Unlike Modern English, Old English is a language rich in morphological diversity. It maintains several distinct cases: the nominative, accusative, genitive, dative and (vestigially) instrumental. The only remnants of this system in Modern English are in the forms of a few pronouns (such as I/me/mine, she/her, who/whom/whose) and in the possessive ending -'s, which derives from the old (masculine and neuter) genitive ending -es. In Old English, however, nouns and their modifying words take appropriate endings depending on their case.


The influence of Old Norse certainly helped move English from a synthetic language along the continuum to a more analytic word order, and Old Norse most likely made a greater impact on the English language than any other language. The eagerness of Vikings in the Danelaw to communicate with their southern Anglo-Saxon neighbors produced a friction that led to the erosion of the complicated inflectional word-endings. Simeon Potter notes: “No less far-reaching was the influence of Scandinavian upon the inflexional endings of English in hastening that wearing away and leveling of grammatical forms which gradually spread from north to south. It was, after all, a salutary influence. The gain was greater than the loss. There was a gain in directness, in clarity, and in strength.”


The form of the verb varies with person (first, second and third), number (singular and plural), tense (present and past), and mood (indicative, subjunctive and imperative). Old English also sometimes uses compound constructions to express other verbal aspects, the future and the passive voice; in these we see the beginnings of the compound tenses of Modern English. Old English verbs include strong verbs, which form the past tense by altering the root vowel, and weak verbs, which use a suffix such as -de. As in Modern English, and peculiar to the Germanic languages, the verbs formed two great classes: weak (regular), and strong (irregular). Like today, Old English had fewer strong verbs, and many of these have over time decayed into weak forms. Then, as now, dental suffixes indicated the past tense of the weak verbs, as in work and worked.


Old English is a West Germanic language, developing out of Ingvaeonic (also known as North Sea Germanic) dialects from the 5th century. It came to be spoken over most of the territory of the Anglo-Saxon kingdoms which became the Kingdom of England. This included most of present-day England, as well as part of what is now southeastern Scotland, which for several centuries belonged to the Anglo-Saxon kingdom of Northumbria. Other parts of the island – Wales and most of Scotland – continued to use Celtic languages, except in the areas of Scandinavian settlements where Old Norse was spoken. Celtic speech also remained established in certain parts of England: Medieval Cornish was spoken all over Cornwall and in adjacent parts of Devon, while Cumbric survived perhaps to the 12th century in parts of Cumbria, and Welsh may have been spoken on the English side of the Anglo-Welsh border. Norse was also widely spoken in the parts of England which fell under Danish law.


Some of the most important surviving works of Old English literature are Beowulf, an epic poem; the Anglo-Saxon Chronicle, a record of early English history; the Franks Casket, an inscribed early whalebone artefact; and Cædmon's Hymn, a Christian religious poem. There are also a number of extant prose works, such as sermons and saints' lives, biblical translations, and translated Latin works of the early Church Fathers, legal documents, such as laws and wills, and practical works on grammar, medicine, and geography. Still, poetry is considered the heart of Old English literature. Nearly all Anglo-Saxon authors are anonymous, with a few exceptions, such as Bede and Cædmon. Cædmon, the earliest English poet we know by name, served as a lay brother in the monastery at Whitby.


Old English developed from a set of Anglo-Frisian or North Sea Germanic dialects originally spoken by Germanic tribes traditionally known as the Angles, Saxons, and Jutes. As the Anglo-Saxons became dominant in England, their language replaced the languages of Roman Britain: Common Brittonic, a Celtic language, and Latin, brought to Britain by Roman invasion. Old English had four main dialects, associated with particular Anglo-Saxon kingdoms: Mercian, Northumbrian, Kentish and West Saxon. It was West Saxon that formed the basis for the literary standard of the later Old English period, although the dominant forms of Middle and Modern English would develop mainly from Mercian. The speech of eastern and northern parts of England was subject to strong Old Norse influence due to Scandinavian rule and settlement beginning in the 9th century.


With the unification of the Anglo-Saxon kingdoms (outside the Danelaw) by Alfred the Great in the later 9th century, the language of government and literature became standardised around the West Saxon dialect (Early West Saxon). Alfred advocated education in English alongside Latin, and had many works translated into the English language; some of them, such as Pope Gregory I's treatise Pastoral Care, appear to have been translated by Alfred himself. In Old English, typical of the development of literature, poetry arose before prose, but King Alfred the Great (871 to 901) chiefly inspired the growth of prose.


Each of these four dialects was associated with an independent kingdom on the island. Of these, Northumbria south of the Tyne, and most of Mercia, were overrun by the Vikings during the 9th century. The portion of Mercia that was successfully defended, and all of Kent, were then integrated into Wessex under Alfred the Great. From that time on, the West Saxon dialect (then in the form now known as Early West Saxon) became standardised as the language of government, and as the basis for the many works of literature and religious materials produced or translated from Latin in that period.


Another source of loanwords was Old Norse, which came into contact with Old English via the Scandinavian rulers and settlers in the Danelaw from the late 9th century, and during the rule of Cnut and other Danish kings in the early 11th century. Many place-names in eastern and northern England are of Scandinavian origin. Norse borrowings are relatively rare in Old English literature, being mostly terms relating to government and administration. The literary standard, however, was based on the West Saxon dialect, away from the main area of Scandinavian influence; the impact of Norse may have been greater in the eastern and northern dialects. Certainly in Middle English texts, which are more often based on eastern dialects, a strong Norse influence becomes apparent. Modern English contains a great many, often everyday, words that were borrowed from Old Norse, and the grammatical simplification that occurred after the Old English period is also often attributed to Norse influence.


Modern editions of Old English manuscripts generally introduce some additional conventions. The modern forms of Latin letters are used, including ⟨g⟩ in place of the insular G, ⟨s⟩ for long S, and others which may differ considerably from the insular script, notably ⟨e⟩, ⟨f⟩ and ⟨r⟩. Macrons are used to indicate long vowels, where usually no distinction was made between long and short vowels in the originals. (In some older editions an acute accent mark was used for consistency with Old Norse conventions.) Additionally, modern editions often distinguish between velar and palatal ⟨c⟩ and ⟨g⟩ by placing dots above the palatals: ⟨ċ⟩, ⟨ġ⟩. The letter wynn ⟨ƿ⟩ is usually replaced with ⟨w⟩, but æsc, eth and thorn are normally retained (except when eth is replaced by thorn).


Like other historical languages, Old English has been used by scholars and enthusiasts of later periods to create texts either imitating Anglo-Saxon literature or deliberately transferring it to a different cultural context. Examples include Alistair Campbell and J. R. R. Tolkien. A number of websites devoted to Neo-Paganism and Historical re-enactment offer reference material and forums promoting the active use of Old English. By far the most ambitious project[peacock term] is the Old English Wikipedia, but most of the Neo-Old English texts published online bear little resemblance to the historical model and are riddled with very basic grammatical mistakes.


A fleet carrier is intended to operate with the main fleet and usually provides an offensive capability. These are the largest carriers capable of fast speeds. By comparison, escort carriers were developed to provide defense for convoys of ships. They were smaller and slower with lower numbers of aircraft carried. Most were built from mercantile hulls or, in the case of merchant aircraft carriers, were bulk cargo ships with a flight deck added on top. Light aircraft carriers were carriers that were fast enough to operate with the fleet but of smaller size with reduced aircraft capacity. Soviet aircraft carriers now in use by Russia are actually called heavy aviation cruisers, these ships while sized in the range of large fleet carriers were designed to deploy alone or with escorts and provide both strong defensive weaponry and heavy offensive missiles equivalent to a guided missile cruiser in addition to supporting fighters and helicopters.


This new-found importance of naval aviation forced nations to create a number of carriers, in efforts to provide air superiority cover for every major fleet in order to ward off enemy aircraft. This extensive usage required the construction of several new 'light' carriers. Escort aircraft carriers, such as USS Bogue, were sometimes purpose-built, but most were converted from merchant ships as a stop-gap measure to provide anti-submarine air support for convoys and amphibious invasions. Following this concept, light aircraft carriers built by the US, such as USS Independence, represented a larger, more "militarized" version of the escort carrier. Although with similar complement to Escort carriers, they had the advantage of speed from their converted cruiser hulls. The UK 1942 Design Light Fleet Carrier was designed for building quickly by civilian shipyards and with an expected service life of about 3 years. They served the Royal Navy during the war and was the hull design chosen for nearly all aircraft carrier equipped navies after the war until the 1980s. Emergencies also spurred the creation or conversion of highly unconventional aircraft carriers. CAM ships, were cargo-carrying merchant ships that could launch (but not retrieve) a single fighter aircraft from a catapult to defend the convoy from long range German aircraft.


Speaking in St. Petersburg, Russia on 30 June 2011, the head of Russia's United Shipbuilding Corporation said his company expected to begin design work for a new carrier in 2016, with a goal of beginning construction in 2018 and having the carrier achieve initial operational capability by 2023. Several months later, on 3 November 2011 the Russian newspaper Izvestiya reported that the naval building plan now included (first) the construction of a new shipyard capable of building large hull ships, after which Moscow will build two (80,000 tons full load each) nuclear-powered aircraft carriers by 2027. The spokesperson said one carrier would be assigned to the Russian Navy's Northern Fleet at Murmansk, and the second would be stationed with the Pacific Fleet at Vladivostok.


As "runways at sea", aircraft carriers have a flat-top flight deck, which launches and recovers aircraft. Aircraft launch forward, into the wind, and are recovered from astern. The flight deck is where the most notable differences between a carrier and a land runway are found. Creating such a surface at sea poses constraints on the carrier – for example, the fact that it is a ship means that a full-length runway would be costly to construct and maintain. This affects take-off procedure, as a shorter runway length of the deck requires that aircraft accelerate more quickly to gain lift. This either requires a thrust boost, a vertical component to its velocity, or a reduced take-off load (to lower mass). The differing types of deck configuration, as above, influence the structure of the flight deck. The form of launch assistance a carrier provides is strongly related to the types of aircraft embarked and the design of the carrier itself.


