Front matter (continued 2)

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.

Nearer and nearer came the huge mass, steering badly and veering round in attempting to gain the lee-side of the trees, lest she should be totally wrecked in the mooring. Two hundred feet of cable suddenly dropped from her bow, and, when it touched the ground, Max gave the signal, and with a wild shout these fierce Bedouin horsemen suddenly broke from cover, and galloped into the open.

"Ye saints!" gasped the Indian judge, when he beheld this wild tournament of galloping horsemen, brandishing their rifles and long spears. "Are we to be eaten alive?" Less than an hour ago he had expressed a pious wish to visit this peaceful garden in the desert; now, it was too near to be pleasant.

"All hands to the cable!" shouted Max in Arabic, and very quickly both horses and men were struggling with the stout hawser.

"This way," shouted the Gotha pilot. "Take it round and round these three trees; they should stand the strain unless the wind gets stronger," and selecting a small group of trees on the leeward side of the grove, he very quickly had the cable made fast in such a way that the leviathan of seven hundred feet in length swung easily head to wind, like a ship riding at anchor and swinging with the tide.

Then the tribesmen, kept well in hand, surrounded the prize, keeping some thirty paces distant, for they had not yet quite overcome their fears. Never before had such a thing been seen resting on the yellow sands of the Hamadian Desert.

As the gondolas of the Empress of India came to rest quietly on the ground, the Scorpion descended in a rapid spiral, touched the sands lightly and taxied up to the fringe of trees.

Then, to the utter amazement of the occupants of the dirigible, some of whom were already descending from the gondolas, a couple of men, wearing the loose flowing robe of the desert, including that distinctive mark of the Mohammedan world, the fez, leapt from the machine and approached the airship.

"Snakes alive!" ejaculated the colonel; "but what have we here?" his eyes fixed upon the two men.

"Some person of note, evidently," remarked his friend the judge, as he saw the foremost of these individuals mount a richly caparisoned horse which was held in readiness for him, and approach in a dignified and almost royal manner.

"This king of the desert is evidently some European renegade who is challenging the right of other nations to cross his domain without his permission," said the soldier.

"He is some daring pilot, at any rate," replied the justiciary.

"I wonder now what he intends to do with us," observed the other.

"Why, he intends to plunder us, of course," replied his companion. "What else could be his motive?"

The captives were not long to be left in doubt as to the proceedings of this daring freebooter. Raising the megaphone which he had used in the air so effectively, he shouted in perfectly good English:--

"Abandon airship!"

And to make this order immediately effective, the desert king ordered Max to see that every member of the great liner, passengers and crew, were immediately assembled before him. The navigating officer and the captain were the last to leave the vessel; they did so unwillingly, and not without a measure of compulsion at the point of a revolver. The skipper's looks as he fixed them upon this desert freebooter astride the fiery steed, conveyed to the brigand much more than mere words could have expressed.

Fixing him with his keen, malicious eyes, the pirate said: "Are you the captain of this vessel?"

"I am," replied the skipper in surly tones.

"Show me your bill of lading."

"Bill of lading?" echoed the captive. "You must hunt for it if you want it."

The self-styled king of the desert frowned. He knew that he was up against an English skipper, and that he must adopt other measures to gain his end. Without lifting his gaze from the commander of the air-liner, or flinching a muscle, he replied firmly, "One word from me, Captain, and your life would be forfeit. You would swing from that tree by one of your own cables."

"I know that, brigand," replied the prisoner. "Get a cable and carry out your threat; the rope that will hang you is not so very far away, either."

"Very well," exclaimed the German. "Then, I need only give the order to these, my faithful subjects, and the whole of your valuable cargo will be strewn on the sands, and your airship will be alight. I do not propose to adopt those measures unless you compel me. I will give you five minutes to decide." As the pirate uttered these words in a cool, nonchalant manner, he glanced at the European emblem on his wrist, a gold, gem-studded wristlet watch with luminous dial.

"I deny your right to interfere with a peaceful trader," blurted out the captain, when he saw the full force of the two alternatives which had been offered to him. He was wondering, moreover, how much the brigand knew about the presence of the specie on the vessel.

"You deny my right, do you?" returned the other.

"Yes. Who are you?"

"I am Sultan von Selim, Air-King of the Hamadian Desert. I told you that once before when I first challenged you in the air."

"Who made you king?" snorted the captain.

There was silence for the space of ten seconds, during which time the brigand consulted his watch again, then replied:--

"The Allies made me king, particularly you verdammt English when you drove me from my Fatherland with those impossible peace terms. King I am, and king I will remain, of all the aerial regions where I choose to abide, until there comes a better man who can beat me in the air. And you, Captain, of all men, must know from what you have already seen that my powers in that realm are considerable."

The captain, having cooled somewhat after this outburst, had to admit to this German irreconcilable that there was certainly some truth in his statement about being king of the air. Certain things were beginning to dawn upon this English captain, and he was now wondering how far it would be wise to humour the brigand. He added, however, to his admission, the following words, "You are only king by might!"

"Ha! ha!" laughed the outlaw, "but that also is some admission. My position is precisely that of the British in India or Egypt. Withdraw your soldiers from these two countries and what becomes of your government there? So am I King of the Hamadian Desert till a stronger man comes. When that time comes one of us must die. There is no room for two kings, even in the desert. Till then I am supreme. But come, captain, four minutes have passed already. Your bill of lading, quickly now, for we are but wasting time, and these my subjects"--and here the brigand waved his hand towards the restive Arabs--"or rather I should say my customs' officials, are waiting to examine your cargo, and to levy the king's tribute."

The captain looked around first upon his own followers and then upon the impatient Bedouins--the vultures around the carcase.

"I could have brought your ship down in flames, but I preferred a milder method," continued the outlaw, as he watched the seconds of the last minute being ticked away on his jewelled watch.

"But helium will not burn!" returned the captain smartly. "That was beyond your powers."

A mocking, sardonic laugh came from the robber chief as the Englishman uttered these words.

"Would you like to see it burn?" he almost hissed.

The captain faltered in his reply; he was not quite so decisive as he had been. Evidently there was some sense of humour, if not much, about this irreconcilable German.

"Here, Carl!" cried the bandit. "Detach one of those nineteen ballonettes from the airship."

"Yes, sir," replied the subordinate, stepping up to the king and saluting smartly.

"Take it away to leeward there, and show this dull Englishman how he may learn chemistry and science even from inhabitants of the Hamadian Desert. Here, take this, you will need it," and the chief handed to his assistant a small cylindrical tube with which to carry out his orders.

Turning next to the Englishman, he observed, "Know, you dullard, that a small admixture of a secret gas, which is known only to three living men, will make your renowned helium flare like hydrogen. You shall see it in a short space of time."

"Recall your man, I will take your word for it, Sultan!" exclaimed the captain, who now felt that it must be so, for he was already bewildered by the strange things which he had witnessed that day, and he had no desire to see this experiment carried out.

"You believe me, then," returned the air-king, who seemed particularly to relish this interview with the Englishman, especially with this group of celebrities within earshot, for they had listened eagerly to every word which he had spoken. And the German knew that though his days might be numbered, as indeed he felt they were, yet his fame would be greatly enhanced by the episodes of this day, for vanity was not the least among his failings.

Once more he glanced at his watch; for the allotted space of time had nearly run.

"How now, Englishman!" he exclaimed in a harsher tone. "The bill of lading, where is it?"

The chief purser, receiving the captain's nod, at once advanced towards the regal horseman, handed him a bundle of papers and said: "Here, sir, is the document you desire."

CHAPTER XII

THE MAHARAJAH'S CHOICE

A dramatic episode followed the examination of the airship's bill of lading by the pseudo monarch and his so-called chancellor of the exchequer, Carl, who aided his master in the task.

"Item one. What does that consist of?" asked the brigand.

"Mails. His Britannic Majesty's mails," replied the chancellor.

"Where from?"

"From India for Egypt and London," replied Carl, maintaining a grave and solemn deportment.

"H'm! They may pass when the usual tribute is paid," remarked the bandit in serious tones, as though he had delivered himself of some weighty pronouncement.

The judge looked at the colonel with raised eyebrows when he heard this strange decision, but the captain, forgetting his position for a moment, blurted out:--

"Tribute indeed? When did the King of England pay tribute for his mails to be carried across the Hamadian desert?"

The air-king eyed the speaker with apparent amazement, mingled with a touch of scorn and pity, then quietly observed:--

"That is the very point, Captain. There has been far too much laxity in this respect in the past. The liberties of the small nations to make their own laws, and possess their own lands in peace, have been greatly endangered of late. It is mere brigandage for a great power to over-ride the native interests of small communities. But from to-day this brigandage must cease, at any rate over the territories where I rule."

The captain could find no reply to this sally of the desert king's, and, while a smile played about the corners of his mouth, he looked beyond this robber chief, in his gaudy trappings, to where the Scorpion lay squatting like an ugly toad upon the sands.

At length the monarch resumed his cross-examination with these words: "Come, Captain, will you pay tribute for the transit of mails across my territory, or will you not?"

"I will not!" replied the skipper.

With a flash of fire in his tones the brigand ordered: "Take the first ten sacks of mails out into the desert and burn them at once."

"It shall be done, O chief," replied Max, who immediately detailed some of the natives to carry the order into effect, when the captain, urged to it by the judge, asked:--

"What is the amount of the tribute?"

"Ten thousand pounds in English gold," came the immediate reply.

