As the officer returned Colston's salute he turned to Soudeikin and said civilly enough—

"I did not know you had another guest. I hope we shall not overcrowd you."

"By no means," replied the commissioner, waving his hand toward Colston as he spoke. "This is only my nephew, Ernst Vronski, who is staying with me for a day or two on his way through to Nizhni Novgorod with his furs, and that is his servant, Ivan Arkavitch. You need not be uneasy. I have plenty of rooms, as I live almost alone, and I have set apart one for the prisoners which I think will satisfy you in every way. Would it please you to come and see it?"

"Yes, we will go now and get them put in safety for the night, if you will lead the way."

As the party left the room Colston caught one swift glance from Natasha which told him that she understood his presence in the house fully, and he felt that, despite her miserable position, he had an ally in her who could be depended upon.

The officer carefully examined the room which had been provided for the two prisoners, tried the heavy shutters with which the windows were closed, and took from Soudeikin the keys of the padlocks to the bars which ran across them. He then directed the prisoners to be released from their handcuffs and locked them in the room, stationing one of the soldiers at the door and sending the other to patrol the back of the house from which the two windows of the room looked out.

At the end of two hours the sentries were to change places, and in two hours more they were to be relieved by a detachment from the night patrol. This arrangement had been foreseen by Soudeikin, and it had been settled that the rescue was to be attempted as soon as the guard had been changed.

This would give the prisoners time to get a brief but much needed rest after their long and miserable journey from Perm, penned up like sheep in iron-barred cattle trucks, and it would leave the drowsiest part of the night, from four o'clock to sunrise, for the hazardous work in hand.

"That is a pretty girl you have there, captain," said Colston, as the officer returned to the sitting-room. "Is she for the mines or Sakhalin?"

"For Sakhalin by sentence, but as a matter of fact for neither, as far as I can see."

"You mean that the Little Father will pardon her or give her a lighter sentence, I suppose."

The officer grinned meaningly as he replied—

"Nu vot! That is hardly likely. What I mean is that Captain Kharkov, who is in command of the convict train from here, has had instructions to convey her as comfortably as possible, and with no more fatigue than is necessary, to Tchit, in the Trans-Baikal, and that he is also charged with a letter from the Governor of Perm to the Governor of Tchit.

"You know these gentlemen like to do each other a good turn when they can, and so, putting two and two together, I should say that his Excellency of Perm has concluded that our pretty prisoner will serve to beguile the dulness of that Godforsaken hole in which his Excellency of Tchit is probably dying of ennui. She will be more comfortable there than at Sakhalin, and it is a lucky thing for her that she has found favour in his Excellency's eyes."

Colston could have shot the fellow where he sat leering across the table; but though his blood was at boiling point, he controlled himself sufficiently to make a reply after the same fashion, and soon after took his leave and retired for the night.

At four o'clock the guard was changed. The new officer, after taking the keys, unlocked the door of the room in which Natasha and the Princess were confined, and roused them up to satisfy himself that they were still in safe keeping. It was a brutal formality, but perfectly characteristic of Siberian officialism.

The man who had been on guard so far joined the patrol and returned to the barracks, while the new officer made himself comfortable with a bottle of brandy, with which Soudeikin had obligingly provided him, in the sitting-room. It was a bitterly cold night, and he drank a couple of glasses of it in quick succession. Ten minutes after he had swallowed the second he rolled backwards on the couch on which he was sitting and went fast asleep. A few moments later he had ceased to breathe.

Then the door opened softly and Soudeikin and Colston slipped into the room. The former shook him by the shoulder. His eyes remained half closed, his head lolled loosely from side to side, and his arms hung heavily downwards.

"He's gone," whispered Soudeikin; and, without another word, they set to work to strip the uniform off the lifeless body. Then Colston dressed himself in it and gave his own clothes to Soudeikin.

As soon as the change was effected, Colston took the keys and went to the door at which the sentry was keeping guard. The man was already half asleep, and blinked at him with drowsy eyes as he challenged him. For all answer the Terrorist levelled his pistol at his head and fired. There was a sharp crack that could hardly have been heard on the other side of the wall, and the man tumbled down with a bullet through his brain.

Colston stepped over the corpse, unlocked the door, and found Natasha and the Princess already dressed in male attire as two peasant boys, with sheepskin coats and shapkas, and wide trousers tucked into their half boots. These disguises had been provided beforehand by Soudeikin, and hidden in the bed in which they were to sleep.

Colston grasped their hands in silence, and the three left the room. In the passage they found Ivan and Soudeikin, the former dressed in the uniform of the soldier who had been on guard outside the house, and whose half-stripped corpse was now lying buried in the snow.

"Ready?" whispered Soudeikin.

"Have you finished in there?" asked Colston, jerking his thumb towards the sitting-room.

Soudeikin nodded in reply, and the five left the house by the back door.

It was then after half-past four. Fortunately it was a dark cloudy morning, and the streets of the town were utterly deserted. By ones and twos they stole through the by-streets and lanes without meeting a soul, until Soudeikin at length stopped at a house on the eastern edge of the town about a mile from the Tobolsk road.

He tapped at one of the windows. The door was softly opened by an invisible hand, and they entered and passed through a dark passage and out into a stable-yard behind the house. Under a shed they found a troika, or three-horse sleigh, with the horses ready harnessed, in charge of a man dressed as a mujik.

They got in without a word, all but Soudeikin, who went to the horses' heads, while the other man went and opened the gates of the yard. The bells had been removed from the harness, and the horses' feet made no sound as Soudeikin led them out through the gate. Ivan took the reins, and Colston held out his hand from the sleigh. There was a roll of notes in it, and as he gave it to Soudeikin he whispered—

"Farewell! If we succeed, the Master shall know how well you have done your part."

Soudeikin took the money with a salute and a whispered farewell, and Ivan trotted his horses quietly down the lane and swung round into the road at the end of it.

So far all had gone well, but the supreme moment of peril had yet to come. A mile away down the road was the guard-house on the Tobolsk road leading out of the town, and this had to be passed before there was even a chance of safety.

As there was no hope of getting the sleigh past unobserved, Colston had determined to trust to a rush when the moment came. He had given Natasha and the Princess a magazine pistol apiece, and held a brace in his own hands; so among them they had a hundred shots.

Ivan kept his horses at an easy trot till they were within a hundred yards of the guard-house. Then, at a sign from Colston, he suddenly lashed them into a gallop, and the sleigh dashed forward at a headlong speed, swept round the curve past the guard-house, hurling one of the sentries on guard to the earth, and away out on to the Tobolsk road.

The next instant the notes of a bugle rang out clear and shrill just as another sounded from the other end of the town. Colston at once guessed what had happened. The inspector of the patrols, in going his rounds, had called at Soudeikin's house to see if all was right, and had discovered the tragedy that had taken place. He looked back and saw a body of Cossacks galloping down the main street towards the guard-house, waving their lanterns and brandishing their spears above their heads.

"Whip up, Ivan, they will be on us in a couple of minutes!" he cried and Ivan swung his long whip out over his horses' ears, and shouted at them till they put their heads down and tore over the smooth snow in gallant style.

By the time the race for life or death really began they had a good mile start, and as they had only four more to go Ivan did not spare his cattle, but plied whip and voice with a will till the trees whirled past in a continuous dark line, and the sleigh seemed to fly over the snow almost without touching it.

Still the Cossacks gained on them yard by yard, till at the end of the fourth mile they were less than three hundred yards behind. Then Colston leant over the back of the sleigh, and taking the best aim he could, sent half a dozen shots among them. He saw a couple of the flying figures reel and fall, but their comrades galloped heedlessly over them, yelling wildly at the tops of their voices, and every moment lessening the distance between themselves and the sleigh.

Colston fired a dozen more shots into them, and had the satisfaction of seeing three or four of them roll into the snow. At the same time he put a whistle to his lips, and blew a long shrill call that sounded high and clear above the hoarse yells of the Cossacks.

Their pursuers were now within a hundred yards of them, and Natasha, speaking for the first time since the race had begun, said—

"I think I can do something now."

As she spoke she leaned out of the sleigh sideways, and began firing rapidly at the Cossacks. Shot after shot told either upon man or beast, for the daughter of Natas was one of the best shots in the Brotherhood; but before she had fired a dozen times a bright gleam of white light shot downwards over the trees, apparently from the clouds, full in the faces of their pursuers.

Involuntarily they reined up like one man, and their yells of fury changed in an instant into a general cry of terror. The Cossacks are as brave as any soldiers on earth, and they can fight any mortal foe like the fiends that they are, but here was an enemy they had never seen before, a strange, white, ghostly-looking thing that floated in the clouds and glared at them with a great blazing, blinding eye, dazzling them and making their horses plunge and rear like things possessed.

