On the following 19th of April, seven months after the unexpected return of Uncle Prudent and Phil Evans, Philadelphia was in a state of unwonted excitement. There were neither elections nor meetings this time. The aerostat “Go-Ahead.” built by the Weldon Institute, was to take possession of her natural element. The celebrated Harry W. Tinder, whose name we mentioned at the beginning of this story, had been engaged as aeronaut. He had no assistant, and the only passengers were to be the president and secretary of the Weldon Institute. Did they not merit such an honor? Did it not come to them appropriately to rise in person to protest against any apparatus that was heavier than air? During the seven months, however, they had said nothing of their adventures; and even Frycollin had not uttered a whisper of Robur and his wonderful clipper. Probably Uncle Prudent and his friend desired that no question should arise as to the merits of the aeronef, or any other flying machine. Although the “Go-Ahead” might not claim the first place among aerial locomotives, they would have nothing to say about the inventions of other aviators. They believed, and would always believe, that the true atmospheric vehicle was the aerostat, and that to it alone belonged the future. Besides, he on whom they had been so terribly—and in their idea so justly—avenged, existed no longer. None of those who accompanied him had survived. The secret of the “Albatross” was buried in the depths of the Pacific! That Robur had a retreat, an island in the middle of that vast ocean, where he could put into port, was only a hypothesis; and the colleagues reserved to themselves the right of making inquiries on the subject later on. The grand experiment which the Weldon Institute had been preparing for so long was at last to take place. The “Go-Ahead” was the most perfect type of what had up to then been invented in aerostatic art—she was what an “Inflexible” or a “Formidable” is in ships of war. She possessed all the qualities of a good aerostat. Her dimensions allowed of her rising to the greatest height a balloon could attain; her impermeability enabled her to remain for an indefinite time in the atmosphere; her solidity would defy any dilation of gas or violence of wind or rain; her capacity gave her sufficient ascensional force to lift with all their accessories an electric engine that would communicate to her propellers a power superior to anything yet obtained. The “Go-Ahead” was of elongated form, so as to facilitate her horizontal displacement. Her car was a platform somewhat like that of the balloon used by Krebs and Renard; and it carried all the necessary outfit, instruments, cables, grapnels, guide-ropes, etc., and the piles and accumulators for the mechanical power. The car had a screw in front, and a screw and rudder behind. But probably the work done by the machines would be very much less than that done by the machines of the “Albatross.”