William Temple Franklin British peace commissioners if something could be done for his father. He noted his father's steadfast defense of the Stamp Act, and hoped that the British government might award him a diplomatic post. During 1784, Temple went to London and reconciled with his father, lengthening his stay several times before returning to Paris at the end of the year. In January 1785, Temple received the first airmail in history when a letter from his father was brought across the English Channel by a hot air balloon flown by Jean-Pierre Blanchard and John Jeffries. When Benjamin Franklin relinquished his post and
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