Since the early 1950s on conventional carriers it has been the practice to recover aircraft at an angle to port of the axial line of the ship. The primary function of this angled deck is to allow aircraft that miss the arresting wires, referred to as a bolter, to become airborne again without the risk of hitting aircraft parked forward. The angled deck allows the installation of one or two "waist" catapults in addition to the two bow cats. An angled deck also improves launch and recovery cycle flexibility with the option of simultaneous launching and recovery of aircraft.


Another deck structure that can be seen is a ski-jump ramp at the forward end of the flight deck. This was first developed to help launch STOVL aircraft take off at far higher weights than is possible with a vertical or rolling takeoff on flat decks. Originally developed by the Royal Navy, it since has been adopted by many navies for smaller carriers. A ski-jump ramp works by converting some of the forward rolling movement of the aircraft into vertical velocity and is sometimes combined with the aiming of jet thrust partly downwards. This allows heavily loaded and fueled aircraft a few more precious seconds to attain sufficient air velocity and lift to sustain normal flight. Without a ski-jump launching fully loaded and fueled aircraft such as the Harrier would not be possible on a smaller flat deck ship before either stalling out or crashing directly into the sea.


An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and facilities for carrying, arming, deploying, and recovering aircraft. Typically, it is the capital ship of a fleet, as it allows a naval force to project air power worldwide without depending on local bases for staging aircraft operations. Aircraft carriers are expensive to build and are critical assets. Aircraft carriers have evolved from converted cruisers to nuclear-powered warships that carry numerous fighter planes, strike aircraft, helicopters, and other types of aircraft.


The 1903 advent of heavier-than-air fixed-wing aircraft was closely followed in 1910 by the first experimental take-off of an airplane, made from the deck of a United States Navy vessel (cruiser USS Birmingham), and the first experimental landings were conducted in 1911. On 9 May 1912 the first airplane take-off from a ship underway was made from the deck of the British Royal Navy's HMS Hibernia. Seaplane tender support ships came next, with the French Foudre of 1911. In September 1914 the Imperial Japanese Navy Wakamiya conducted the world's first successful ship-launched air raid: on 6 September 1914 a Farman aircraft launched by Wakamiya attacked the Austro-Hungarian cruiser SMS Kaiserin Elisabeth and the German gunboat Jaguar in Kiaochow Bay off Tsingtao; neither was hit. The first carrier-launched airstrike was the Tondern Raid in July 1918. Seven Sopwith Camels launched from the converted battlecruiser HMS Furious damaged the German airbase at Tønder and destroyed two zeppelins.


Modern navies that operate such aircraft carriers treat them as the capital ship of the fleet, a role previously held by the battleship. This change took place during World War II in response to air power becoming a significant factor in warfare, driven by the superior range, flexibility and effectiveness of carrier-launched aircraft. Following the war, carrier operations continued to increase in size and importance. Supercarriers, displacing 75,000 tonnes or greater, have become the pinnacle of carrier development. Some are powered by nuclear reactors and form the core of a fleet designed to operate far from home. Amphibious assault ships, such as USS Tarawa and HMS Ocean, serve the purpose of carrying and landing Marines, and operate a large contingent of helicopters for that purpose. Also known as "commando carriers" or "helicopter carriers", many have the capability to operate VSTOL aircraft.


The Royal Australian Navy is in the process of procuring two Canberra-class LHD's, the first of which was commissioned in November 2015, while the second is expected to enter service in 2016. The ships will be the largest in Australian naval history. Their primary roles are to embark, transport and deploy an embarked force and to carry out or support humanitarian assistance missions. The LHD is capable of launching multiple helicopters at one time while maintaining an amphibious capability of 1,000 troops and their supporting vehicles (tanks, armoured personnel carriers etc.). The Australian Defence Minister has publicly raised the possibility of procuring F-35B STOVL aircraft for the carrier, stating that it "has been on the table since day one and stating the LHD's are "STOVL capable".


The British Royal Navy is constructing two new larger STOVL aircraft carriers, the Queen Elizabeth class, to replace the three Invincible-class carriers. The ships will be named HMS Queen Elizabeth and HMS Prince of Wales. They will be able to operate up to 40 aircraft in peace time with a tailored group of up to 50, and will have a displacement of 70,600 tonnes. The ships are due to become operational from 2020. Their primary aircraft complement will be made up of F-35B Lightning IIs, and their ship's company will number around 680 with the total complement rising to about 1,600 when the air group is embarked. Defensive weapons will include the Phalanx Close-In Weapons System for anti-aircraft and anti-missile defence; also 30 mm Automated Small Calibre Guns and miniguns for use against fast attack craft. The two ships will be the largest warships ever built for the Royal Navy.


The constraints of constructing a flight deck affect the role of a given carrier strongly, as they influence the weight, type, and configuration of the aircraft that may be launched. For example, assisted launch mechanisms are used primarily for heavy aircraft, especially those loaded with air-to-ground weapons. CATOBAR is most commonly used on USN supercarriers as it allows the deployment of heavy jets with full loadouts, especially on ground-attack missions. STOVL is used by other navies because it is cheaper to operate and still provides good deployment capability for fighter aircraft.


On the recovery side of the flight deck, the adaptation to the aircraft loadout is mirrored. Non-VTOL or conventional aircraft cannot decelerate on their own, and almost all carriers using them must have arrested-recovery systems (-BAR, e.g. CATOBAR or STOBAR) to recover their aircraft. Aircraft that are landing extend a tailhook that catches on arrestor wires stretched across the deck to bring themselves to a stop in a short distance. Post-WWII Royal Navy research on safer CATOBAR recovery eventually led to universal adoption of a landing area angled off axis to allow aircraft who missed the arresting wires to "bolt" and safely return to flight for another landing attempt rather than crashing into aircraft on the forward deck.


Key personnel involved in the flight deck include the shooters, the handler, and the air boss. Shooters are naval aviators or Naval Flight Officers and are responsible for launching aircraft. The handler works just inside the island from the flight deck and is responsible for the movement of aircraft before launching and after recovery. The "air boss" (usually a commander) occupies the top bridge (Primary Flight Control, also called primary or the tower) and has the overall responsibility for controlling launch, recovery and "those aircraft in the air near the ship, and the movement of planes on the flight deck, which itself resembles a well-choreographed ballet." The captain of the ship spends most of his time one level below primary on the Navigation Bridge. Below this is the Flag Bridge, designated for the embarked admiral and his staff.


The disadvantage of the ski-jump is the penalty it exacts on aircraft size, payload, and fuel load (and thus range); heavily laden aircraft can not launch using a ski-jump because their high loaded weight requires either a longer takeoff roll than is possible on a carrier deck, or assistance from a catapult or JATO rocket. For example, the Russian Su-33 is only able to launch from the carrier Admiral Kuznetsov with a minimal armament and fuel load. Another disadvantage is on mixed flight deck operations where helicopters are also present such as a US Landing Helicopter Dock or Landing Helicopter Assault amphibious assault ship a ski jump is not included as this would eliminate one or more helicopter landing areas, this flat deck limits the loading of Harriers but is somewhat mitigated by the longer rolling start provided by a long flight deck compared to many STOVL carriers.


One STOBAR carrier: Liaoning was originally built as the 57,000 tonne Soviet Admiral Kuznetsov-class carrier Varyag and was later purchased as a stripped hulk by China in 1998 on the pretext of use as a floating casino, then partially rebuilt and towed to China for completion. Liaoning was commissioned on 25 September 2012, and began service for testing and training. On 24 or 25 November 2012, Liaoning successfully launched and recovered several Shenyang J-15 jet fighter aircraft. She is classified as a training ship, intended to allow the navy to practice with carrier usage. On 26 December 2012, the People's Daily reported that it will take four to five years for Liaoning to reach full capacity, mainly due to training and coordination which will take significant amount of time for Chinese PLA Navy to complete as this is the first aircraft carrier in their possession. As it is a training ship, Liaoning is not assigned to any of China's operation fleets.


India started the construction of a 40,000-tonne, 260-metre-long (850 ft) Vikrant-class aircraft carrier in 2009. The new carrier will operate MiG-29K and naval HAL Tejas aircraft along with the Indian-made helicopter HAL Dhruv. The ship will be powered by four gas-turbine engines and will have a range of 8,000 nautical miles (15,000 kilometres), carrying 160 officers, 1,400 sailors, and 30 aircraft. The carrier is being constructed by Cochin Shipyard. The ship was launched in August 2013 and is scheduled for commissioning in 2018.


Carriers have evolved since their inception in the early twentieth century from wooden vessels used to deploy balloons to nuclear-powered warships that carry dozens of aircraft, including fighter jets and helicopters. As of 3 March 2016, there are thirty-seven active aircraft carriers in the world within twelve navies. The United States Navy has 10 large nuclear-powered carriers (known as supercarriers, carrying up to 90 aircraft each), the largest carriers in the world; the total deckspace is over twice that of all other nations' combined. As well as the supercarrier fleet, the US Navy has nine amphibious assault ships used primarily for helicopters (sometimes called helicopter carriers); these can also carry up to 25 fighter jets, and in some cases, are as large as some other nations' fixed-wing carriers.


There is no single definition of an "aircraft carrier", and modern navies use several variants of the type. These variants are sometimes categorized as sub-types of aircraft carriers, and sometimes as distinct types of naval aviation-capable ships. Aircraft carriers may be classified according to the type of aircraft they carry and their operational assignments. Admiral Sir Mark Stanhope, former head of the Royal Navy, has said that "To put it simply, countries that aspire to strategic international influence have aircraft carriers".


The aircraft carrier dramatically changed naval combat in World War II, because air power was becoming a significant factor in warfare. The advent of aircraft as focal weapons was driven by the superior range, flexibility and effectiveness of carrier-launched aircraft. They had higher range and precision than naval guns, making them highly effective. The versatility of the carrier was demonstrated in November 1940 when HMS Illustrious launched a long-range strike on the Italian fleet at their base in Taranto, signalling the beginning of the effective and highly mobile aircraft strikes. This operation incapacitated three of the six battleships at a cost of two torpedo bombers. World War II in the Pacific Ocean involved clashes between aircraft carrier fleets. The 1941 Japanese surprise attack on Pearl Harbor was a clear illustration of the power projection capability afforded by a large force of modern carriers. Concentrating six carriers in a single unit turned naval history about, as no other nation had fielded anything comparable. However, the vulnerability of carriers compared to traditional battleships when forced into a gun-range encounter was quickly illustrated by the sinking of HMS Glorious by German battleships during the Norwegian campaign in 1940.


