Part 4

"Your orders shall be carried out, Rittmeister," replied Max, who was glad to be relieved of his monotonous task of listening hour after hour for coded messages, and looked forward with some pleasure to the coming adventure.

Shortly afterwards, Max, having delivered his message to the Arabian chief, was standing beside Carl under the shadow of a cluster of trees on the very margin of the pool. That wonderful instrument, the vibrative drum, which is fashioned somewhat on the principle of the human ear, but with a large horn-shaped receptacle for receiving the very minutest sound waves, and focussing them on to a very sensitive drum, was engaging their attention.

Every now and then, when they fancied they heard a sound that broke the stillness of the desert, they would listen acutely, turning the horn this way and that way to discover whence came the sound.

"They are due about mid-day, the chief says," remarked Carl, after a brief pause in their conversation. "What time do you make it now?"

"A quarter of an hour yet," responded Max, consulting his chronometer, and making a rapid calculation to allow for the difference in longitude, for he still carried Central European time.

"And they're sure to follow the 30th parallel?"

"Yes, it's their shortest route," replied the wireless expert.

"Then they should pass within three or four miles from here," observed Carl.

"Yes, unless they've drifted a little out of their course."

"But we should hear them on the vibrator even if they were fifty miles away in a silent land like this."

"Undoubtedly."

"Listen! Can you hear anything?" exclaimed Max in a slightly nervous tone, after a brief silence.

"No, I don't think so, but those fellows over there must be quiet; they're getting excited about the promised loot."

"Go and tell them, Carl; you speak the best Arabic."

The German left the drum for a moment and after expostulating for a while with the sheik, he gained his point and the word was passed along for silence.

The Arabs were greatly mystified by this strange instrument, as well as by those aerial wires affixed to the trees, and most of all by that strange, weird machine, hidden away behind the sand-proof curtains of the little camouflaged hangar, like the sacred ark in the holy of holies.

With wondering eyes they had on occasion watched the _Scorpion_ mount to the heavens with marvellous ease and descend with like facility--bearing its human burden aloft to the very skies and bringing them safely to earth again.

These strange gods which the infidels had brought with them to their desert home were greatly feared even by these brave, proud men, and it was only the largesse and the promise of still better things to come, from the great white chief, which prevented these sons of the desert from leaving this dreaded spot.

The scout pilot, having obtained his wish, now returned to the instrument, for his companion was already beckoning to him. Evidently the approach of the airship had been indicated by the sensitive drum, but, ere Carl reached the margin of the pool, he noticed the Rittmeister emerge from the hangar where he had been decoding the message, and wave for him to approach.

"What is it, Rittmeister?" he called.

"The message. Come here a moment!"

Max, who thought that a faint sound he had just heard from the instrument might portend the distant approach of the liner, left the drum, for he knew there would be plenty of time, and joined the other two by the hangar on the other side of the pool, for he also was curious about the cryptic message, which he had taken earlier in the day.

"Was it from the professor?" he asked in his first breath.

"Yes, he is in for a bad time, I fear," replied the Rittmeister. "He will not be able to communicate again for some time."

"What is the matter?" asked the others simultaneously.

"Why, Keane and Sharpe are on his track again. You know the rascals; they were secret service pilots and spies during the war, and now they are scout pilots in the British aerial police. They're the left-hand and the right hand of that confounded Tempest, the little tin god at Scotland Yard, and the brains of the aerial police."

"Himmel! I hope he can outwit them," exclaimed Carl. "They're keen birds, both of them, and they have some exploits to their credit."

"If he can't, then the length of our existence is the capacity of those remaining eight cylinders of uranis," ventured Max.

"And the length of the rope round our necks as well," murmured his companion.

They all laughed at this, but Spitzer looked keenly for an instant into the eyes of the two pilots, as though he would search their innermost souls, and make sure that they would be game to the end. But they evidently read his thoughts also, for Max announced:--

"It's all right, Rittmeister; we're not going back upon our word. The die is cast!" and Carl in a brave attempt at another sally, added:--

"The cast is--die!" at which they all laughed again, as the old sea pirates laughed before they blew up their ship, when they saw that the game was up.

