Aqua-lung

For the firms named Aqua Lung, see Aqua Lung/La Spirotechnique and Aqua Lung America. For other uses, see Aqualung (disambiguation).

Further information: Scuba set

Aqua-Lung was the original name of the first open-circuit free-swimming underwater breathing set to reach worldwide popularity and commercial success. Nowadays simply known under the names of regulator or demand valve the Aqua-Lung was invented in Paris during the 1942-1943 winter by two Frenchmen: the engineer Émile Gagnan and the lieutenant de vaisseau (ship-of-the-line lieutenant) Jacques Cousteau.

Invention and patent

A previous regulator was invented in France in 1860 by Benoît Rouquayrol, the régulateur. First conceived as a flooded mines escape set the Rouquayrol regulator was adapted to diving in 1864 when Rouquayrol met the lieutenant de vaisseau Auguste Denayrouze. The Rouquayrol-Denayrouze apparatus started mass-production and commercialization as of August the 28th, 1865 when the French Navy Minister ordered the first apparati. After 1884 several companies and entrepreneurs bought or inherited the patent and produced it until 1965. In 1942, during German occupation, the patent was held by the Bernard Piel Company (Établissements Bernard Piel). One of the Bernard Piel Rouquayrol-Denayrouze apparati went to Émile Gagnan, an engineer employed by the Air Liquide company. Gagnan miniaturized and adapted it to gas generators in response to a fuel shortage, consequence of the German requisitioning. Gagnan's boss, Henri Melchior, knew that his son-in-law Jacques-Yves Cousteau was looking for an automatic demand regulator, so he introduced Cousteau to Gagnan in December 1942. On Cousteau's initiative the Gagnan's regulator was adapted to diving and the new Cousteau-Gagnan patent was registered some weeks later in 1943. After the war, in 1946, both men founded La Spirotechnique (as a division of Air Liquide) in order to mass-produce and sell their invention, this time under a new 1945 patent, known as CG45 ("C" for Cousteau, "G" for Gagnan and "45" for 1945). This same CG45 regulator, produced for more than ten years and commercialized in France as of 1946, was the first to be called the "Aqua-Lung". In France the terms scaphandre autonome ('scuba set'), scaphandre Cousteau-Gagnan ('Cousteau-Gagnan scuba set') or CG45 were meaningful enough for commercialization, but to sell his invention in English-speaking countries Cousteau needed an appealing name following the English language standards. He then just coined the trade name Aqua-Lung.

In the late 1940s and early 1950s La Spirotechnique started exporting the Aqua-Lung or letting its patent to foreigner companies (like the British Siebe Gorman), obtaining a great success. The Rouquayrol-Denayrouze apparatus didn't achieve the same success because the compressed-air tanks made with the technology of its time could only hold 30 atmospheres, allowing dives of only 30 minutes at no more than ten metres deep. Before 1945 French divers preferred then their traditional helmets and diving dresses. When the Aqua-Lung started to be commercialized, divers around the world found a scuba device smaller and easier to carry than its precursor, which in fact was almost completely unknown outside of France. In addition, and most important, the Aqua-Lung could be mounted on stronger and reliable air-compressed tanks, holding 200 atmospheres and allowing to extend duration of the dives more than an hour in significant depths, including the needed time for decompression stops.

The first Cousteau-Gagnan Aqua-Lungs, like the CG45 (1945) or the Mistral (1955) were mainly twin-hose open-circuit scuba, and since then made by various manufacturers with varying design details and number of cylinders. Like modern single-hose regulators do nowadays consist, they consisted of one or more high pressure diving cylinders and a diving regulator (the Aqua-Lung) that supplied the diver with breathing gas at ambient pressure, via a demand valve. For more than ten years, as it can be seen in the films Épaves (Shipwrecks, 1943) and Le Monde du silence (The Silent World, 1956) the main scuba set equipement used by Cousteau and his divers was an Aqua-Lung mounted on three diving cylinders, one of them being used as a safe air reserve.

Open/closed circuit

Classic twin-hose Cousteau-type aqualung

The original "Aqua-Lung" was an "open-circuit" design, so called because gas flows from the cylinder, to the diver, out into the water. Other scuba gear, invented earlier than the "Aqua-Lung", are now termed "closed circuit" or "rebreather", as gas flows from the cylinder, to the diver, through a scrubber (which removes carbon dioxide), back to a secondary bag, and back to the diver again, in a relatively closed loop; this design is commonly called a rebreather, and its old pure-oxygen form is regarded as archaic and risky when used underwater.

The Aqua-Lung was not the first, but it was the most popular. In 1934 René Commeinhes developed a firefighter's breathing apparatus that was adapted by his son Georges to diving in 1937 and used by the French Navy, even if only during the few first years of World War II. The twin-hose Aqua-Lung, also known as a double hose, is the same type of regulator used today, based on the diaphragm technology, the only difference between both modern single hose and former twin-hose regulators being the separation of the reducing pressure process into two different steps. Modern single hose regulators derive then from the design of Australian Ted Eldred, who developed the Porpoise scuba in Melbourne in 1949, commonly called the single hose scuba. The modern version was first known as a mouthpiece regulator, as it separates the reduction valve on the tank with a mouth piece demand valve. The two are linked by a low pressure hose.

