1535 - Guglielmo de Loreno developed what is considered to be a true diving bell. 1650 - Von Guericke developed the first effective air pump. Edit - jacknicklaus2 – You are right a diving bell is compressed air fed from the top. Scuba is self-containted. In 1825, English inventor, William James designed a self-contained breather -a cylindrical iron "belt" attached to a copper helmet. The belt held about 450psi of air, enough for a seven-minute dive. Definition of “diving bell” noun: diving apparatus for underwater work; has an open bottom and is supplied with compressed air SCUBA – definition - noun: a device (trade name Aqua-Lung) that lets divers breathe under water; scuba is an acronym for self-contained underwater breathing apparatus.

Jacques-Yves Cousteau and Emile Gagnan, during 1942 -43, redesigned a pressure regulator Gagnan had originally designed to allow automobiles to run on vegetable oil because of petroleum shortages in WWII. The redesigned regulator would automatically provide compressed air to a diver at the proper pressure to counter balance the pressure of the water on his chest. They improved the designs of other diving equipment. Their regulator was connected to three cylinders, each holding 2,500 psi of air. They called the equipment with the pressure regulator, the "Aqua-lung." The "Aqua-lung" is the basis for modern equipment used today, most historians consider Gagnan and Cousteau to be the fathers of modern scuba diving gear. SCUBA stands for Self Contained Underwater Breathing Apparatus. The key words are' Self Contained,' the other methods of diving, the diving bell, the hardhat divers with the big round helmet and similar, all rely on a hose leading to the surface where it is attached to a pump forcing air down at sufficient pressure to counteract the pressure of the water on the chest. Some of the earliest diving bells didn't have the hose, the only air supply available to the 'diver' was what was originally in the bell, ya could say they were "self contained," but the restricted air supply restricted activity and length of time under water. ( Sometimes the diver would use up all the air and then could stay down indefinitely, but with his movements permanently restricted. You could say his self was now contained.) Aristotle described a diving bell in 360 BCE, Alexander the Great supposedly made several dives in a crude bell 332BCE. After those early beginnings advances were made in technology but divers still remained 'tethered' to the surface by the airhose, which restricted their mobility. Most folks think of SCUBA as being a system allowing a diver to be freeswimming, not to be confused with 'freediving' which means with no breathing equipment, Often SCUBA is used as a synonym for the Aqualung, the aqualung is just one of, but the most popular and familiar due to its simplicity and safety, type of SCUBA . There were several important steps in developing a Self Contained Apparatus before the Aqualung was invented by Cousteau and Gagnan. In 1772 Sieur Freminet invented a 'rebreathing' device that recycled the exhaled air inside a diving bell. This was the first self-contained air device, but the inventor died from lack of oxygen after being in his own device for twenty minutes. 1825 William James designed a self-contained breather a cylindrical iron "belt" attached to a copper helmet. The belt held enough air for a seven-minute dive. This was still hardhat and not free swimming diving and depth was limited since there was no self regulating pressure device. 1865 - Benoit Rouquayrol and Auguste Denayrouse develop a horizontal steel tank of air on a diver's back, connected to a mouth-piece. The diver was still tethered to the surface by a hose that pumped air into the tank, but he could disconnect the hose and dive with just the tank on his back for a few minutes. 1876 Henry Fleuss invented a closed circuit, pure oxygen rebreather. and made a thirty-foot dive. He died, pure oxygen is toxic to humans under pressure. 1939, Dr. Christian Lambertsen designed a 'Self-Contained Underwater Oxygen Breathing Apparatus' for the U.S. military war effort, code-named 'SCUBA'. The first appearance of the acronym. Lambertsen's 'SCUBA' gear worked for shallow dives, but the gas mixture was wrong for greater depths due to oxygen toxicity. Researchers, especially Cousteau, determined that the best gas mixture was regular old filtered and purified compressed air. That's what is used in most 'every-day' Aqualungs and Scuba gear today. "Air" is mostly nitrogen and that causes the 'bends.'( You'll find discussions of the 'bends' and different mixtures of oxygen and other inert gasses developed to combat it, higher up the list of 'scuba questions.) Scuba systems other than the aqualung have also been developed, usually for specific situations, such as deeper or longer time dives, some of them are very complex and even 'computerized,' monitoring water pressure and temperatures, the diver's heart and breath rate, blood oxygen levels and other factors. Since Gagnan and Cousteau are credited with the invention of the gear, I s'pose they oughta be credited with actually using it, and thus inventing 'Scuba diving.' Maybe some super Googler will discover that Jacques and Emile were no fools and actually hired somebody else to try the equipment for the first time, and post the name of that unknown true inventor, but don't hold your breath.

The true single line breathing apparatus was actually developed in Melbourne, Australia by Ted Eldred who originally worked on pneaumatic systems for Boeing. The air on demand valve found in todays' mouthpieces and regulators was developed over a number of years and originally developed out of tin foil of all things. Extensive testing was done throughout Port Phillip Bay and Glen Maggie Weir on maintenance and repair dives. The system was called 'Porpoise' and was quickly taken up by the Australian Navy. I know all of this because my grandfather was the first test diver for this technology. He helped provide feedback to Ted. Aqua-Lung eventually bought the rights to his technology and made it famous a few years later but Ted was proud to have been at the forefront of Scuba for a few years at least! If you would like to read a more comprehensive article you can find it here... http://www.theage.com.au/articles/2003/08/31/1062268475963.html

i did.

Jacques-Yves Cousteau and Emile Gagnan ( originator for the scuba diving gear ) gave name to their device ‘Aqua-lung’ . http://www.aquariusscuba.com

Charles Momsen dived on the Squalus to rescue trapped submariners in 1939 with a bell and diving equipment he developed for the navy from 1927 including the use of helium mix (the Squalus went down in around 200ft of water ) this was consider a major success for the program and submarine rescue .?Momsen was also accreditted with invent or developing a self contained rebreathing aqualung?From what sounds like the units favoured by the sas of recent times for covert ops .although this was not used for the Squalas Rescue. comments please?