Editing Timeline of diving technology (section)

===Twentieth century===
* 1900: [[John P. Holland]] built the first [[submarine]] to be formally commissioned by the U.S. Navy, ''Holland'' (also called ''A-1'').<ref name="Paine 2000" />
** [[Leonard Erskine Hill|Leonard Hill]] used a frog model to prove that decompression causes bubbles and that recompression resolves them.<ref name="Acott 1999" />
* 1903: [[Siebe Gorman]] started to make a submarine [[escape set]] in England; in the years afterwards it was improved, and later was called the [[Davis Escape Set]] or [[Davis Submerged Escape Apparatus]].<ref name="rebreather_hx" />
* from 1903 to 1907: Professor [[Georges Jaubert]], invented Oxylithe, a mixture of [[sodium peroxide|peroxides of sodium]] (Na<sub>2</sub>O<sub>2</sub>) and potassium with a small amount of salts of copper or nickel, which produces oxygen in the presence of water.<ref name="Larousse" />
* 1905:
** Several sources, including the 1991 [[United States Navy|US Navy]] Dive Manual (pg 1–8), state that the [[MK V Deep Sea Diving Dress]] was designed by the Bureau of Construction & Repair in 1905, but in reality, the 1905 Navy Handbook shows British Siebe-Gorman helmets in use. Since the earliest known MK V is dated 1916, these sources are probably referring to the earlier MK I, MK II, MK III & MK IV [[Morse Diving|Morse]] and [[August Schrader|Schrader]] helmets.<ref name="Lonsdale 2012" />
** The first rebreather with metering valves to control the supply of oxygen was made.<ref name="divedesco" />
* 1907: [[Draegerwerk|Draeger]] of [[Lübeck]] made a [[Diving rebreather|rebreather]] called the ''U-Boot-Retter.'' (submarine rescuer).<ref name="Draeger history" />
* 1908: 
** [[Arthur Boycott]], [[Guybon Chesney Castell Damant|Guybon Damant]], and [[John Scott Haldane|John Haldane]] published "The Prevention of Compressed-Air Illness", detailed studies on the cause and symptoms of decompression sickness, and proposed a table of [[decompression stop]]s to avoid the effects.<ref name="Acott 1999" /><ref name="Boycott et al 1908" />
** The Admiralty Deep Diving Committee adopted the [[Haldane's decompression model|Haldane tables]] for the Royal Navy, and published [[Haldane's decompression model|Haldane's diving tables]] to the general public.<ref name="Acott 1999" />
* 1910: the British [[Robert Davis (inventor)|Robert Davis]] invented his own submarine rescuer rebreather, the [[Davis Submerged Escape Apparatus]], for the Royal Navy submarine crews.{{citation needed|date=February 2017}}
* 1912: 
** US Navy adopted the [[Haldane's decompression model|decompression tables published by Haldane, Boycott and Damant]]. Driven by Chief Gunner [[George Stillson]], the navy set up a program to test tables and staged decompression based on the work of Haldane.<ref name="nedu" />
** [[Maurice Fernez]] introduced a simple lightweight underwater breathing apparatus as an alternative to helmet diving suits.<ref name="Fernez patent" />
** [[Draegerwerk|Dräger]] started the commercialization of his rebreather in both configuration types, mouthpiece and helmet.<ref name="Diving heritage Draeger" />
* 1913: The US Navy began developing the future MK V, influenced by [[Schrader]] and [[Morse Diving|Morse]] designs.<ref name="nedu" /><ref name="Lonsdale 2012" />
* 1914: Modern swimfins were invented by the Frenchman [[Louis de Corlieu]], ''capitaine de corvette'' ([[Lieutenant Commander]]) in the [[French Navy]]. In 1914 De Corlieu made a practical demonstration of his first [[prototype]] for a group of navy officers.<ref name="Perrier 2008" />{{rp|65}}
* 1915: The submarine {{USS|F-4|SS-23|6}} was salvaged from 304 feet establishing the practical limits for air diving. Three US Navy divers, [[Frank W. Crilley]], William F. Loughman, and Nielson, reached 304 fsw using the MK V dress.<ref name="Lonsdale 2012" />
* 1916:
** The basic design of the MK V dress was finalized by including a battery-powered telephone, but several more detail improvements were made over the next two years.<ref name="Lonsdale 2012" />
** The [[Drägerwerk|Draeger]] model DM 2 became standard equipment of the [[Imperial German Navy]].{{citation needed|date=February 2017}}
* 1917: The [[Bureau of Construction & Repair]] adopted the MK V helmet and dress, which remained the standard for US Navy diving until the introduction of the MK 12 in the late seventies.<ref name="Lonsdale 2012" />
