The hot-air balloon [1]
The hot-air balloon, a ballon in hot air, was invented in France in 1783 by Joseph and Étienne Montgolfier [2], natives of Ardèche [3]. They were paper manufacturers. One day, Joseph threw a letter into fire and for warming up himself, he put his sweater over the fire. It began to swell and the pieces of paper flew off.
He told his brother about it and that was also how they invented the hot-air balloon. First, they load a sheep, a roaster and a dog on board before repeating the experiment with a human.
The principle of operation of the hot-air balloon: propane gas heats a nylon polyamide envelope. The hot air, which inflates the hot-air balloon and allows it to fly off because hot air is lighter than cold air. The hot-air balloon then can fly like a hot air bubble in the air mass.
[1]. Translated by me from: p. 149. La montgolfière. Better Reading French. Annie Heminway. McGraw Hill. New York … Toronto. 2003.
[2]. Montgolfier. https://en.wikipedia.org/wiki/Montgolfier_brothers
[2]. Ardèche. Located in southeastern France. https://en.wikipedia.org/wiki/Ard%C3%A8che
