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..