They were not long left in doubt as to the intentions of their new enemy. Something came rushing through the air and struck the ground almost at the feet of their first rank. Then there was a flash of green light, a stunning report, and men and horses were rent into fragments and hurled into the air like dead leaves before a hurricane.

Only three or four who had turned tail at once were left alive; and these, without daring to look behind them, drove their spurs into their horses' flanks and galloped back to Tiumen, half mad with terror, to tell how a demon had come down from the skies, annihilated their comrades, and carried the fugitives away into the clouds upon its back.

When they reached the town it was a scene of the utmost panic. Soldiers were galloping and running hither and thither, bugles were sounding, and the whole population were turning out into the snow-covered streets. On every lip there were only two words—"Natas!" "The Terrorists!"

The death sentence on Soudeikin, the sub-commissioner of police, had been found pinned with a dagger to the table in the room in which lay the body of the lieutenant, with the bloody *T* on his forehead. Soudeikin had vanished utterly, leaving only his uniform behind him; so had the two prisoners for whom he had made himself responsible, and at the door of their room lay the corpse of the sentry with a bullet-hole clean through his head from front to back, while in the snow under one of the windows of the room lay the body of the other sentry, stabbed through the heart.

From the very midst of one of the strongholds of Russian tyranny in Siberia, two important prisoners and a police official had been spirited away as though by magic, and now upon the top of all the wonder and dismay came the fugitive Cossacks with their wild tale about the air-demon that had swooped down and destroyed their troop at a single blow. To crown all, half an hour later three horses, mad with fear, came galloping up the Tobolsk road, dragging behind them an empty sleigh, to one of the seats of which was pinned a scrap of paper on which was written—

"The daughter of Natas sends greeting to the Governor of Tiumen, and thanks him for his hospitality."



CHAPTER XIV.

THE PSYCHOLOGICAL MOMENT.

On the morning of Tuesday, the 9th of March 1904, the Times published the following telegram at the head of its Foreign Intelligence:—

ASTOUNDING OCCURRENCE IN RUSSIA.

Destruction of Kronstadt by an unknown Air-Ship. (From our own Correspondent.)

St. Petersburg, March 8th, 4 P.M.

Between six and seven this morning, the fortress of Kronstadt was partially destroyed by an unknown air-ship, which was first sighted approaching from the westward at a tremendous speed.

Four shots in all were fired upon the fortress, and produced the most appalling destruction. There was no smoke or flame visible from the guns of the air-ship, and the explosives with which the missiles were charged must have been far more powerful than anything hitherto used in warfare, as in the focus of the explosion masses of iron and steel and solid masonry were instantly reduced to powder.

Two shots were fired as the strange vessel approached, and two as she left the fortress. The two latter exploded over one of the powder magazines, dissolved the steel roof to dust, and ignited the whole contents of the magazine, blowing that portion of the fortification bodily into the sea. At least half the garrison has disappeared, most of the unfortunate men having been practically annihilated by the terrific force of the explosions.

The air-ship was not of the navigable balloon type, and is described by the survivors as looking more like a flying torpedo-boat than anything else. She flew no flag, and there is no clue to her origin.

After destroying the fortress, she ascended several thousand feet, and continued her eastward course at such a prodigious speed, that in less than five minutes she was lost to sight.

The excitement in St. Petersburg almost reaches the point of panic. All efforts to keep the news of the disaster secret have completely failed, and I have therefore received permission to send this telegram, which has been revised by the Censorship, and may therefore be accepted as authentic.

Within an hour of the appearance of this telegram, which appeared only in the Times, the Russian Censorship having refused to allow any more to be despatched, the astounding news was flying over the wires to every corner of the world.

The Times had a lengthy and very able article on the subject, which, although by no means alarmist in tone, told the world, in grave and weighty sentences, that there could now be no doubt but that the problem of aerial navigation had been completely solved, and that therefore mankind stood confronted by a power that was practically irresistible, and which changed the whole aspect of warfare by land and sea.

In the face of this power, the fortresses, armies, and fleets of the world were useless and helpless. The destruction of Kronstadt had proved that to demonstration. From a height of several thousand feet, and a distance of nearly seven miles, the unknown air-vessel had practically destroyed, with four shots from her mysterious, smokeless, and flameless guns, the strongest fortress in Europe. If it could do that, and there was not the slightest doubt but that it had done so, it could destroy armies wholesale without a chance of reprisals, sink fleets, and lay cities in ruins, at the leisure of those who commanded it.

And here arose the supreme question of the hour—a question beside which all other questions of national or international policy sank instantly into insignificance—Who were those who held this new and appalling power in their hands? It was hardly to be believed that they were representatives of any regularly-constituted national Power, for, although the air was full of rumours of war, there was at present unbroken peace all over the world.

Even in the hands of a recognised Power, the possession of such a frightful engine of destruction could not be viewed by the rest of the world with anything but the gravest apprehension, for that Power, however insignificant otherwise, would now be in a position to terrorise any other nation, or league of nations, however great. Manifestly those who had built the one air-vessel that had been seen, and had given such conclusive proof of her terrible powers, could construct a fleet if they chose to do so, and then the world would be at their mercy.

If, however, as seemed only too probable, the machine was in the hands of a few irresponsible individuals, or, still worse, in those of such enemies of humanity as the Nihilists, or that yet more mysterious and terrible society who were popularly known as the Terrorists, then indeed the outlook was serious beyond forecast or description. At any moment the forces of destruction and anarchy might be let loose upon the world, in such fashion that little less than the collapse of the whole fabric of Society might be expected as the result.

* * * * *

The above necessarily brief and imperfect digest gives only the headings of an article which filled nearly two columns of the Times, and it is needless to say that such an article in the leading columns of the most serious and respectable newspaper in the world produced an intense impression wherever it was read.

Of course the telegram was instantly copied by the evening papers, which ran out special editions for the sole purpose of reproducing it, with their own comments upon it, which, after all, were not much more original than the telegram. Meanwhile the Berliner Tageblatt, the Newe Freie Presse, the Koelnische Zeitung, and the Journal des Debats had received later and somewhat similar telegrams, and had given their respective views of the catastrophe to the world.

By noon all the capitals of Europe were in a fever of expectation and apprehension. The cables had carried the news to America and India; and when the evening of the same day brought the telegraphic account of the extraordinary occurrence at Tiumen in the grey dusk of the early morning, proving almost conclusively that the rescue had been effected by the same agency that had destroyed Kronstadt, and that, worse than all, the air-vessel was at the command of Natas, the unknown Chief of the mysterious Terrorists, excitement rose almost to frenzy, and everywhere the wildest rumours were accepted as truth.

In a word, the "psychological moment" had come all over Europe, the moment in which all men were thinking of the same thing, discussing the same event, and dreading the same results. To have found a parallel state of affairs, it would have been necessary to go back more than a hundred years, to the hour when the head of Louis XVI. fell into the basket of the guillotine, and the monarchies of Europe sprang to arms to avenge his death.

Meanwhile other and not less momentous events had, unknown to the newspapers or the public, been taking place in three very different parts of the world.

On the evening of Saturday, the 6th, Lord Alanmere had called upon Mr. Balfour in Downing Street, and laid the duplicates of the secret treaty between France and Russia, and copies of all the memoranda appertaining to it, before him, and had convinced him of their authenticity. At the same time he showed him plans of the war-balloons, of which a fleet of fifty would within a few days be at the command of the Tsar.

The result of this interview was a meeting of a Cabinet Council, and the immediate despatch of secret orders to mobilise the fleet and the army, to put every available ship into commission, and to double the strength of the Mediterranean Squadron at once. That evening three Queen's messengers left Charing Cross by the night mail, one for Berlin, one for Vienna, and one for Rome, each of them bearing a copy of the secret treaty.

On Monday morning a Council of Ministers was held at the Peterhof Palace in St. Petersburg, presided over by the Tsar, and convened to discuss the destruction of Kronstadt.

At this Council it was announced that the fleet of war-balloons would be ready to take the air in a week's time from then, and that the concentration of troops on the Afghan frontier was as complete as it could be without provoking immediate hostilities with Britain. In fact, so close were the Cossacks and the Indian troops to each other, both on the Pamirs and on the western slopes of the Hindu Kush, that a collision might be expected at any moment.

The Council of the Tsar decided to let matters take their course in the East, and to make all arrangements with France to simultaneously attack the Triple Alliance as soon as the war-balloons had been satisfactorily tested.

