Émile Gagnan

Émile Gagnan was a French engineer and, in 1943, co-inventor with French Navy diver Jacques-Yves Cousteau of the Aqua-Lung, the diving regulator used for the first Scuba equipment. The demand-valve, or regulator, was designed for regulating gas in gas-generator engines, but was found to be excellent for regulating air-supply under varied pressure conditions. This allowed people to explore the ocean more easily, even though the original purpose was different.