The development of flattop vessels produced the first large fleet ships. In 1918, HMS Argus became the world's first carrier capable of launching and recovering naval aircraft. As a result of the Washington Naval Treaty of 1922, which limited the construction of new heavy surface combat ships, most early aircraft carriers were conversions of ships that were laid down (or had served) as different ship types: cargo ships, cruisers, battlecruisers, or battleships. These conversions gave rise to the Lexington-class aircraft carriers (1927), Akagi and Courageous class. Specialist carrier evolution was well underway, with several navies ordering and building warships that were purposefully designed to function as aircraft carriers by the mid-1920s, resulting in the commissioning of ships such as Hōshō (1922), HMS Hermes (1924), and Béarn (1927). During World War II, these ships would become known as fleet carriers.[citation needed]


In December 2009, then Indian Navy chief Admiral Nirmal Kumar Verma said at his maiden navy week press conference that concepts currently being examined by the Directorate of Naval Design for the second indigenous aircraft carrier (IAC-2), are for a conventionally powered carrier displacing over 50,000 tons and equipped with steam catapults (rather than the ski-jump on the Gorshkov/Vikramaditya and the IAC) to launch fourth-generation aircraft. Later on in August 2013 Vice Admiral RK Dhowan, while talking about the detailed study underway on the IAC-II project, said that nuclear propulsion was also being considered. The navy also evaluated the Electromagnetic Aircraft Launch System (EMALS), which is being used by the US Navy in their latest Gerald R. Ford-class aircraft carriers. General Atomics, the developer of the EMALS, was cleared by the US government to give a technical demonstration to Indian Navy officers, who were impressed by the new capabilities of the system. The EMALS enables launching varied aircraft including unmanned combat air vehicles (UCAV). The aim is to have a total of three aircraft carriers in service, with two fully operational carriers and the third in refit.


In August 2013, a launching ceremony for Japan's largest military ship since World War II was held in Yokohama. The 820-foot-long (250 m), 19,500-ton flattop Izumo was deployed in March 2015. The ship is able to carry up to 14 helicopters; however, only seven ASW helicopters and two SAR helicopters were planned for the initial aircraft complement. For other operations, 400 troops and fifty 3.5 t trucks (or equivalent equipment) can also be carried. The flight deck has five helicopter landing spots that allow simultaneous landings or take-offs. The ship is equipped with two Phalanx CIWS and two SeaRAM for its defense. The destroyers of this class were initially intended to replace the two ships of the Shirane class, which were originally scheduled to begin decommissioning in FY2014.


The current US fleet of Nimitz-class carriers will be followed into service (and in some cases replaced) by the ten-ship Gerald R. Ford class. It is expected that the ships will be more automated in an effort to reduce the amount of funding required to staff, maintain and operate its supercarriers. The main new features are implementation of Electromagnetic Aircraft Launch System (EMALS) (which replace the old steam catapults) and unmanned aerial vehicles. With the deactivation of USS Enterprise in December 2012 (decommissioning scheduled for 2016), the U.S. fleet comprises 10 active supercarriers. On 24 July 2007, the House Armed Services Seapower subcommittee recommended seven or eight new carriers (one every four years). However, the debate has deepened over budgeting for the $12–14.5 billion (plus $12 billion for development and research) for the 100,000 ton Gerald R. Ford-class carrier (estimated service 2016) compared to the smaller $2 billion 45,000 ton America-class amphibious assault ships able to deploy squadrons of F-35B of which one is already active, another is under construction and nine more are planned.


If the aircraft are VTOL-capable or helicopters, they do not need to decelerate and hence there is no such need. The arrested-recovery system has used an angled deck since the 1950s because, in case the aircraft does not catch the arresting wire, the short deck allows easier take off by reducing the number of objects between the aircraft and the end of the runway. It also has the advantage of separating the recovery operation area from the launch area. Helicopters and aircraft capable of vertical or short take-off and landing (V/STOL) usually recover by coming abreast the carrier on the port side and then using their hover capability to move over the flight deck and land vertically without the need for arresting gear.


The superstructure of a carrier (such as the bridge, flight control tower) are concentrated in a relatively small area called an island, a feature pioneered on the HMS Hermes in 1923. While the island is usually built on the starboard side of the fight deck, the Japanese aircraft carriers Akagi and Hiryū had their islands built on the port side. Very few carriers have been designed or built without an island. The flush deck configuration proved to have significant drawbacks, primary of which was management of the exhaust from the power plant. Fumes coming across the deck were a major issue in USS Langley. In addition, lack of an island meant difficulties managing the flight deck, performing air traffic control, a lack of radar housing placements and problems with navigating and controlling the ship itself.


1 CATOBAR carrier: Charles de Gaulle is a 42,000 tonne nuclear-powered aircraft carrier, commissioned in 2001 and is the flagship of the French Navy (Marine Nationale). The ship carries a complement of Dassault-Breguet Super Étendard, Dassault Rafale M and E‑2C Hawkeye aircraft, EC725 Caracal and AS532 Cougar helicopters for combat search and rescue, as well as modern electronics and Aster missiles. It is a CATOBAR-type carrier that uses two 75 m C13‑3 steam catapults of a shorter version of the catapult system installed on the U.S. Nimitz-class carriers, one catapult at the bow and one across the front of the landing area.


With the deactivation of USS Enterprise in December 2012, the U.S. fleet comprises 10 supercarriers. The House Armed Services Seapower subcommittee on 24 July 2007, recommended seven or maybe eight new carriers (one every four years). However, the debate has deepened over budgeting for the $12–14.5 billion (plus $12 billion for development and research) for the 100,000 ton Gerald R. Ford-class carrier (estimated service 2016) compared to the smaller $2 billion 45,000 ton America-class amphibious assault ships, which are able to deploy squadrons of F-35Bs. The first of this class, USS America, is now in active service with another, USS Tripoli, under construction and 9 more are planned.


Since World War II, aircraft carrier designs have increased in size to accommodate a steady increase in aircraft size. The large, modern Nimitz class of US carriers has a displacement nearly four times that of the World War II–era USS Enterprise, yet its complement of aircraft is roughly the same—a consequence of the steadily increasing size and weight of military aircraft over the years. Today's aircraft carriers are so expensive that nations which operate them risk significant political, economic, and military impact if a carrier is lost, or even used in conflict.


Conventional ("tailhook") aircraft rely upon a landing signal officer (LSO, radio call sign paddles) to monitor the aircraft's approach, visually gauge glideslope, attitude, and airspeed, and transmit that data to the pilot. Before the angled deck emerged in the 1950s, LSOs used colored paddles to signal corrections to the pilot (hence the nickname). From the late 1950s onward, visual landing aids such as Optical Landing System have provided information on proper glide slope, but LSOs still transmit voice calls to approaching pilots by radio.


Although STOVL aircraft are capable of taking off vertically from a spot on the deck, using the ramp and a running start is far more fuel efficient and permits a heavier launch weight. As catapults are unnecessary, carriers with this arrangement reduce weight, complexity, and space needed for complex steam or electromagnetic launching equipment, vertical landing aircraft also remove the need for arresting cables and related hardware. Russian, Chinese, and future Indian carriers include a ski-jump ramp for launching lightly loaded conventional fighter aircraft but recover using traditional carrier arresting cables and a tailhook on their aircraft.


One CATOBAR carrier: São Paulo is a Clemenceau-class aircraft carrier currently in service with the Brazilian Navy. São Paulo was first commissioned in 1963 by the French Navy as Foch and was transferred in 2000 to Brazil, where she became the new flagship of the Brazilian Navy. During the period from 2005–2010, São Paulo underwent extensive modernization. At the end of 2010, sea trials began, and as of 2011[update] São Paulo had been evaluated by the CIASA (Inspection Commission and Training Advisory). She was expected to rejoin the fleet in late 2013, but suffered another major fire in 2012.


1 STOBAR carrier: Admiral Flota Sovetskovo Soyuza Kuznetsov: 55,000 tonne Admiral Kuznetsov-class STOBAR aircraft carrier. Launched in 1985 as Tbilisi, renamed and operational from 1995. Without catapults she can launch and recover lightly fueled naval fighters for air defense or anti-ship missions but not heavy conventional bombing strikes.[citation needed] Officially designated an aircraft carrying cruiser, she is unique in carrying a heavy cruiser's complement of defensive weapons and large P-700 Granit offensive missiles. The P-700 systems will be removed in the coming refit to enlarge her below decks aviation facilities as well as upgrading her defensive systems.


The Royal Navy is constructing two new larger STOVL aircraft carriers, the Queen Elizabeth class, to replace the three now retired Invincible-class carriers. The ships are HMS Queen Elizabeth and HMS Prince of Wales. They will be able to operate up to 40 aircraft on peace time operations with a tailored group of up to 50, and will have a displacement of 70,600 tonnes. HMS Queen Elizabeth is projected to commission in 2017 followed by Prince of Wales in about 2020. The ships are due to become operational starting in 2020. Their primary aircraft complement will be made up of F-35B Lightning IIs, and their ship's company will number around 680 with the total complement rising to about 1600 when the air group is embarked. The two ships will be the largest warships ever built for the Royal Navy.


