And if there had been any disbeliever there he would have been simply annihilated.
But why was there no wind to assist at this magnificent experiment?
It was regrettable.

Doubtless the spectators would have seen the "Go-Ahead" unhesitatingly execute all the movements of a sailing-vessel in beating to windward, or of a steamer driving in the wind's eye.
At this moment the aerostat rose a few hundred yards.

The maneuver was understood below.

Uncle Prudent and his companions were going in search of a breeze in the higher zones, so as to complete the experiment.

The system of cellular balloons--analogous to the swimming bladder in fishes--into which could be introduced a certain amount of air by pumping, had provided for this vertical motion.
Without throwing out ballast or losing gas the aeronaut was able to rise or sink at his will.