Soon after daybreak on Wednesday, the 10th, an affair of outposts took place near the northern end of the Sir Ulang Pass of the Hindu Kush, between two considerable bodies of Cossacks and Ghoorkhas, in which, after a stubborn fight, the Russians gave way before the magazine fire of the Indian troops, and fled, leaving nearly a fourth of their number on the field.

The news of this encounter reached London on Wednesday night, and was published in the papers on Thursday morning, together with the intelligence that the fight had been watched from a height of nearly three thousand feet by a small party of men and women in an air-ship, evidently a vessel of war, from the fact that she carried four long guns. She took no part in the fight, and as soon as it was over went off to the south-west at a speed which carried her out of sight in a few minutes.



CHAPTER XV.

A VOYAGE OF DISCOVERY.

While all Europe was thrilling with the apprehension of approaching war, and the excitement caused by the appearance of the strange air-ship and the news of its terrible exploits at Kronstadt and Tiumen, the Ariel herself was quietly pursuing her way in mid-air south-westerly from the scene of the skirmish outside the Sir Ulang Pass.

She was bound for a region in the midst of Africa, which, even in the first decade of the twentieth century, was still unknown to the geographer and untrodden by the explorer.

Fenced in by huge and precipitous mountains, round whose bases lay vast forests and impenetrable swamps and jungles, from whose deadly areas the boldest pioneers had turned aside as being too hopelessly inhospitable to repay the cost and toil of exploration, it had remained undiscovered and unknown save by two men, who had reached it by the only path by which it was accessible—through the air and over the mountains which shut it in on every side from the external world.

These two adventurous travellers were a wealthy and eccentric Englishman, named Louis Holt, and Thomas Jackson, his devoted retainer, and these two had taken it into their heads—or rather Louis Holt had taken it into his head—to achieve in fact the feat which Jules Verne had so graphically described in fiction, and to cross Africa in a balloon.

They had set out from Zanzibar towards the end of the last year of the nineteenth century, and, with the exception of one or two vague reports from the interior, nothing more had been heard of them until, nearly a year later, a collapsed miniature balloon had been picked up in the Gulf of Guinea by the captain of a trading steamer, who had found in the little car attached to it a hermetically sealed meat-tin, which contained a manuscript, the contents of which will become apparent in due course.

The captain of the steamer was a practical and somewhat stupid man, who read the manuscript with considerable scepticism, and then put it away, having come to the conclusion that it was no business of his, and that there was no money in it anyhow. He thought nothing more of it until he got back to Liverpool, and then he gave it to a friend of his, who was a Fellow of the Royal Geographical Society, and who duly laid it before that body.

It was published in the Transactions, and there was some talk of sending out an expedition under the command of an eminent explorer to rescue Louis Holt and his servant; but when that personage was approached on the subject, it was found that the glory would not be at all commensurate with the expense and risk, and so, after being the usual nine days' wonder, and being duly elaborated by several able editors in the daily and weekly press, the strange adventures of Louis Holt had been dismissed, as of doubtful authenticity, into the limbo of exhausted sensations.

One man, however, had laid the story to heart somewhat more seriously, and that was Richard Arnold, who, on reading it, had formed the resolve that, if ever his dream of aerial navigation were realised, the first use he would make of his air-ship would be to discover and rescue the lonely travellers who were isolated from the rest of the world in the strange, inaccessible region of which the manuscript had given a brief but graphic and fascinating account. He was now carrying out that resolve, and at the same time working out a portion of a plan that was not his own, and which he had been very far from foreseeing when he made the resolution.

Louis Holt's original MS. had been purchased by the President of the Inner Circle, and the Ariel was now, in fact, on a voyage of exploration, the object of which was the discovery of this unknown region, with a view to making it the seat of a settlement from which the members of the Executive could watch in security and peace the course of the tremendous struggle which would, ere long, be shaking the world to its foundations.

In such a citadel as this, fenced in by a series of vast natural obstacles, impassable to all who did not possess the means of aerial locomotion, they would be secure from molestation, though all the armies of Europe sought to attack them; and the Ariel could, if necessary, traverse in twenty-five hours the three thousand odd miles which separated it from the centre of Europe.

After the rescue of Natasha and the Princess on the Tobolsk road, the Ariel, in obedience to the orders of the Council, had shaped her course southward to the western slopes of the Hindu Kush, in order to be present at the prearranged attack of the Cossacks on the British reconnoitring force.

Arnold's orders were simply to wait for the engagement, and only to watch it, unless the British were attacked in overwhelming numbers. In that case he was to have dispersed the Russian force, as the plan of the Terrorists did not allow of any advantage being gained by the soldiers of the Tsar in that part of the world just then.

As the British had defeated them unaided, the Ariel had taken no part in the affair, and, after vanishing from the sight of the astonished combatants, had proceeded upon her voyage of discovery.

As a good month would have to elapse before she could keep her rendezvous with the steamer that was to bring out the materials for the construction of the new air-ships from England, there was plenty of time to make the voyage in a leisurely and comfortable fashion. As soon, therefore, as he was out of sight of the skirmishers, he had reduced the speed of the Ariel to about forty miles an hour, using only the stern-propeller driven by one engine, and supporting the ship on the air-planes and two fan-wheels.

At this speed he would traverse the three thousand odd miles which lay between the Hindu Kush and "Aeria"—as Louis Holt had somewhat fancifully named the region that could be reached only through the air—in a little over seventy-five hours, or rather more than three days.

Those three days were the happiest that his life had so far contained. The complete success of his invention, and the absolute fulfilment of his promises to the Brotherhood, had made him a power in the world, and a power which, as he honestly believed, would be used for the highest good of mankind when the time came to finally confront and confound the warring forces of rival despotisms.

But far more than this in his eyes was the fact that he had been able to use the unique power which his invention had placed in his hands, to rescue the woman that he loved so dearly from a fate which, even now that it was past, he could not bring himself to contemplate.

When she had first greeted him in the Council-chamber of the Inner Circle, the distance that had separated her from him had seemed immeasurable, and she—the daughter of Natas and the idol of the most powerful society in the world—might well have looked down upon him—the nameless dreamer of an unrealised dream, and a pauper, who would not have known where to have looked for his next meal, had the Brotherhood not had faith in him and his invention.

But now all that was changed. The dream had become the reality, and the creation of his genius was bearing her with him swiftly and smoothly through a calm atmosphere, and under a cloudless sky, over sea and land, with more ease than a bird wings its flight through space. He had accomplished the greatest triumph in the history of human discovery. He had revolutionised the world, and ere long he would make war impossible. Surely this entitled him to approach even her on terms of equality, and to win her for his own if he could.

Natasha saw this too as clearly as he did—more clearly, perhaps; for, while he only arrived at the conclusion by a process of reasoning, she reached it intuitively at a single step. She knew that he loved her, that he had loved her from the moment that their hands had first met in greeting, and, peerless as she was among women, she was still a woman, and the homage of such a man as this was sweet to her, albeit it was still unspoken.

She knew, too, that the hopes of the Revolution, which, before all things human, claimed her whole-souled devotion, now depended mainly upon him, and the use that he might make of the power that lay in his hands, and this of itself was no light bond between them, though not necessarily having anything to do with affection.

So far she was heart-whole, and though many had attempted the task, no man had yet made her pulses beat a stroke faster for his sake. Ever since she had been old enough to know what tyranny meant, she had been trained to hate it, and prepared to work against it, and, if necessary, to sacrifice herself body and soul to destroy it.

Thus hatred rather than love had been the creed of her life and the mainspring of her actions, and, save her father and her one friend Radna, she stood aloof from mankind and its loves and friendships, rather the beautiful incarnation of an abstract principle than a woman, to whom love and motherhood were the highest aims of existence.

More than this, she was the daughter of a Jew, and therefore held herself absolutely at her father's disposal as far as marriage was concerned, and if he had given her in wedlock even to a Russian official, telling her that the Cause demanded the sacrifice, she would have obeyed, though her heart had broken in the same hour.

Although he had never hinted directly at such a thing, the conviction had been growing upon her for the last two or three years that Natas really intended her to marry Tremayne, and so, in the case of his own death, form a bond that should hold him to the Brotherhood when the chain of his own control was snapped. Though she instinctively shrank from such a union of mere policy, she would enter it without hesitation at her father's bidding, and for the sake of the Cause to which her life was devoted.

How great such a sacrifice would be, should it ever be asked of her, no one but herself could ever know, for she was perfectly well aware that in Tremayne's strange double life there were two loves, one of which, and that not the real and natural one, was hers.

Had she felt that she had the disposal of herself in her own hands, she would not, perhaps, have waited with such painful apprehension the avowal which hour after hour, now that they were brought into such close and constant relationships on board this little vessel high in mid-air, she saw trembling on the lips of her rescuer.

