At this moment the aerostat rose a few hundred yards. The maneuver was understood below. Uncle Prudent and his companions were going in search of a breeze in the higher zones, so as to complete the experiment. The system of cellular balloons--a.n.a.logous to the swimming bladder in fishes--into which could be introduced a certain amount of air by pumping, had provided for this vertical motion.

Without throwing out ballast or losing gas the aeronaut was able to rise or sink at his will. Of course there was a valve in the upper hemisphere which would permit of a rapid descent if found necessary.

All these contrivances are well known, but they were here fitted in perfection.

The "Go-Ahead" then rose vertically. Her enormous dimensions gradually grew smaller to the eye, and the necks of the crowd were almost cricked as they gazed into the air. Gradually the whale became a porpoise, and the porpoise became a gudgeon. The ascensional movement did not cease until the "Go-Ahead" had reached a height of fourteen thousand feet. But the air was so free from mist that she remained clearly visible.

However, she remained over the clearing as if she were a fixture. An immense bell had imprisoned the atmosphere and deprived it of movement; not a breath of wind was there, high or low. The aerostat maneuvered without encountering any resistance, seeming very small owing to the distance, much as if she were being looked at through the wrong end of a telescope.

Suddenly there was a shout among the crowd, a shout followed by a hundred thousand more. All hands were stretched towards a point on the horizon. That point was the northwest. There in the deep azure appeared a moving body, which was approaching and growing larger. Was it a bird beating with its wings the higher zones of s.p.a.ce? Was it an aerolite shooting obliquely through the atmosphere? In any case, its speed was terrific, and it would soon be above the crowd. A suspicion communicated itself electrically to the brains of all on the clearing.

But it seemed as though the "Go-Ahead" had sighted this strange object. a.s.suredly it seemed as though she feared some danger, for her speed was increased, and she was going east as fast as she could.

Yes, the crowd saw what it meant! A name uttered by one of the members of the Weldon Inst.i.tute was repeated by a hundred thousand mouths:

"The "Albatross!" The "Albatross!""

Chapter XXIII

THE GRAND COLLAPSE

It was indeed the "Albatross!" It was indeed Robur who had reappeared in the heights of the sky! It was he who like a huge bird of prey was going to strike the "Go-Ahead."

And yet, nine months before, the aeronef, shattered by the explosion, her screws broken, her deck smashed in two, had been apparently annihilated.

Without the prodigious coolness of the engineer, who reversed the gyratory motion of the fore propeller and converted it into a suspensory screw, the men of the "Albatross" would all have been asphyxiated by the fall. But if they had escaped asphyxia, how had they escaped being drowned in the Pacific?

The remains of the deck, the blades of the propellers, the compartments of the cabins, all formed a sort of raft. When a wounded bird falls on the waves its wings keep it afloat. For several hours Robur and his men remained unhelped, at first on the wreck, and afterwards in the india-rubber boat that had fallen uninjured. A few hours after sunrise they were sighted by a pa.s.sing ship, and a boat was lowered to their rescue.

Robur and his companions were saved, and so was much of what remained of the aeronef. The engineer said that his ship had perished in a collision, and no further questions were asked him.

The ship was an English three-master, the "Two Friends," bound for Melbourne, where she arrived a few days afterwards.

Robur was in Australia, but a long way from X Island, to which he desired to return as soon as possible.

In the ruins of the aftermost cabin he had found a considerable sum of money, quite enough to provide for himself and companions without applying to anyone for help. A short time after he arrived in Melbourne he became the owner of a small brigantine of about a hundred tons, and in her he sailed for X Island.

There he had but one idea--to be avenged. But to secure his vengeance he would have to make another "Albatross." This after all was an easy task for him who made the first. He used up what he could of the old material; the propellers and engines he had brought back in the brigantine. The mechanism was fitted with new piles and new acc.u.mulators, and, in short, in less than eight months, the work was finished, and a new "Albatross," identical with the one destroyed by the explosion, was ready to take flight. And he had the same crew.

The "Albatross" left X Island in the first week of April. During this aerial pa.s.sage Robur did not want to be seen from the earth, and he came along almost always above the clouds. When he arrived over North America he descended in a desolate spot in the Far West. There the engineer, keeping a profound incognito, learnt with considerable pleasure that the Weldon Inst.i.tute was about to begin its experiments, and that the "Go-Ahead," with Uncle Prudent and Phil Evans, was going to start from Philadelphia on the 29th of April.

