Science was a subject of speculation and intense debate at the end of the 18 century. The public were invited to various experiments to attest to scientific advances. Balloons were a firm favorite of the masses in the 1780s and in particular on July 11, 1784. The Montgolfier brothers were among the first men to launch manned ascents in hot air balloons. Brothers Joseph and Étienne conducted an experiment in Paris under the patronage of the French Academy of Sciences. On September 9, 1783, a balloon was flown with the first living beings: a sheep, a duck and a rooster.*
* Sounds like the beginning of a great joke.
"A sheep, a duck and a rooster all get in a big balloon and float away."
"Haha. What happened next?"
"I don't know. They were literally never seen again."
That same year in Paris, Jean-François Pilâtre de Rozier and the Marquis d'Arlandes would be the first humans to lift off in a balloon. The crowd of curious onlookers gathered to witness the scene.