Arnold's life of hard, honest work, and his constant habit of facing truth in its most uncompromising forms, had made dissimulation almost impossible to him; and added to that, situated as he was, there was no necessity for it. Colston knew of his love, and the Princess had guessed it long ago. Did Natasha know his open secret? Of that he hardly dared to be sure, though something told him that the inevitable moment of knowledge was near at hand.

For the first twenty-four hours of the voyage he had seen very little of either her or the Princess, as they had mostly remained in their cabins, enjoying a complete rest after the terrible fatigue and suffering they had gone through since their capture in Moscow, but on the Thursday morning they had had breakfast in the saloon with him and Colston, and had afterwards spent a portion of the morning on deck, deeply interested in watching the fight between the British and Russians. Thanks to Radna's foresight, they had each found a trunk full of suitable clothing on board the Ariel. These had been taken to Drumcraig by Colston, and placed in the cabins intended for their use, and so they were able to discard the uncouth but useful costumes in which they had made their escape.

In the afternoon Arnold had had to perform the pleasant task of showing them over the Ariel, explaining the working of the machinery, and putting the wonderful vessel through various evolutions to show what she was capable of doing.

He rushed her at full speed through the air, took flying leaps over outlying spurs of mountain ranges that lay in their path, swooped down into valleys, and flew over level plains fifty yards from the ground, like an albatross over the surface of a smooth tropic sea. Then he soared up from the earth again, until the horizon widened out to vast extent, and they could see the mighty buttresses of "the Roof of the World" stretching out below them in an endless succession of ranges as far as the eye could reach.

Neither Natasha nor the Princess could find words to at all adequately express all that they saw and learnt during that day of wonders, and all night Natasha could hardly sleep for waking dreams of universal empire, and a world at peace equitably ruled by a power that had no need of aggression, because all the realms of earth and air belonged to those who wielded it.

When at last she did go to sleep, it was to dream again, and this time of herself, the Angel of the Revolution, sharing the aerial throne of the world-empire with the man who had made revolutions impossible by striking the sword from the hand of the tyrants of earth for ever.



CHAPTER XVI.

A WOOING IN MID AIR.

After breakfast on the Friday morning, Natasha and Arnold were standing in the bows of the Ariel, admiring the magnificent panorama that lay stretched out five thousand feet below them.

The air-ship had by this time covered a little over 2000 miles of her voyage, and was now speeding smoothly and swiftly along over the south-western shore of the Red Sea, a few miles southward of the sixteenth parallel of latitude. Eastward the bright blue waves of the sea were flashing behind them in the cloudless morning sun; the high mountains of the African coast rose to right and left and in front of them; and through the breaks in the chain they could see the huge masses of Abyssinia to the southward, and the vast plains that stretched away westward across the Blue and White Niles, away to the confines of the Libyan Desert.

"What a glorious world!" exclaimed Natasha, after gazing for many silent minutes with entranced eyes over the limitless landscape. "And to think that, after all, all this is but a little corner of it!"

"It is yours, Natasha, if you will have it," replied Arnold quietly, yet with a note in his voice that warned her that the moment which she had expected and yet dreaded, had already come. There was no use in avoiding the inevitable for a time. It would be better if they understood each other at once; and so she looked round at him with eyebrows elevated in well-simulated surprise, and said—

"Mine! What do you mean, my friend?"

There was an almost imperceptible emphasis on the last word that brought the blood to Arnold's cheek, and he answered, with a ring in his voice that gave unmistakable evidence of the effort that he was making to restrain the passion that inspired his words—

"I mean just what I say. All the kingdoms of the world, and the glory of them, from pole to pole, and from east to west, shall be yours, and shall obey your lightest wish. I have conquered the air, and therefore the earth and sea. In two months from now I shall have an aerial navy afloat that will command the world, and I—is it not needless to tell you, Natasha, why I glory in the possession of that power? Surely you must know that it is because I love you more than all that a subject world can give me, and because it makes it possible for me, if not to win you, at least not to be unworthy to attempt the task?"

It was a distinctly unconventional declaration—such a one, indeed, as no woman had ever heard since Alexander the Great had whispered in the ears of Lais his dreams of universal empire, but there was a straightforward earnestness about it which convinced her beyond question that it came from no ordinary man, but from one who saw the task before him clearly, and had made up his mind to achieve it.

For a moment her heart beat faster than it had ever yet done at the bidding of a man's voice, and there was a bright flush on her cheeks, and a softer light in her eyes, as she replied in a more serious tone than Arnold had ever heard her use—

"My friend, you have forgotten something. You and I are not a man and a woman in the relationship that exists between us. We are two factors in a work such as has never been undertaken since the world began; two units in a mighty problem whose solution is the happiness or the ruin of the whole human race. It is not for us to speak of individual love while these tremendous issues hang undecided in the balance.

"One does not speak of love in the heat of war, and you and I and those who are with us are at war with the powers of the earth, and higher things than the happiness of individuals are at stake. You know my training has been one of hate and not of love, and till the hate is quenched I must not know what love is.

"Remember your oath—the oath which I have taken as well as you—'As long as I live those ends shall be my ends, and no human considerations shall weigh with me where those ends are concerned.' Is not this love of which you speak a human consideration that might clash with the purposes of the Brotherhood whose ends you and I have solemnly sworn to hold supreme above all earthly things?

"My father has told me that when love takes possession of a human soul, reason abdicates her throne, and great aims become impossible. No, no; that great power which you hold in your hands was not given you just to win the love of a woman, and I tell you frankly that you will never win mine with it.

"More than this, if I saw you using it for such an end, I would take care that you did not use it for long. No man ever had such an awful responsibility laid upon him as the possession of this power lays upon you. It is yours to make or mar the future of the human race, of which I am but a unit. It is not the power that will ever win either my respect or my love, but the wisdom and the justice with which it may be used."

"Ah! I see you distrust me. You think that because I have the power to be a despot, that therefore I may forget my oath and become one. I forgive you for the thought, unworthy of you as it is, and also, I hope, of me. No, Natasha; I am no skilled hand at love-making, for I have never wooed any mistress but one before to-day, and she is won only by plain honesty and hard service; just what I will devote to the winning of you, whether you are to be won or not—but I must have expressed myself clumsily indeed for you to have even thought of treason to the Cause.

"You are no more devoted adherent of it than I am. You have suffered in one way and I in another from the falsehood and rottenness of present-day Society, but you do not hate it more utterly than I do, and you would not go to greater lengths than I would to destroy it. Yours is a hatred of emotion, and mine is a hatred of reason. I have proved that, as Society is constituted, it is the worst and not the best qualities of humanity that win wealth and power, and such respect as the vulgar of all classes can give. But it is not such power as this that I would lay at your feet, when I ask you to share the world-empire with me. It is an empire of peace and not of war that I shall offer to you."

"Then," said Natasha, taking a step towards him, and laying her hand on his arm as she spoke, "when you have made war impossible to the rivalry of nations and races, and have proclaimed peace on earth, then I will give myself to you, body and soul, to do with as you please, to kill or to keep alive, for then truly you will have done that which all the generations of men before you have failed to do, and it will be yours to ask and to have."

As she spoke these last words Natasha bowed her proudly-carried head as though in submission to the dictum that her own lips had pronounced; and Arnold, laying his hand on hers and holding it for a moment unresisting in his own, said—

"I accept the condition, and as you have said so shall it be. You shall hear no more words of love from my lips until the day that peace shall be proclaimed on earth and war shall be no more; and when that day comes, as it shall do, I will hold you to your words, and I will claim you and take you, body and soul, as you have said, though I break every other human tie save man's love for woman to possess you."

Natasha looked him full in the eyes as he spoke these last words. She had never heard such words before, and by their very strength and audacity they compelled her respect and even her submission. Her heart was still untamed and unconquered, and no man was its lord, yet her eyes sank before the steady gaze of his, and in a low sweet voice she answered—

"So be it! There never was a true woman yet who did not love to meet her master. When that day comes I shall have met my master, and I will do his bidding. Till then we are friends and comrades in a common Cause to which both our lives are devoted. Is it not better that it should be so?"

"Yes, I am content. I would not take the prize before I have won it. Only answer me one question frankly, and then I have done till I may speak again."

"What is that."

"Have I a rival—not among men, for of that I am careless—but in your own heart?"

"No, none. I am heart-whole and heart-free. Win me if you can. It is a fair challenge, and I will abide by the result, be it what it may."

"That is all I ask for. If I do not win you, may Heaven do so to me that I shall have no want of the love of woman for ever!"

So saying, he raised her hand to his lips and kissed it, in token of the compact that was made between them. Then, intuitively divining that she wished to be alone, he turned away without another word, and walked to the after end of the vessel.