"I cannot pay it," returned the captain. "It is mere plunder," though the judge pointed out to the commander quietly that it would probably be more profitable to pay it and to get away with the mails in a damaged airship, than to leave the mails behind to be lost or destroyed in the desert.

"He will take the gold anyhow, when he comes to it on the bill of lading," added the colonel, "though devil a penny I'd pay him."

"It isn't my money," argued the captain, "so there's an end of it."

"How now, Englishmen! We are wasting time. Will you pay the sum demanded?"

"No, I will not!"

"Very good. Get out the rest of the mails and burn them at once!" ordered the monarch, and a couple of minutes afterwards the first bags of mails, sprayed with some inflammatory liquid, were blazing furiously.

"Item two!" called the desert king.

"Gold. Nineteen boxes of bullion for the Bank of England," called out the chancellor.

"Gold?" echoed the air-fiend, as though he were utterly unconscious of the presence of such a commodity, in face of the captain's refusal to pay over a trifling ten thousand pounds to secure right of way for his mails.

"Yes, sir. Nearly one hundred thousand pounds in specie."

"I thought we had prohibited the importation of gold into these regions, chancellor, because of its evil effects upon the minds of the people."

"Yes, sir," returned the chancellor. "We decided to abolish its importation altogether on that account, save only as tribute money for the royal chest."

"Exactly," replied the bandit, in a tone of assumed moral injury. Then, turning to the Englishman, he said: "You must know, Captain, that most wars are caused by gold, and by the unbrotherly strife which it foments. You must know also that all wars are sustained by it."

"Yes, I agree with you for once," returned the prisoner, boldly, wondering at the ease with which this confirmed brigand could turn moralist.

"Then what must be done with the gold, sir?" asked the chancellor.

"Every ounce of gold on the airship must be confiscated," exclaimed the king of robbers as he uplifted his hands in pious horror. "Let it be removed at once."

"Very well, sir," and this second operation, which was more pleasing still to the waiting Arabs, was immediately put into effect.

"Item three!" called out the chief.

"Ten boxes of valuables, including the personal property and belongings of one of the passengers," came the reply.

"What, do they belong to one person?"

"Yes, sir."

"What is his name?"

"The Maharajah of Bangapore, sir," returned the wise man of the exchequer, whose task promised to be an easy one in the future, judging by the vast amount of spoil which had already fallen into his lap.

"The Maharajah of Bangapore?" repeated the monarch, raising his hand to his forehead for an instant, as though he would recall some long forgotten episode. "Is he amongst the company present?"

"I believe so."

"Ask him to stand forth."

And the Indian prince, hearing his name called in English, stepped forth and confronted his old enemy of the Mesopotamian campaign. When their eyes met a flash of fire, more eloquent than words, revealed what was in each man's mind. The prince expected to be tortured to death and was prepared for it, for, like all his people, he was brave as well as fierce. At last the robber spoke.

"Prince Jaipur, you are an enemy of mine," he said.

"I know it!"

"Do you expect mercy after the way your tribesmen massacred my men at Kerbela?"

The maharajah shrugged his shoulders, but disdained to reply to this upstart robber chief who styled himself a king.

"Do you know that your life is in my hands?" exclaimed the bandit fiercely.

"I am not afraid of anything you can do, brigand!" hissed the prince, and his voice sounded not unlike the angry, venomous snake in the jungle. Another man might have quailed before those glaring eyes and those hissing tones. But the German quavered not.

"I will give you a kingly choice," he said, "as you are the scion of half a hundred kings in your illustrious line."

"I ask no favours of a common Bedouin robber," snarled the other.

"Listen. I will give you the choice of drinking this deadly poison, or of being dropped ten thousand feet from my aeroplane. Which will you take?"

The prince shuddered slightly, and glanced up into the cloudless blue, as though anticipating what such a death might mean, then looked at the small phial which the brigand held forth in his hand.

"Yes, ten thousand feet!" continued the German, as he noted the anxious look which overcast the Hindoo's face for an instant, as he gazed up into the sky. "Then I will loop the machine, and, with your hands pinioned, you will be thrown out and drop, drop---- Which will you choose?"

"I will drink the poison," replied the prince, who had now regained his usual composure.

"Very well. Let him be securely tied to that tree to await our pleasure," and the maharajah was instantly seized by three or four powerful Arabs, and secured to a tree some twenty paces away.

"What about his valuables, sir?" asked Carl.

"Have you examined them?"

"Yes, sir."

"And what do they consist of?" asked the king.

"His jewels, his gold and silver plate, studded with rare gems of priceless value. They are worth five times the value of the specie," whispered Carl.

"And what else? You said there were ten boxes."

"Part of his regalia and numerous ceremonial robes."

"They are all confiscated!" announced the monarch. "The sun will set in another two hours, and at sunset the Indian must die."

"There is nothing else, sir, of much value. All the gold and this personal property has been secured. Here is the list of passengers, for there are scarcely any passports held by the strangers," and here Carl, who had paid a visit to the aerial, whispered something to his chief.

"Good! Then, in your opinion, chancellor, sufficient tribute has now been obtained from these strangers who have crossed our territory without permission," said the bandit aloud for all to hear.

"Yes, sir."

"Then let them board the airship at once. She will be cast adrift in ten minutes."

At this there was a scramble for the gondolas, and very quickly all, save the captain and the navigating officer, were aboard. The judge and the colonel, however, prevailed upon by the maharajah's men, descended again to intercede for the life of the Indian.

"You have taken the man's jewels," said the colonel. "At least you might spare his life."

"You may have his body," remarked the airman, "but he must first drink the phial," and a stern look appeared once more in the robber-bandit's eyes. On this point he was unbending, and remained like adamant.

"The airship is ready now, sir," said the captain, making a final appeal for the life of the maharajah. "I should like to report, at any rate, when I do complete my journey, that all my passengers are safe, though I expect to be two days late with only two engines and this beam wind. Once more, will you release the Indian?"

"Bring him before me!" commanded the monarch at last, with a bored expression, and the Indian, still bound hand and foot, was brought before the pseudo king.

"Unloose his hands," came the order.

"They ask me to spare your life, Indian dog!" continued the robber, addressing the prince in contemptuous tones. "If you sue for it yourself, you may have it, otherwise..." and, instead of completing his sentence, the speaker shook the little phial in the face of the prisoner.

"I will not ask my life of you, serpent!" hissed the captive. "From you I will accept no favours. Robbed of my family heirlooms, my jewels and my household gods, I prefer to die. Give me the poison, and I will show you how a real prince of the royal line of Indus can die!"

For one awful instant, the desert chief glared at his enemy, who had dared to refuse his generous offer. Then, in angry tones, he cried:--

"Indian dog! I offered you mercy, but you spurn the gift of Allah and ask for death. Then take this and drink it!" and he tossed him the phial.

"Stay!" cried half a dozen voices from amongst the group of passengers.

But their expostulations were in vain, for, with an eagerness to hide his disgrace in death, which only a proud oriental can show, the prisoner caught the phial, withdrew the small cork, and drained the contents before his horrified friends could interfere.

The next moment, the body of the maharajah lay prostrate upon the sands of the Hamadian desert.

CHAPTER XIII

THE MISSING AIRSHIP

Horrified and aghast at the foul deed which had been done, the passengers and crew of the air-liner, who had left the gondolas at the cry of consternation which went up, now crowded around the fallen prince. Even those fierce sons of the desert who witnessed the dire act could not restrain an involuntary shudder, but they merely shrugged their shoulders, or remarked: "Kismet! It is the will of Allah, the Compassionate, the Merciful," and after some such invocation, their piety appeared to be satisfied, for they immediately returned to their treasure.

The captain and his friends were loud in their protestations and imprecations after their first and futile attempts to rouse the prostrate man, for they believed him to be already dead. They glared at the pseudo caliph, who appeared to be entirely unmoved by the heart-rending spectacle. And if, at that moment, any weapon of offence had remained in their possession, it would certainly have been turned upon the offender, whom they now regarded as a murderer.

But every weapon had been carefully removed from the air-liner and her complement; even the unmounted machine-gun and the one box of ammunition placed aboard on her first voyage, were now in possession of the bandits.

The captain in particular was furious, and he turned upon the German fiercely, shook his fist at him and cried, "One day you will pay for this, sirrah! The arm of Britain is long enough to reach you!"

A mocking laugh was the only reply which the German gave. Then, looking once more at his jewelled watch, he signified that the time for the airship's departure had almost arrived.

"Three minutes more and I shall cut her adrift," he said.

"But the maharajah?" asked the captain. "What can we do with him; we cannot leave his body to the vultures."

"Bah! Take him away with you. He will live again in seven hours; it was only morphine!"

Bewildered, but yet relieved by these words, they quickly ascertained that the prostrate man was not actually dead, and they hurriedly placed him aboard the airship and administered emetics.

"Let us get him away at once," urged the Indian judge; "perhaps the higher altitudes will quickly dissipate the effects of the morphine."

"Are you ready there?" shouted the caliph, who had ridden with his escort up to the central gondola.

"Yes," came the response.

"Then remember, the next time that you invade my dominions without my permission you will not escape so easily. As you know to your cost, the King of the Hamadian desert is able to defend himself and his people, even from the insults of a great power."

The captain made a slight bow, half ironical, in response to this kingly assertion, and asked,

"Is there any communication which your majesty would like to have delivered to my Government?"

"Yes," replied the monarch, drawing from under his loose robe a sealed packet, which he appeared to have had in readiness for the occasion. It was addressed as follows:--

"To Colonel John Tempest, D.S.O., M.C.. Chief Commissioner of the British Aerial Police, Scotland Yard, London,"

and across the top left-hand corner it was marked "Confidential," and also "To be delivered personally by the Captain of the Air-Liner, Empress of Britain."

