The Ithuriel and her consorts crossed the northern coast of Africa soon after daybreak on the 27th, in the longitude of Alexandria, at an elevation of nearly 4000 feet. From thence they pursued almost the same course as that steered by the deserters, as Natas had rightly judged that they would first make for Russia, probably St. Petersburg, and there hand the air-ship over to the representatives of the Tsar.
There was, of course, another alternative, and that was the supposition that they had stolen the Lucifer--the " fallen Angel," as Natasha had now re-named her--for purposes of piracy and private revenge; but that was negatived by the fact that Tamboff knew that he only had a certain supply of motive power which he could not renew, and which, once exhausted, left his air-ship as useless as a steamer without coal. His only reasonable course, therefore, would be to sell the vessel to the Tsar, and leave his Majesty's chemists to discover and renew the motive power if they could.
These conclusions once arrived at, it was an easy matter for the keen and subtle intellect of Natas to deduce from them almost the exact sequence of events that had actually taken place. The Lucifer had a sufficient supply of power-cylinders and shells for present use, and these would doubtless be employed at once by the Tsar, who would trust to his chemists and engineers to discover the nature of the agents employed.
For this purpose it would be absolutely necessary for him to give them one or two of the shells, and at least two of the spare power-cylinders as subjects for their experiments.
Now Natas knew that if there was one man in Russia who could discover the composition of the explosives, that man was Professor Volnow of the Imperial Arsenal Laboratory, and therefore the shells and cylinders would be sent to him at the Arsenal for examination. The whereabouts of the deserters for the present mattered nothing in comparison with the possible discovery of the secret on which the whole power of the Terrorists depended.
That once revealed, the sole empire of the air was theirs no longer. The Tsar, with millions of money at his command, could very soon build an aerial fleet, not only equal, but numerically at least, vastly superior to their own, and this would practically give him the command of the world.
Natas therefore came to the conclusion that no measures could be too extreme to be justified by such a danger as this, and so, after a consultation with the commanders of the three vessels, it was decided to, if necessary, destroy the Arsenal at St. Petersburg, on the strength of the reasoning that had led to the logical conclusion that within its precincts the priceless secret either might be or had already been discovered.
As the crow flies, St. Petersburg is thirty degrees of latitude, or eighteen hundred geographical miles, north of Alexandria, and this distance the Ithuriel and her consorts, flying at a speed of a hundred and twenty miles an hour, traversed in fifteen hours, reaching the Russian capital a few minutes after seven on the evening of the 27th.
The Rome of the North, basking in the soft evening sunlight of the incomparable Russian summer, lay vast and white and beautiful on the islands formed by the Neva and its ten tributaries; its innumerable palaces, churches, and theatres, and long straight streets of stately houses, its parks and gardens, and its green shady suburbs, making up a picture which forced an exclamation of wonder from Arnold's lips as the air-ships slowed down and he left the conning-tower of the Ithuriel to admire the magnificent view from the bows. They passed over the city at a height of four thousand feet, and so were quite near enough to see and enjoy the excitement and consternation which their sudden appearance instantly caused among the inhabitants. The streets and squares filled in an inconceivably short space of time with crowds of people, who ran about like tiny ants upon the ground, gesticulating and pointing upwards, evidently in terror lest the fate of Kronstadt was about to fall upon St. Petersburg.
The experimental department of the Arsenal had within the last two or three years been rebuilt on a large space of waste ground outside the northern suburbs, and to this the three airships directed their course after passing over the city. It was a massive three-storey building, built in the form of a quadrangle. The three air-ships stopped within a mile of it at an elevation of two thousand feet. It had been decided that, before proceeding to extremities, which, after all, might still leave them in doubt as to whether or not they had really destroyed all means of analysing the explosives, they should make an effort to discover whether Professor Volnow had received them for experiment, and, if so, what success he had had.
Mazanoff had undertaken this delicate and dangerous task, and so, as soon as the Ithuriel and the Orion came to a standstill, and hung motionless in the air, with all their guns ready trained on different parts of the building, the Ariel sank suddenly and swiftly down, and stopped within forty feet of the heads of a crowd of soldiers and mechanics, who had rushed pell-mell out of the building, under the impression that it was about to be destroyed.
The bold manoeuvre of the Ariel took officers and men completely by surprise. So intense was the terror in which these mysterious air-ships were held, and so absolute was the belief that they were armed with perfectly irresistible means of destruction, that the sight of one of them at such close quarters paralysed all thought and action for the time being. The first shock over, the majority of the crowd took to their heels and fled incontinently. Of the remainder a few of the bolder spirits handled their rifles and looked inquiringly at their officers. Mazanoff saw this, and at once raised his hand towards the sky and shouted--
"Ground arms! If a shot is fired the Arsenal will be destroyed as Kronstadt was, and then we shall attack Petersburg."
The threat was sufficient. A grey-haired officer in undress uniform glanced up at the Ithuriel and her consort, and then at the guns of the Ariel, all four of which had been swung round and brought to bear on the side of the building near which she had descended. He was no coward, but he saw that Mazanoff had the power to do what he said, and that even if this air-ship were captured or destroyed, the other two would take a frightful vengeance. He thought of Kronstadt, and decided to parley. The rifle butts had come to the ground before Mazanoff had done speaking
"Order arms, and keep silence!" said the officer, and then he advanced alone from the crowd and said--
"Who are you, and what is your errand?"
"Alexis Mazanoff, late prisoner of the Tsar, and now commander of the Terrorist air-ship Ariel. I have not come to destroy you unless you force me to do so, but to ask certain questions, and demand the giving up of certain property delivered into your hands by deserters and traitors."
"What are your questions?"
"First, is Professor Volnow in the building?"
