![](http://www.alamy.com/thumbs/6/6B11A09C-1ED9-40A4-AFCA-B775D8410AB2/HTMKEN.jpg)
Jean Baptiste Biot (1774-1864) and Joseph Louis Gay-Lussac (1778-1850), left, making measurements at a height of 4,000 metres during their balloon ascent of 20 August 1804. This was the first balloon ascent made specifically for scientific purposes. From
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Photo credit: © Photo12/Ann Ronan Picture Library / Alamy / Afripics
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Keywords: /, 000, 4, 20, 1804., 19th, aeronautics, ascent, august, balloon, ballooning, baptiste, biot, century, experiment, flight, height, innovation, jean, left, making, measurements, metres, purposes., science, scientific, specifically