Emile Gagnan (born November 1900) was a French engineer and co-inventor (together with Jacques-Yves 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. 1900 (MCM) was an exceptional common year starting on Monday. ... Jacques-Yves Cousteau in 1976. ... ... 1943 (MCMXLIII) was a common year starting on Friday (the link is to a full 1943 calendar). ...

Gagnan was born in the French province of Burgoyne in November, 1900, and graduated from technical school in the early 1920's. He was employed as an engineer specializing in high-pressure pneumatic design by the large gas-supply firm L’aire Liquide. The first production ‘Scaphandre Autonome’ - or ‘Aqualung’ was released in France in 1946. A year later, Emile Gagnan and his family immigrated to Montreal, Canada and he transferred to the employ of Canadian Liquid Air Ltd. There he set up a lab and proceeded to engineer, design, and prototype an incredible number of SCUBA and undersea technology ‘firsts’, including the direct ancestors of virtually every type of Scuba regulator in common use today.