In 2007, two FAA whistleblowers, inspectors Charalambe "Bobby" Boutris and Douglas E. Peters, alleged that Boutris said he attempted to ground Southwest after finding cracks in the fuselage, but was prevented by supervisors he said were friendly with the airline. This was validated by a report by the Department of Transportation which found FAA managers had allowed Southwest Airlines to fly 46 airplanes in 2006 and 2007 that were overdue for safety inspections, ignoring concerns raised by inspectors. Audits of other airlines resulted in two airlines grounding hundreds of planes, causing thousands of flight cancellations. The House Transportation and Infrastructure Committee held hearings in April 2008. Jim Oberstar, former chairman of the committee said its investigation uncovered a pattern of regulatory abuse and widespread regulatory lapses, allowing 117 aircraft to be operated commercially although not in compliance with FAA safety rules. Oberstar said there was a "culture of coziness" between senior FAA officials and the airlines and "a systematic breakdown" in the FAA's culture that resulted in "malfeasance, bordering on corruption." In 2008 the FAA proposed to fine Southwest $10.2 million for failing to inspect older planes for cracks, and in 2009 Southwest and the FAA agreed that Southwest would pay a $7.5 million penalty and would adopt new safety procedures, with the fine doubling if Southwest failed to follow through.


On July 22, 2008, in the aftermath of the Southwest Airlines inspection scandal, a bill was unanimously approved in the House to tighten regulations concerning airplane maintenance procedures, including the establishment of a whistleblower office and a two-year "cooling off" period that FAA inspectors or supervisors of inspectors must wait before they can work for those they regulated. The bill also required rotation of principal maintenance inspectors and stipulated that the word "customer" properly applies to the flying public, not those entities regulated by the FAA. The bill died in a Senate committee that year.


The FAA gradually assumed additional functions. The hijacking epidemic of the 1960s had already brought the agency into the field of civil aviation security. In response to the hijackings on September 11, 2001, this responsibility is now primarily taken by the Department of Homeland Security. The FAA became more involved with the environmental aspects of aviation in 1968 when it received the power to set aircraft noise standards. Legislation in 1970 gave the agency management of a new airport aid program and certain added responsibilities for airport safety. During the 1960s and 1970s, the FAA also started to regulate high altitude (over 500 feet) kite and balloon flying.


On the eve of America's entry into World War II, CAA began to extend its ATC responsibilities to takeoff and landing operations at airports. This expanded role eventually became permanent after the war. The application of radar to ATC helped controllers in their drive to keep abreast of the postwar boom in commercial air transportation. In 1946, meanwhile, Congress gave CAA the added task of administering the federal-aid airport program, the first peacetime program of financial assistance aimed exclusively at promoting development of the nation's civil airports.


By the mid-1970s, the agency had achieved a semi-automated air traffic control system using both radar and computer technology. This system required enhancement to keep pace with air traffic growth, however, especially after the Airline Deregulation Act of 1978 phased out the CAB's economic regulation of the airlines. A nationwide strike by the air traffic controllers union in 1981 forced temporary flight restrictions but failed to shut down the airspace system. During the following year, the agency unveiled a new plan for further automating its air traffic control facilities, but progress proved disappointing. In 1994, the FAA shifted to a more step-by-step approach that has provided controllers with advanced equipment.


The Air Commerce Act of May 20, 1926, is the cornerstone of the federal government's regulation of civil aviation. This landmark legislation was passed at the urging of the aviation industry, whose leaders believed the airplane could not reach its full commercial potential without federal action to improve and maintain safety standards. The Act charged the Secretary of Commerce with fostering air commerce, issuing and enforcing air traffic rules, licensing pilots, certifying aircraft, establishing airways, and operating and maintaining aids to air navigation. The newly created Aeronautics Branch, operating under the Department of Commerce assumed primary responsibility for aviation oversight.


The approaching era of jet travel, and a series of midair collisions (most notable was the 1956 Grand Canyon mid-air collision), prompted passage of the Federal Aviation Act of 1958. This legislation gave the CAA's functions to a new independent body, the Federal Aviation Agency. The act transferred air safety regulation from the CAB to the new FAA, and also gave the FAA sole responsibility for a common civil-military system of air navigation and air traffic control. The FAA's first administrator, Elwood R. Quesada, was a former Air Force general and adviser to President Eisenhower.


On October 31, 2013, after outcry from media outlets, including heavy criticism  from Nick Bilton of The New York Times, the FAA announced it will allow airlines to expand the passengers use of portable electronic devices during all phases of flight, but mobile phone calls will still be prohibited. Implementation will vary among airlines. The FAA expects many carriers to show that their planes allow passengers to safely use their devices in airplane mode, gate-to-gate, by the end of 2013. Devices must be held or put in the seat-back pocket during the actual takeoff and landing. Mobile phones must be in airplane mode or with mobile service disabled, with no signal bars displayed, and cannot be used for voice communications due to Federal Communications Commission regulations that prohibit any airborne calls using mobile phones. If an air carrier provides Wi-Fi service during flight, passengers may use it. Short-range Bluetooth accessories, like wireless keyboards, can also be used.


In 1967, a new U.S. Department of Transportation (DOT) combined major federal responsibilities for air and surface transport. The Federal Aviation Agency's name changed to the Federal Aviation Administration as it became one of several agencies (e.g., Federal Highway Administration, Federal Railroad Administration, the Coast Guard, and the Saint Lawrence Seaway Commission) within DOT (albeit the largest). The FAA administrator would no longer report directly to the president but would instead report to the Secretary of Transportation. New programs and budget requests would have to be approved by DOT, which would then include these requests in the overall budget and submit it to the president.


The Aeronautics Branch was renamed the Bureau of Air Commerce in 1934 to reflect its enhanced status within the Department. As commercial flying increased, the Bureau encouraged a group of airlines to establish the first three centers for providing air traffic control (ATC) along the airways. In 1936, the Bureau itself took over the centers and began to expand the ATC system. The pioneer air traffic controllers used maps, blackboards, and mental calculations to ensure the safe separation of aircraft traveling along designated routes between cities.


In 2014, the FAA changed a long-standing approach to air traffic control candidates that eliminated preferences based on training and experience at flight schools in favor of a personality test open to anyone irrespective of experience. The move was made to increase flight traffic controller racial diversity. Before the change, candidates who had completed coursework at participating colleges and universities could be "fast-tracked" for consideration. The agency eliminated that program and instead switched to an open system to the general public, with no need for any experience or even a college degree. Instead, applicants could take "a biographical questionnaire" that many applicants found baffling.


The FAA has been cited as an example of regulatory capture, "in which the airline industry openly dictates to its regulators its governing rules, arranging for not only beneficial regulation, but placing key people to head these regulators." Retired NASA Office of Inspector General Senior Special Agent Joseph Gutheinz, who used to be a Special Agent with the Office of Inspector General for the Department of Transportation and with FAA Security, is one of the most outspoken critics of FAA. Rather than commend the agency for proposing a $10.2 million fine against Southwest Airlines for its failure to conduct mandatory inspections in 2008, he was quoted as saying the following in an Associated Press story: "Penalties against airlines that violate FAA directives should be stiffer. At $25,000 per violation, Gutheinz said, airlines can justify rolling the dice and taking the chance on getting caught. He also said the FAA is often too quick to bend to pressure from airlines and pilots." Other experts have been critical of the constraints and expectations under which the FAA is expected to operate. The dual role of encouraging aerospace travel and regulating aerospace travel are contradictory. For example, to levy a heavy penalty upon an airline for violating an FAA regulation which would impact their ability to continue operating would not be considered encouraging aerospace travel.


The boroughs of Liverpool, Knowsley, St Helens and Sefton were included in Merseyside. In Greater Manchester the successor boroughs were Bury, Bolton, Manchester, Oldham (part), Rochdale, Salford, Tameside (part), Trafford (part) and Wigan. Warrington and Widnes, south of the new Merseyside/Greater Manchester border were added to the new non-metropolitan county of Cheshire. The urban districts of Barnoldswick and Earby, Bowland Rural District and the parishes of Bracewell and Brogden and Salterforth from Skipton Rural District in the West Riding of Yorkshire became part of the new Lancashire. One parish, Simonswood, was transferred from the borough of Knowsley in Merseyside to the district of West Lancashire in 1994. In 1998 Blackpool and Blackburn with Darwen became independent unitary authorities.


The Duchy of Lancaster is one of two royal duchies in England. It has landholdings throughout the region and elsewhere, operating as a property company, but also exercising the right of the Crown in the County Palatine of Lancaster. While the administrative boundaries changed in the 1970s, the county palatine boundaries remain the same as the historic boundaries. As a result, the High Sheriffs for Lancashire, Greater Manchester and Merseyside are appointed "within the Duchy and County Palatine of Lancaster".


Lancashire has a mostly comprehensive system with four state grammar schools. Not including sixth form colleges, there are 77 state schools (not including Burnley's new schools) and 24 independent schools. The Clitheroe area has secondary modern schools. Sixth form provision is limited at most schools in most districts, with only Fylde and Lancaster districts having mostly sixth forms at schools. The rest depend on FE colleges and sixth form colleges, where they exist. South Ribble has the largest school population and Fylde the smallest (only three schools). Burnley's schools have had a new broom and have essentially been knocked down and started again in 2006. There are many Church of England and Catholic faith schools in Lancashire.


Lancashire produced well known teams in super league such as St Helens, Wigan, and Warrington. The county was once the focal point for many of the sport's professional competitions including the Lancashire League competition which ran from 1895 to 1970, and the Lancashire County Cup which was abandoned in 1993. Rugby League has also seen a representative fixture between Lancashire and Yorkshire contested 89 times since its inception in 1895. Currently there are several rugby league teams that are based within the ceremonial county which include Blackpool Panthers, East Lancashire Lions, Blackpool Sea Eagles, Bamber Bridge, Leyland Warriors, Chorley Panthers, Blackpool Stanley, Blackpool Scorpions and Adlington Rangers.


Lancashire had a lively culture of choral and classical music, with very large numbers of local church choirs from the 17th century, leading to the foundation of local choral societies from the mid-18th century, often particularly focused on performances of the music of Handel and his contemporaries. It also played a major part in the development of brass bands which emerged in the county, particularly in the textile and coalfield areas, in the 19th century. The first open competition for brass bands was held at Manchester in 1853, and continued annually until the 1980s. The vibrant brass band culture of the area made an important contribution to the foundation and staffing of the Hallé Orchestra from 1857, the oldest extant professional orchestra in the United Kingdom. The same local musical tradition produced eminent figures such as Sir William Walton (1902–88), son of an Oldham choirmaster and music teacher, Sir Thomas Beecham (1879–1961), born in St. Helens, who began his career by conducting local orchestras and Alan Rawsthorne (1905–71) born in Haslingden. The conductor David Atherton, co-founder of the London Sinfonietta, was born in Blackpool in 1944. Lancashire also produced more populist figures, such as early musical theatre composer Leslie Stuart (1863–1928), born in Southport, who began his musical career as organist of Salford Cathedral.