Natasha remained where she was for a good half-hour, leaning on the rail that surrounded the deck, and gazing out dreamily over the splendid and ever-changing scene that lay spread out beneath her. Truly it was a glorious world, as she had said, even now, cursed as it was with war and the hateful atrocities of human selfishness, and the sordid ambition of its despots.

What would it be like in the day when the sword should lie rusting on the forgotten battle-field, and the cannon's mouth be choked with the desert dust for ever? What was now a hell of warring passions would then be a paradise of peaceful industry, and he who had the power, if any man had, to turn that hell into the paradise that it might be, had just told her that he loved her, and would create that paradise for her sake.

Could he do it? Was not this marvellous creation of his genius, that was bearing her in mid-air over land and sea, as woman had never travelled before, a sufficient earnest of his power? Truly it was. And to be won by such a man was no mean destiny, even for her, the daughter of Natas, and the peerless Angel of the Revolution.

Situated as they were, it would of course have been impossible, even if it had been in any way desirable, for Arnold and Natasha to have kept their compact secret from their fellow-travellers, who were at the same time their most intimate friends.

There was not, however, the remotest reason for attempting to do so. Although with regard to the rest of the world the members of the Brotherhood were necessarily obliged to live lives of constant dissimulation, among themselves they had no secrets from each other.

Thus, for instance, it was perfectly well known that Tremayne, during those periods of his double life in which he acted as Chief of the Inner Circle, regarded the daughter of Natas with feelings much warmer than those of friendship or brotherhood in a common cause, and until Arnold and his wonderful creation appeared on the scene, he was looked upon as the man who, if any man could, would some day win the heart of their idolised Angel.

Of the other love that was the passion of his other life, no one save Natasha, and perhaps Natas himself, knew anything; and even if they had known, they would not have considered it possible for any other woman to have held a man's heart against the peerless charms of Natasha. In fact they would have looked upon such rivalry as mere presumption that it was not at all necessary for their incomparable young Queen of the Terror to take into serious account.

In Arnold, however, they saw a worthy rival even to the Chief himself, for there was a sort of halo of romance, even in their eyes, about this serious, quiet-spoken young genius, who had come suddenly forth from the unknown obscurity of his past life to arm the Brotherhood with a power which revolutionised their tactics and virtually placed the world at their mercy. In a few months he had become alike their hero and their supreme hope, so far as all active operations went; and now that with his own hand he had snatched Natasha from a fate of unutterable misery, and so signally punished her persecutors, it seemed to be only in the fitness of things that he should love her, win her for his own, if won she was to be by any man.

This, at any rate, was the line of thought which led the Princess and Colston each to express their unqualified satisfaction with the state of affairs arrived at in the compact that had been made between Natasha and Arnold—"armed neutrality," as the former smilingly described to the Princess while she was telling her of the strange wooing of her now avowed lover. Natasha was no woman to be wooed and won in the ordinary way, and it was fitting that she should be the guerdon of such an achievement as no man had ever undertaken before, since the world began.

The voyage across Africa progressed pleasantly and almost uneventfully for the thirty-six hours after the crossing of the Red Sea. After passing over the mountains of the coast, the Ariel had travelled at a uniform height of about 3000 feet over a magnificent country of hill and valley, forest and prairie, occasionally being obliged to rise another thousand feet or so to cross some of the ridges of mountain chains which rose into peaks and mountain knots, some of which touched the snow-line.

Several times the air-ship was sighted by the people of the various countries over which she passed, and crowds swarmed out of the villages and towns, gesticulating wildly, and firing guns and beating drums to scare the flying demon away.

Once or twice they heard bullets singing through the air, but of these they took little heed, beyond quickening the speed of the air-ship for the time, knowing that there was not a chance in a hundred thousand of the Ariel being hit, and that even if she were the bullet would glance harmlessly off her smooth hull of hardened aluminium.

Once only they descended in a delightful little valley among the mountains, which appeared to be totally uninhabited, and here they renewed their store of fresh water, and laid in one of fruit, as well as taking advantage of the opportunity to stretch their legs on terra firma.

This was on the Saturday morning; and when they again rose into the air to continue their voyage, they saw that they had crossed the great mountain mass that divides the Sahara from the little-known regions of Equatorial Africa, and that in front of them to the south-west lay, as far as the eye could reach, a boundless expanse of dense forest and jungle and swamp, a gloomy and forbidding-looking region which it would be well-nigh impossible to traverse on foot.

Early in the afternoon the four voyagers were gathered in the deck-saloon, closely examining a somewhat rudely-drawn chart that was spread out on the table. It was the map that formed part of the manuscript which had been found in the car of Louis Holt's miniature balloon, and sketched out his route from Zanzibar to Aeria, and the country lying round so far as he had been able to observe it.

"This gives us, after all, very little idea of the distance we have yet to go," said Arnold; "for though Holt has got his latitude presumably right, we have very little clue to his longitude, for he says himself that his watch was stopped in a thunder-storm, and that in the same storm he lost all count of the distance he had travelled. Added to that, he admits that he was blown about for twelve days in one direction and another, so that all we really know is that somewhere across this fearful wilderness beneath us we shall find Aeria, but where is still a problem."

"What is your own idea?" asked Colston.

"Not a very clear one, I must confess. At this elevation we can see about sixty miles as the atmosphere is now, and as far as we can see to the south-west there is nothing but the same kind of country that we have under us. We have travelled rather more than 2700 miles since we left the Hindu Kush, and according to my reckoning Aeria lies somewhere between 3000 and 3200 miles south-west of where we started from on Thursday morning. That means that we are within between three and five hundred miles of Aeria, unless, indeed, our calculations are wholly at fault, and at that rate, as we only have about four and a half hours' daylight left, we shall not get there to-day at our present speed."

"Couldn't we go a bit faster?" put in Natasha. "You know I and the Princess are dying to see this mysterious unknown country that only two other people have ever seen."

"You have but to say so, Natasha, and it is already done," replied Arnold, signalling at the same moment to the engine-room by means of a similar arrangement of electric buttons to that which was in the wheel-house. "Only you must remember that you must not go out on deck now, or you will be blown away like a feather into space."

While he was speaking the three propellers had begun to revolve at full speed, and the Ariel darted forward with a velocity that caused the mountains she had just crossed to sink rapidly on the horizon.

All the afternoon the Ariel flew at full speed over the seemingly interminable wilderness of swamp and jungle, until, when the equatorial sun was within a few degrees of the horizon, one of the crew, who had been stationed in the conning tower at the bows, signalled to call the attention of the man in the wheel-house. Arnold, who was in the after-saloon at the time, heard the signal, and hurried forward to the look-out. He gave one quick glance ahead, signalled "half-speed" to the engine-room, and then went aft again to the saloon, and said—

"Aeria is in sight!"

Immediately everyone hastened to the deck saloon, from the windows of which could be seen a huge mass of mountains looming dark and distinct against the crimsoning western sky.

It rose like some vast precipitous island out of the sea of forest that lay about its base; and above the mighty rock-walls that seemed to rise sheer from the surrounding plain at least a dozen peaks towered into the sky, two of their summits covered with eternal snow, and shining like points of rosy fire in the almost level rays of the sun.

As nearly as Arnold could judge in the deceptive state of the atmosphere, they were still between thirty and forty miles from it, and as it would not be safe to approach its lofty cliffs at a high rate of speed in the half light that would so soon merge into darkness, he said to his companions—

"We shall have to find a resting-place up among the cliffs on this side to-night, for we have lost the moon, and unless it were absolutely necessary to cross the mountains in the dark, I should not care to do so with the ladies on board. Besides, there is no hurry now that we are here, and we shall get a much finer first impression of our new kingdom if we cross at sunrise. What do you think?"

All agreed that this would be the best plan, and so the Ariel ran up to within a mile of the rocks, and then the forward engine was connected with the dynamo, and the searchlight, which had so disconcerted the Cossacks on the Tobolsk road, was turned on to the cliffs, which they carefully explored, until they found a little plateau covered with luxuriant vegetation and well watered, about two thousand feet above the plain below.

Here it was decided to come to a halt for the night, and to reserve the exploration of Aeria for the morning, and so the fan-wheels were sent aloft, and the Ariel, after hovering for a few minutes over the verdant little plain seeking for a suitable spot to alight in, sank gently to the earth after her flight of more than three thousand miles.



CHAPTER XVII.

AERIA FELIX.

Every one on board the Ariel was astir the next morning as soon as the first rays of dawn were shooting across the vast plain that stretched away to the eastward, and by the time it was fairly daylight breakfast was over and all were anxiously speculating as to what they would find on the other side of the tremendous cliffs, on an eyrie in which they had found a resting-place for the night.