Here was a chance for Robur and his crew to gratify their longing for revenge. Here was a chance for inflicting on their foes a terrible vengeance, which in the "Go-Ahead" they could not escape. A public vengeance, which would at the same time prove the superiority of the aeronef to all aerostats and contrivances of that nature!

And that is why, on this very day, like a vulture from the clouds, the aeronef appeared over Fairmount Park.

Yes! It was the "Albatross," easily recognizable by all those who had never before seen her.

The "Go-Ahead" was in full flight; but it soon appeared that she could not escape horizontally, and so she sought her safety in a vertical direction, not dropping to the ground, for the aeronef would have cut her off, but rising to a zone where she could not perhaps be reached. This was very daring, and at the same time very logical.

But the "Albatross" began to rise after her. Although she was smaller than the "Go-Ahead," it was a case of the swordfish and the whale.

This could easily be seen from below and with what anxiety! In a few moments the aerostat had attained a height of sixteen thousand feet.

The "Albatross" followed her as she rose. She flew round her flanks, and maneuvered round her in a circle with a constantly diminishing radius. She could have annihilated her at a stroke, and Uncle Prudent and his companions would have been dashed to atoms in a frightful fall.

The people, mute with horror, gazed breathlessly; they were seized with that sort of fear which presses on the chest and grips the legs when we see anyone fall from a height. An aerial combat was beginning in which there were none of the chances of safety as in a sea-fight.

It was the first of its kind, but it would not be the last, for progress is one of the laws of this world. And if the "Go-Ahead" was flying the American colors, did not the "Albatross" display the stars and golden sun of Robur the Conqueror?

The "Go-Ahead" tried to distance her enemy by rising still higher.

She threw away the ballast she had in reserve; she made a new leap of three thousand feet; she was now but a dot in s.p.a.ce. The "Albatross,"

which followed her round and round at top speed, was now invisible.

Suddenly a shout of terror rose from the crowd. The "Go-Ahead"

increased rapidly in size, and the aeronef appeared dropping with her. This time it was a fall. The gas had dilated in the higher zones of the atmosphere and had burst the balloon, which, half inflated still, was falling rapidly.

But the aeronef, slowing her suspensory screws, came down just as fast. She ran alongside the "Go-Ahead" when she was not more than four thousand feet from the ground.

Would Robur destroy her?

No; he was going to save her crew!

And so cleverly did he handle his vessel that the aeronaut jumped on board.

Would Uncle Prudent and Phil Evans refuse to be saved by him? They were quite capable of doing so. But the crew threw themselves on them and dragged them by force from the "Go-Ahead" to the "Albatross."

Then the aeronef glided off and remained stationary, while the balloon, quite empty of gas, fell on the trees of the clearing and hung there like a gigantic rag.

An appalling silence reigned on the ground. It seemed as though life were suspended in each of the crowd; and many eyes had been closed so as not to behold the final catastrophe. Uncle Prudent and Phil Evans had again become the prisoners of the redoubtable Robur. Now he had recaptured them, would he carry them off into s.p.a.ce, where it was impossible to follow him?

It seemed so.

However, instead of mounting into the sky the "Albatross" stopped six feet from the ground. Then, amid profound silence, the engineer's voice was heard.

"Citizens of the United States," he said, "The president and secretary of the Weldon Inst.i.tute are again in my power. In keeping them I am only within my right. But from the pa.s.sion kindled in them by the success of the "Albatross" I see that their minds are not prepared for that important revolution which the conquest of the air will one day bring, Uncle Prudent and Phil Evans, you are free!"

The president, the secretary, and the aeronaut had only to jump down.

Then Robur continued.

"Citizens of the United States, my experiment is finished; but my advice to those present is to be premature in nothing, not even in progress. It is evolution and not revolution that we should seek. In a word, we must not be before our time. I have come too soon today to withstand such contradictory and divided interests as yours. Nations are not yet fit for union.

"I go, then; and I take my secret with me. But it will not be lost to humanity. It will belong to you the day you are educated enough to profit by it and wise enough not to abuse it. Citizens of the United States--Good-by!"

And the "Albatross," beating the air with her seventy-four screws, and driven by her propellers, shot off towards the east amid a tempest of cheers.

The two colleagues, profoundly humiliated, and through them the whole Weldon Inst.i.tute, did the only thing they could. They went home.