Lancashire emerged as a major commercial and industrial region during the Industrial Revolution. Manchester and Liverpool grew into its largest cities, dominating global trade and the birth of modern capitalism. The county contained several mill towns and the collieries of the Lancashire Coalfield. By the 1830s, approximately 85% of all cotton manufactured worldwide was processed in Lancashire. Accrington, Blackburn, Bolton, Burnley, Bury, Chorley, Colne, Darwen, Nelson, Oldham, Preston, Rochdale and Wigan were major cotton mill towns during this time. Blackpool was a centre for tourism for the inhabitants of Lancashire's mill towns, particularly during wakes week.


The county was subject to significant boundary reform in 1974 that removed Liverpool and Manchester and most of their surrounding conurbations to form the metropolitan counties of Merseyside and Greater Manchester. The detached northern part of Lancashire in the Lake District, including the Furness Peninsula and Cartmel, was merged with Cumberland and Westmorland to form Cumbria. Lancashire lost 709 square miles of land to other counties, about two fifths of its original area, although it did gain some land from the West Riding of Yorkshire. Today the county borders Cumbria to the north, Greater Manchester and Merseyside to the south and North and West Yorkshire to the east; with a coastline on the Irish Sea to the west. The county palatine boundaries remain the same[clarification needed] with the Duke of Lancaster exercising sovereignty rights, including the appointment of lords lieutenant in Greater Manchester and Merseyside.


Lancashire is smaller than its historical extent following a major reform of local government. In 1889, the administrative county of Lancashire was created, covering the historical county except for the county boroughs such as Blackburn, Burnley, Barrow-in-Furness, Preston, Wigan, Liverpool and Manchester. The area served by the Lord-Lieutenant (termed now a ceremonial county) covered the entirety of the administrative county and the county boroughs, and was expanded whenever boroughs annexed areas in neighbouring counties such as Wythenshawe in Manchester south of the River Mersey and historically in Cheshire, and southern Warrington. It did not cover the western part of Todmorden, where the ancient border between Lancashire and Yorkshire passes through the middle of the town.


During the 20th century, the county became increasingly urbanised, particularly the southern part. To the existing county boroughs of Barrow-in-Furness, Blackburn, Bolton, Bootle, Burnley, Bury, Liverpool, Manchester, Oldham, Preston, Rochdale, Salford, St Helens and Wigan were added Blackpool (1904), Southport (1905), and Warrington (1900). The county boroughs also had many boundary extensions. The borders around the Manchester area were particularly complicated, with narrow protrusions of the administrative county between the county boroughs – Lees urban district formed a detached part of the administrative county, between Oldham county borough and the West Riding of Yorkshire.


To the east of the county are upland areas leading to the Pennines. North of the Ribble is Beacon Fell Country Park and the Forest of Bowland, another AONB. Much of the lowland in this area is devoted to dairy farming and cheesemaking, whereas the higher ground is more suitable for sheep, and the highest ground is uncultivated moorland. The valleys of the River Ribble and its tributary the Calder form a large gap to the west of the Pennines, overlooked by Pendle Hill. Most of the larger Lancashire towns are in these valleys South of the Ribble are the West Pennine Moors and the Forest of Rossendale where former cotton mill towns are in deep valleys. The Lancashire Coalfield, largely in modern-day Greater Manchester, extended into Merseyside and to Ormskirk, Chorley, Burnley and Colne in Lancashire.


The Duchy administers bona vacantia within the County Palatine, receiving the property of persons who die intestate and where the legal ownership cannot be ascertained. There is no separate Duke of Lancaster, the title merged into the Crown many centuries ago – but the Duchy is administered by the Queen in Right of the Duchy of Lancaster. A separate court system for the county palatine was abolished by Courts Act 1971. A particular form of The Loyal Toast, 'The Queen, Duke of Lancaster' is in regular use in the county palatine. Lancaster serves as the county town of the county palatine.


The Lancashire economy relies strongly on the M6 motorway which runs from north to south, past Lancaster and Preston. The M55 connects Preston to Blackpool and is 11.5 miles (18.3 km) long. The M65 motorway from Colne, connects Burnley, Accrington, Blackburn to Preston. The M61 from Preston via Chorley and the M66 starting 500 metres (0.3 mi) inside the county boundary near Edenfield, provide links between Lancashire and Manchester] and the trans-Pennine M62. The M58 crosses the southernmost part of the county from the M6 near Wigan to Liverpool via Skelmersdale.


The major settlements in the ceremonial county are concentrated on the Fylde coast (the Blackpool Urban Area), and a belt of towns running west-east along the M65: Preston, Blackburn, Accrington, Burnley, Nelson and Colne. South of Preston are the towns of Leyland and Chorley; the three formed part of the Central Lancashire New Town designated in 1970. The north of the county is predominantly rural and sparsely populated, except for the towns of Lancaster and Morecambe which form a large conurbation of almost 100,000 people. Lancashire is home to a significant Asian population, numbering over 70,000 and 6% of the county's population, and concentrated largely in the former cotton mill towns in the south east.


Liverpool produced a number of nationally and internationally successful popular singers in the 1950s, including traditional pop stars Frankie Vaughan and Lita Roza, and one of the most successful British rock and roll stars in Billy Fury. Many Lancashire towns had vibrant skiffle scenes in the late 1950s, out of which by the early 1960s a flourishing culture of beat groups began to emerge, particularly around Liverpool and Manchester. It has been estimated that there were around 350 bands active in and around Liverpool in this era, often playing ballrooms, concert halls and clubs, among them the Beatles. After their national success from 1962, a number of Liverpool performers were able to follow them into the charts, including Gerry & the Pacemakers, the Searchers and Cilla Black. The first act to break through in the UK who were not from Liverpool, or managed by Brian Epstein, were Freddie and the Dreamers, who were based in Manchester, as were Herman's Hermits and the Hollies. Led by the Beatles, beat groups from the region spearheaded the British Invasion of the US, which made a major contribution to the development of rock music. After the decline of beat groups in the late 1960s the centre of rock culture shifted to London and there were relatively few local bands who achieved national prominence until the growth of a disco funk scene and the punk rock revolution in the mid and late 1970s.


Lancashire has a long and highly productive tradition of music making. In the early modern era the county shared in the national tradition of balladry, including perhaps the finest border ballad, "The Ballad of Chevy Chase", thought to have been composed by the Lancashire-born minstrel Richard Sheale. The county was also a common location for folk songs, including "The Lancashire Miller", "Warrington Ale" and "The soldier's farewell to Manchester", while Liverpool, as a major seaport, was the subject of many sea shanties, including "The Leaving of Liverpool" and "Maggie May", beside several local Wassailing songs. In the Industrial Revolution changing social and economic patterns helped create new traditions and styles of folk song, often linked to migration and patterns of work. These included processional dances, often associated with rushbearing or the Wakes Week festivities, and types of step dance, most famously clog dancing.


The county was established in 1182, later than many other counties. During Roman times the area was part of the Brigantes tribal area in the military zone of Roman Britain. The towns of Manchester, Lancaster, Ribchester, Burrow, Elslack and Castleshaw grew around Roman forts. In the centuries after the Roman withdrawal in 410AD the northern parts of the county probably formed part of the Brythonic kingdom of Rheged, a successor entity to the Brigantes tribe. During the mid-8th century, the area was incorporated into the Anglo-Saxon Kingdom of Northumbria, which became a part of England in the 10th century.


By the census of 1971, the population of Lancashire and its county boroughs had reached 5,129,416, making it the most populous geographic county in the UK. The administrative county was also the most populous of its type outside London, with a population of 2,280,359 in 1961. On 1 April 1974, under the Local Government Act 1972, the administrative county was abolished, as were the county boroughs. The urbanised southern part largely became part of two metropolitan counties, Merseyside and Greater Manchester. The new county of Cumbria incorporates the Furness exclave.


A local pioneer of folk song collection in the first half of the 19th century was Shakespearean scholar James Orchard Halliwell, but it was not until the second folk revival in the 20th century that the full range of song from the county, including industrial folk song, began to gain attention. The county produced one of the major figures of the revival in Ewan MacColl, but also a local champion in Harry Boardman, who from 1965 onwards probably did more than anyone to popularise and record the folk song of the county. Perhaps the most influential folk artists to emerge from the region in the late 20th century were Liverpool folk group The Spinners, and from Manchester folk troubadour Roy Harper and musician, comedian and broadcaster Mike Harding. The region is home to numerous folk clubs, many of them catering to Irish and Scottish folk music. Regular folk festivals include the Fylde Folk Festival at Fleetwood.


The Red Rose of Lancaster is the county flower found on the county's heraldic badge and flag. The rose was a symbol of the House of Lancaster, immortalised in the verse "In the battle for England's head/York was white, Lancaster red" (referring to the 15th-century Wars of the Roses). The traditional Lancashire flag, a red rose on a white field, was not officially registered. When an attempt was made to register it with the Flag Institute it was found that it was officially registered by Montrose in Scotland, several hundred years earlier with the Lyon Office. Lancashire's official flag is registered as a red rose on a gold field.


More recent Lancashire-born composers include Hugh Wood (1932- Parbold), Sir Peter Maxwell Davies (1934-, Salford), Sir Harrison Birtwistle (1934-, Accrington), Gordon Crosse (1937-, Bury),John McCabe (1939-2015, Huyton), Roger Smalley (1943-2015, Swinton), Nigel Osborne (1948-, Manchester), Steve Martland (1954-2013, Liverpool), Simon Holt (1958-, Bolton) and Philip Cashian (1963-, Manchester). The Royal Manchester College of Music was founded in 1893 to provide a northern counterpart to the London musical colleges. It merged with the Northern College of Music (formed in 1920) to form the Royal Northern College of Music in 1972.