As soon as all was ready for a start, Arnold said to Natasha, who was standing alone with him on the after part of the deck—

"If you would like to steer the Ariel into your new kingdom, I shall be delighted to give you the lesson in steering that I promised you yesterday."

Natasha saw the inner meaning of the offer at a glance, and replied with a smile that made his blood tingle—

"That would be altogether too great a responsibility for a beginner. I might run on to some of these fearful rocks. But if you will take the helm when the dangerous part comes, I will learn all I can by watching you."

"As long as you are with me in the wheel-house for the next hour or so," said Arnold, with almost boyish frankness, "I shall be content. I need scarcely tell you why I want to be alone with you when we first sight this new home of our future empire."

"I have half a mind not to come after that very injudicious speech. Still, if only for the sake of its delightful innocence, I will forgive you this time. You really must practise the worldly art of dissimulation a little, or I shall have to get the Princess to play chaperon."

Natasha spoke these words in a bantering tone, and with a flush on her lovely cheeks, that forced Arnold to cut short the conversation for the moment, by giving an order to Andrew Smith, who at that instant put his head out of the wheel-house door to say—

"All ready, sir!"

"Very well," replied Arnold. "I will take the wheel, and do you tell every one to keep under cover."

Smith saluted, and disappeared, and then Natasha and Arnold went into the wheel-house, while Colston and the Princess took their places in the deck-saloon, the two men off duty going into the conning tower forward.

"Why every one under cover, Captain Arnold?" asked Natasha, as soon as the two were ensconced in the wheel-house and the door shut.

"Because I am going to put the Ariel through her paces, and enter Aeria in style," replied he, signalling for the fan-wheels to revolve. "The fact is that, so far as I can see, these mountains are too high for us to rise over them by means of the lifting-wheels, which are only calculated to carry the ship to a height of about five thousand feet. After that the air gets too rarefied for them to get a solid grip. Now, these mountains look to me more like seven thousand feet high."

"Then how will you get over them?"

"I shall first take a cruise and see if I can find a negotiable gap, and then leap it."

"What! Leap seven thousand feet?"

"No; you forget that we shall be over five thousand up when we take the jump, and I have no doubt that we shall find a place where a thousand feet or so more will take us over. That we shall rise easily with the planes and propellers, and you will see such a leap as man never made in the world before."

While he was speaking the Ariel had risen from the ground, and was hanging a few hundred feet above the little plateau. He gave the signal for the wheels to be lowered, and the propellers to set to work at half-speed. Then he pulled the lever which moved the air-planes, and the vessel sped away forwards and upwards at about sixty miles an hour.

Arnold headed her away from the mountains until he had got an offing of a couple of miles, and then he swung her round and skirted the cliffs, rising ever higher and higher, and keeping a sharp look-out for a depression among the ridges that still towered nearly three thousand feet above them.

When he had explored some twenty miles of the mountain wall, Arnold suddenly pointed towards it, and said—

"There is a place that I think will do. Look yonder, between those two high peaks away to the southward. That ridge is not more than six thousand feet from the earth, and the Ariel can leap that as easily as an Irish hunter would take a five-barred gate."

"It looks dreadfully high from here," said Natasha, in spite of herself turning a shade paler at the idea of taking a six thousand foot ridge at a flying leap. She had splendid nerves, but this was her first aerial voyage, and it was also the first time that she had ever been brought so closely face to face with the awful grandeur of Nature in her own secret and solitary places.

She would have faced a levelled rifle without flinching, but as she looked at that frowning mass of rocks towering up into the sky, and then down into the fearful depths below, where huge trees looked like tiny shrubs, and vast forests like black patches of heather on the earth, her heart stood still in her breast when she thought of the frightful fate that would overwhelm the Ariel and her crew should she fail to rise high enough to clear the ridge, or if anything went wrong with her machinery at the critical moment.

"Are you sure you can do it?" she asked almost involuntarily.

"Perfectly sure," replied Arnold quietly, "otherwise I should not attempt it with you on board. The Ariel contains enough explosives to reduce her and us to dust and ashes, and if we hit that ridge going over, she would go off like a dynamite shell. No, I know what she can do, and you need not have the slightest fear!"

"I am not exactly afraid, but it looks a fearful thing to attempt."

"If there were any danger I should tell you—with my usual lack of dissimulation. But really there is none, and all you have to do is to hold tight when I tell you, and keep your eyes open for the first glimpse of Aeria."

By this time the Ariel was more than ten miles away from the mountains. Arnold, having now got offing enough, swung her round again, headed her straight for the ridge between the two peaks, and signalled "full speed" to the engine-room.

In an instant the propellers redoubled their revolutions, and the Ariel gathered way until the wind sang and screamed past her masts and stays. She covered eight miles in less than four minutes, and it seemed to Natasha as though the rock-wall were rushing towards them at an appalling speed, still frowning down a thousand feet above them. For the instant she was all eyes. She could neither open her lips nor move a limb for sheer, irresistible, physical terror. Then she heard Arnold say sharply—

"Now, hold on tight!"

The nearest thing to her was his own arm, the hand of which grasped one of the spokes of the steering wheel. Instinctively she passed her own arm under it, and then clasped it with both her hands. As she did so she felt the muscles tighten and harden. Then with his other hand he pulled the lever back to the full, and inclined the planes to their utmost.

Suddenly, as though some Titan had overthrown it, the huge black wall of rock in front seemed to sink down into the earth, the horizon widened out beyond it, and the Ariel soared upwards and swept over it nearly a thousand feet to the good.

"Ah!"

The exclamation was forced from her white lips by an impulse that Natasha had no power to resist. All the pride of her nature was conquered and humbled for the moment by the marvel that she had seen, and by the something, greater and stranger than all, that she saw in the man beside her who had worked this miracle with a single touch of his hand. A moment later she had recovered her self-possession. She unclasped her hands from his arm, and as the colour came back to her cheeks she said, as he thought, more sweetly than she had ever spoken to him before—

"My friend, you have glorious nerves where physical danger is concerned, and now I freely forgive you for fainting in the Council-chamber when Martinov was executed. But don't try mine again like that if you can help it. For the moment I thought that the end of all things had come. Oh, look! What a paradise! Truly this is a lovely kingdom that you have brought me to!"



"And one that you and I will yet reign over together," replied Arnold quietly, as he moved the lever again and allowed the Ariel to sink smoothly down the other side of the ridge over which she had taken her tremendous leap.

When she had called it a paradise, Natasha had used almost the only word that would fitly describe the scene that opened out before them as the Ariel sank down after her leap across the ridge. The interior of the mountain mass took the form of an oval valley, as nearly as they could guess about fifty miles long by perhaps thirty wide. All round it the mountains seemed to rise unbroken by a single gap or chasm to between three and four thousand feet above the lowest part of the valley, and above this again the peaks rose high into the sky, two of them to the snow-line, which in this latitude was over 15,000 feet above the sea.

Of the two peaks which reached to this altitude, one was at either end of a line drawn through the greater length of the valley, that is to say, from north to south. At least ten other peaks all round the walls of the valley rose to heights varying from eight to twelve thousand feet.

The centre of the valley was occupied by an irregularly shaped lake, plentifully dotted with islands about its shores, but quite clear of them in the middle. In its greatest length it would be about twelve miles long, while its breadth varied from five miles to a few hundred yards. Its sloping shores were covered with the most luxuriant vegetation, which reached upwards almost unbroken, but changing in character with the altitude, until there was a regular series of transitions, from the palms and bananas on the shores of the lake, to the sparse and scanty pines and firs that clung to the upper slopes of the mountains.

The lake received about a score of streams, many of which began as waterfalls far up the mountains, while two of them at least had their origin in the eternal snows of the northern and southern peaks. So far as they could see from the air-ship, the lake had no outlet, and they were therefore obliged to conclude that its surplus waters escaped by some subterranean channel, probably to reappear again as a river welling from the earth, it might be, hundreds of miles away.

Of inhabitants there were absolutely no traces to be seen, from the direction in which the Ariel was approaching. Animals and birds there seemed to be in plenty, but of man no trace was visible, until in her flight along the valley the Ariel opened up one of the many smaller valleys formed by the ribs of the encircling mountains.

There, close by a clump of magnificent tree-ferns, and nestling under a precipitous ridge, covered from base to summit with dark-green foliage and brilliantly-coloured flowers, was a well-built log-hut surrounded by an ample verandah, also almost smothered in flowers, and surmounted by a flagstaff from which fluttered the tattered remains of a Union-Jack.

