Early experiments[edit]
Of the two brothers, it was Joseph who first contemplated building machines as early as 1782 when he observed laundry drying over a fire incidentally form pockets that billowed upwards.[4] Joseph made his first definitive experiments in November 1782 while living in the city of Avignon. He reported some years later that he was watching a fire one evening while contemplating one of the great military issues of the day—an assault on the fortress of Gibraltar, which had proved impregnable from both sea and land.[5] Joseph mused on the possibility of an air assault using troops lifted by the same force that was lifting the embers from the fire. He believed that contained within the smoke was a special gas, which he called Montgolfier Gas, with a special property he called levity.