replied Fuller. "We've just missed being left on the top branches of some pines. By Jove, there's quite a steady breeze. If we crash into anything there'll be trouble."
Almost as he spoke Tressidar's feet came in contact with the ground. Then like an indiarubber ball the balloon shot ten feet in the air and again dropped, until the sub. found his boots trailing over a field of grass.
"Stand by!" shouted Fuller warningly. "Mind you don't get entangled in the netting."
Both men unbuckled their straps. They were now clinging with both hands to the network. The bumps became more and more violent, as the balloon lost buoyancy, but at the same time their rate of progress over the ground was too quick to enable them to find a footing.
Suddenly their boots caught in the top rail of a fence.
"Let go!" shouted Fuller.
Tressidar obeyed promptly, to find himself sprawling head downwards in a ditch. Regaining his feet, he found his chum kneeling a few feet from him. There was no sign of the balloon. Relieved of the twenty-four stone weight of the two passengers, it had soared upwards once more and had vanished from their sight.