Paris in the 18th century Paris from across Europe and from the United States to share ideas; Benjamin Franklin came in 1766 to meet with Voltaire and to talk about his experiments with electricity. The 18th century in Paris was a particularly inventive period. Some of the discoveries of Paris scientists, particularly in the field of chemistry, were quickly put to practical use; the experiments of Lavoisier were used to create the first modern chemical plants in Paris, and the production of hydrogen gas enabled the Montgolfier Brothers to launch the first manned flight in a hot-air balloon on 21 November 1783, from the Château
Hot air balloon indicators would be useless) and direction. The combined mass of an average system can be calculated as follows: using a density of 0.9486 kg/m³ for dry air heated to 210 °F (99 °C). Increasing the air temperature inside the envelope makes it less dense than the surrounding (ambient) air. The balloon floats because of the buoyant force exerted on it. This force is the same force that acts on objects when they are in water and is described by Archimedes' principle. The amount of lift (or buoyancy) provided by a hot air balloon depends primarily upon the difference between the