The Aqua-Lung: Cousteau and Gagnan, 1943.

The two men

Encyclopedia.com gives Jacques-Yves Cousteau's birth as 11 June 1910 in Saint-Andre-de-Cubzac, France, and his death in Paris on 25 June 1997, aged 87. Cousteau was injured in a car accident, though its year is given differently: National Geographic (Rachel Hartigan, 22 November 2021) places it in 1930, after he entered the naval academy, and Encyclopedia.com says 1936. National Geographic says fellow officer Philippe Tailliez suggested swimming in the ocean as part of his recovery and lent him a pair of goggles. According to Wikipedia, Tailliez nicknamed himself, Cousteau and the free-diver Frederic Dumas the "Mousquemers", after The Three Musketeers.

Wikipedia says Emile Gagnan was born in Burgundy in November 1900 and worked at Air Liquide as an engineer specialising in high-pressure pneumatics. It gives his death as 1984, citing a French newspaper of 16 May that year; a search summary noted another source giving 1979.

From a gas valve to a regulator

National Geographic says Gagnan had designed a fuel-flow valve that let cars run on cooking gas during the German occupation, and that this regulator became the basis of the Aqua-Lung after Cousteau visited him in Paris in 1942. Wikipedia describes the same valve as a miniaturised version of the Rouquayrol-Denayrouze type of regulator from the 1860s, adapted to gas generators because of wartime fuel restrictions. (The 1860s device is described on before the Aqua-Lung.)

When the partnership began is disputed. Wikipedia says Cousteau was introduced to Gagnan in December 1942. Encyclopedia.com says their collaboration began in 1937.

National Geographic says the prototype was tested in the River Marne east of Paris. It worked while the diver was horizontal but leaked when he was upright, until the hoses were rearranged. Over many months of 1943, it says, Cousteau, Tailliez and Dumas made more than 500 dives with the device in the Mediterranean.

The depth of Dumas's October 1943 test dive is recorded two ways. Wikipedia says he reached 62 m on 17 October 1943 and was the first scuba diver to report nitrogen narcosis. National Geographic says the team had reached 130 feet by that autumn and that Dumas then went 90 feet deeper in October.

How "first" is phrased

• Britannica, seen only as a search summary because the page refused our request, credits Cousteau and Gagnan with the first fully automatic compressed-air Aqua-Lung, developed in 1943.
• Wikipedia describes it as a twin-hose system and calls it the first successful and safe open-circuit scuba, and elsewhere the first reliable and commercially successful one.
• Blutime Scuba History, a diving-history site, argues that Cousteau imitated and copied much of Yves Le Prieur's earlier work. That is the site's opinion, and no other source in our research makes it.

The patents

The patent record is the least settled part of the story. No patent office record was checked directly, so each version below is as its source gives it.

Credit on the first French patent is disputed as well. A German-language article by Luc Fuster, seen only as a search summary because the file could not be opened, says Air Liquide and Cousteau filed the 1943 French patent without naming Gagnan, with a US patent following in 1947 under both names. Wikipedia says both men patented the regulator in 1943. We could not confirm the Fuster account.

Production and the spread abroad

According to Wikipedia, the first production model was sold in France as the CG45: C for Cousteau, G for Gagnan, and 45 for 1945. Wikipedia says Air Liquide created La Spirotechnique in 1946 as its division to design and mass-produce regulators and diving equipment, and that it remained part of Air Liquide until 2016; one source seen in a search summary gives 1947 for its founding. Gagnan himself emigrated to Montreal in 1947 to join Canadian Liquid Air, Wikipedia says.

Wikipedia says the Aqua-Lung trademark was licensed to U.S. Divers in 1948, and the Cousteau-Gagnan patent to Siebe Gorman in England. When the equipment reached the United States, and when U.S. Divers was formed, varies by source, and none of these could be fully confirmed:

• An International Scuba Diving Hall of Fame museum note, seen only in a search summary, says the first CG45 imports reached the US in 1948 and that Rene Bussoz formed U.S. Divers in 1950.
• The Aqualung brand timeline, also seen only in a search summary, says US distribution began around 1950.
• Wikipedia gives 1952 for U.S. Divers.

The Aqua-Lung was a twin-hose design. Wikipedia says Ted Eldred of Melbourne sold the first single-hose open-circuit scuba, the Porpoise Model CA, in early 1952, and that La Spirotechnique pursued single-hose regulators partly so that divers could share mouthpieces in narrow caves.

Cousteau after the Aqua-Lung

National Geographic says Maurice Fargues, of the French Navy's underwater research group, died in 1947 during a test attempt to pass 120 m. Cousteau's ship Calypso arrived in his life on a date the sources give differently: National Geographic says he left the navy and acquired the former British minesweeper in 1949, while Encyclopedia.com gives the purchase as 19 July 1950, calls the ship a converted US minesweeper, and says he resigned from the navy in 1957.

• 1953: the book The Silent World, by Cousteau with Dumas, is published (Encyclopedia.com; Britannica via search summary).
• 1956: the film The Silent World, made with Louis Malle, wins the Palme d'Or at Cannes, followed by an Academy Award in 1957 (Encyclopedia.com, National Geographic).
• 1957: Cousteau is named director of the Oceanographic Institute and Museum of Monaco; he runs the Conshelf saturation programme in the early 1960s (Encyclopedia.com).
• 1959: Wikipedia says Cousteau became the first president of CMAS, the world underwater federation founded in Monaco that January.
• 1968 to 1976: The Undersea World of Jacques Cousteau premieres in 1968 and runs eight seasons, ending in May 1976 (Encyclopedia.com).

National Geographic's 2021 article says more than 28 million people had learned to scuba dive in the 79 years since the invention. That is the magazine's figure, and it does not say how it was counted. For how diver numbers are counted today, see how many people dive.

According to Wikipedia, the word "scuba" itself was first applied to a different machine, an American military rebreather; that story is on Lambertsen and the word SCUBA. How the regulator works today is covered on regulators.