Stock Photo - Experiment to calculate the speed of sound in air, Paris, 1822, (c1880). In 1822 the French appointed a commission to find the speed of sound in air. Two hills near Paris were chosen for the experiment, at Villejuif and Montlhery. On each hill a gun was discharged. Observers on the other hill, by noting the time of the flash and the time at which they heard the report, calculated the speed to be 1,118.152 feet (340.8m) per second. Gay-Lussac, Humboldt and Bouvard were at Montlhery. Arago, Mathieu and Prony were at Villejuif. From Science for All by Robert Brown. (London, c1880).

@ 0.014 --> Keywords launching task... @ 0.015 --> GetKeywords: Getting cache @ 0.031 --> _srcset calculated @ 0.056 --> begin dades json... @ 0.067 --> begin waiting GetItemsAsync... @ 0.067 --> GetKeywords: Request cached? True @ 0.088 --> itemsController.Get() completed! @ 0.099 --> pricing done @ 0.100 --> Dades JSON completed! @ 0.100 --> Keywords task start waiting @ 0.156 --> GetKeywords: File obtained @ 0.156 --> GetKeywords: File to Json @ 0.158 --> GetKeywords: DocLastUpdate checked @ 0.158 --> GetKeywords: Cached item @ 0.159 --> GetKeywords: keywords ampliacion @ 0.159 --> Keywords task completed @ 0.173 --> Schema completed @ 0.173 --> Adobe ads... @ 0.173 --> Adobe ads done @ 0.173 --> controller done