And so propositions of the following kind began to fly about the room: "Turn him out!" "Throw him off the platform!" "Prove that he is heavier than the air!" But these were only words, not means to an end.
Robur remained impassible, and continued: "There is no progress for your aerostats, my citizen balloonists; progress is for flying machines.

The bird flies, and he is not a balloon, he is a piece of mechanism!" "Yes, he flies!" exclaimed the fiery Bat T.Fynn; "but he flies against all the laws of mechanics." "Indeed!" said Robur, shrugging his shoulders, and resuming, "Since we have begun the study of the flight of large and small birds one simple idea has prevailed--to imitate nature, which never makes mistakes.

Between the albatross, which gives hardly ten beats of the wing per minute, between the pelican, which gives seventy--" "Seventy-one," said the voice of a scoffer.
"And the bee, which gives one hundred and ninety-two per second--" "One hundred and ninety-three!" said the facetious individual.
"And, the common house fly, which gives 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.