John Jeffries a letter he dropped from the balloon during his historic flight, considered the oldest piece of airmail in existence. He fled to Halifax, Nova Scotia in 1776 and later to England 1779, and was employed by the Crown during this time. In 1785, Jeffries and Jean-Pierre Blanchard crossed the English Channel in a balloon, becoming the first human beings to cross the Channel by air. Jeffries lived in England from 1779 to 1790. Despite being named in the Massachusetts Banishment Act, he returned to private practice in Boston, staying there until his death in 1819. His son John Jeffries II
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