Mr. Prudent and Mr. Evans then returned to Philadelphia. They had learned that the "Albatross" had been constructed on an unknown isle of the Pacific called Island X; but since the location of this hiding-place was wholly unknown, its discovery lay scarcely within the bounds of possibility. Moreover, the search seemed entirely unnecessary, as the vengeful prisoners were quite certain that they had destroyed their jailers.

Hence the two millionaires, restored to their homes, went calmly on with the construction of their own machine, the "Go-Ahead." They hoped by means of it to soar once more into the regions they had traversed with Robur, and to prove to themselves that their lighter than air machine was at least the equal of the heavy "Albatross." If they had not persisted, they would not have been true Americans.

On the twentieth of April in the following year the "Go-Ahead" was finished and the ascent was made, from Fairmount Park in Philadelphia. I myself was there with thousands of other spectators. We saw the huge balloon rise gracefully; and, thanks to its powerful screws, it maneuvered in every direction with surprising ease. Suddenly a cry was heard, a cry repeated from a thousand throats. Another airship had appeared in the distant skies and it now approached with marvelous rapidity. It was another "Albatross," perhaps even superior to the first. Robur and his men had escaped death in the Pacific; and, burning for revenge, they had constructed a second airship in their secret Island X.

Like a gigantic bird of prey, the "Albatross" hurled itself upon the "Go-Ahead." Doubtless, Robur, while avenging himself wished also to prove the immeasurable superiority of the heavier than air machines.

Mr. Prudent and Mr. Evans defended themselves as best they could. Knowing that their balloon had nothing like the horizontal speed of the "Albatross," they attempted to take advantage of their superior lightness and rise above her. The "Go-Ahead," throwing out all her ballast, soared to a height of over twenty thousand feet. Yet even there the "Albatross" rose above her, and circled round her with ease.

Suddenly an explosion was heard. The enormous gas-bag of the "Go-Ahead," expanding under the dilation of its contents at this great height, had finally burst.

Half-emptied, the balloon fell rapidly.

Then to our universal astonishment, the "Albatross" shot down after her rival, not to finish the work of destruction but to bring rescue. Yes! Robur, forgetting his vengeance, rejoined the sinking "Go-Ahead," and his men lifted Mr. Prudent, Mr. Evans, and the aeronaut who accompanied them, onto the platform of his craft. Then the balloon, being at length entirely empty, fell to its destruction among the trees of Fairmount Park.

The public was overwhelmed with astonishment, with fear! Now that Robur had recaptured his prisoners, how would he avenge himself? Would they be carried away, this time, forever?

The "Albatross" continued to descend, as if to land in the clearing at Fairmount Park. But if it came within reach, would not the infuriated crowd throw themselves upon the airship, tearing both it and its inventor to pieces?

The "Albatross" descended within six feet of the ground. I remember well the general movement forward with which the crowd threatened to attack it. Then Robur's voice rang out in words which even now I can repeat almost as he said them:

"Citizens of the United States, the president and the secretary of the Weldon Institute are again in my power. In holding them prisoners I would but be exercising my natural right of reprisal for the injuries they have done me. But the passion and resentment which have been roused both in them and you by the success of the 'Albatross,' show that the souls of men are not yet ready for the vast increase of power which the conquest of the air will bring to them. Uncle Prudent, Phillip Evans, you are free."

The three men rescued from the balloon leaped to the ground. The airship rose some thirty feet out of reach, and Robur recommenced:

"Citizens of the United States, the conquest of the air is made; but it shall not be given into your hands until the proper time.