three hundred and thirty—"

"And a half!"

"And the mosquito, which gives millions—"

"No, milliards!"

But Robur, the interrupted, interrupted not his demonstration. "Between these different rates—" he continued.

"There is a difference," said a voice.

"There is a possibility of finding a practical solution. When De Lucy showed that the stag beetle, an insect weighing only two grammes, could lift a weight of four hundred grammes, or two hundred times its own weight, the problem of aviation was solved. Besides, it has been shown that the wing surface decreases in proportion to the increase of the size and weight of the animal. Hence we can look forward to such contrivances—"

"Which would never fly!" said secretary Phil Evans.

"Which have flown, and which will fly," said Robur, without being in the least disconcerted, "and which we can call streophores, helicopters, orthopters—or, in imitation of the word 'nef,' which comes from 'navis,' call them from 'avis,' 'efs,'—by means of which man will become the master of space. The helix—"

"Ah, the helix!" replied Phil Evans. "But the bird has no helix; that we know!"

"So," said Robur; "but Penaud has shown that in reality the bird makes a helix, and its flight is helicopteral. And the motor of the future is the screw—"

"From such a maladee Saint Helix keep us free!" sung out one of the members, who had accidentally hit upon the air from Herold's "Zampa."

And they all took up the chorus: "From such a maladee Saint Helix keep us free!" with such intonations and variations as would have made the French composer groan in his grave.

As the last notes died away in a frightful discord Uncle Prudent took advantage of the momentary calm to say, "Stranger, up to now, we let you speak without interruption." It seemed that for the president of the Weldon Institute shouts, yells, and catcalls were not interruptions, but only an exchange of arguments.

"But I may remind you, all the same, that the theory of aviation is condemned beforehand, and rejected by the majority of American and foreign engineers. It is a system which was the cause of the death of the Flying Saracen at Constantinople, of the monk Volador at Lisbon, of De Leturn in 1852, of De Groof in 1864, besides the victims I forget since the mythological Icarus—"

"A system," replied Robur, "no more to be condemned than that whose martyrology contains the names of Pilâtre de Rozier at Calais, of Blanchard at Paris, of Donaldson and Grimwood in Lake Michigan, of Sivel and of Crocé-Spinelli, and others whom it takes good care, to forget."

This was a counter-thrust with a vengeance.

"Besides," continued Robur, "With your balloons as good as you can make them you will never obtain any speed worth mentioning. It would take you ten years to go round the world—and a flying machine could do it in a week!"

Here arose a new tempest of protests and denials which lasted for three long minutes. And then Phil Evans look up the word.

"Mr. Aviator," he said "you who talk so much of the benefits of aviation, have you ever aviated?"

"I have."

"And made the conquest of the air?"

"Not unlikely."

"Hooray for Robur the Conqueror!" shouted an ironical voice.

"Well, yes! Robur the Conqueror! I accept the name and I will bear it, for I have a right to it!"

"We beg to doubt it!" said Jem Chip.

"Gentlemen," said Robur, and his brows knit, "when I have just seriously stated a serious thing I do not permit anyone to reply to me by a flat denial, and I shall be glad to know the name of the interrupter."

"My name is Chip, and I am a vegetarian."

"Citizen Chip," said Robur, "I knew that vegetarians had longer alimentary canals than other men—a good foot longer at the least. That is quite long enough; and so do not compel me to make you any longer by beginning at your ears and—"

"Throw him out."

"Into the street with him!"

"Lynch him!"

"Helix him!"

The rage of the balloonists burst forth at last. They rushed at the platform. Robur disappeared amid a sheaf of hands that were thrown about as if caught in a storm. In vain the steam whistle screamed its fanfares on to the assembly. Philadelphia might well think that a fire was devouring one of its quarters and that all the waters of the Schuyllkill could not put it out.

Suddenly there was a recoil in the tumult. Robur had put his hands into his pockets and now held them out at the front ranks of the infuriated mob.

In each hand was one of those American institutions known as revolvers which the mere pressure of the fingers is enough to fire—pocket mitrailleuses in fact.

And taking advantage not only of the recoil of his assailants but also of the silence which accompanied it.

"Decidedly," said he, "it was not Amerigo that discovered the New World, it was Cabot! You are not Americans, citizen balloonists! You are only Cabo—"

Four or five shots cracked out, fired into space. They hurt nobody. Amid the smoke, the engineer vanished; and when it had thinned away there was no trace of him. Robur the Conqueror had flown, as if some apparatus of aviation had borne him into the air.

Chapter V

ANOTHER DISAPPEARANCE

This was not the first occasion on which, at the end of their stormy discussions, the members of the Weldon Institute had filled Walnut Street and its neighborhood with their tumult. Several times had the inhabitants complained of the noisy way in which the proceedings ended, and more than once had the policemen had to interfere to clear the thoroughfare for the passersby, who for the most part were supremely indifferent on the question of aerial navigation. But never before had the tumult attained such proportions, never had the complaints been better founded, never had the intervention of the police been more necessary.

But there was some excuse for the members of the Weldon Institute. They had been attacked in their own house. To these enthusiasts for "lighter than air" a no less enthusiast for "heavier than air" had said things absolutely abhorrent. And at the moment they were about to treat him as he deserved, he had disappeared.

So they cried aloud for vengeance. To leave such insults unpunished was impossible to all with American blood in their veins. Had not the sons of Amerigo been called the sons of Cabot? Was not that an insult as unpardonable as it happened to be just—historically?

The members of the club in several groups rushed down Walnut Street, then into the adjoining streets, and then all over the neighborhood. They woke up the householders; they compelled them to search their houses, prepared to indemnify them later on for the outrage on their privacy. Vain were all their trouble and searching. Robur was nowhere to be found; there was no trace of him. He might have gone off in the "Go-Ahead," the balloon of the Institute, for all they could tell. After an hour's hunt the members had to give in and separate, not before they had agreed to extend their search over the whole territory of the twin Americas that form the new continent.

By eleven o'clock quiet had been restored in the neighborhood of Walnut Street. Philadelphia was able to sink again into that sound sleep which is the privilege of non-manufacturing towns. The different members of the club parted to seek their respective houses. To mention the most distinguished amongst them, William T. Forbes sought his large sugar establishment, where Miss Doll and Miss Mat had prepared for him his evening tea, sweetened with his own glucose. Truck Milnor took the road to his factory in the distant suburb, where the engines worked day and night. Treasurer Jim Chip, publicly accused of possessing an alimentary canal twelve inches longer than that of other men, returned to the vegetable soup that was waiting for him.

Two of the