In 1784 he wrote an essay on balloons, and his loge of Vauban, read by him publicly, won him the commendation of Prince Henry of Prussia.
A structure is supported either by resting on the solid crust of the earth, as buildings do, or by floating in a fluid, as ships do in water and balloons in air.
The parade, with its smiles, applause, and balloons, was over in a half hour.
At great heights free balloons seem necessary.
Many novelties, too, such as the field telegraph, balloons and signalling, were employed.
Flying animals differ entirely from sailing ships and from balloons, with which they are not unfrequently though erroneously compared; and a flying machine constructed upon proper principles can have nothing in common with either of those creations.
Largely in consequence of this progress, and partly no doubt owing to the stimulus given by the activity of builders of dirigible balloons, the construction of motor-driven aeroplanes began to attract a number of workers, especially in France.
His last subject of investigation was the motion of balloons, and the last subject on which he conversed was the newly discovered planet Herschel (Uranus).
Jean Pierre Minckelers, professor of natural philosophy in the university of Louvain, and later of chemistry and physics at Maestricht, made experiments on distilling gas from coal with the view of obtaining a permanent gas sufficiently light for filling balloons, and in 1785 experimentally lighted his lecture room with gas so obtained as a demonstration to his students, but no commercial application was made of the fact.
Balloons danced in the warm breeze and red, white, and blue abounded everywhere.
Santos Dumont, after a number of successful experiments with dirigible cigarshaped gas balloons, completed an aeroplane flying machine.
Thus the declaration of Paris, 1856 (to which, however, the United States, Venezuela and Bolivia have not yet formally acceded), prohibits the use of privateers and protects the commerce of neutrals; the Geneva conventions, 1864 and 1906, give protection to the wounded and to those in attendance upon them; the St Petersburg declaration, 1868, prohibits the employment of explosive bullets weighing less than 400 grammes; and the three Hague declarations of 1899 prohibit respectively (I) the launching of projectiles from balloons, (2) the use of projectiles for spreading harmful gases, and (3) the use of expanding bullets.