Balloonomania their ballooning stunts, with Blanchard and his companion Dr. John Jeffries being the first to cross the English channel in a balloon on January 7, 1785. The public reaction among intellectuals and academics was generally cooler, with some critics of balloonomania including the likes of Sir Joseph Banks and Samuel Johnson, who wrote in a 1783 letter to Hester Thrale, who had inquired about the nature of hot air balloons, “Happy are you, Madam, that have ease and leisure to want intelligence of air balloons. Their existence is, I believe, indubitable, but I know not that they can possibly be
Hot air balloon course) stated in the previous section. Liftoff would require a slightly greater temperature, depending on the desired rate of climb. In reality, the air contained in the envelope is not all the same temperature, as the accompanying thermal image shows, and so these calculations are based on averages. For typical atmospheric conditions (20 °C, 68 °F), a hot air balloon heated to (99 °C, 210 °F) requires about 3.91 m³ of envelope volume to lift 1 kilogram (62.5 ft³/lb). The precise amount of lift provided depends not only upon the internal temperature mentioned above, but the external temperature, altitude above