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 sea level, and humidity of the air surrounding. On a warm day, a balloon cannot lift as much as on a cool day, because the temperature required for launch will exceed the maximum sustainable for nylon envelope fabric. Also, in the lower atmosphere, the lift provided by a hot air balloon decreases about 3% for each 1,000 meters (1% per 1,000 ft) of altitude gained. Standard hot air balloons are known as Montgolfier balloons and rely solely on the buoyancy of hot air provided by the burner and contained by the envelope. This style of balloon was developed by the