This is a list of aviation-related events during the 18th century (January 1, 1701 – December 31, 1800): 1700s–1770s 1709 Portuguese Father Bartolomeu de Gusmão demonstrates a practical model of a hot-air balloon made of a paper envelope with burning material suspended below it to King John V of Portugal in the Ambassadors drawing room. Worried that it will set fire to the curtains, servants end its flight by dashing it to the ground. It is the first known demonstration of a practical lighter-than-air craft. 1716 Well thought-out glider-project of the Swedish scholar Emanuel Swedenborg. Basis for his construction are bird flight and the glider kite. 1738 In his Hydrodynamica the Swiss scholar Daniel Bernoulli (1700–1782) formulates the principle of the conservation of energy for fluids (Bernoulli's principle), the relationship between pressure and velocity in a flow. 1746 English military engineer Benjamin Robins (1707–1751) invented a whirling arm centrifuge to determine drag. 1766 British chemist Henry Cavendish determines the specific weight of hydrogen gas. 1780s–1790s 1782 December 14, The Montgolfier brothers first test fly an unmanned hot air balloon in France; it floats nearly . 1783 June 4, Unmanned flight of the Montgolfier brothers 900 m linen Montgolfière hot air balloon at Annonay near Lyon in the Vivarais region of France as a public demonstration. The flight covers 2 km and lasts 10 minutes, to an estimated altitude of 1600–2000 metres. August 27, Flight of Le Globe, an unmanned experimental hydrogen-balloon, in Paris (built by Professor Charles and the Robert brothers). It flies from Paris to Gonesse and is destroyed by frightened peasants. September 19, the Montgolfiers launch a sheep, duck and rooster in a hot-air balloon in a demonstration for King Louis XVI of France. The balloon rises some and returns the animals unharmed to the ground. October 15, Pilâtre de Rozier and Marquis d'Arlandes rise into the air in a Montgolfière tethered to the ground in Paris. de Rozier becomes the first human passenger in a hot-air balloon, rising . November 21, In a flight lasting 25 minutes, de Rozier and d'Arlandes take the first untethered ride in a Montgolfière in Paris, the first human passengers carried in free flight by a hot-air balloon. December 1, Jacques Charles and his assistant Nicolas-Louis Robert make the first flight in a hydrogen-filled balloon, La Charlière. They travel from Paris to Nesles-la-Vallée, a distance of . On his second flight the