* 1918: the "[[Ohgushi's Peerless Respirator]]" was first patented. Invented in 1916 by Riichi Watanabi and the blacksmith Kinzo Ohgushi, and used with either surface-supplied air or a 150 bar steel scuba cylinder holding 1000 litres free air, the valve-supplied air to a mask over the diver's nose and eyes and the demand valve was operated by the diver's teeth. Gas flow was proportional to bite force and duration. The breathing apparatus was used successfully for fishing and salvage work and by the military Japanese Underwater Unit until the end of the Pacific War.<ref name="Ohgushi manual" /><ref name="Monday 2004" />
* Around 1920: Hanseatischen Apparatebau-Gesellschaft made a 2-cylinder breathing apparatus with double-lever single-stage demand valve and single wide corrugated [[Breathing tube (in breathing apparatus)|breathing tube]] with mouthpiece, and a "duck's beak" exhalent valve in the regulator. It was described in a [[mine rescue]] handbook in 1930. They were successors to Ludwig von Bremen of [[Kiel]], who had the licence to make the Rouquayrol-Denayrouze apparatus in Germany.<ref name="Historical diving society 45" />
* 1924:
** De Corlieu left the French Navy to fully devote himself to his invention.<ref name="Taillez 1954 fins" />
** Experimental dives using helium-oxygen mixtures sponsored by the US Navy and Bureau of Mines.<ref name="Lonsdale 2012" />
* 1925: 
** [[Maurice Fernez]] introduced a new model of his underwater surface-supplied apparatus at the [[Grand Palais]]. [[Yves le Prieur]], an assistant at the exhibition, decided to meet Fernez in person and asked him to transform the equipment into a manually-controlled constant flow [[scuba set|self-contained underwater breathing apparatus]].<ref name="Fernez" />
** Due to post World War I cutbacks, the US Navy found it had only 20 divers qualified to dive deeper than 90 feet when salvaging the submarine [[USS S-51 (SS-162)|S-51]].<ref name="Lonsdale 2012" />
* 1926: 
** [[Maurice Fernez|Fernez-Le Prieur]] self-contained underwater breathing apparatus was demonstrated to the public in Paris,<ref name="Gallant 2" /> and adopted by the French Navy.{{citation needed|date=March 2017}}
** Dräger introduced a rescue breathing apparatus that the wearer could swim with. Previous devices served only for submarine escape and were designed to provide buoyancy so that the wearer was lifted to the surface without effort, the diving set had weights, which made it possible to dive for search and rescue after an accident.{{citation needed|date=February 2017}}
*1927: [[US Navy School of Diving and Salvage]] was re-established at Washington Navy Yard, and the Experimental Diving Unit brought from Pittsburgh to Washington Navy Yard.<ref name="Lonsdale 2012" />
*1928: Davis invented the Submersible Decompression Chamber (SDC) diving bell.<ref name="Lonsdale 2012" />
*1929: Lieutenant [[Swede Momsen|C.B."Swede" Momsen]], a submariner and diver, developed and tested the submarine escape apparatus named the [[Momsen Lung]].<ref name="Lonsdale 2012" /> 
* The 1930s:
**In France, [[Guy Gilpatric]] started swim diving with waterproof goggles, derived from the swimming goggles which were invented by [[Maurice Fernez]] in 1920.{{citation needed|date=February 2017}}
**Sport [[spearfishing]] became common in the [[Mediterranean]], and spearfishers gradually developed the [[diving mask]], fins and snorkel, with [[Georges Beuchat]] in Marseille, France, who created the [[speargun]]. Italian sport spearfishers started using oxygen [[Diving rebreather|rebreathers]]. This practice came to the attention of the [[Italian Navy]], which developed its frogman unit [[Decima Flottiglia MAS]].{{citation needed|date=February 2017}}
* 1933:
** In April [[Louis de Corlieu]] registered a new patent (number 767013, which in addition to two fins for the feet included two spoon-shaped fins for the hands) and called this equipment ''propulseurs de natation et de sauvetage'' (which can be translated as "swimming and rescue propulsion device").<ref name="Perrier 2008"/>{{rp|65}}
** In [[San Diego, California]], the first sport diving club was started by Glenn Orr, Jack Prodanovich and Ben Stone, called the San Diego Bottom Scratchers.<ref name="Bottom scratchers" /> As far as it is known, it did not use breathing sets; its main aim was [[spearfishing]].