The skipper, apparently bewildered for a moment by this strange request, for it seemed to him like a letter from a condemned man to his executioner, looked the packet over for a few seconds. Noting the great red seal on the back, he read the imprint embossed on the huge wafer. It read as follows, and was circular in form:--

"From Sultan von Selim, Air-King of the Hamadian desert," and the crest was a scorpion, with the solitary word in Latin, "Scorpio."

The caliph waited patiently until the captain had examined the exterior of the packet, and recovered from his amazement, and then said, "Before you depart, Captain, you must promise me that you will deliver that packet in person to Colonel Tempest, who is not unknown to me."

The captain did not answer for a few seconds, for he was wondering what new conspiracy was this. He was wondering also whether the conveyance of this packet was not after all the real reason for the forced descent of the airship.

"Do you promise, Captain?" asked his interrogator, looking at him fixedly.

"Yes, I promise."

"On your honour?"

"On my word of honour, I promise to deliver it."

"Then good-bye. I will 'wireless' the patrols to look out for you."

"Thank you," replied the skipper acidly.

And the next moment, seeing that only his own accomplices and reputed subjects were left on the ground, the Sultan gave the order, "Let go!"

So the huge cable was slipped, and the leviathan left her moorings at once. The north-west wind carried her clear of the trees, and, as she had left nearly two tons of her most precious cargo behind, she rose rapidly, then started falteringly on her long journey to Cairo as her two remaining Sunbeam-Maori engines burst into life.

The sun, which had shone with pitiless might upon the Arabian desert that day, was sinking like a huge red ball beneath the horizon when the great air-liner, drifting considerably from her course, but still making progress in her journey towards Cairo, disappeared from the watchers' view.

With strange impartiality, inexplicable in such a robber-bandit, the spoil had been divided amongst the Bedouins, who, to their bewilderment and surprise, were now rich, each one of them, beyond the dreams of avarice. Their gratitude to Allah, the Giver of all Good, and to the great white sheik was unbounded. Never before had their greedy eyes beheld such treasure; never before had they gained a prize so easily; and some of them even wondered whether, after all, Mohammed had not appeared to the Faithful once more in the person of the great white sheik.

Long before midnight, however, the last man, with heavily-laden beast of burden, had disappeared, swallowed up, as it were, by the very sands of the desert, so that, when the full round moon approached the meridian and changed the gold of the desert to silver, not a vestige of man or beast remained. And of the camp, only a few ashes marked the spot where once a fire had burned. The Scorpion, too, had taken its departure for an unknown destination, carrying its mysterious crew far, far away from these burning sands, for the indomitable commander knew only too well that the captain spoke truthfully when he said that the arm of Britain was very long, and could even reach to this wild desert land.

Before his departure, however, Heinrich von Spitzer had sent off his promised message in laconic terms to the Cairo patrols. It ran as follows:--

"Air-liner Empress with damaged engines crossing desert towards Cairo. Lat. 29-50 N., Long. 40-25 E. drifting W.S.W. Wireless deranged. SCORPIO."

"Piece of bad luck, sir!" remarked the commissioner's assistant at Cairo when he received the message.

"H'm! She carries the Indian mail, too," replied his chief.

"Yes, and a good deal more, sir."

"What else does she carry this trip besides passengers and mails?" asked the alert commissioner.

"That big loading of specie, sir, for the Bank of England. Nearly a ton of gold, I believe."

"Phew! And isn't the maharajah of somewhere or other coming on a state visit to the King also?"

"Yes, by Jove, so he is! We had a message this morning saying that he would travel by the Empress."

"Heaven help us if she comes down in the desert with that cargo. The Bedouins would soon make short work of it. The authorities rely too much upon the patrols for these long journeys," said the commissioner.

"We were asked to take particular care over her this trip. The Delhi patrols accompanied her part of the way, and she was all right up to mid-day, but she hasn't spoken to us since. I have sent out one or two messages and have had the patrols ready to go out and meet her, as soon as I heard again from her, giving her position, sir."

"And you've had no further reply till this message came in?" asked the chief.

"No, sir."

"By the way, is her wireless damaged as well as her engine? I didn't notice."

"Yes, sir. The message says: 'Wireless deranged,'" replied the assistant, re-reading from the aerogram.

"Then who the deuce sent the message?"

"Scorpio---- But who Scorpio is I can't make out. It must have been some passing airman, for it cannot have been one of our own patrols."

"Phew! The mystery deepens. Get the patrols out at once, and tell them to take plenty of ammunition with them. It will take a few rounds to scare off those Bedouin fiends if once they get round a carcase where there are such pickings."

"I don't think there's much to worry about in that respect. Those Arabs have a wholesome fear of these air-liners, sir. However, I will get the machines off at once."

CHAPTER XIV

BETRAYED BY THE CAMERA

The order was quickly given for the aerial police scouts to start. Within a few minutes the patrols left Cairo and the adjoining air-stations, and, spreading out fan-wise, they crossed the Canal, the Gulf of Sinai, the wild mountainous peninsula which bears the same name, and the Hedjaz coast, until they entered the desert regions beyond. Then they commenced their search by moonlight for the battered and drifting air-liner over the trackless, desert lands which lie between the 28th and the 30th parallels.

By a pre-arranged system of Very lights, the patrols kept each other informed of their exact positions during the night, and watched keenly the eastern horizon for any response which might come from the belated airship.

Meanwhile the air-liner, fighting manfully against the freshening wind, made very slow progress, and drifted still further and further away from her course. The air was full of wireless messages both from Cairo and the patrols, but she was as yet unable to reply and define her position. The engineer and wireless operator, however, had been able to receive some of the messages indistinctly, and they knew at any rate that help was not far away.

The captain was naturally very much depressed by the turn of events. Somehow he felt that he had not acted very heroically in the matter. He had considered the safety of his distinguished passengers perhaps too much.

"If I had had no passengers to consider, I would have remained aloft until the whole liner had been shot to ribbons!" he declared to himself, when he at last retired for a few minutes to his private cabin. "They should never have taken me alive! But there, my instructions stand--the safety of the passengers and crew before anything else. I was a fool, though, to act as I did. I ought to have sent out the S.O.S. to Cairo without a second's delay, instead of arguing with this brigand; but there, whoever expected to encounter anything like this?"

Then as his thoughts turned to the wonderful machine, he endeavoured to docket all the information he could remember about the brigand's aeroplane, for he knew that he would be expected to recount every detail when he met the court of enquiry, "which," he murmured, "is as certain to take place as to-morrow's sunrise.

"Gee whiz! Three hundred miles an hour, and silent engines to boot! Phew! nobody will believe me, anyhow. Still, I shall have to face the music, and also to explain why I have lost a hundred thousand pounds of specie," and the skipper looked down on the white sands below, and for a moment he almost contemplated suicide.

"I wouldn't mind if I could only bring sufficient information to the authorities to lead to the speedy capture of the villain, but I can't. There wasn't time even for a photograph. The bandit was aware of all that, and I understand that every camera was removed from the airship before he let us go."

At that instant there came a slight tap at the cabin door.

"Come in!" cried the commander, expecting some further report from the sick-berth steward about the condition of the maharajah, who, half an hour ago, was said to be showing signs of recovery, owing to the bracing air at three thousand feet.

The door opened, and Gadget, the ship's mascot, appeared. Now Gadget's newest hobby was photography, and through the kindness of the photographic officer he had become the proud possessor of a small pocket camera.

"I got her, sir! Thought you'd like to see her ... begging your pardon," and Gadget, with his dirty, but sunny, smiling face stopped short and pulled his lock of hair by way of salute, as the captain pulled him up sharply by snapping out:--

"Got whom? Like to see whom, Gadget?"

"The 'Clutchin' Hand,' sir," explained Gadget, who now found himself floored for once by his want of English.

"I don't understand, boy?"

"The bloke what played the dirty on us, sir," replied the boy, opening wide his bright blue eyes, and holding out three wet and recently developed pocket films.

"Him what got the swag, sir," continued the urchin, endeavouring to make himself clear.

"Oh, you mean that you photographed the brigand!" replied the skipper as he caught sight of the negatives, and snatched at them eagerly, a new light coming into his eyes.

"Yessir!" exclaimed the lad. "Him what said he was a King of the Desert."

"Gadget!" exclaimed the captain, after a brief examination of the films, which were really three fine, clearly defined pictures of the Scorpion, showing her in mid-air, when alongside the Empress.

"Yessir," replied the excited youth, not yet certain whether he was going to be hanged or praised for his offence.

"You have shown more wit and skill than anyone on board the airship. You shall be well rewarded for this, I promise you. How on earth you managed to get three good snapshots like these, all showing different angles of the machine, and to hide them away, is beyond me!"

"Thank you, sir! Thought you'd like 'em," and the boy's eyes sparkled even more than ever as the captain shook him by the hand, and planted five new, crisp Bradburys therein, then dismissed him.

"Great Scott!" exclaimed the captain, "but that little urchin's saved my reputation. These photographs may prove of more value to the authorities than the lost treasure. I feel a different man. Here is extraordinary evidence against the culprit. One photograph shows the fiend actually firing a burst at the twin engines in the rear gondola, and another the faces of the two occupants above the fuselage. They will show more evidence still when they have been enlarged." And the captain, after carefully drying them, placed them in an envelope and put them into his inner coat pocket, muttering:--

"Smart little beggar! I wish I hadn't punished him the other day for smuggling that tobacco aboard."