The next instant their thoughts were diverted to another subject. It was already mid-day, for the sun by his altitude announced it. As they approached the drum, they could now distinctly hear the hum of mighty engines though still forty miles away, recorded in that delicate instrument, and one thought, uttered or unexpressed, came instinctively to each mind:--

"Aircraft approaching!"

*CHAPTER IX*

*THE PHANTOM BIRD*

"Airship or aeroplane?" asked von Spitzer, a moment later, as Carl closely watched the delicate recorder, which, as the vibration caused by the sound waves increased, indicated not only the type of craft, but the type of engine by which it was driven, and also whether the engine was running with or without defects. So wonderful are the secrets which man has already wrested from nature.

"Airship, decidedly!" replied Carl, after a second's pause. "Full-powered too; there are four or five Sunbeam-Maori engines, and all running smoothly."

"Her position?" demanded the Rittmeister next.

"Forty-four miles due east," came the answer.

"Then it must be the aerial mail from India; she is just about due."

"Is she steering due west?" the chief asked.

"About two degrees south, that's all," replied Carl. "She's evidently getting a little drift from the upper currents."

"Good!" remarked the chief airman. "Then if she continues steering steady, she should pass within a couple of miles of us in another twenty or twenty-five minutes. Come along, Carl, it is time for us to get away. You will remain on the ground, Max. You have a difficult job. As soon as we get away, see that the tents are struck, and all men and horses placed under cover of the trees."

"Yes, sir."

"And now sound the alarm signal, and help us to get out the _Scorpion_; it is going to bite to-day," ordered the Rittmeister as he strode away, exclaiming,

"Who wouldn't be a king of the desert? For one day at least it will be, '_Deutschland, Deutschland ueber alles_!'"

The alarm being sounded, all the occupants of the little camp went to quarters, just as they had been rehearsed during the last few days. The camouflaged fabric was stripped from the little hangar, and the _Scorpion_ was set free to bite once more. She was released from the ropes which held her down and turned head to wind. The steel folding wings were snapped back into their sockets and made secure.

"Are you ready, Carl?" asked the chief, as he completed his rapid survey of the machine, during which neither the propellers, planes, tail-fin nor rudder escaped his scrutiny.

"Aye, ready, sir!" came the reply from the junior, who was now seated in the armour-plated conning-tower, testing the controls and examining his machine guns.

Without a moment's delay the chief clambered up through the little trapdoor and joined his companion. Then he paused for a moment whilst he swept the eastern horizon with his powerful binoculars.

"I cannot see her yet, Carl," he said. Then turning to Max, who stood by the starboard engine, he shouted, "Just try to pick up her position again from the drum. She may have changed her course a trifle."

The Gotha pilot dashed off on his errand, and after carefully listening for a moment, he returned and said, "East-south-east, about four degrees east."

"Good, she'll pass about five miles south of us then; but she's not visible yet," replied Spitzer.

"She's getting a good deal of drift, I fancy," returned Max.

"Anyhow, we'll get up into the blue and wait for her," said the airman, and waving his hand for the signal to stand clear, he pressed the self-starting knob, and instantaneously both engines sprang into life, and the whirring propellers started up such a dust storm from the loose sand of the desert that the Arabs were startled, and rushed to secure their frightened steeds.

Within ten seconds the rev.-counter indicated two thousand five hundred, and, sufficient power for flying speed being thus obtained, Max deftly removed the chocks from the wheels, and this new type of desert steed dashed off across the sands, and leapt into the air, amid the cheers of the astonished Bedouins.

"Allah, the Compassionate, the Merciful!" cried the Arab chief, as he raised his hands imploringly towards heaven. "It is the bird of destiny, my children, the phantom of the desert!" and Max could scarcely restrain a smile as he beheld the momentary fear which had seized these strong, fierce men.