"He is."
"Then I must ask you to send for him at once."
It went sorely against the grain of the servant of the Tsar to acquiesce in the demand of an outlaw, but there was nothing else for it. The outlaw could blow him and all his subordinates into space with a pressure of his finger; and so he sent an orderly with a request for the presence of the professor. Meanwhile Mazanoff continued--
"An air-ship similar to this arrived here three days ago, I believe?"
The officer bit his lips with rage at his helpless position, and bowed affirmatively.
"And certain articles were taken out of her for examination here--two gas cylinders and a projectile, I believe?"
Again the officer bowed, wondering how on earth the Terrorist could have come by such accurate information.
"And the air-ship has been sent on to the seat of war, while the Professor is trying to discover the composition of the gases and the explosive used in the shell?" went on Mazanoff, risking a last shot at the truth.
The officer did not bow this time. Giving way at last to his rising fury, he stamped on the ground and almost screamed--
"Great God! you insolent scoundrel! Why do you ask me questions when you know the answers as well as I do, and better? Yes, we have got one of your diabolical ships of the air, and we will build a fleet like it and hunt you from the world!"
"All in good time, my dear sir," replied Mazanoff ironically. "When you have found a place in which to build them that we cannot blow off the face of the earth before you get one finished. Meanwhile, let me beg of you to keep your temper, and to remember that there is a lady present. That girl standing yonder by the gun was once stripped and flogged by Russians calling themselves men and soldiers. Her fingers are itching to make the movement that would annihilate you and every one standing near you, so pray try keep your temper; for if we fire a shot the air-ships up yonder will at once open fire, and not stop while there is a stone of that building left upon another. Ah! here comes the Professor."
As he spoke the man of science advanced, looking wonderingly at the air-ship. Mazanoff made a sign to the old officer to keep silence, and continued in the same polite tone that he had used all along--
"Good evening, Professor! I have come to ask you whether you have yet made any experiments on the contents of the shell and the two cylinders that were given to you for examination?"
"I must first ask for your authority to put such an inquiry to me on a confidential subject," replied the Professor stiffly.
"On the authority given me by the power to enforce an answer, sir," returned the Terrorist quietly. "I know that Professor Volnow will not lie to me, even at the order of the Tsar, and when I tell you that your refusal to reply will cost the lives of every one here, and possibly involve the destruction of Petersburg itself, I feel sure that, as a mere matter of humanity, you will comply with my request."
"Sir, the orders of my master are absolute secrecy on this subject, and I will obey them to the death. I have analysed the contents of one of the cylinders, but what they are I will tell to no one save by the direct command of his Majesty. That is all I have done."
"Then in that case, Professor, I must ask you to surrender yourself prisoner of war, and to come on board this vessel at once."
As Mazanoff said this the Ariel dropped to within ten feet of the ground, and a rope-ladder fell over the side.
"Come, Professor, there is no time to be lost. I shall give the order to fire in one minute from now."
He took out his watch, and began to count the seconds. Ten, twenty, thirty passed and the Professor stood irresolute. Two of the Ariel's guns pointed at the gables of the Arsenal and two swept the crowded space in front.
Konstantin Volnow knew enough to see clearly the frightful slaughter and destruction that twenty seconds more would bring if he refused to give himself up. As Mazanoff counted "forty" he threw up his hands with a gesture of despair, and cried--
"Stop! I will come. The Tsar has as good servants as I am! Colonel, tell his Majesty that I gave myself up to save the lives of better men."
Then the Professor mounted the ladder amidst a murmur of relief and applause from the crowd, and, gaining the deck of the Ariel, bowed coldly to Mazanoff and said--
"I am your prisoner, sir!"
The captain of the Ariel bowed in reply, and stamped thrice on the deck. The fan-wheels whirled round, and the air-ship rapidly ascended, at the same time moving diagonally across the quadrangle of the Arsenal.
Scarcely had she reached the other side when there was a tremendous explosion in the north-eastern angle of the building. A sheet of flame shot up through the roof, the walls split asunder, and masses of stone, wood, and iron went flying in all directions, leaving only a fiercely burning mass of ruins where the gable had been.
The Professor turned ashy pale, staggered backwards with both his hands clasped to his head, and gasped out brokenly as he stared at the conflagration--
"God have mercy on me! My laboratory! My assistant--I told him--
"What did you tell him, Professor?" said Mazanoff sternly, grasping him suddenly by the arm.
"I told him not to open the other cylinder."
"And he has done so, and paid for his disobedience with his life," said Mazanoff calmly. "Console yourself, my dear sir! He has only saved me the trouble of destroying your laboratory. I serve a sterner and more powerful master than yours. He ordered me to make your experiments impossible if it cost a thousand lives to do so, and I would have done it if necessary. Rest content with the knowledge that you have saved, not only the rest of the Arsenal, but also Petersburg, by your surrender; for sooner than that secret had been revealed, we should have laid the city in ruins to slay the man who had discovered it."
The prisoner of the Terrorists made no reply, but turned away in silence to watch the rapidly receding building, in the angle of which the flames were still raging furiously. A few minutes later the Ariel had rejoined her consorts. Her captain at once went on board the flagship to make his report and deliver up his prisoner to Natas, who looked sharply at him and said--
"Professor, will you give me your word of honour to attempt no communication with the earth while it may be found necessary to detain you? If not, I shall be compelled to keep you in strict confinement till it is beyond your power to do so."
"Sir, I give you my word that I will not do so," said the Professor, who had now somewhat regained his composure.
"Very well," replied Natas. "Then on that condition you will be made free of the vessel, and we will make you as comfortable as we can. Captain Arnold, full speed to the south-westward, if you please."