The captain, who had left strict instructions that he should be called half an hour before the end of the watch, in order that he might relieve the navigating officer, was just about to lie down on the couch for a brief spell, when suddenly another knock at his cabin door startled him, and immediately after his servant entered and announced: "Seven bells, sir."

"Already?" exclaimed the captain.

"Yes, sir."

"Has the moon set, yet?"

"Yes, it is quite dark now, sir."

"All right. Tell the navigating officer that I'll be down in one moment."

At this very instant the telephone bell which connected the cabin with the navigating gondola rang furiously. Snatching up the receiver, the captain asked, "What's the matter, Donaldson? Is there another raider on the starboard bow?"

"No, sir, but there's something very much like a signal flash away in the north-west."

"Sure it wasn't a shooting star?"

"More like a Very light, sir, but very faint," replied the navigating officer. "Shall I reply, sir?"

"Yes, give him three red lights. I expect it's one of the patrols looking for us. I'm coming down now," and the captain replaced the receiver, and made haste down the corridor which led to the chart and navigation room.

The next instant three red balls of fire fell from the airship earthwards in rapid succession, and within a couple of minutes a faint gleam of greenish light fell like an arc in the north-western sky.

"Yes, the patrols have found us, sure enough," exclaimed the captain, who had now joined the officer.

After several further exchanges of fire-balls, repeated now from two or three quarters, the searchers closed in upon the straggler. Then a rapid dialogue took place by means of the morse lamp, and, when dawn came, shortly afterwards, no less than six fighting scouts, running at about a quarter throttle, surrounded the wounded leviathan, and escorted her towards Cairo.

When the Empress reached that town, she was already twenty-four hours overdue at London, so the cables and the wireless stations were busy with messages relating to the missing liner, and with more than one inquiry as to the safety of her cargo, evidently from the consignees, or more likely still, from the underwriters.

And when the captain told his story to the Commissioner of Aerial Police at Cairo there was another mighty stir, and both the cables and the wireless were busy again, for the whole civilized world was tingling with excitement to know something tangible about this man of mystery--the phantom airman. And the story of Gadget's photographs was told to the world.

CHAPTER XV

DIAMOND CUT DIAMOND

While the events recorded in the last few chapters were taking place, a series of adventures not less exciting and perilous had befallen the two airmen, Keane and Sharpe, in their endeavours to track that ingenious conspirator, Professor Rudolf Weissmann, in his secret retreat within the dark recesses of the Schwarzwald.

After their midnight consultation with Colonel Tempest at Scotland Yard, their instructions were to proceed early next day, by whatever aircraft was then available, to Germany, and once there to adopt some suitable disguise, and institute forthwith a most rigorous search for the secret aerodrome. They were to leave no stone unturned in their efforts to track down this great German irreconcilable, who had dared to hold a pistol at the civilized world, and to bring back, if possible, some tangible clue concerning his two great discoveries.

"Time is short," the colonel said. "Immediate action on our part is vital. Spare no expense in the venture, and if necessary you must even proceed to extreme measures to capture this daring outlaw and his accomplices."

"And what about this phantom aeroplane?" asked Keane. "Apparently it has already left the Schwarzwald on its piratical expedition."

"It may return, and you must watch for it. Some of those scattered inhabitants of the Black Forest are sure to have seen or heard something of it. Its trial trips must have been carried out somewhere in the vicinity."

"They are a simple and primitive type of people who still inhabit those forest wastes; wood cutters, lumbermen, makers of little wooden clocks and musical boxes, most of them, I believe," added Sharpe, who had often traversed those regions as a British spy during the Great War.

"Then they should be easier to handle," added the commissioner of aerial police, who had a ready method of brushing away apparent difficulties. "I am compelled to rely almost entirely upon your efforts. Take your pocket-wireless telephones with you and a sufficient quantity of German gold and silver, and start directly you have had a few hours' rest."

"We will get away immediately after breakfast, sir," replied Keane, who had already made up his mind as to how he should proceed in the matter, for he had fixed up his jumping-off ground for the Schwarzwald, and also the type of disguise he intended to adopt.

"Good-bye, both of you, and may good fortune attend you!" said the colonel.

"Good-bye, sir."

Big Ben was striking three o'clock as they left Scotland Yard and made for their quarters, which were in that part of London known as The Adelphi, a quaint, old-fashioned ensemble of buildings of the Georgian period, overlooking the Thames, not far from the Watergate. A few minutes later they bade each other good-night, and turned in for a few hours' sleep before their long flight across England and France.

At seven o'clock they were breakfasting together in a private room overlooking the river, and discussing the details of their coming adventure.

"The Schwarzwald!" Sharpe was saying, as he helped himself to another egg and a rasher of ham. "Where do you think, now, we had better start from, Captain Keane?"

"Mulhausen," replied the other promptly, for with Keane the initial procedure was already cut and dried.

"Mulhausen? Capital! I was thinking of Strasburg, but your idea is better still. Is there a good aerodrome there where we can land?"

"Yes, on the banks of the little river Ill, which runs into the Rhine a little lower down. And once across the Rhine we are already in the Black Forest, though we shall still have a long tramp to the place which I suspect," added Keane, pouring out another cup of coffee.

"Oh, yes, I remember the place; the aerodrome is near the junction of the Rhine-Rhone Canal," replied his companion.

"You've got it, exactly. Now we must get away; it must already be seven o'clock, and a fine morning to boot. What says the weather report about the Channel crossing?"

"Here it is," exclaimed Sharpe, passing a copy of the Times across to his friend, who turned over the pages and read as follows:--

"Flying prospects for to-day:--South-east England and Continent, including the Channel crossing, favourable for flying for all types of machines till mid-day, after that conditions will deteriorate, squalls and heavy rains will predominate, visibility will be poor, and conditions will become unsuitable for cross-country flying."

"Good! Then we must get away at once," observed Sharpe, and within another five minutes they were being hurled along towards Hounslow, the aerodrome from which this new adventure was to begin.

Forty-five minutes later a couple of S.E.9s, the fastest machines in the service, rose from the flying ground and steered a course east-south-east for the Straits of Dover. Thirty-five minutes later, the necessary signals having been accepted by the Dover patrols, with throttles wide open, the two daring young aviators rushed the Channel at one hundred and fifty miles an hour.

The French patrols having been informed by Dover, permitted them to pass unchallenged. And now changing course till they steered almost due south-east, they sped onwards, catching now and again a glimpse of the old battle-front of the days of 1914-1918, where the shell-marked craters of the Hindenberg line were still visible from the air.

Then they followed the railway line from Laon to Rheims, left the ancient town of Nancy to their left, and, crossing the Vosges Mountains and forests a little to the north of Belfort, they dropped down quietly to the landing ground outside Mulhausen in Alsace, as the clock in the Market Square struck the hour of noon.

Having left their machines and flying gear in charge of the commandant, they entered the town, purchased a portable camp outfit, and, dressed as tourists of the pedestrian and naturalist type, continued their journey, crossed the Rhine and entered the Schwarzwald, ostensibly to study the fauna and flora of the Black Forest.

"Phew! I'm tired of this load. Let us camp here for the night, by this little clearing, where these seldom trodden footpaths diverge," said Keane, some hours later, as, weary and dusty with his three hours' tramp through the bracken and the tousled undergrowth, he threw down his heavy knapsack and nets, and began to wipe the perspiration from his forehead.

Then they lit a small fire of dried twigs, cooked their evening meal, and lit their pipes.

After a quiet smoke, during which time they carefully re-examined a survey map of the Schwarzwald, they began to talk in low whispers, whilst the sun descended amongst the pines on the western heights, over which they had dragged their weary feet.

"It is my opinion," whispered Keane, "that we are within five miles of that secret aerodrome."

His companion nodded, almost drowsily, although every faculty was kept constantly alert.

"It is just possible that one of these paths leads to the very spot, but it will be necessary to explore them both. We must be extremely careful, however, for this professor is sure to prove a wily opponent. I hope, however, some wood-cutter or peasant may pass this way soon, and that we may learn something from him which will help us," continued the senior airman.

"What if the wood-cutter should prove to be the professor himself?" asked Sharpe, with a humorous twinkle in his eyes.

"It is even possible," returned his companion.

"In that case it would be diamond cut diamond, Keane, eh?"

The other shrugged his shoulder at the very thought, and prayed that such a contingency might not happen, at any rate until something tangible had first been discovered.

"In three hours it will be midnight," he said. "If no one passes this way by then, I think we must carry out our search in the dark. Time is pressing; we must find something within another forty-eight hours, or poor old Tempest will be at his wit's end, and calling us home again. He cannot leave us long on this trail."

"The greater the pity. A fortnight is not too long to follow a trail like this," said Sharpe.

"Yet you had to do things pretty smartly in those dark days of 1917 and 1918, Sharpe."

"Yes, and there was some danger and excitement attached to it, which sharpened one's wits."

"Never fear! There'll be both before we have finished this trek," returned Keane.

"Hist! What was that?" said Sharpe in an undertone, as he caught the sound of broken twigs.

"Someone approaching," whispered his companion.

They listened acutely now, with every sense keenly alert. Again they heard the sound, and it seemed to come from the western side of the open glade, where the last dull glow of the sunset still revealed the edge of the forest.

The camp fire had died down to a smoulder, but Keane instinctively held his ground sheet before the dying embers, lest their presence should be betrayed. He was anxious to learn something of the nature of this visitor before he revealed himself.

