Joseph-Michel Montgolfier (August 26, 1740 - June 26, 1810) and Jacques-?tienne Montgolfier (January 6, 1745 - August 2, 1799) were the inventors of the Montgolfi癡re-style hot air balloon, globe a矇rostatique. On June 4, 1783, they flew their craft in front of a group of dignitaries. Its flight covered 1.2 miles, lasted 10 minutes, and had an estimated altitude of 5,200-6,600 ft. The brothers succeeded in launching the first manned ascent, when ?tienne made a tethered flight on October 15, 1783. Later, in December 1783, in recognition of their achievement, their father Pierre was elevated to the nobility and the hereditary appellation of de Montgolfier by King Louis XVI of France. At the time, the brothers believed they had discovered a new gas. However, in 1785, the buoyancy was shown to be caused by heated air, which is less dense than the surrounding atmosphere. The two brothers were honored by the French Acad矇mie des Sciences. During their careers, they published books on aeronautics, Joseph invented a calorimeter and the hydraulic ram, and ?tienne developed a process for manufacturing vellum. ?tienne died in 1799 at the age of 54. Joseph died in 1810 at the age of 69.