Previously, scuba divers were only able to explore the sea using diving bells or helmeted diving suits which were cumbersome and expensive. Divers were also dependent on air hoses connected to a surface source. Jacques-Yves Cousteau was searching for an underwater breathing apparatus that would allow divers to enjoy unencumbered swimming. He teamed with Emile Gagnan in the early 1940’s, a Parisian engineer working at Air Liquide who had created a valve for regulating gas flow to gas-generator engines. Combining Gagnan’s engineering expertise with Cousteau’s practical experience, they created a demand valve system that could provide a diver with compressed air on demand and that adjusted to the surrounding pressure.
After years of somewhat crude inventions ranging from goggles to snorkels to 16th century "diving bells," technology began to advance and inventors devised equipment such as the air pump, created in 1771 by John Smeaton; a breathing belt, invented in 1825 by William James; underwater breathing systems created in 1828 by John and Charles Deane, and in 1837 by Augustus Siebe; a self-contained underwater breathing unit created by Henry Fleuss in 1873; and a breathing system for the U.S. military designed by Christian Lambertson in 1939. Lambertson's system, designed for the miltary's SCUBA program (for "Self-Contained Underwater Breathing Apparatus") was somewhat successful, but divers were injured or killed frequently from oxygen toxicity. Shortly thereafter, in 1943, Jacques-Yves Cousteau and Emile Gagnan invented a system that would revolutionize the world of deep-sea exploration and push diving into the mainstream.
Emile Gagnan, with Cousteau, began working to create a demand-valve for what was to become the Aqua-lung system. A similar type of valve had been used in gas-generator engines and Gagnan imagined it would also be useful in regulating air supply in a variable pressure environment. His theory was correct, and this valve would be a central component of the Aqua-lung's demand regulator, which adjusts air pressure automatically and supplies air as a diver needs it, so that air pressure inside a diver's lungs match the pressure of the water. This would prove a critical and groundbreaking safety feature. In general, there are thousands of pounds of air pressure (measured in pounds per square inch or PSI) in a sealed non-flexible scuba cylinder. Scuba regulators break down that massive amount of air pressure and deliver it to a diver in easy to inhale breaths that are delivered on breathing demand. It takes two stages of pressure regulation (hence the name regulator) to accomplish this feat. The first stage of a regulator is the part that connects directly to the scuba tank. This first stage’s main job is to divert air from the tank to the high pressure hose so it can gauge how much air is needed to break down the 3000 psi or so in a scuba tank to about 150 psi. Once the air reaches the second stage or the mouthpiece, the air is blocked by a piston-like device. When a diver inhales, a vacuum is created in the second stage. This vacuum pulls in a rubber gasket, which in turn presses down on a lever. That lever moves the piston and breaks the seal, keeping the air back. Once the seal is broken, the air that is needed rushes into the diver’s mouth.
The following link provides a narrative and basic illustration on how a scuba regulator functions.
III. Biography of the Investigator(s)
Jacques-Yves Cousteau (on left in photo above)
Cousteau was born June 11, 1910, in Saint-Andre-de-Cubzac, France, near Bordeaux. He was well-traveled thanks to his lawyer-father, who moved often and took his family with him on frequent trips. Cousteau was a restless student but an avid swimmer with an interest in film and natural technical ability. In 1930, he was admitted to France's Naval Academy. He served in the navy and later entered naval aviation school, but after a car accident at age 26 he was transferred to sea duty and began a rigorous swimming program to regain strength in his arms.
During World War II, he served as a spy for the French Resistance and was decorated with the Legion of Honor at the war's conclusion. Meanwhile he pursued an interest in sea exploration and managed to make several underwater films during wartime. He also met fellow Frenchman and engineer Emile Gagnan, with whom he collaborated on creating a machine that he hoped would turn him into somewhat of a "man-fish" underseas. Oxygen and air-pressure regulation, he knew, would be key.
Emile Gagnan (on right in photo above)
Emile Gagnan was born in Burgoyne, France, in 1900. He earned a technical degree and began working as an engineer for L'aire Liquide, with specialization in high-pressure pneumatic design. With Cousteau he began working to create a demand-valve for what was to become the Aqua-lung system. A similar type of valve had been used in gas-generator engines and Gagnan imagined it would also be useful in regulating air supply in a variable pressure environment. His theory was correct, and this valve would be a central component of the Aqua-lung's demand regulator, which adjusts air pressure automatically and supplies air as a diver needs it, so that air pressure inside a diver's lungs match the pressure of the water. This would prove a critical and groundbreaking safety feature.
IV. Impact on the World/Humanity
The invention of scuba would change the diving scene forever. The Aqua-lung was first sold in France in 1946. By 1951, Aqua-lung systems were being sold in England and in Canada. U.S. distribution rights were acquired in 1952 and U.S. Divers launched to great success. Air Liquide, a French company, bought U.S. Divers in 1958 and changed the name to Aqua Lung America, which became part of Aqua Lung International, established by Air Liquide in 1988 and now the world's largest diving company. The Aqua-lung system is now part of virtually every set of modern SCUBA gear in the world, with thousands upon thousands of units sold, and recreational scuba diving has become an international phenomenon.
Leaney, L. (1997, Fall). Jacques Yves Cousteau, The Pioneering Years, “Allons Voir,” Historical Diver 14-29
Matsen, B (2009). Jacques Cousteau The Sea King. New York: Random House Inc.
Richardson, D. (1996). The Encyclopedia of Recreational Diving. California: PADI Inc.
fig. 1 retrieved from: http://physics.kenyon.edu/EarlyApparatus/Pneumatics/Diving_Bell/Diving_Bell.html
fig 2 retrieved from: http://www.google.com/imgres?imgurl=http://www.fremantleports.com.au/sitePrintVariant/About/PhotoGallery/C1945_Hard_Hat_Diver_rdax_1024x761.jpg&imgrefurl=http://picsicio.us/keyword/hardhat%2520dive/&usg=__K2CwA5k431Yfyu9Plzy_Mh-OT_Q=&h=761&w=1024&sz=111&hl=en&start=0&zoom=1&tbnid=JtIC8WKDwceGZM:&tbnh=140&tbnw=178&prev=/images%3Fq%3Dhard%2Bhat%2Bdiving%2Bimages%26um%3D1%26hl%3Den%26client%3
fig. 3 retrieved from: http://1.bp.blogspot.com/_04kZGR_ltmE/SpPAl-gkx3I/AAAAAAAAEkE/Vi5Z6jM0Fr0/s1600-h/Jacques-Yves-Cousteau-with-Emile-Gagnan.jpg