The Early Triassic was between 250 million to 247 million years ago and was dominated by deserts as Pangaea had not yet broken up, thus the interior was nothing but arid. The Earth had just witnessed a massive die-off in which 95% of all life went extinct. The most common life on earth were Lystrosaurus, Labyrinthodont, and Euparkeria along with many other creatures that managed to survive the Great Dying. Temnospondyli evolved during this time and would be the dominant predator for much of the Triassic.


The climatic changes of the late Jurassic and Cretaceous provided for further adaptive radiation. The Jurassic was the height of archosaur diversity, and the first birds and eutherian mammals also appeared. Angiosperms radiated sometime in the early Cretaceous, first in the tropics, but the even temperature gradient allowed them to spread toward the poles throughout the period. By the end of the Cretaceous, angiosperms dominated tree floras in many areas, although some evidence suggests that biomass was still dominated by cycad and ferns until after the Cretaceous–Paleogene extinction.


The lower (Triassic) boundary is set by the Permian–Triassic extinction event, during which approximately 90% to 96% of marine species and 70% of terrestrial vertebrates became extinct. It is also known as the "Great Dying" because it is considered the largest mass extinction in the Earth's history. The upper (Cretaceous) boundary is set at the Cretaceous–Tertiary (KT) extinction event (now more accurately called the Cretaceous–Paleogene (or K–Pg) extinction event), which may have been caused by the impactor that created Chicxulub Crater on the Yucatán Peninsula. Towards the Late Cretaceous large volcanic eruptions are also believed to have contributed to the Cretaceous–Paleogene extinction event. Approximately 50% of all genera became extinct, including all of the non-avian dinosaurs.


The Late Cretaceous spans from 100 million to 65 million years ago. The Late Cretaceous featured a cooling trend that would continue on in the Cenozoic period. Eventually, tropics were restricted to the equator and areas beyond the tropic lines featured extreme seasonal changes in weather. Dinosaurs still thrived as new species such as Tyrannosaurus, Ankylosaurus, Triceratops and Hadrosaurs dominated the food web. In the oceans, Mosasaurs ruled the seas to fill the role of the Ichthyosaurs, and huge plesiosaurs, such as Elasmosaurus, evolved. Also, the first flowering plants evolved. At the end of the Cretaceous, the Deccan traps and other volcanic eruptions were poisoning the atmosphere. As this was continuing, it is thought that a large meteor smashed into earth, creating the Chicxulub Crater in an event known as the K-T Extinction, the fifth and most recent mass extinction event, in which 75% of life on earth went extinct, including all non-avian dinosaurs. Everything over 10 kilograms went extinct. The age of the dinosaurs was over.


The climate of the Cretaceous is less certain and more widely disputed. Higher levels of carbon dioxide in the atmosphere are thought to have caused the world temperature gradient from north to south to become almost flat: temperatures were about the same across the planet. Average temperatures were also higher than today by about 10°C. In fact, by the middle Cretaceous, equatorial ocean waters (perhaps as warm as 20 °C in the deep ocean) may have been too warm for sea life,[dubious – discuss][citation needed] and land areas near the equator may have been deserts despite their proximity to water. The circulation of oxygen to the deep ocean may also have been disrupted.[dubious – discuss] For this reason, large volumes of organic matter that was unable to decompose accumulated, eventually being deposited as "black shale".


The Late Triassic spans from 237 million to 200 million years ago. Following the bloom of the Middle Triassic, the Late Triassic featured frequent heat spells, as well as moderate precipitation (10-20 inches per year). The recent warming led to a boom of reptilian evolution on land as the first true dinosaurs evolve, as well as pterosaurs. All this climatic change, however, resulted in a large die-out known as the Triassic-Jurassic extinction event, in which all archosaurs (excluding ancient crocodiles), most synapsids, and almost all large amphibians went extinct, as well as 34% of marine life in the fourth mass extinction event of the world. The cause is debatable.


The Early Cretaceous spans from 145 million to 100 million years ago. The Early Cretaceous saw the expansion of seaways, and as a result, the decline and extinction of sauropods (except in South America). Many coastal shallows were created, and that caused Ichthyosaurs to die out. Mosasaurs evolved to replace them as head of the seas. Some island-hopping dinosaurs, like Eustreptospondylus, evolved to cope with the coastal shallows and small islands of ancient Europe. Other dinosaurs rose up to fill the empty space that the Jurassic-Cretaceous extinction left behind, such as Carcharodontosaurus and Spinosaurus. Of the most successful would be the Iguanodon which spread to every continent. Seasons came back into effect and the poles got seasonally colder, but dinosaurs still inhabited this area like the Leaellynasaura which inhabited the polar forests year-round, and many dinosaurs migrated there during summer like Muttaburrasaurus. Since it was too cold for crocodiles, it was the last stronghold for large amphibians, like Koolasuchus. Pterosaurs got larger as species like Tapejara and Ornithocheirus evolved.


Sea levels began to rise during the Jurassic, which was probably caused by an increase in seafloor spreading. The formation of new crust beneath the surface displaced ocean waters by as much as 200 m (656 ft) more than today, which flooded coastal areas. Furthermore, Pangaea began to rift into smaller divisions, bringing more land area in contact with the ocean by forming the Tethys Sea. Temperatures continued to increase and began to stabilize. Humidity also increased with the proximity of water, and deserts retreated.


The Early Jurassic spans from 200 million years to 175 million years ago. The climate was much more humid than the Triassic, and as a result, the world was very tropical. In the oceans, Plesiosaurs, Ichthyosaurs and Ammonites fill waters as the dominant races of the seas. On land, dinosaurs and other reptiles stake their claim as the dominant race of the land, with species such as Dilophosaurus at the top. The first true crocodiles evolved, pushing out the large amphibians to near extinction. All-in-all, reptiles rise to rule the world. Meanwhile, the first true mammals evolve, but remained relatively small sized.


Compared to the vigorous convergent plate mountain-building of the late Paleozoic, Mesozoic tectonic deformation was comparatively mild. The sole major Mesozoic orogeny occurred in what is now the Arctic, creating the Innuitian orogeny, the Brooks Range, the Verkhoyansk and Cherskiy Ranges in Siberia, and the Khingan Mountains in Manchuria. This orogeny was related to the opening of the Arctic Ocean and subduction of the North China and Siberian cratons under the Pacific Ocean. Nevertheless, the era featured the dramatic rifting of the supercontinent Pangaea. Pangaea gradually split into a northern continent, Laurasia, and a southern continent, Gondwana. This created the passive continental margin that characterizes most of the Atlantic coastline (such as along the U.S. East Coast) today.


Recent research indicates that the specialized animals that formed complex ecosystems, with high biodiversity, complex food webs and a variety of niches, took much longer to reestablish, recovery did not begin until the start of the mid-Triassic, 4M to 6M years after the extinction and was not complete until 30M years after the Permian–Triassic extinction event. Animal life was then dominated by various archosaurian reptiles: dinosaurs, pterosaurs, and aquatic reptiles such as ichthyosaurs, plesiosaurs, and mosasaurs.


The era began in the wake of the Permian–Triassic extinction event, the largest well-documented mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event, another mass extinction which is known for having killed off non-avian dinosaurs, as well as other plant and animal species. The Mesozoic was a time of significant tectonic, climate and evolutionary activity. The era witnessed the gradual rifting of the supercontinent Pangaea into separate landmasses that would eventually move into their current positions. The climate of the Mesozoic was varied, alternating between warming and cooling periods. Overall, however, the Earth was hotter than it is today. Non-avian dinosaurs appeared in the Late Triassic and became the dominant terrestrial vertebrates early in the Jurassic, occupying this position for about 135 million years until their demise at the end of the Cretaceous. Birds first appeared in the Jurassic, having evolved from a branch of theropod dinosaurs. The first mammals also appeared during the Mesozoic, but would remain small—less than 15 kg (33 lb)—until the Cenozoic.


The Middle Triassic spans from 247 million to 237 million years ago. The Middle Triassic featured the beginnings of the breakup of Pangaea, and the beginning of the Tethys Sea. The ecosystem had recovered from the devastation that was the Great Dying. Phytoplankton, coral, and crustaceans all had recovered, and the reptiles began to get bigger and bigger. New aquatic reptiles evolved such as Ichthyosaurs and Nothosaurs. Meanwhile, on land, Pine forests flourished, bringing along mosquitoes and fruit flies. The first ancient crocodilians evolved, which sparked competition with the large amphibians that had since ruled the freshwater world.


The Late Jurassic spans from 163 million to 145 million years ago. The Late Jurassic featured a massive extinction of sauropods and Ichthyosaurs due to the separation of Pangaea into Laurasia and Gondwana in an extinction known as the Jurassic-Cretaceous extinction. Sea levels rose, destroying fern prairies and creating shallows in its wake. Ichthyosaurs went extinct whereas sauropods, as a whole, did not die out in the Jurassic; in fact, some species, like the Titanosaurus, lived up to the K-T extinction. The increase in sea-levels opened up the Atlantic sea way which would continue to get larger over time. The divided world would give opportunity for the diversification of new dinosaurs.


The Triassic was generally dry, a trend that began in the late Carboniferous, and highly seasonal, especially in the interior of Pangaea. Low sea levels may have also exacerbated temperature extremes. With its high specific heat capacity, water acts as a temperature-stabilizing heat reservoir, and land areas near large bodies of water—especially the oceans—experience less variation in temperature. Because much of the land that constituted Pangaea was distant from the oceans, temperatures fluctuated greatly, and the interior of Pangaea probably included expansive areas of desert. Abundant red beds and evaporites such as halite support these conclusions, but evidence exists that the generally dry climate of the Triassic was punctuated by episodes of increased rainfall. Most important humid episodes were the Carnian Pluvial Event and one in the Rhaetian, few million years before the Triassic–Jurassic extinction event.


The dominant land plant species of the time were gymnosperms, which are vascular, cone-bearing, non-flowering plants such as conifers that produce seeds without a coating. This is opposed to the earth's current flora, in which the dominant land plants in terms of number of species are angiosperms. One particular plant genus, Ginkgo, is thought to have evolved at this time and is represented today by a single species, Ginkgo biloba. As well, the extant genus Sequoia is believed to have evolved in the Mesozoic.