The next moment, however, they were all busy striking the tents and bringing horses, equipment, and all the camp effects under the shadow of the trees.

Meanwhile the _Scorpion_, appearing exactly like a huge grey phantom bird, soared away in a north-westerly direction, lest it should be observed by the occupants of the approaching liner.

And in a few minutes, rising rapidly by steep spirals, and an almost vertical climb, it had disappeared from sight. Soon it soared over the camp again at ten thousand feet, and appeared but a speck in the cloudless blue, like the faintest suspicion of a tiny cirrus cloud.

Shortly afterwards a cry from one of the natives directed the attention of all present towards another tiny streak in the opposite direction. His sharp, piercing eyes had been the first to discern the approaching airship.

"Allah, the Compassionate!" again began the sheik, and Max, fearing that this strange visitant might affect their nerves, called out aloud in the best Arabic he could muster:--

"Allah be praised! This stranger carries gold and rare jewels across the desert. He must pay tribute to the sons of Jebel and Shomer!"

This appeal to their cupidity instantly changed the demeanour of these fanatics. Their fear departed. Even when, later, they heard the roar of the powerful engines which propelled the airship, their one thought was of plunder.

"The treasures of twenty Damascus' caravans are in that great airship," cried Max, fulfilling with considerable skill the part which Spitzer had allotted to him.

The Bedouins, whose feelings were now raised to the highest pitch of excitement, began to fear lest, after all, so rich a prize might be lost, and they eagerly searched the skies for the phantom airman, as they called the Rittmeister, and shouted:--

"Where is the phantom bird? Where is the great white sheik?" and they would have dashed out into the desert on their fiery steeds, for they were already mounted, but the German restrained them, saying:--

"There is no need to hunt the quarry. The great white sheik will bring down the airship on this very spot. Be ready, when I give the signal, to surround it."

Another anxious moment passed, and the airship, travelling rapidly at some three thousand feet above the ground, would have passed them by some few miles to the south, but at that instant, the Indian judge caught sight of the picturesque oasis with its cluster of palms far down below, and said to his soldier companion:--

"Look, Colonel Wilson! Just look at that beauty spot after two hundred miles of yellow desert."

"Ah, wonderful!" exclaimed the delighted soldier. "It is a little garden planted by Nature in the solitary wastes."

"How picturesque! I should like to land there," returned the other.

"Let us ask the captain at least to change his course slightly, so that we may pass over it and photograph it as a souvenir of our pleasant journey," said the officer.

At that moment the captain, passing down the gangway, overheard the remark, and being eager to oblige his distinguished passengers, he telephoned his orders to the navigating officer, who slightly altered the ship's course, so as to pass almost directly over the oasis.

It was while they were engaged in delightful contemplation of this emerald isle embedded in the gold of the desert, that another object attracted the attention of the judge. Chancing to glance upwards, he caught sight of a silvery speck six thousand feet above them, and a little way on their beam.

"See, a tiny cloudlet in the sky; the first I have ever seen in crossing these deserts."

"A cloud, where?" asked his companion.

"There, right up in the blue vault of heaven," said the judge, pointing out the speck which now seemed to have grown larger.

"Why, it is a bird; some great vulture of the desert. It seems to be diving right down upon us! These vultures, I hear, have often attacked the airships in the desert. It evidently takes us for some new kind of prey."

"A bird!" cried the captain, who had now joined the speakers. "Let me see it?"

"There it is!" cried the two men simultaneously, pointing out the grey, swift phantom.

The captain saw the bird-like object, and one glance sufficed.

"It is an aeroplane," he said, and there was just a touch of uneasiness in his voice.

"An aeroplane?" echoed the others, and an instant later, viewing it through his glasses, the colonel added:--

"Why, so it is; but I say, Captain, what a peculiar type of aeroplane! It is one of the patrols, I expect, come to meet us."

"Your glasses, if you please, for one moment," asked the captain, and he almost snatched them from the hands of the officer.

The next instant a violent expletive burst from the captain's lips.