"Bah! It is some creature of the forest," observed Sharpe, after a moment's hesitation. "A wild boar or a red-spotted deer, most likely."

He was right, for the next moment a series of grunts proceeded from the spot whence came the sounds, and, as though suddenly startled by the consciousness of some human presence, the beast, a fine specimen of the Sus Scrofa, with fierce protruding tusks and long stiff bristles, broke cover, trotted swiftly across the glade, within thirty yards of the two watchers, and entered the forest on the other side.

"So much for that little incident," muttered Sharpe, as he released his grip of the Webley pistol, which his right hand had instinctively grasped, when the dark shadow broke from the margin of the trees.

Keane shook his head as though he disagreed with his companion, and remarked in a low voice, "The creature was evidently startled or it would not have fled like that. Its scent is very keen, and as the wind is blowing from the west, it suspected danger from that quarter."

CHAPTER XVI

THE GHOSTLY VISITANT

A few moments later the two men were startled by the sound of a human voice, trolling out the words of some German folk-song, and approaching from the same quarter towards the clearing.

"This is our man," exclaimed Keane, as he removed the screen from the fire and stirred the dying embers into a cheerful blaze, piling on more dried twigs, so that the trees about the glade seemed to dance like fairies.

"Some woodman or peasant returning from a party," observed Sharpe.

"I wonder where his cottage is," replied his friend; "it must be somewhere in the neighbourhood."

"We must welcome him to a belated supper. Perhaps this good Rhine wine will open his lips still more, and he may tell us something about the birds of the Schwarzwald."

"Particularly the phantom-bird," facetiously observed Keane with a smile.

Nearer and nearer came the stranger, breaking occasionally into snatches of song, as though he would frighten away the goblins and weird creatures of the forest, for of the superstitious peoples of Europe, the peasantry of the Black Forest are most given to credulous beliefs. Perhaps this is because no other district of Europe is so rich in quaint legend, folklore and ghostly tradition.

Now and then the approaching stranger would stop his singing to address some remark to a companion; evidently some beast of burden trudging beside him. The next moment the figure of a man, leading a pack-horse through the forest, suddenly emerged upon the clearing. Catching a sight of the dancing flames which mounted skyward as one of the airmen stirred the fire into life, and beholding the dark figures of the two strangers, the newcomer, suddenly stopped, apparently half-terrified by the sudden apparition.

"Geistlich!" he muttered, staring with wide-open eyes towards the sudden flame.

"Guten abend, freund!" exclaimed Keane, wishing to draw the man into conversation.

The man's fears departed as soon as he discovered that he was addressed by human beings like himself, for in his first wild flight of fancy he feared it was far otherwise, and that he had suddenly come upon one of those forbidden glades, where the sprites and goblins dance after dark.

"Guten abend!" he replied, and, being asked to join the company, made haste to do so, reining in his loaded horse and tethering him to a tree-stump close by.

"'Tis late to travel these lonely woods, friend," said Keane in excellent German.

"Yes, 'tis late, but the moon will soon be up, and then, why, 'twill be better footing," replied the stranger, whose full, round face and longing eyes were already directed towards a wicker-covered bottle, which seemed to hold something good, so that he smacked his lips once or twice, and in fancy he was already draining the sweet nectar which the bottle contained.

"Have you far to go?" asked Sharpe.

"Why, yes, 'tis another seven miles to my cottage in the woods."

"Then stay with us an hour until the moon shall rise and clear away the goblins of the Schwarzwald," urged Keane, who, by this time, had been able to examine the stranger's face by the light of the fire, and to read it like a book.

"A simple, credulous fellow, a true peasant of the Schwarzwald, untouched by the outer world," he told himself. "He should be useful to us." Then, passing to him the wicker-covered bottle, he said:--

"Good Rhine wine from Bacharach, Hans. Taste it!"

"Ach, from Bacharach on the Rhine,

Comes the finest sort of wine,"

exclaimed the stranger in the rude dialect of the Black Forest, and his round eyes sparkled as he clutched the bottle, raised it to his lips, and drank half a pint without stopping to take breath.

"'Tis a long time since I tasted such rich and luscious wine, gentlemen," said the peasant, handing back the bottle.

"Pray be seated and rest awhile," urged his companions, and nothing loath to keep such excellent company, Hans, if such was really his name, sat down by the fire.

"Pray, what brings you to the lonely Schwarzwald, gentlemen? Have you come to hunt for the wild boar, or to fish the mountain streams?" he asked, "for I can show you where the biggest fish are to be found, and where the wild pig rears her litters."

"Butterflies and birds, especially birds," replied Keane, pointing to his nets, and his neat little boxes for packing specimens.

"Birds? Ach, there is one bird which sometimes flies in these parts which you will never catch," said the peasant, speaking in lowered tones, as though half-frightened by his own words.

"Ha! What bird is that?" asked the others.

"Hist!" exclaimed Hans, raising his forefinger, and looking guardedly around. "It is the phantom-bird!"

"The phantom-bird?" echoed the two airmen, who could scarcely believe their eyes and ears, as they earnestly regarded this solemn, frightened, half-childish man, who had evidently seen the very thing they had come so far to find, but who believed it to be something supernatural.

The two Englishmen glanced at each other. Had they really found someone who could enlighten them about this mysterious aeroplane, for he could certainly be referring to nothing else? And at that moment Keane blessed his lucky star, which had led him to choose these wild forest regions for their jumping-off ground. Still, they must not appear too curious, lest they should betray the reason of their presence here.

Keane shook his head as, with an apparently incredulous laugh, and a sympathetic motion of the hand, he would banish all tales of ghostly visitants to the realm of limbo. This only had the effect of egging on the speaker to tell his tale, however.

"Ach, Himmel!" he exclaimed. "Es war geistlich!"

"Did you see it, then?"

"Ya, das hab ich!" returned the other.

"Was it in the day or the night-time when you saw it?" asked Sharpe.

"It was night, about this time, and there was but a half-moon above the tree tops."

"Were you very much frightened, Hans?"

"Yes, I was scared to death almost. I thought the old man of the mountains had come for me. I had been to market to sell my little wooden-clocks, and near this very place the huge grey phantom bird swooped down, then circled round and round and disappeared there, over there!" and the peasant, his eyes almost starting out of his head with terror, pointed away to the east.

"Bah! It was no bird, it was an aeroplane, Hans. You should not have been frightened," exclaimed Keane, who had been taking particular note of the direction in which the mysterious machine had disappeared.

"Yes, a ghost-aeroplane!" iterated the Schwarzwalder. "There has never been anything like it before."

"Did anybody else see it?" queried Sharpe, passing the bottle once again to Hans, who stayed but a moment to wipe his lips with his sleeve, and to take another deep drink of the wine.

"Ja, it was seen by Jacob Stendahl the same night, not far from this very place."

"And who is Jacob Stendahl?" asked Keane.

"He is the woodcutter whose cottage is down by the stream, two miles away. That path leads to his house. He was terrified; he said it was an evil omen, and next morning his little Gretchen died."

"And what happened to you, Hans?" asked Sharpe.

"That same night my sow farrowed, and all the litter were dead next morning," replied the peasant gravely.

A deep silence followed this last remark, and the Schwarzwalder brooded over his misfortune, and lamented to himself the loss of his fine litter of young pigs.

The two airmen felt certain now that Hans had really seen the mysterious aeroplane, and they plied him with a dozen further questions as to the noise it made in passing, and the speed at which it travelled, and whether anyone else had seen or heard of it. To some of their questions Hans could give no coherent answer. He said, however, that very few people lived in this part of the forest, and parts of it were seldom or never trodden by human foot. He had spoken to one or two about it, and they also had either seen or heard of it from someone else, and the general opinion amongst the Schwarzwalders in that part, was, that it was one of the dead German airmen, whose spirit came to visit the spot in a ghost-aeroplane.

"Which of the German aces is it, then, that revisits this place, do they think?" asked Keane.

"Some say that it is the ghost of Immelmann, who used to come here before the war to hunt the wild boar; others say that it is the spirit of Richthofen, but I cannot say," replied Hans.

On the question of speed and noise, however, the peasant declared that he was certain.

"It must have been a ghost-aeroplane," he said, "because it was silent, and its speed was like the passing of a spirit when it leaves the body."

A deep silence followed these words, but at the end of a few minutes Hans, pointing to the east, said:--

"Look, friends, the moon is rising already. It is getting lighter, and I must go."

Then, untethering his pack-horse, he thanked the strangers for their hospitality, gave them the direction and situation of his cottage, where they would be welcome, should they care to visit him during their stay in the Schwarzwald, and, bidding them adieu, started off on his journey through the forest.

CHAPTER XVII

THE WATCHERS

They watched the Schwarzwalder and his beast of burden disappear into the forest, then for some minutes the two Englishmen, buried in thought, sat by the embers of the fire. Neither spake to his companion for a while, as, deep in contemplation, each endeavoured to fathom in his own mind this secret of the phantom aeroplane, this riddle of the sphinx. At last Keane addressed his colleague.

"This travelling clock-maker has confirmed our theory, Sharpe," he said.

"Yes, the simple fellow has helped us not a little," replied the other.

"We must continue our search without further delay, lest this talkative peasant should himself encounter this genius, and unwittingly announce the presence of two strangers in the forest. That is my great fear now."

"You don't think this fellow misled us, Keane?"

"Why do you ask? He was too dull-witted to be anything in the nature of an accomplice," replied the captain.

"Quite so, but he might have been a tool in the hands of this mystery man," added Sharpe, as a sudden feeling of suspicion shot across his mind.

