science · 30 November 1784 · 240 years ago
In 1784, John Jeffries, an American physician and scientist, recorded the first scientific data for free air, to a height of 9,309-ft, during a balloon flight in London, England, including twelve observations of temperature, pressure, and humidity. Jeffries' values agree closely with modern determinations. Jeffries had provided himself with thermometer, barometer, electrometer, hygrometer and timepiece. He also took air samples at different elevations for Cavendish, who subsequently made a chemical analysis of the air. This was the first of two balloon flights Jeffries financed. He flew with Frenchman Jean Pierre Blanchard, who had experience in balloon flight. On 7 Jan 1785, they made the first balloon crossing of the English Channel.
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