It was only in the 1980s that digital telephony transmission networks became possible, such as with ISDN networks, assuring a minimum bit rate (usually 128 kilobits/s) for compressed video and audio transmission. During this time, there was also research into other forms of digital video and audio communication. Many of these technologies, such as the Media space, are not as widely used today as videoconferencing but were still an important area of research. The first dedicated systems started to appear in the market as ISDN networks were expanding throughout the world. One of the first commercial videoconferencing systems sold to companies came from PictureTel Corp., which had an Initial Public Offering in November, 1984.


The MC controls the conferencing while it is active on the signaling plane, which is simply where the system manages conferencing creation, endpoint signaling and in-conferencing controls. This component negotiates parameters with every endpoint in the network and controls conferencing resources. While the MC controls resources and signaling negotiations, the MP operates on the media plane and receives media from each endpoint. The MP generates output streams from each endpoint and redirects the information to other endpoints in the conference.


High speed Internet connectivity has become more widely available at a reasonable cost and the cost of video capture and display technology has decreased. Consequently, personal videoconferencing systems based on a webcam, personal computer system, software compression and broadband Internet connectivity have become affordable to the general public. Also, the hardware used for this technology has continued to improve in quality, and prices have dropped dramatically. The availability of freeware (often as part of chat programs) has made software based videoconferencing accessible to many.


Videophone calls (also: videocalls, video chat as well as Skype and Skyping in verb form), differ from videoconferencing in that they expect to serve individuals, not groups. However that distinction has become increasingly blurred with technology improvements such as increased bandwidth and sophisticated software clients that can allow for multiple parties on a call. In general everyday usage the term videoconferencing is now frequently used instead of videocall for point-to-point calls between two units. Both videophone calls and videoconferencing are also now commonly referred to as a video link.


Technological developments by videoconferencing developers in the 2010s have extended the capabilities of video conferencing systems beyond the boardroom for use with hand-held mobile devices that combine the use of video, audio and on-screen drawing capabilities broadcasting in real-time over secure networks, independent of location. Mobile collaboration systems now allow multiple people in previously unreachable locations, such as workers on an off-shore oil rig, the ability to view and discuss issues with colleagues thousands of miles away. Traditional videoconferencing system manufacturers have begun providing mobile applications as well, such as those that allow for live and still image streaming.


Videoconferencing provides students with the opportunity to learn by participating in two-way communication forums. Furthermore, teachers and lecturers worldwide can be brought to remote or otherwise isolated educational facilities. Students from diverse communities and backgrounds can come together to learn about one another, although language barriers will continue to persist. Such students are able to explore, communicate, analyze and share information and ideas with one another. Through videoconferencing, students can visit other parts of the world to speak with their peers, and visit museums and educational facilities. Such virtual field trips can provide enriched learning opportunities to students, especially those in geographically isolated locations, and to the economically disadvantaged. Small schools can use these technologies to pool resources and provide courses, such as in foreign languages, which could not otherwise be offered.


One of the first demonstrations of the ability for telecommunications to help sign language users communicate with each other occurred when AT&T's videophone (trademarked as the "Picturephone") was introduced to the public at the 1964 New York World's Fair –two deaf users were able to communicate freely with each other between the fair and another city. Various universities and other organizations, including British Telecom's Martlesham facility, have also conducted extensive research on signing via videotelephony. The use of sign language via videotelephony was hampered for many years due to the difficulty of its use over slow analogue copper phone lines, coupled with the high cost of better quality ISDN (data) phone lines. Those factors largely disappeared with the introduction of more efficient video codecs and the advent of lower cost high-speed ISDN data and IP (Internet) services in the 1990s.


In the increasingly globalized film industry, videoconferencing has become useful as a method by which creative talent in many different locations can collaborate closely on the complex details of film production. For example, for the 2013 award-winning animated film Frozen, Burbank-based Walt Disney Animation Studios hired the New York City-based husband-and-wife songwriting team of Robert Lopez and Kristen Anderson-Lopez to write the songs, which required two-hour-long transcontinental videoconferences nearly every weekday for about 14 months.


A videoconference system is generally higher cost than a videophone and deploys greater capabilities. A videoconference (also known as a videoteleconference) allows two or more locations to communicate via live, simultaneous two-way video and audio transmissions. This is often accomplished by the use of a multipoint control unit (a centralized distribution and call management system) or by a similar non-centralized multipoint capability embedded in each videoconferencing unit. Again, technology improvements have circumvented traditional definitions by allowing multiple party videoconferencing via web-based applications.


This technique was very expensive, though, and could not be used for applications such as telemedicine, distance education, and business meetings. Attempts at using normal telephony networks to transmit slow-scan video, such as the first systems developed by AT&T Corporation, first researched in the 1950s, failed mostly due to the poor picture quality and the lack of efficient video compression techniques. The greater 1 MHz bandwidth and 6 Mbit/s bit rate of the Picturephone in the 1970s also did not achieve commercial success, mostly due to its high cost, but also due to a lack of network effect —with only a few hundred Picturephones in the world, users had extremely few contacts they could actually call to, and interoperability with other videophone systems would not exist for decades.


While videoconferencing technology was initially used primarily within internal corporate communication networks, one of the first community service usages of the technology started in 1992 through a unique partnership with PictureTel and IBM Corporations which at the time were promoting a jointly developed desktop based videoconferencing product known as the PCS/1. Over the next 15 years, Project DIANE (Diversified Information and Assistance Network) grew to utilize a variety of videoconferencing platforms to create a multi-state cooperative public service and distance education network consisting of several hundred schools, neighborhood centers, libraries, science museums, zoos and parks, public assistance centers, and other community oriented organizations.


Simultaneous videoconferencing among three or more remote points is possible by means of a Multipoint Control Unit (MCU). This is a bridge that interconnects calls from several sources (in a similar way to the audio conference call). All parties call the MCU, or the MCU can also call the parties which are going to participate, in sequence. There are MCU bridges for IP and ISDN-based videoconferencing. There are MCUs which are pure software, and others which are a combination of hardware and software. An MCU is characterised according to the number of simultaneous calls it can handle, its ability to conduct transposing of data rates and protocols, and features such as Continuous Presence, in which multiple parties can be seen on-screen at once. MCUs can be stand-alone hardware devices, or they can be embedded into dedicated videoconferencing units.


Videoconferencing can enable individuals in distant locations to participate in meetings on short notice, with time and money savings. Technology such as VoIP can be used in conjunction with desktop videoconferencing to enable low-cost face-to-face business meetings without leaving the desk, especially for businesses with widespread offices. The technology is also used for telecommuting, in which employees work from home. One research report based on a sampling of 1,800 corporate employees showed that, as of June 2010, 54% of the respondents with access to video conferencing used it “all of the time” or “frequently”.


Finally, in the 1990s, Internet Protocol-based videoconferencing became possible, and more efficient video compression technologies were developed, permitting desktop, or personal computer (PC)-based videoconferencing. In 1992 CU-SeeMe was developed at Cornell by Tim Dorcey et al. In 1995 the first public videoconference between North America and Africa took place, linking a technofair in San Francisco with a techno-rave and cyberdeli in Cape Town. At the Winter Olympics opening ceremony in Nagano, Japan, Seiji Ozawa conducted the Ode to Joy from Beethoven's Ninth Symphony simultaneously across five continents in near-real time.


The core technology used in a videoconferencing system is digital compression of audio and video streams in real time. The hardware or software that performs compression is called a codec (coder/decoder). Compression rates of up to 1:500 can be achieved. The resulting digital stream of 1s and 0s is subdivided into labeled packets, which are then transmitted through a digital network of some kind (usually ISDN or IP). The use of audio modems in the transmission line allow for the use of POTS, or the Plain Old Telephone System, in some low-speed applications, such as videotelephony, because they convert the digital pulses to/from analog waves in the audio spectrum range.


Typical use of the various technologies described above include calling or conferencing on a one-on-one, one-to-many or many-to-many basis for personal, business, educational, deaf Video Relay Service and tele-medical, diagnostic and rehabilitative use or services. New services utilizing videocalling and videoconferencing, such as teachers and psychologists conducting online sessions, personal videocalls to inmates incarcerated in penitentiaries, and videoconferencing to resolve airline engineering issues at maintenance facilities, are being created or evolving on an ongoing basis.


Videoconferencing is a highly useful technology for real-time telemedicine and telenursing applications, such as diagnosis, consulting, transmission of medical images, etc... With videoconferencing, patients may contact nurses and physicians in emergency or routine situations; physicians and other paramedical professionals can discuss cases across large distances. Rural areas can use this technology for diagnostic purposes, thus saving lives and making more efficient use of health care money. For example, a rural medical center in Ohio, United States, used videoconferencing to successfully cut the number of transfers of sick infants to a hospital 70 miles (110 km) away. This had previously cost nearly $10,000 per transfer.


VRS services have become well developed nationally in Sweden since 1997 and also in the United States since the first decade of the 2000s. With the exception of Sweden, VRS has been provided in Europe for only a few years since the mid-2000s, and as of 2010 has not been made available in many European Union countries, with most European countries still lacking the legislation or the financing for large-scale VRS services, and to provide the necessary telecommunication equipment to deaf users. Germany and the Nordic countries are among the other leaders in Europe, while the United States is another world leader in the provisioning of VRS services.


In May 2005, the first high definition video conferencing systems, produced by LifeSize Communications, were displayed at the Interop trade show in Las Vegas, Nevada, able to provide video at 30 frames per second with a 1280 by 720 display resolution. Polycom introduced its first high definition video conferencing system to the market in 2006. As of the 2010s, high definition resolution for videoconferencing became a popular feature, with most major suppliers in the videoconferencing market offering it.


Some systems are capable of multipoint conferencing with no MCU, stand-alone, embedded or otherwise. These use a standards-based H.323 technique known as "decentralized multipoint", where each station in a multipoint call exchanges video and audio directly with the other stations with no central "manager" or other bottleneck. The advantages of this technique are that the video and audio will generally be of higher quality because they don't have to be relayed through a central point. Also, users can make ad-hoc multipoint calls without any concern for the availability or control of an MCU. This added convenience and quality comes at the expense of some increased network bandwidth, because every station must transmit to every other station directly.