In a little clearing to one side of the hut, a man, who might very well have passed for a modern edition of Robinson Crusoe, so far as his attire was concerned, was busily skinning an antelope which hung from a pole suspended from two trees. His back was turned towards them, and so swift and silent had been their approach that he did not hear the soft whirring of the propellers until they were within some three hundred yards of him.

Then, just as he looked round to see whence the sound came, Andrew Smith, who was standing in the bows near the conning tower, put his hands to his mouth and roared out a regular sailor's hail—

"Thomas Jackson, ahoy!"

The man straightened himself up, stared open-mouthed for a moment at the strange apparition, and then, with a yell either of terror or astonishment, bolted into the house as hard as he could run.

As soon as he was able to speak for laughing at the queer incident, Arnold sent the fan-wheels aloft and lowered the Ariel to within about twenty feet of the ground over a level patch of sward, across which meandered a little stream on its way to the lake. While she was hanging motionless over this, the man who had fled into the house reappeared, almost dragging another man, somewhat similarly attired, after him, and pointing excitedly towards the Ariel.

The second comer, if he felt any astonishment at the apparition that had invaded his solitude, certainly betrayed none. On the contrary, he walked deliberately from the hut to the bit of sward over which the Ariel hung motionless, and, seeing two ladies leaning on the rail that ran round the deck, he doffed his goatskin cap with a well-bred gesture, and said, in a voice that betrayed not the slightest symptom of surprise—

"Good morning, ladies and gentlemen! Good morning, and welcome to Aeria! I see that the problem of aerial navigation has been solved; I always said it would be in the first ten years of the twentieth century, though I often got laughed at by the wiseacres who know nothing until they see a thing before their noses. May I ask whether that little message that I sent to the outside world some years ago has procured me the pleasure of this visit?"

"Yes, Mr. Holt. Your little balloon was picked up about three years ago in the Gulf of Guinea, and, after various adventures and much discussion, has led to our present voyage."

"I am delighted to hear it. I suppose there were plenty of noodles who put it down to a practical joke or something of that sort? What's become of Stanley? Why didn't he come out and rescue me, as he did Emin? Not glory enough, I suppose? It would bother him, too, to get over these mountains, unless he flew over. By the way, has he got an air-ship?"

"No," replied Arnold, with a laugh. "This is the only one in existence, and she has not been a week afloat. But if you'll allow us, we'll come down and get generally acquainted, and after that we can explain things at our leisure."

"Quite so, quite so; do so by all means. Most happy, I'm sure. Ah! beautiful model. Comes down as easily as a bird. Capital mechanism. What's your motive-power? Gas, electricity—no, not steam, no funnels! Humph! Very ingenious. Always said it would be done some day. Build flying navies next, and be fighting in the clouds. Then there'll be general smash. Serve 'em right. Fools to fight. Why can't they live in peace?"

While Louis Holt was running along in this style, jerking his words out in little short snappy sentences, and fussing about round the air-ship, she had sunk gently to the earth, and her passengers had disembarked.

Arnold for the time being took no notice of the questions with regard to the motive-power, but introduced first himself, then the ladies, and then Colston, to Louis Holt, who may be described here, as elsewhere, as a little, bronzed, grizzled man, anywhere between fifty-five and seventy, with a lean, wiry, active body, a good square head, an ugly but kindly face, and keen, twinkling little grey eyes, that looked straight into those of any one he might be addressing.

The introductions over, he was invited on board the Ariel, and a few minutes later, in the deck-saloon, he was chattering away thirteen to the dozen, and drinking with unspeakable gusto the first glass of champagne he had tasted for nearly five years.



CHAPTER XVIII.

A NAVY OF THE FUTURE.

Arnold's instructions from the Council had been to remain in Aeria, and make a thorough exploration of the wonderful region described in Louis Holt's manuscript, until the time came for him to meet the Avondale, the steamer which was to bring out the materials for constructing the Terrorists' aerial navy.

Louis Holt and his faithful retainer, during the three years and a half that they had been shut up in it from the rest of the world, had made themselves so fully acquainted with its geography that very little of its surface was represented by blanks on the map which the former had spent several months in constructing, and so no better or more willing guides could have been placed at their service than they were.

Holt was an enthusiastic naturalist, and he descanted at great length on the strangeness of the flora and fauna that it had been his privilege to discover and classify in this isolated and hitherto unvisited region. It appeared that neither its animals nor its plants were quite like those of the rest of the continent, but seemed rather to belong to an anterior geological age.

From this fact he had come to the conclusion that at some very remote period, while the greater portion of Northern Africa was yet submerged by the waters of that ocean of which what is now the Sahara was probably the deepest part, Aeria was one of the many islands that had risen above its surface; and that, as the land rose and the waters subsided, its peculiar shape had prevented the forms of life which it contained from migrating or becoming modified in the struggle for existence with other forms, just as the flora and fauna of Australia have been shut off from those of the rest of the world.

There were no traces of human inhabitants to be found; but there were apparently two or three families of anthropoid apes, that seemed, so far as Holt had been able to judge—for they were extremely shy and cunning, and therefore difficult of approach—to be several degrees nearer to man, both in structure and intelligence, than any other members of the Simian family that had been discovered in other parts of the world.

As may well be imagined, a month passed rapidly and pleasantly away, what with exploring excursions by land and air, in the latter of which by no means the least diverting element was the keen and quaintly-expressed delight of Louis Holt at the new method of travel. Two or three times Arnold had, for his satisfaction, sent the Ariel flying over the ridge across which she had entered Aeria, but he had always been content with a glimpse of the outside world, and was always glad to get back again to the "happy valley," as he invariably called his isolated paradise.

The brief sojourn in this delightful land had brought back all the roses to Natasha's lovely cheeks, and had completely restored both her and the Princess to the perfect health that they had lost during their short but terrible experience of Russian convict life; but towards the end of the month they both began to get restless and anxious to get away to the rendezvous with the steamer that was bringing their friends and comrades out from England.

So it came about that an hour or so after sunrise on Friday, the 20th of May, the company of the Ariel bade farewell for a time to Louis Holt and his companion, leaving with them a good supply of the creature comforts of civilisation which alone were lacking in Aeria, rose into the air, and disappeared over the ridge to the north-west.

They had rather more than 2500 miles of plain and mountain and desert to cross, before they reached the sea-coast on which they expected to meet the steamer, and Arnold regulated the speed of the Ariel so that they would reach it about daybreak on the following morning.

The voyage was quite uneventful, and the course that they pursued led them westward through the Zegzeb and Nyti countries, then north-westward along the valley of the Niger, and then westward across the desert to the desolate sandy shores of the Western Sahara, which they crossed at sunrise on the Sunday morning, in the latitude of the island which was to form their rendezvous with the steamer.

They sighted the island about an hour later, but there was no sign of any vessel for fifty miles round it. The ocean appeared totally deserted, as, indeed, it usually is, for there is no trade with this barren and savage coast, and ships going to and from the southward portions of the continent give its treacherous sandbanks as wide a berth as possible. This, in fact, was the principal reason why this rocky islet, some sixty miles from the coast, had been chosen by the Terrorists for their temporary dockyard.

According to their calculations, the steamer would not be due for another twenty-four hours at the least, and at that moment would be about three hundred miles to the northward. The Ariel was therefore headed in that direction, at a hundred miles an hour, with a view to meeting her and convoying her for the rest of her voyage, and obviating such a disaster as Natasha's apprehensions pointed to.

The air-ship was kept at a height of two thousand feet above the water, and a man was stationed in the forward conning tower to keep a bright look-out ahead. For more than three hours she sped on her way without interruption, and then, a few minutes before twelve, the man in the conning tower signalled to the wheel-house—"Steamer in sight."

The signal was at once transmitted to the saloon, where Arnold was sitting with the rest of the party; he immediately signalled "half-speed" in reply to it, and went to the conning tower to see the steamer for himself.

She was then about twelve miles to the northward. At the speed at which the Ariel was travelling a very few minutes sufficed to bring her within view of the ocean voyagers. A red flag flying from the stern of the air-ship was answered by a similar one from the mainmast of the steamer. The Ariel's engines were at once slowed down, the fan-wheels went aloft, and she sank gently down to within twenty feet of the water, and swung round the steamer's stern.

As soon as they were within hailing distance, those on board the air-ship recognised Nicholas Roburoff and his wife, Radna Michaelis, and several other members of the Inner Circle, standing on the bridge of the steamer. Handkerchiefs were waved, and cries of welcome and greeting passed and re-passed from the air to the sea, until Arnold raised his hand for silence, and, hailing Roburoff, said—

"Are you all well on board?"

"Yes, all well," was the reply, "though we have had rather a risky time of it, for war was generally declared a fortnight ago, and we have had to run the blockade for a good part of the way. That is why we are a little before our time. Can you come nearer? We have some letters for you."

