Joseph-Louis Gay-Lussac’s balloon flight of 1804 is featured in several early to mid-19th century comparative views. I invite you to read my discussions of Thomson and Lizar’s comparative showing his balloon and and of the differing altitudes shown on across comparatives of the day.
On September 16, 1804, following a flight in the previous month with fellow scientist Biot, Gay-Lussac launched his balloon in Paris on a dual purpose scientific and publicity mission. He stayed aloft for 6 hours, landing in St. Gourgon. At the time, hot air and gas filled balloon technologies competed. Each had advantages and short comings. Charles and Robert’s hydrogen filled balloons retained their buoyancy as the gas cooled although they were prone to explosion. The Montgolfier hot air balloon wasn’t filled with an explosive gas, but required the pilots to stoke fires to prevent the air from cooling (a good thing that the gas was not flammable as embers from the fire had a tendency to ignite the envelope!).
Gay-Lussac’s balloon was smaller than that which he used for his 2 person flight from the previous month to 3,000 m. From contemporary illustrations we see that it was a hydrogen balloon of the Charles & Roberts design.
I have found few records of his flight, and particularly sparse descriptions of his preparations or supplies. As it was a hydrogen gas balloon, it’s unlikely he brought any form of open flame as a source of heat. Beyond the obvious, using a flame to warm his body, he could also use a heat source to drive a reaction where an oxygen containing compound decomposes, liberating the oxygen as gas. Hydrogen was well known to be flammable; the prospect of an ember striking the gas bag would be terrifying as it would be disastrous. Other compounds can be mixed to release oxygen, but these reactions are exothermic, meaning they release heat, and would again be a risky provision on such a lighter-than-air flying machine. Regardless, something for warmth would have certainly benefited him. The surface temperature in Paris was about 28°C (82°F), dropping to nearly -10°C at altitude.
He did carry several instruments. He recorded temperature at several points along his ascent, so we can infer that he carried a thermometer, likely mercury. He also carried a hygrometer (de Saussure variety, where a piece of human hair is connected to a needle, applying differing tension on the needle according to humidity) and observed decreasing humidity as he ascended. Gay-Lussac carried some kind of flasks or bottles to collect air samples. To measure altitude, we can infer that he carried a barometer, although perhaps he used triangulation to determine his altitude.
We know that Gay-Lussac carried bread based on his account that his mouth was too dry from the low humidity to eat. His eagerness to go as high as possible is recalled in a charming anecdote. Upon reaching 7,000 m and wanting to climb higher, he jettisoned a white, wooden chair. Being so high, his balloon was not visible from the ground, so when the chair plopped down next to a shepherd woman, she concluded it was of divine origin. Not until he relayed that he threw it overboard to and it was published by the press, was the true origin known.
Gay-Lussac’s altitude record stood for nearly 50 years.
© Peter Roehrich, 2015.