Jacques Cousteau and Pierre-Antoine was released in 1954. During the 1940s, Cousteau is credited with improving the aqua-lung design which gave birth to the open-circuit scuba technology used today. According to his first book, "" (1953), Cousteau started diving with Fernez goggles in 1936, and in 1939 used the self-contained underwater breathing apparatus invented in 1926 by Commander Yves le Prieur. Cousteau was not satisfied with the length of time he could spend underwater with the Le Prieur apparatus so he improved it to extend underwater duration by adding a demand regulator, invented in 1942 by Émile Gagnan. In 1943 Cousteau tried
Émile Gagnan Émile Gagnan Émile Gagnan (November 1900 – 1979) was a French engineer and, in 1943, co-inventor with French Navy diver Jacques-Yves Cousteau of the Aqua-Lung, the diving regulator (a.k.a. demand-valve) 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. Gagnan was born in the French province of Burgundy in November 1900, and graduated from technical school in the early 1920s. He was