** More is known of [[Yves Le Prieur]]'s constant-flow open-circuit breathing set. It is said that it could allow a 20-minute stay at 7 meters and 15 minutes at 15 meters. It has one cylinder feeding into a circular [[fullface mask]]. Its air cylinder was often worn at an angle to get its on/off valve in reach of the diver's hand.{{citation needed|date=February 2017}}
* 1934:
** In France, [[Beuchat]] established a [[scuba diving]] and [[spearfishing]] equipment manufacturing company.<ref name="Beuchat" />
** In France a sport diving club was started, called the ''Club des Sous-l'Eau'' = "club of those [who are] under the water". It did not use breathing sets as far as is known. Its main aim was [[spearfishing]]. ("''Club des Sous-l'Eau''" was later realized to be a [[homophone]] of "''club des soulôts''" = "club of the drunkards", and was changed to ''Club des Scaphandres et de la Vie Sous L'Eau'' = "Club of the diving apparatuses and of underwater life".){{citation needed|date=February 2017}}
** [[Otis Barton]] and [[William Beebe]] dived to 3028 feet using a [[bathysphere]].<ref name="Beebe and Barton" />
* 1935: The [[French Navy]] adopted the Le Prieur breathing set.<ref name="Marx 1990a" />
** On the [[French Riviera]], the first known sport scuba diving club Club Des Scaphandres et de la Vie Sous L'eau (The club for divers and life underwater) was started by Le Prieur & Jean Painleve. It used Le Prieur's breathing sets.{{citation needed|date=December 2019}}
* 1937: US Navy published its revised diving tables based on the work of O.D. Yarbrough.<ref name="nedu" />
* 1937: The American [[Diving Equipment and Salvage Company]] (now known as DESCO) developed a heavy bottom-walking-type diving suit with a self-contained mixed-gas helium and oxygen rebreather.{{citation needed|date=February 2017}}
* 1939: After floundering for years, even producing his fins in his own [[apartment|flat]] in [[Paris]], De Corlieu finally started [[mass production]] of his invention in France. The same year he rented a licence to [[Owen P. Churchill]] for mass production in the [[United States]]. To sell his fins in the USA [[Owen Churchill]] changed the French De Corlieu's name (''propulseurs'') to "swimfins", which is still the [[English language|English]] name. Churchill presented his fins to the US Navy, who decided to acquire them for its [[Underwater Demolition Team]] (UDT).{{citation needed|date=February 2017}}
** [[Hans Hass]] and Hermann Stelzner of Dräger, in Germany made the M138 rebreather. It was developed from the 1912 [[escape set]], a type of rebreather used to exit sunken submarines. The M138 sets were oxygen rebreathers with a 150 bar, 0.6 liter tank and appeared in many of his [[movie]]s and books.{{citation needed|date=February 2017}}
* 1941: The Italian Navy's [[Decima Flottiglia MAS]] using oxygen [[Diving rebreather|rebreathers]] and [[manned torpedo]]es, [[Raid on Alexandria (1941)|attacked the British fleet in Alexandria harbor]].<ref name="O'Hara 2015" />
* 1944: [[United States|American]] UDT and [[United Kingdom|British]] COPP [[Frogman|frogmen]] (COPP: [[Combined Operations Pilotage Parties]]) used the "Churchill fins" during all prior underwater [[demining]]s, allowing this way in 1944 the [[Normandy landings]]. During years after [[World War II]] had ended, De Corlieu spent time and efforts struggling with [[civil procedure]]s for [[patent infringement]].<ref name="Perrier 2008" />{{rp|66}}