"In that case we ought to have followed him, but I scarcely think it worth while. A dull-witted man of that type would have been too dangerous to his employer, even when used merely as a tool. The only danger I anticipate from that quarter, unless I am utterly mistaken, is that the fellow may encounter someone in the forest who is engaged in the plot, and thus reveal our presence, as I stated previously," observed Keane, as he began to get his traps together, ready for the march.

"Anyhow, we have learned something from the Schwarzwalder."

"By the way, Sharpe, you might tune up your little wireless pocket 'phone, and ascertain if there are any messages floating around."

"So I will; we might pick up something," replied the junior airman, and the next moment he climbed into a straggling, low-branched tree, uncoiled a small aerial, and, starting his little battery, listened attentively for any stray message that might be floating through the ether.

"Anything?" asked Keane, coming to the foot of the tree.

"Nothing," remarked the other.

"Then we'll push off."

Five minutes later, having adjusted their packs, collected their nets, and having stamped out the remains of the fire, they were ready to start.

"Which path shall we take?" asked Sharpe, for there were two ill-defined, grass-grown tracks which led away from the clearing. One led past Jacob Stendahl's cottage, and had been followed by the Schwarzwalder, and the other, the lesser trodden of the two, led they knew not where.

"Let us take the one on the right," said Keane, indicating the latter. "It is more likely to yield us something," and the next moment they were hidden from sight amid the dense undergrowth of this part of the forest.

Scarcely had they disappeared from view when one of the upper branches of a tree near to the edge of the clearing suddenly appeared to move, then to swing loosely for a second, and drop to the ground. Then for a moment there was silence, save for the call of a nightjar which had been disturbed, but a moment later a dark shadow debouched from the edge of the forest and crossed quietly but quickly to where the fire had been burning a few minutes previously.

A low whistle, repeated twice, brought a similar shadow from the opposite side of the clearing, and the two indistinct, but human shapes, met each other face to face.

"Who were they, Professor?" asked the second arrival of the first.

"Himmel! Ich weiss nicht, Strauss," replied his companion, who was none other than the renowned Professor Rudolf Weissmann, "but I fear that they portend us no good."

"Let us examine the ground to see if they have left any clue behind."

So for the next few minutes the professor and his mechanic searched the ground carefully for any little souvenir which the travellers might have left behind them. And whilst they searched, they talked in low, but eager whispers.

"Did you hear that half-witted Schwarzwalder talking aloud about the Scorpion?" asked the professor.

"Yes. He called it a phantom-bird, did he not?" replied Strauss. "I heard nearly all he said, he spoke so loudly and coarsely."

"Could you hear what the others said?"

"Not a word; they spoke so quietly, save once or twice when they spoke to the clock-maker."

"Nor could I, and that is what makes me so suspicious," returned Weissmann.

"They spoke good German, though," ventured the mechanic.

"Bah! Of course they would. Nevertheless, it's my firm opinion that they're foreigners, and that they're here for some special reason."

"And that reason is?"

"To find out about the Scorpion," snarled the mathematician.

"Ach!" exclaimed the other; "the Scorpion is two thousand miles away."

"Then their next business is to find the aerodrome," said the professor.

"Blitz! that they'll never do except by accident. Think of those live wires waiting for them if they get within a hundred yards of it. We have found six dead men there already; I don't want to dig any more graves," returned Strauss.

They had continued the search for fully ten minutes, and the professor, occasionally flashing his pocket torch, was carefully examining the long grass within a radius of some twelve of fifteen feet of the spot where the fire had been. Wise man that he was, he carried out his final investigation to the leeward of the fire, trusting that the breeze might have carried some paper fragment, used in lighting a pipe or starting the fire, in that direction. Nor was he disappointed. He was just about to conclude his search, however, when his sharp eyes caught sight of a piece of half burnt and twisted paper hidden away amongst the longer grass.

"Donnerwetter!" he exclaimed under his breath, as he flashed his torch upon the paper for a second. "I thought so; here is evidence enough for an execution."

"What is it, mein herr?" asked the mechanic, hastening to his side.

"Do you see that?" said his companion, untwisting the paper once again and flashing a light upon it.

"Ja! ja!" replied the other as he strained his eyes in the attempt to decipher the handwriting on the half-burnt sheet. "But I cannot understand it, for it is in a foreign language."

"It is part of a small fragment of an envelope, and the writing, which is in English, is certainly almost undecipherable, but I can distinguish the letters '...eane'."

"Ach, Himmel! That is Keane!" replied Strauss. "He is one of the aerial police, is he not?"

"You are right, Fritz. This letter was addressed through the English post to Captain Keane, one of Tempest's best men, if not indeed his most brilliant 'brain-wave,'" hissed the professor.

"Donner und blitzen! Then he has come here to search for the Scorpion, and the aerodrome."

"Yes, but look, he only left London a few hours ago, for here is the London postmark in the corner, bearing yesterday's date."

"And his companion? Who is he?" asked the mechanic.

"It must be that other scout pilot, Sharpe; they work together. But, mark my word, Friedrich Strauss, they are mistaken if they think to find an easy victim in Professor Rudolf Weissmann. I'll teach them to track me like a murderer through the Schwarzwald. They have come to the Black Forest, and here they shall stay." And for once, the quiet, mild-mannered professor jerked out his words with unusual vehemence.

The mechanic saw that his chief was deeply agitated by this sudden discovery, which confirmed all his recent fears, and to allay his feelings, he said,

"But they will never find the aerodrome, Professor, or, if indeed they find it, they will never enter it alive; think of the preparations you have made for all uninvited guests," and the speaker shuddered, for he knew something of the terrors of that "death-circle" in the lonely forest.

"Bah! it is my secret they want, the secret of that mysterious power which drives the Scorpion."

"Uranis?" ventured the other.

The professor nodded, for he regarded it as the greater success of the two. Without it the Scorpion would be useless; with it a dozen Scorpions could be built, once the facilities were provided. Unfortunately the discovery had been effected too late to win the war for the Fatherland. Besides, he had not received the encouragement from the government that he had deserved, and his soul was consequently embittered.

"Come," he said at last, "we must get back to the aerodrome and watch for these half-witted Englishmen. Once there we can afford to laugh at them. They will soon be held in a vice. But I must send a further message to the Scorpion out on the Hamadian plains, hinting how matters stand. After that communications may have to cease for a while. As for these death-hunters, they will find out presently that they are up against something far more terrible than anything which old Jacob Stendahl or the wood-cutter have ever imagined in their wildest fancy. The secret of the Schwarzwald is not for them. I hold the master-key, Fritz, and when I die that master-key will be broken."

And the two men, who had been aware of the presence of the Englishmen ever since they entered the forest, and had watched them accordingly, now moved off in the same direction which the latter had taken half an hour before.

CHAPTER XVIII

"LIVE WIRES"

Matters in the Schwarzwald were now rapidly nearing a climax; the final contest between German brains and English wit could not much longer be delayed. For the moment Keane and Sharpe, unknown to themselves, were enmeshed in the network of a deathly trap. Nothing less than a miracle, or something approaching the same, could now set them free from their perilous position. One thing was certain, and that was that this clever but unscrupulous mathematician and engineer, who was now their declared enemy, would not hesitate to adopt the most extreme measures to get rid of his unwelcome visitors. Unfortunately his power, which almost approached the supernatural, made him a dangerous and a wily foe.

It was now past midnight, but the two Englishmen, who had left the track some time before at a point where its course was suddenly changed, and had continued their journey by the aid of a luminous compass, and the uncertain light of the moon, came at last to another halt.

"Let us stay here a while, Sharpe," his companion had whispered. "I have a strong premonition of some impending danger."

"The deuce you have!" remarked Sharpe, who well knew what this meant in a man like Keane, whose psychic faculties were not to be sneered at.

"Yes. I cannot explain it, but there is some hidden danger right ahead of us; of that I am as certain as that we are in the Schwarzwald. We had better lie down a while and await developments quietly."

Nothing loath, Sharpe unfastened his shoulder straps, slid his equipment quietly to the ground, and laid himself down beside his companion.

For the moment all was quiet. The moon was hidden behind a bank of clouds, and it was therefore very dark, but sounds travel far in the night air of the forest, and when they conversed, they spoke only in whispers.

"It may be," remarked Keane, "that the spot we seek is just in front of us, though I cannot see any glade or clearing as yet; it is too dark."

"Is it likely that there are any booby-traps hereabouts, set by this wily professor?" asked his companion.

"I cannot say; he may have some outer system of defence."

"Or even a system of ground signals to announce the approach of strangers, whose presence might be undesirable to him," added Sharpe.

"It is possible," whispered Keane, whose mind was actively engaged in preparation for eventualities, in view of his inexplicable premonitions. Suddenly he started and touched his comrade lightly with his raised forefinger.

"Hist!" he said, in a voice which could not have carried further than a couple of yards Then he carefully raised his head, and, turning his eyes towards the thicket through which they had come, he tried to read the secret which it contained. His alarm was justified, yet was he mystified not a little, for the more immediate danger seemed to come from behind.

"Can you hear it, Sharpe?"

"Yes, the same crackling of twigs; another wild boar," remarked his friend facetiously.

Keane shook his head, for his sensitive ears had told him that the footsteps which he had heard were those of human beings. Nor was he mistaken, for a moment later they both heard distinctly, not merely the crackling of twigs and the rustle of the bracken under heavy footfalls, but voices, human voices, conversing in a guarded and careful manner.