"Tadpoles"

In the early years of scuba diving in Britain, "tadpole" was a nickname for a type of diving gear that had two meanings:

• A type of ex-RAF pilot's oxygen cylinder with a tapering end, which was often used as an aqualung cylinder in the 1960s and earlier.
• An early make of Siebe Gorman aqualung with a twin-hose regulator and two air cylinders, with both ends hemispherical, 13 inches long and 7 inches in diameter. Siebe Gorman's trade catalog describing this set showed two sorts of diver wearing this set, both with weighted boots, and no mention of free-swimming. A 1950s Royal Navy diving manual also said that the aqualung was (only) for bottom-walking diving. Siebe Gorman had no idea then of sport diving, or was against sport diving, but expected aqualungs to be used for light commercial diving. Later, as is well known, most divers were free-swimming scuba divers; bottom-walkers became a tiny minority.

Trademark issues

Aqualung, Aqua-Lung, and Aqua Lung are registered trademarks for SCUBA-diving breathing equipment. That trade name is owned in the United States by the firm formerly known as U.S. Divers. The term was in use before the trade mark was registered by Rene Bussoz. Rene owned a sporting goods store called Rene Sports in Los Angeles. He obtained a contract with the French firm L'Air Liquide to import the new scuba into the USA for sale on the west coast. SPACO had the contract for the east coast. He changed the name of his company to US Divers and registered the name Aqua-Lung. This turned out to be a wise move because when the French company decided not to renew his 5 year contract, no one had of heard of their product, but everyone was familiar with the names he had registered. He sold the company and the trade names for a handsome profit and returned to France. The name US Divers sounded very official and very American, but it was owned by a Frenchman and sold to French company.

L'Air Liquide held the patent on the original "Aqualung" also written as Aqua-Lung or Aqua Lung, until the patent expired some time around 1960–63. The term "aqualung" as far as is known first appeared in print on page 3 of Jacques-Yves Cousteau's first book, The Silent World in 1953. Public use of the word "aqualung", and public interest in aqualungs and scuba diving, were started around 1953 in English-speaking counties by a National Geographical Society Magazine article about Cousteau's underwater archaeological expedition to Grand Congloué. In France aqualung diving was popularized by Cousteau's movie Épaves. Cousteau's book The Silent World helped also.

As with some other registered trademarks, the term "aqualung" became a genericized trademark in English-speaking countries, as a result of much use by the public and in publications including in the BSAC's official diving manuals. Presumably lawyers for Cousteau or Air Liquide could have slowed or stopped this genericization by taking prompt action, but this seems not to have been done in Britain, where Siebe Gorman had the British rights to the trade name and the patent.

In the United States the term Aqualung was popularized by the popular television series Sea Hunt (1958), which never said that an aqualung could be called anything else or could be made by anyone else, but the company that supplied the fearless Mike Nelson. Voit provided most of the diving equipment used in the series, but actual Aqua-Lungs appeared in the early episodes. The word "aqualung" was commonly used in speech and in publications as a term for divers' open-circuit demand-valve-controlled breathing apparatus (even after Air Liquide's patent expired and other manufacturers started making identical equipment), and occasionally also for rebreathers, and in figurative uses such as "the water spider's aqualung of air bubbles". The word entered the Russian language as the generic noun акваланг ("akvalang").

In the United States, U.S. Divers managed to keep "Aqualung" as a trademark, and the acronym "SCUBA" ("Self Contained Underwater Breathing Apparatus", originating in the United States Navy, where it meant a frogman's rebreather) became the generic term for that type of open-circuit breathing set, and soon the acronym SCUBA became a noun — "scuba" — all in lower-case. "Scuba" was a trademark for a time, used by Healthways, now known as Scubapro, one of U.S. Divers' competitors.

In Britain Siebe Gorman (who held the rights to the tradename "Aqualung") made no serious attempt to control use of the word, and "aqualung" remained the common public generic word for that sort of scuba set, including in the British Sub-Aqua Club's official publications, for many years.

Aqua Lung America now makes rebreathers whose tradenames or catalog descriptions include the word "Aqualung".

Popular culture

The classic Jethro Tull song Aqualung and the album of the same name were named after the apparatus. Also, English singer-songwriter Matthew Hales uses the stage name Aqualung.

See also

• Timeline of underwater technology, The diving regulator reappears for details of the development of a similar regulator, not related to the Aqua-Lung.
• Timeline of underwater technology, World War II for details of the development of the Aqua-Lung
• Scuba sets for description of modern breathing sets.
• Frogman, Mistakes in fiction for common mistakes in depicting scuba gear.

External links

• Aqua Lung manufacturers site (English, French, German, Italian, Czech, and Japanese language versions available)
• Aqua Lung (Also known as "Mistral Regulator" because of a particular model from 1955. The original Aqua-Lung was the CG45 model from 1945)
• Two Jacques Cousteau Aqua-Lungs are shown in this 1950s video recorded on the island of Maui.