The U.S. Social Security Administration (SSA), which oversees the world's largest administrative judicial system under its Office of Disability Adjudication and Review (ODAR), has made extensive use of videoconferencing to conduct hearings at remote locations. In Fiscal Year (FY) 2009, the U.S. Social Security Administration (SSA) conducted 86,320 videoconferenced hearings, a 55% increase over FY 2008. In August 2010, the SSA opened its fifth and largest videoconferencing-only National Hearing Center (NHC), in St. Louis, Missouri. This continues the SSA's effort to use video hearings as a means to clear its substantial hearing backlog. Since 2007, the SSA has also established NHCs in Albuquerque, New Mexico, Baltimore, Maryland, Falls Church, Virginia, and Chicago, Illinois.


To unambiguously specify the date, dual dating or Old Style (O.S.) and New Style (N.S.) are sometimes used with dates. Dual dating uses two consecutive years because of differences in the starting date of the year, or includes both the Julian and Gregorian dates. Old Style and New Style (N.S.) indicate either whether the start of the Julian year has been adjusted to start on 1 January (N.S.) even though documents written at the time use a different start of year (O.S.), or whether a date conforms to the Julian calendar (O.S.) rather than the Gregorian (N.S.).


The Gregorian calendar was a reform of the Julian calendar instituted in 1582 by Pope Gregory XIII, after whom the calendar was named, by papal bull Inter gravissimas dated 24 February 1582. The motivation for the adjustment was to bring the date for the celebration of Easter to the time of year in which it was celebrated when it was introduced by the early Church. Although a recommendation of the First Council of Nicaea in 325 specified that all Christians should celebrate Easter on the same day, it took almost five centuries before virtually all Christians achieved that objective by adopting the rules of the Church of Alexandria (see Easter for the issues which arose).


Philip II of Spain decreed the change from the Julian to the Gregorian calendar, which affected much of Roman Catholic Europe, as Philip was at the time ruler over Spain and Portugal as well as much of Italy. In these territories, as well as in the Polish–Lithuanian Commonwealth (ruled by Anna Jagiellon) and in the Papal States, the new calendar was implemented on the date specified by the bull, with Julian Thursday, 4 October 1582, being followed by Gregorian Friday, 15 October 1582. The Spanish and Portuguese colonies followed somewhat later de facto because of delay in communication.


During the period between 1582, when the first countries adopted the Gregorian calendar, and 1923, when the last European country adopted it, it was often necessary to indicate the date of some event in both the Julian calendar and in the Gregorian calendar, for example, "10/21 February 1750/51", where the dual year accounts for some countries already beginning their numbered year on 1 January while others were still using some other date. Even before 1582, the year sometimes had to be double dated because of the different beginnings of the year in various countries. Woolley, writing in his biography of John Dee (1527–1608/9), notes that immediately after 1582 English letter writers "customarily" used "two dates" on their letters, one OS and one NS.


The calendar was a refinement to the Julian calendar amounting to a 0.002% correction in the length of the year. The motivation for the reform was to bring the date for the celebration of Easter to the time of the year in which it was celebrated when it was introduced by the early Church. Because the celebration of Easter was tied to the spring equinox, the Roman Catholic Church considered the steady drift in the date of Easter caused by the year being slightly too long to be undesirable. The reform was adopted initially by the Catholic countries of Europe. Protestants and Eastern Orthodox countries continued to use the traditional Julian calendar and adopted the Gregorian reform after a time, for the sake of convenience in international trade. The last European country to adopt the reform was Greece, in 1923.


The Gregorian calendar is a solar calendar. A regular Gregorian year consists of 365 days, but as in the Julian calendar, in a leap year, a leap day is added to February. In the Julian calendar a leap year occurs every 4 years, but the Gregorian calendar omits 3 leap days every 400 years. In the Julian calendar, this leap day was inserted by doubling 24 February, and the Gregorian reform did not change the date of the leap day. In the modern period, it has become customary to number the days from the beginning of the month, and February 29th is often considered as the leap day. Some churches, notably the Roman Catholic Church, delay February festivals after the 23rd by one day in leap years.


Easter was the Sunday after the 15th day of this moon, whose 14th day was allowed to precede the equinox. Where the two systems produced different dates there was generally a compromise so that both churches were able to celebrate on the same day. By the 10th century all churches (except some on the eastern border of the Byzantine Empire) had adopted the Alexandrian Easter, which still placed the vernal equinox on 21 March, although Bede had already noted its drift in 725—it had drifted even further by the 16th century.


Lilius's proposals had two components. Firstly, he proposed a correction to the length of the year. The mean tropical year is 365.24219 days long. As the average length of a Julian year is 365.25 days, the Julian year is almost 11 minutes longer than the mean tropical year. The discrepancy results in a drift of about three days every 400 years. Lilius's proposal resulted in an average year of 365.2425 days (see Accuracy). At the time of Gregory's reform there had already been a drift of 10 days since the Council of Nicaea, resulting in the vernal equinox falling on 10 or 11 March instead of the ecclesiastically fixed date of 21 March, and if unreformed it would drift further. Lilius proposed that the 10-day drift should be corrected by deleting the Julian leap day on each of its ten occurrences over a period of forty years, thereby providing for a gradual return of the equinox to 21 March.


Most Western European countries changed the start of the year to 1 January before they adopted the Gregorian calendar. For example, Scotland changed the start of the Scottish New Year to 1 January in 1600 (this means that 1599 was a short year). England, Ireland and the British colonies changed the start of the year to 1 January in 1752 (so 1751 was a short year with only 282 days) though in England the start of the tax year remained at 25 March (O.S.), 5 April (N.S.) till 1800, when it moved to 6 April. Later in 1752 in September the Gregorian calendar was introduced throughout Britain and the British colonies (see the section Adoption). These two reforms were implemented by the Calendar (New Style) Act 1750.


Extending the Gregorian calendar backwards to dates preceding its official introduction produces a proleptic calendar, which should be used with some caution. For ordinary purposes, the dates of events occurring prior to 15 October 1582 are generally shown as they appeared in the Julian calendar, with the year starting on 1 January, and no conversion to their Gregorian equivalents. For example, the Battle of Agincourt is universally considered to have been fought on 25 October 1415 which is Saint Crispin's Day.


A language-independent alternative used in many countries is to hold up one's two fists with the index knuckle of the left hand against the index knuckle of the right hand. Then, starting with January from the little knuckle of the left hand, count knuckle, space, knuckle, space through the months. A knuckle represents a month of 31 days, and a space represents a short month (a 28- or 29-day February or any 30-day month). The junction between the hands is not counted, so the two index knuckles represent July and August.


The Gregorian reform contained two parts: a reform of the Julian calendar as used prior to Pope Gregory XIII's time and a reform of the lunar cycle used by the Church, with the Julian calendar, to calculate the date of Easter. The reform was a modification of a proposal made by Aloysius Lilius. His proposal included reducing the number of leap years in four centuries from 100 to 97, by making 3 out of 4 centurial years common instead of leap years. Lilius also produced an original and practical scheme for adjusting the epacts of the moon when calculating the annual date of Easter, solving a long-standing obstacle to calendar reform.


Prior to 1917, Turkey used the lunar Islamic calendar with the Hegira era for general purposes and the Julian calendar for fiscal purposes. The start of the fiscal year was eventually fixed at 1 March and the year number was roughly equivalent to the Hegira year (see Rumi calendar). As the solar year is longer than the lunar year this originally entailed the use of "escape years" every so often when the number of the fiscal year would jump. From 1 March 1917 the fiscal year became Gregorian, rather than Julian. On 1 January 1926 the use of the Gregorian calendar was extended to include use for general purposes and the number of the year became the same as in other countries.


Up to February 28 in the calendar you are converting from add one day less or subtract one day more than the calculated value. Remember to give February the appropriate number of days for the calendar you are converting into. When you are subtracting days to move from Julian to Gregorian be careful, when calculating the Gregorian equivalent of February 29 (Julian), to remember that February 29 is discounted. Thus if the calculated value is -4 the Gregorian equivalent of this date is February 24.


In addition to the change in the mean length of the calendar year from 365.25 days (365 days 6 hours) to 365.2425 days (365 days 5 hours 49 minutes 12 seconds), a reduction of 10 minutes 48 seconds per year, the Gregorian calendar reform also dealt with the accumulated difference between these lengths. The canonical Easter tables were devised at the end of the third century, when the vernal equinox fell either on 20 March or 21 March depending on the year's position in the leap year cycle. As the rule was that the full moon preceding Easter was not to precede the equinox the equinox was fixed at 21 March for computational purposes and the earliest date for Easter was fixed at 22 March. The Gregorian calendar reproduced these conditions by removing ten days.


The Council of Trent approved a plan in 1563 for correcting the calendrical errors, requiring that the date of the vernal equinox be restored to that which it held at the time of the First Council of Nicaea in 325 and that an alteration to the calendar be designed to prevent future drift. This would allow for a more consistent and accurate scheduling of the feast of Easter. In 1577, a Compendium was sent to expert mathematicians outside the reform commission for comments. Some of these experts, including Giambattista Benedetti and Giuseppe Moleto, believed Easter should be computed from the true motions of the sun and moon, rather than using a tabular method, but these recommendations were not adopted. The reform adopted was a modification of a proposal made by the Calabrian doctor Aloysius Lilius (or Lilio).


A month after having decreed the reform, the pope with a brief of 3 April 1582 granted to Antonio Lilio, the brother of Luigi Lilio, the exclusive right to publish the calendar for a period of ten years. The Lunario Novo secondo la nuova riforma printed by Vincenzo Accolti, one of the first calendars printed in Rome after the reform, notes at the bottom that it was signed with papal authorization and by Lilio (Con licentia delli Superiori... et permissu Ant(onii) Lilij). The papal brief was later revoked, on 20 September 1582, because Antonio Lilio proved unable to keep up with the demand for copies.