"None of your Schwarzwald peasants this time," he murmured, fingering his Webley already, for he instinctively felt that this time they were beset by danger both before and behind. And indeed, these two men, during all their adventures in the secret service during the war, were never in more deadly peril than at this moment, as they were soon to learn.

Scarcely daring to breathe, much less to whisper now, the two Englishmen watched furtively for the coming of the strangers, who were now less than a score of yards away, but were approaching very stealthily, as though they were searching for something on the ground.

"Who can they be?" wondered Keane. "And what can they be searching for?"

"Poachers," Sharpe was thinking, "merely poachers, searching for their booby-traps."

Nearer and nearer came the dark shadows, and both the airmen had their Webleys trained on them now. In that moment they might have shot them down easily, and before long they would regret they had not done so. But that is not the English way, for the ordinary Englishman would give even a dog his chance, as the saying goes. Still, there are dogs and dogs, and sometimes human dogs are worse than the four-footed ones. But the Englishmen were uncertain; they did not know what world-wide conspirators were these two men. They did not know what fearful deeds would happen even that day on the Hamadian desert, two thousand miles away, but all of it engineered from this spot, and made possible by these two men. And as they did not know, they did not fire, but waited.

"Gott in Himmel, where does that verdammt live wire begin?" asked one of the men in a low but vehement voice. It was the professor himself, searching for one of his own man-traps.

Sharpe glanced at Keane, but the other motioned him not to fire.

"We're learning something, old man!" he whispered. "This is the gateway to the aerodrome."

The two men had passed them now, passed within six yards, and yet had missed them. They were now groping a little way ahead, looking for secret signs and marks lest they should be hoist upon their own petard.

"Donner und Blitzen! Have you found it yet, Fritz?" called the professor a little louder to his friend.

"Here it is, Professor! Be careful ... there are six wires already laid for those verdammt Englishmen, Keane and--what is the name of the other?"

"Sharpe!" rapped out the professor, as though he had known the man all his life.

At these words the two Englishmen looked at each other in blank amazement. And before their astonishment could subside, the opportunity which had been given to them of ridding the world of two great conspirators had passed.

"One--two--six!" they heard the mechanic say, as he helped the professor over the deadly maze, scarcely fifteen yards in front of them, and then their dark forms had merged into the trees and disappeared, their voices becoming fainter and fainter.

"Great Scott!" gasped Sharpe, when he recovered from his astonishment; "we've walked right into the hornets' nest."

"We should have done if we'd gone another fifteen yards," replied Keane, wiping the perspiration from his forehead.

"Fortunate you had that presentiment of impending danger," said his friend.

"We should have been lying dead and half grilled over his deadly wires but for that strange, weird feeling of mine," replied Keane.

"But there, after all our attempts at concealment, he knows all about us."

"Even our names seem familiar to him," remarked the senior airman, greatly puzzled.

"I cannot understand it," replied the other. "Who can have given him this information?"

"Who indeed?" asked Keane. "It is as great a mystery as the other matter."

"Can it be the woodcutter or the clockmaker, do you think, for Hans is sure to have called at Jacob Stendahl's cottage and told him the news."

But Keane shook his head, as he remarked: "Neither Hans nor yet the woodcutter could possibly have told the professor our names. This evil genius must have other sources of information at his command. Possibly he has an agent at Mulhausen aerodrome, or even at Scotland Yard. To a man like this, a thousand ways are open. I cannot say, but this I know, we are on the edge of the biggest mystery I have ever encountered."

"And we might easily have shot him. Bah! it would have been better to have fired, Keane," added Sharpe somewhat bitterly. "Cannot we follow him now?"

"No!" replied his companion, firmly. "It is better as it is."

"Why?" demanded the other.

"Rest content, Sharpe," said Keane. "To-day we have discovered the aerodrome; to-morrow we will capture it."

CHAPTER XIX

THE DEVIL'S WORKSHOP

Patiently, now, the two Englishmen waited for the dawn. Till then it would not be safe to move in any direction. As they lay in the long bracken and ferns, however, they were able to converse quietly, and to discuss their plans for the coming day. The spot they had come so far to seek was now before them. The live wires, just a few feet ahead of them, had been duly located, and now that the danger was known, it was not insuperable. It was an added mystery to them, nevertheless, how this wizard secured sufficient voltage to make these wires so deadly. They assumed, however, that powerful dynamos, worked by this same silent energy that propelled the aeroplane, were at work somewhere near this spot.

Dawn came at last; a faint yellow streak lit up the horizon away to the east. Then a crimson flush revealed the distant tree-tops, and the moon and stars faded away. A hundred songsters awoke the stillness of the forest, for another day had dawned, and the sable curtain of night rolled westward.

"See, there is a clearing fifty yards ahead," were Keane's first words to his companion.

"It is the aerodrome, the secret aerodrome!" replied Sharpe, peering through the trees.

"Let us work round a little way and find the workshop or hangar. I fancy we shall find it on the other side of the glade."

"Mind those beastly wires, then!" replied Sharpe, as he began to crawl through the dense undergrowth after his companion, who had already started to make a circuit of the outer defences on his hands and knees.

The next half-hour was spent in cautious creeping and crawling just outside those death-dealing wires. At the end of that time, however, Keane made a discovery. He had completed about half the circuit, when, peering carefully through the trees, he fancied he could make out the camouflaged fabric which covered some temporary building. So carefully was this place hidden amongst the trees that he had to look twice or three times before he could make up his mind that he was not mistaken. At last he convinced himself that he had located the workshop, else, why should the place have been so carefully hidden. Waiting for his companion to reach him, he pointed to the object and whispered, "There it is, not thirty yards away!"

"Shall we get over these wires, and rush the place?" asked Sharpe.

"No. Let us continue our journey until we have completed the circuit. We may make another discovery yet. Come along; fortune favours the brave."

They had scarcely crept another hundred yards, however, when a rustling in the leaves, accompanied by a snort, revealed the presence of another wild boar, which had evidently scented their presence.

"Confound the pig!" muttered Sharpe, who was afraid the sounds might lead to their premature discovery. But Keane thought otherwise, for, to his quick mind and instructive genius, this trifling event seemed providential.

"The pig!" he whispered, pointing to the spot whence came the occasional snorts of the angry, disturbed creature.

"What of it?" queried Sharpe.

"Let's get to the other side of the beast and drive it against the wires."

"And roast the brute alive for the benefit of their breakfast, I suppose."

Keane laughed silently, and wondered how far the conspirators used this live wire to keep themselves supplied with food. He knew, however, that a wild boar on the live wires would soon bring out the inmates of that mysterious house in the woods, and would sufficiently distract their attention to give the airmen their opportunity.

The next moment, having made a sufficiently extensive circuit, so as to get the wild boar between them and the wires, they began closing in on the beast, an operation not devoid of peril, should the boar decide to attack them. Fortune favoured them, however. The angry beast, noting the approach of some unseen enemy, by the movements of the tangled undergrowth, half frightened and half infuriated, made off in the direction of the clearing, uttering further snorts. The next moment he had touched the first of those deadly wires, and, with a wild scream which rang through the forest, he leapt into the air, then fell back quivering but dead across that fatal grill.

"Back--back for your life!" hissed Keane, as he made haste back to the spot where they had sheltered, close to the camouflaged hangar.

The next instant the watchers saw the professor and his assistant rush out of the little building, towards the place where the animal lay right across the first four wires. In their excitement they both seemed to have forgotten the presence of the two Englishmen in the woods during the previous evening, for they were both unarmed. Or perhaps it was that they imagined them to be the present victims of their cunning.

"Hoch! Another royal boar for the larder, Fritz!" exclaimed the professor. "We shall have the winter's supply complete very soon."

"Gut, mein herr!" came the answer.

"Better go back and switch off the current, so that we can take it away," urged the chief, and, staying but a second to see the royal victim, the assistant complied.

This was what the two Englishmen had been waiting for. The moment of action had come at last. Gripping their pistols, they made ready to advance and take possession of the hangar during the absence of the inmates.

"Sind Sie fertig, Friedrich?" called the professor.

"Ja, das bin ich!" replied the other, as he left the workshop, and rejoined his companion.

"Come along, the wires are dead now," whispered Keane, and, keeping well within the shadows of the trees, the two men crept forward, gained the rear of the structure, then cautiously worked their way round and entered the hangar unobserved.

One glance about the well-fitted workshop sufficed. There were no further occupants, and they lowered their pistols. Sharpe at once sprang to the lever which regulated the powerful electrical current and clutched it. In another instant the two men without would have paid the extreme penalty, for they would have been instantly killed by their own evil device, but Keane stopped him:--

"Don't!" he said. "We have much to learn. The professor at least must be taken alive, if possible. The secret he holds is too precious to be lost. Let us hide!"

"Where can we hide?" asked the other, somewhat disappointed, and amazed at the further risks which his companion appeared willing to take in order to gratify an insatiable curiosity. "The tables may be quickly turned upon us."

"We can shoot them as a last resort, if that is necessary," urged Keane, who knew the priceless value of the secrets which this place contained.

"Hist! They are coming."

"This way!" whispered Keane, and he drew his companion into a little recess, which had evidently been curtained off for the mechanic's sleeping berth.

They had barely withdrawn themselves into this narrow apartment when the two men entered, dragging the carcase of the wild boar with them.

"Leave it there for a moment, Strauss. The message from the Rittmeister is due. I must also send him that other message again, as the first has not been acknowledged," were the professor's first words.

"Yes, sir. Shall I start the dynamos again?" asked the assistant.

"Perhaps you'd better, but first hand me that message book and the secret code."