Leaving his companions, he dashed down the corridor to the wireless operator's room. The operator was already engaged in conversation with the aerial visitor by means of the wireless telephone, and the captain took in the situation at a glance.

"What does he want? Who is he?" blurted out the skipper.

*CHAPTER X*

*THE BRIGAND OF THE EASTERN SKIES*

"Someone has signalled us to stop, Captain!" said the wireless operator.

"Who is it?" demanded the irate skipper.

"He will not declare himself, sir!"

"Hand me that receiver, Robson!" and the commander, clamping the ear-piece of the wireless telephone to his ear, asked of the intruder, "Who are you that thus dares to order me to stop on a lawful voyage?"

"It is I, Sultan von Selim, Air-King of the Hamadian Desert, who orders you to stop!" came the reply from the aerial raider, who now rode just a little way above the large airship, and on the starboard side.

"Then I refuse!" thundered the skipper.

"You will do so at your peril," came the quiet, cool reply, which rather disconcerted the captain.

"I will call up the patrols, you brigand!" continued the commander of the liner.

"One word to the patrols and I will blow your wireless to pieces. I have two guns already trained on it," replied the air-king.

"I dare you to do it!" replied the brave skipper. Then, turning to the operator, he said, "Send the S.O.S. with the latitude and longitude to the patrols. Smartly there, Robson."

"Yes, sir."

"This is that raider we heard of at Delhi, but he can't touch us."

The raider, however, had caught the sentence, or part of it, and he understood the order. The next instant a burst of fire from a machine gun, trained with wonderful accuracy, blew the main part of the wireless apparatus to pieces, and rendered it perfectly useless for either receiving or transmitting. How the captain and the operator escaped injury or death will for ever remain a mystery.

Seizing a megaphone, the former dashed out of the cabin, down the keel corridor and the narrow slip-way, to the central touring gondola on the starboard side, and, shaking his fist at the raider, who sailed calmly alongside about a hundred feet away, shouted through the instrument: "You brigand! You shall hang for this!"

A mocking laugh, drowned by the roar of the engines, which still continued full speed ahead, was the only reply. Evidently this mad airman was enjoying the fun immensely. At any rate he appeared very careless of the other's threats.

"I mean it, you felon!" roared the skipper.

"Are you going to heave to?" came the the reply through the raider's megaphone.

"No, certainly not!"

"Then you must take the consequence!" came the mocking taunt, and the next instant, "Rep-r-r-r-r-r-r-r!" came another burst from that deadly machine-gun, which seemed so effective every time it spoke.

This time the starboard engine, a 250-H.P. motor, conked out entirely, and, for a moment, there was danger of fire in the gondola, owing to the petrol-feed being smashed in the general break-up.

This made the captain think furiously. He now recognised, for the first time, that he was absolutely at the mercy of this strange highwayman of the air. Evidently he was a determined character, a master criminal, and the skipper looked round for some means of defence.

There was certainly an old machine-gun aboard the airship, but it had never been used and was not even mounted, for it was believed that a peaceful trader would never need it. The police patrols constituted the real defence of the trade routes, and even with them a few smugglers were the chief offenders.

The captain's eyes were fixed for the next few seconds on the wonderful machine which sailed along so easily and so quietly. Once, he had noticed, when the raider made a circuit of the great liner, that the machine had shot ahead at twice or thrice the speed of the _Empress_. The armoured conning-tower, over the top of which the heads of the pilot and his companion could just be seen, gave the skipper an impression of strength, against which he knew that even if he could have replied with a machine gun, the bullets would have pattered harmlessly against the sides, and fallen away like rain-drops.

He was in a quandary, this brave air-skipper. He had missed his chance of calling up the patrols. Yet, how could he, a British captain, surrender to some foreign marauder, or perhaps even to a British renegade; for he knew not as yet who this bold fellow was. Then he thought of his passengers, those distinguished guests committed to his charge, and last of all of the valuable lading: that consignment of gold for the vaults of the Bank of England.