"Yes," replied Arnold. "I'll come alongside. You go ahead, I'll do the rest."

So saying, he ran the Ariel up close to the quarter of the Avondale as easily as though she had been lying at anchor instead of going twenty miles an hour through the water, and went forward and shook hands with Roburoff over the rail, taking a packet of letters from him at the same time. Meanwhile Colston, who had grasped the situation at a glance, had swung himself on to the steamer's deck, and was already engaged in an animated conversation with Radna.

The first advantage that Arnold took of the leisure that was now at his disposal, was to read the letter directed to himself that was among those for Natasha, the Princess, and Colston, which had been brought out by the Avondale. He recognised the writing as Tremayne's, and when he opened the envelope he found that it contained a somewhat lengthy letter from him, and an enclosure in an unfamiliar hand, which consisted of only a few lines, and was signed "Natas."

He started as his eye fell on the terrible name, which now meant so much to him, and he naturally read the note to which it was appended first. There was neither date nor formal address, and it ran as follows:—

You have done well, and fulfilled your promises as a true man should. For the personal service that you have rendered to me I will not thank you in words, for the time may come when I shall be able to do so in deeds. What you have done for the Cause was your duty, and for that I know that you desire no thanks. You have proved that you hold in your hands such power as no single man ever wielded before. Use it well, and in the ages to come men shall remember your name with blessings, and you, if the Master of Destiny permits, shall attain to your heart's desire.

NATAS.

Arnold laid the little slip of paper down almost reverently, for, few as the words were, they were those of a man who was not only Natas, the Master of the Terror, but also the father of the woman whose love, in spite of his oath, was the object to the attainment of which he held all things else as secondary, and who therefore had the power to crown his life-work with the supreme blessing without which it would be worthless, however glorious, for he knew full well that, though he might win Natasha's heart, she herself could never be his unless Natas gave her to him.

The other letter was from Tremayne, dated more than a fortnight previously, and gave him a brief resume of the course of events in Europe since his voyage of exploration had begun. It also urged him to push on the construction of the aerial navy as fast as possible, as there was now no telling where or how soon its presence might be required to determine the issue of the world-war, the first skirmishes of which had already taken place in Eastern Europe. Natas and the Chief were both in London, making the final arrangements for the direction of the various diplomatic and military agents of the Brotherhood throughout Europe. From London they were to go to Alanmere, where they would remain until all arrangements were completed. As soon as the fleet was built and the crews and commanders of the air-ships had thoroughly learned their duties, the flagship was to go to Plymouth, where the Lurline would be lying. The news of her arrival would be telegraphed to Alanmere, and Natas and Tremayne would at once come south and put to sea in her. The air-ship was to wait for them at a point two hundred miles due south-west of the Land's End, and pick them up. The yacht was then to be sunk, and the Executive of the Terrorists would for the time being vanish from the sight of men.

It is unnecessary to say that Arnold carried out the plans laid down in this letter in every detail, and with the utmost possible expedition. The Avondale arrived the next day at the island which had been chosen as a dockyard, and the ship-building was at once commenced.

All the material for constructing the air-ships had been brought out completely finished as far as each individual part was concerned, and so there was nothing to do but to put them together. The crew and passengers of the steamer included the members of the Executive of the Inner Circle, and sixty picked members of the Outer Circle, chiefly mechanics and sailors, destined to be first the builders and then the crews of the new vessels.

These, under Arnold's direction, worked almost day and night at the task before them. Three of the air-ships were put together at a time, twenty men working at each, and within a month from the time that the Avondale discharged her cargo, the twelve new vessels were ready to take the air.

They were all built on the same plan as the Ariel, and eleven of them were practically identical with her as regards size and speed; but the twelfth, the flagship of the aerial fleet, had been designed by Arnold on a more ambitious scale.

This vessel was larger and much more powerful than any of the others. She was a hundred feet long, with a beam of fifteen feet amidships. On her five masts she carried five fan-wheels, capable of raising her vertically to a height of ten thousand feet without the assistance of her air-planes, and her three propellers, each worked by duplex engines, were able to drive her through the air at a speed of two hundred miles an hour in a calm atmosphere.

She was armed with two pneumatic guns forward and two aft, each twenty-five feet long and with a range of twelve miles at an altitude of four thousand feet; and in addition to these she carried two shorter ones on each broadside, with a range of six miles at the same elevation. She also carried a sufficient supply of power-cylinders to give her an effective range of operations of twenty thousand miles without replenishing them.

In addition to the building materials and the necessary tools and appliances for putting them together, the cargo of the Avondale had included an ample supply of stores of all kinds, not the least important part of which consisted of a quantity of power-cylinders sufficient to provide the whole fleet three times over.

The necessary chemicals and apparatus for charging them were also on board, and the last use that Arnold made of the engines of the steamer, which he had disconnected from the propeller and turned to all kinds of uses during the building operations, was to connect them with his storage pumps and charge every available cylinder to its utmost capacity.

At length, when everything that could be carried in the air-ships had been taken out of the steamer, she was towed out into deep water, and then a shot from one of the flagship's broadside guns sent her to the bottom of the sea, so severing the last link which had connected the now isolated band of revolutionists with the world on which they were ere long to declare war.

The naming of the fleet was by common consent left to Natasha, and her half-oriental genius naturally led her to appropriately name the air-ships after the winged angels and air-spirits of Moslem and other Eastern mythologies. The flagship she named the Ithuriel, after the angel who was sent to seek out and confound the Powers of Darkness in that terrific conflict between the upper and nether worlds, which was a fitting antetype to the colossal struggle which was now to be waged for the empire of the earth.

Arnold's first task, as soon as the fleet finally took the air, was to put the captains and crews of the vessels through a thorough drilling in management and evolution. A regular code of signals had been arranged, by means of which orders as to formation, speed, altitude, and direction could be at once transmitted from the flagship. During the day flags were used, and at night flashes from electric reflectors.

The scene of these evolutions was practically the course taken by the Ariel from Aeria to the island; and as the captains and lieutenants of the different vessels were all men of high intelligence, and carefully selected for the work, and as the mechanism of the air-ships was extremely simple, the whole fleet was well in hand by the time the mountain mass of Aeria was sighted a week after leaving the island.

Arnold in the Ithuriel led the way to a narrow defile on the south-western side, which had been discovered during his first visit, and which admitted of entrance to the valley at an elevation of about 3000 feet. Through this the fleet passed in single file soon after sunrise one lovely morning in the middle of June, and within an hour the thirteen vessels had come to rest on the shores of the lake.

Then for the first time, probably, since the beginning of the world, the beautiful valley became the scene of a busy activity, in the midst of which the lean wiry figure of Louis Holt seemed to be here, there, and everywhere at once, doing the honours of Aeria as though it were a private estate to which the Terrorists had come by his special invitation.

He was more than ever delighted with the air-ships, and especially with the splendid proportions of the Ithuriel, and the brilliant lustre of her polished hull, which had been left unpainted, and shone as though her plates had been of burnished silver. Altogether he was well pleased with this invasion of a solitude which, in spite of its great beauty and his professed contempt for the world in general, had for the last few months been getting a good deal more tedious than he would have cared to admit.

In the absence of Natas and the Chief, the command of the new colony devolved, in accordance with the latter's directions, upon Nicholas Roburoff, who was a man of great administrative powers, and who set to work without an hour's delay to set his new kingdom in order, marking out sites for houses and gardens, and preparing materials for building them and the factories for which the water-power of the valley was to be utilised.

Arnold, as admiral of the fleet, had transferred the command of the Ariel to Colston, but he retained him as his lieutenant in the Ithuriel for the next voyage, partly because he wanted to have him with him on what might prove to be a momentous expedition, and partly because Natasha, who was naturally anxious to rejoin her father as soon as possible, wished to have Radna for a companion in place of the Princess, who had elected to remain in the valley. As another separation of the lovers, who, according to the laws of the Brotherhood, now only waited for the formal consent of Natas to their marriage, was not to be thought of, this arrangement gave everybody the most perfect satisfaction.

Three days sufficed to get everything into working order in the new colony, and on the morning of the fourth the Ithuriel, having on board the original crew of the Ariel, reinforced by two engineers and a couple of sailors, rose into the air amidst the cheers of the assembled colonists, crossed the northern ridge, and vanished like a silver arrow into space.



CHAPTER XIX.

THE EVE OF BATTLE.

It will now be necessary to go back about six weeks from the day that the Ithuriel started on her northward voyage, and to lay before the reader a brief outline of the events which had transpired in Europe subsequently to the date of Tremayne's letter to Arnold.