Main Page | See live article | Alphabetical index French engineer. Co-inventor (together with Jacques Cousteau) of the demand-valve used for the first Scuba equipment ("Aqua-Lung")in 1943. The demand-valve was designed for regulating gas in gas-generator engines, but was found to be excellent for regulating air-supply under variating pressure conditions. born November 1900 Links history (http://www.auas-nogi.org/gagnan.htm ) This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.