The next moment the professor was busy at the wireless keys, transmitting some message to the far deserts of Arabia.

"By all the saints," gasped Keane, "he's sending a message to the raider, the Scorpion, as he calls it. I must have that secret code at all hazards. I wonder what he is saying?"

For some time the chief conspirator was engaged coding and decoding messages at the little table where the aerials, carefully hidden amongst the trees without, had their terminus. And in that moment Keane thanked his stars that he had waited for this, for he saw new possibilities opening out before him. Once in possession of this mechanism and the necessary codes, he could communicate at will with the distant raider, who was threatening the whole civilised world by his almost superhuman powers of brigandage. He could recall the raider also, and make his capture certain, once he could secure absolute possession of this little citadel.

For the present he could do nothing but wait, however, and see how matters developed. Once, the assistant came quite close to their hiding-place, and both men again gripped their Webleys. At this moment even to breathe seemed fraught with danger. If the man should enter the little apartment, he must die, and the professor must be immediately threatened with the same penalty unless he surrendered.

"Ha! So far so good!" gasped Keane, as the mechanic recrossed the workshop without actually entering their hiding-place.

"Teufel!" spluttered the professor. "Here is that fool Tempest trying to communicate with those two verdammt Englishmen who are still roaming about in the Schwarzwald. He little knows that we possess his secret code."

"Himmel! What does he say?" asked the other.

"Wants them to report progress at once, and let him know how matters stand," said Weissmann in a mocking tone. "He says he will come over himself, if necessary."

"Donnerwetter! Ask him to come, Professor. He might as well grill with his accomplices on the live wires, for that's where they'll be before the day is out, unless they abandon their futile search," replied Strauss.

"This fiend is a perfect wizard!" thought Keane, and his glance signified as much to Sharpe. "How he manages to get hold of these secrets is beyond me. And yet, there is a defect in his mad science, for he does not know that we're here, and that his own life is in our hands. Fool that he is, he will soon learn that the wit of an Englishman is more than a match for his boasted knowledge," and here the senior airman carefully withdrew a cartridge from his Webley and inserted another, silently--a cartridge that had a specific mission. His companion watched him and repeated the action with his own weapon, for he understood.

"Blitz! but I've half a mind to send for Tempest," mused the professor, who was still toying with the keys of the wireless instrument.

"Send for him, Professor," urged his accomplice. "Those Englishmen are getting too close to be pleasant. The British army of occupation will be carrying out a thorough search of the Schwarzwald if these men get away, and then where shall we be?"

"We are in the neutral zone, though," replied the other.

"But we're contravening the Peace Regulations, sir, and the English will not stand upon ceremony. It will be too late should these men get away."

"Donner und Teufel!" rasped out the angry professor. "Don't speak to me of the Peace Regulations. There will be no peace till Germany regains all and more than all she has lost. I will send for this Commissioner of Aerial Police, for I believe that he and his two accomplices, Keane and Sharpe, are the only ones so far who know anything that matters about the secret of the Schwarzwald," and he began to tap the keys, reeling out the words as he sent them.

Keane listened acutely for the cyphers of the code. They were:--

"Z--X--B--T--V--O--P..."

and he understood that Tempest was to come at once, make for Mulhausen aerodrome, then take a bee-line, east-north-east over the Schwarzwald until he saw a smoke column, where a suitable landing-ground would be found, and his accomplices would await him.

"Ach!" shrieked the professor, with a fiendish laugh. "The smoke column will mark his last resting-place. They shall all be buried together, these mad Englishmen. We will have more live wires stretched across his landing-ground, and as the wild boar died, so will these men die who dared to follow me into the Schwarzwald."

"The wild boar! Hoch! Hoch!" exclaimed his companion. "It is a fitting tribute for the English are swine!"

"And the Scorpion shall witness the inglorious end of these men," cried the professor, as a sudden idea came into his mind.

"Der Scorpion?" queried Fritz, looking up amazed from his task. "What do you mean, Professor?"

"Why, the Rittmeister will have finished his work in the Hamadian Desert this afternoon. His instructions are to resign the Sultanate of those regions for the present, for the skies will be thick with British scouts by to-morrow."

"But then he goes to Ireland to work with the revolutionists there, does he not, mein herr?"

"Ja! ja! but I will ask him to call here for a day or two before he proceeds. He will have much to tell us, and Spitzer, Carl and Max would like to see these dangerous opponents safely out of the way, for at present they are the only enemies to be considered."

"Gut!" ejaculated Strauss, catching something of the professor's enthusiasm.

Keane would have intervened before this, for he had noted Sharpe's impatience, but he intimated as well as he could by mute signs and otherwise, that the fiend was doing their work for them.

"Let him send this message first," he whispered in his companion's ears, "and then----" But the sentence was completed by further cabalistic signs.

Again the professor turned to the keys, and sent his last instructions through the ether waves to his confederate, the brigand of the eastern skies.

CHAPTER XX

"HANDS UP!"

"Haende in die hohe!" cried Keane as soon as the last message had been sent.

"Der Teufel!" gasped the professor as two swift shadows darted out from behind the curtain, and the two men whom he had just been discussing with such utter contempt confronted him and his accomplice with gleaming pistols.

"Hands up!" repeated Keane, anxious to give the professor another chance.

With a blasphemous oath the man of evil genius, who saw that he had been outwitted, reached for a small hand grenade which lay beside him on the table, and shouted:--

"Never!"

"Then take that!" cried the Englishman, and two puffs of greenish smoke, following a sharp crackle, burst simultaneously from the pistols, for they had both fired together.

The new Asphixor bullets took immediate effect. Both the Germans staggered, clutched their throats as though to ward off the effects of this new powerful gas recently discovered and adapted by that eminent British scientist, Sir Joseph Verne--then lurched and fell, whilst their opponents stepped back and quickly fitted on their safety masks.

"They are both sound asleep," observed Keane, when, the fumes having cleared away, he threw aside his respirator and carefully examined the unconscious men.

"Let them sleep," said Sharpe, who would have adopted even more drastic measures if he could have had his own way. "'Tis scant mercy they would have shown to us if we had been in their power."

"And now let us get to work, for they will awaken in seven or eight hours, and we have much to do. We must prepare for Colonel Tempest, and also for this raider," urged Keane.

"But they will not come to-day, Captain."

"Scarcely, but we must be prepared for anything. There are only a couple of us."

"Shall we secure these men, in case they awake earlier than the stipulated time?"

"No, let us remove their slumbering forms behind the curtain there; we will attend to them before they awake. I do not like the idea of strapping down unconscious men, even though they are criminals. We will watch them from time to time."

Then for the next half-hour they carried out a careful examination of the hangar and its contents. They were amazed at the intricate and wonderful mechanism with which the place was fitted. It seemed impossible that these things could have been transported hither without attracting attention. Parts of aeroplane wings, struts, propellers, engine-fittings, strange, weird-looking cylinders, retorts, analytical appliances, instruments and vessels for chemical research, powerful but silent dynamos, and numberless other things, all neatly arranged, and apparently in working order, half filled the place.

The further they carried their investigation the more were these two Englishmen bewildered by what they saw.

"Is it possible," gasped Keane, "or am I only dreaming? We have discovered the home of the super-alchemist. After this, nothing will surprise me."

"We have discovered the devil's workshop," replied Sharpe, who did not appear to be half so enraptured as his friend.

"Nay, we shall find the philosopher's stone, or the elixir vitae soon," replied Keane, continuing his investigation.

"We are more likely to find the elixir mortis than anything else," said the gloomy one. "This place gives me the shivers. I am sure that I shall have cold feet for the rest of my life."

"After this, Hermes and Geber will be dull reading," continued the enthusiast. "Give me the Schwarzwald every time for the real thrill of the alchemist."

"Their time might have been more profitably employed, at any rate," remarked Sharpe.

"Yes, it is a thousand pities that the wonderful brain which designed and organised all this should have had nothing better in view than brigandage and world revolution."

"More misdirected energy," moaned Sharpe; "the greatest brains often make the greatest criminals."

"You're a veritable misanthrope, Sharpe!" said his companion, laughing.

"I have reason to be," returned the other.

"What do you mean?"

"I mean this--we're not out of the wood yet."

"I agree; we're in the very centre of it," replied Keane.

"Yet you did not inflict the coup de grâce on the diabolical vipers, and they will shortly awake. Moreover, the Scorpion may arrive unexpectedly, and we shall be unprepared for her."

"What would you do?"

"Bring over the machines from Mulhausen, ready to fight this air fiend when he comes."

"Ho! So you're longing for another real air fight, are you, like the 'scraps' we used to have with the Richthofen 'circus'?"

"At any rate, we'd better prepare. Then I'd bind those two criminals hand and foot or surround them with live wires, so that, should they awake unexpectedly, they would not dare to stir."

"There is certainly something in what you suggest about bringing the aeroplanes over, though we should have a deuce of a job to land them in this place; they're by no means possessed of the powers of a helicopter. However, I'll get into touch with Colonel Tempest and ask for immediate assistance, and also ask him to bring over Professor Verne to investigate these mysterious engineering and chemical appliances."

So, leaving the workshop, the live wires and the prisoners to the care of Sharpe, the senior airman devoted all the rest of that morning to investigating the wireless apparatus, examining the secret codes, and trying to get into touch with the Commissioner of Aerial Police. In this, however, he was not very successful, for the air was full of messages, concerning an overdue air-liner which had been expected for some time at Cairo. Perhaps his message had been jammed or lost in the aerial jostle.