When, on June 5 1783, Joseph and Etienne de Montgolfier launched for the first time in public their MACHINE AEROSTATIQUE, an immense enthusiasm took over the whole world. Never, except perhaps with the discovery of America, did any scientific event captured so much the passions of the masses: It seemed that finally MAN had conquered the atmosphere. HE was the master of the air just as much as he was already the master of the Earth and the Sea. Space belonged to him, and for most enthusiasts going to the moon was going to be just a game. Now a century or more has passed, and the hopes that the invention of Montgolfier had raised have not yet been realized in spite of the very large progresses that have been made. [Are] ... the roads of the a...