"By heaven, it's the gold they're after!" he exclaimed. "I never thought of it before. They've had the news ahead of us and they've waited for the airship in this out-of-the-world spot. Confound them, but they shan't get it if I can help it!" and the captain nerved himself to still further resistance, though he felt it was hopeless, unless some outlying patrol should come up quickly.

The raider seemed to have read his thoughts, for he sailed close up again, and shouted through his megaphone, "For the last time, Captain, will you heave to?"

"No--o!" the courageous man replied, though this time his voice wavered a bit, for he wondered what devilry the stranger would attempt next.

He had not long to wait, for the pirate suddenly banked his machine, turned swiftly outwards, and circling round till he came up level with the great twin-engine in the rear gondola, which drove the giant propeller near the rudder, he opened once more a terrific burst of fire which instantly put both engines out of action.

This almost brought the huge liner to a stop. At any rate, she now made more leeway than headway, for the only remaining engines which could now be used were those in the foremost gondola and port centre cabin.

"Stop!" signalled the captain to the remaining engineers in charge of those engines.

And the next instant the huge, looming mass, with her engines silent, lay there helpless, levering away to windward, shorn of her pride, and with the wreckage hanging loose from her rear and central gondolas.

Another surprise that now awaited the crew and passengers of the air-liner was to see the phantom raider careering wildly around the beaten giant at enormous speed, in almost perfect silence, though his two propellers raced wildly as he dipped, spun and rolled to celebrate his victory, and to show off his amazing powers to the victims.

"Good heavens!" ejaculated the captain as he watched all this. "It was only too true, then, what we heard at Delhi."

"You mean about the silent engines and the speed of three hundred miles an hour," added the navigating officer, who now stood by the skipper.

"Yes. It's some amazing conspiracy. I cannot help admiring the rascals, though I should like to hang the pair of them."

"Hullo! here he comes again. I wonder what he wants this time," and the next instant the raider throttled down, and came close up to the gondola, shouting as he did so in perfectly good English:--

"Start that port engine, please, and bring her to earth by that cluster of palm-trees over there."

"What more do you want with us?" replied the captain.

"I must see your passports, and examine your cargo for contraband."

"Eh, what's that?" exclaimed the amazed commander. "What does he want to examine our passports for?"

"We haven't any," remarked the navigating officer.

"And why the deuce is he to search for contraband, I should like to know?" groaned the skipper.

"Did you hear what I said?" called the raider, who now appeared to be getting angry at the delay.

"Yes," growled the other.

"Then bring her down at once, and let out that mooring cable!"

And as there was no apparent help for it, and not a single patrol had yet hove in sight, the captain of the liner reluctantly complied, wasting as much time as he dared in the operation.

*CHAPTER XI*

*THE AIR-KING'S TRIBUTE*

Far down below, the Arab sheik and his party, ambushed amid the waving palms of the oasis, had watched with keen and eager eyes this thrilling encounter in the heavens between the phantom-bird and the great leviathan. To them it seemed impossible that the aeroplane, sometimes diminished by distance to a tiny speck, could overcome the mighty airship.

As the fight continued, and they heard the rat-tat-tat of the machine-gun, sometimes their doubts and fears overcame them, and many were the cries that went up to Allah the Compassionate, the Faithful, etc. But when they saw that at last the great white sheik had won and the disabled liner was slowly coming lower and lower, their pent-up feelings gave place to wild excitement, and shouts of,

"Allah be praised! The bird of destiny has won! The great white chief has triumphed!" while others, more practical, and also more piratical, exclaimed: "Allah is sending down the treasures of heavens into the lap of the faithful. Praise be to Allah and to Mohammed his Prophet!"

It was with some difficulty that Max restrained these wild men from dashing out in their frenzy to capture and loot the huge, lowering mass that now loomed but a little way above them. He began to fear that they would not wait for the pre-arranged signal, and he urged the Arab sheik to restrain them, and to repeat the orders that the occupants of the airship must not be touched.