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
Scuba set of 1918), and Commandant le Prieur's hand-controlled regulator in France (as of 1926); see Timeline of diving technology. This system consists of one or more diving cylinders containing breathing gas at high pressure, typically , connected to a diving regulator. The demand regulator supplies the diver with as much gas as needed at the ambient pressure. This type of breathing set is sometimes called an "aqualung". The word "Aqua-Lung", which first appeared in the Cousteau-Gagnan patent, is a trademark, currently owned by Aqua Lung/La Spirotechnique. This is the first type of diving demand valve to come into general use, and