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
Tradeoffs for locomotion in air and water balloons. By changing the amount of gas in these swim bladders, fish actively control their density. If they increase the amount of air in their swim bladder, their overall density will become less than the surrounding water, and increased upward buoyancy pressures will cause the fish to rise until they reach a depth at which they are again at equilibrium with the surrounding water. In this way, fish behave essentially as a hot air balloon does in air. Some seabird species utilize surface feeding or plunge diving during foraging in which gravity and/or momentum is used to counteract buoyancy effects