Anti-aircraft warfare or counter-air defence is defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action". They include surface based and air-based weapon systems, associated sensor systems and control arrangements and passive measures, it may be used to protect naval and air forces in any location. However, for most countries the main effort has tended to be'homeland defence'. NATO refers to airborne naval air defence as anti-aircraft warfare. Missile defence is an extension of air defence as are initiatives to adapt air defence to the task of intercepting any projectile in flight. In some countries, such as Britain and Germany during the Second World War, the Soviet Union, NATO, the United States, ground-based air defence and air defence aircraft have been under integrated command and control. However, while overall air defence may be for homeland defence including military facilities, forces in the field, wherever they are, invariably deploy their own air defence capability if there is an air threat.
A surface-based air defence capability can be deployed offensively to deny the use of airspace to an opponent. Until the 1950s, guns firing ballistic munitions ranging from 7.62 mm to 152.4 mm were the standard weapons. The term air defence was first used by Britain when Air Defence of Great Britain was created as a Royal Air Force command in 1925. However, arrangements in the UK were called'anti-aircraft', abbreviated as AA, a term that remained in general use into the 1950s. After the First World War it was sometimes prefixed by'Light' or'Heavy' to classify a type of gun or unit. Nicknames for anti-aircraft guns include AA, AAA or triple-A, an abbreviation of anti-aircraft artillery. NATO defines anti-aircraft warfare as "measures taken to defend a maritime force against attacks by airborne weapons launched from aircraft, ships and land-based sites". In some armies the term All-Arms Air Defence is used for air defence by nonspecialist troops. Other terms from the late 20th century include GBAD with related terms SHORAD and MANPADS.
Anti-aircraft missiles are variously called surface-to-air missile and pronounced "SAM" and Surface to Air Guided Weapon. Non-English terms for air defence include the German FlaK, whence English flak, the Russian term Protivovozdushnaya oborona, a literal translation of "anti-air defence", abbreviated as PVO. In Russian the AA systems are called zenitnye systems. In French, air defence is called DCA; the maximum distance at which a gun or missile can engage an aircraft is an important figure. However, many different definitions are used but unless the same definition is used, performance of different guns or missiles cannot be compared. For AA guns only the ascending part of the trajectory can be usefully used. One term is "ceiling", the maximum ceiling being the height a projectile would reach if fired vertically, not useful in itself as few AA guns are able to fire vertically, maximum fuse duration may be too short, but useful as a standard to compare different weapons; the British adopted "effective ceiling", meaning the altitude at which a gun could deliver a series of shells against a moving target.
By the late 1930s the British definition was "that height at which a directly approaching target at 400 mph can be engaged for 20 seconds before the gun reaches 70 degrees elevation". However, effective ceiling for heavy AA guns was affected by nonballistic factors: The maximum running time of the fuse, this set the maximum usable time of flight; the capability of fire control instruments to determine target height at long range. The precision of the cyclic rate of fire, the fuse length had to be calculated and set for where the target would be at the time of flight after firing, to do this meant knowing when the round would fire; the essence of air defence is to destroy them. The critical issue is to hit a target moving in three-dimensional space; this means that projectiles either have to be guided to hit the target, or aimed at the predicted position of the target at the time the projectile reaches it, taking into account speed and direction of both the target and the projectile. Throughout the 20th century, air defence was one of the fastest-evolving areas of military technology, responding to the evolution of aircraft and exploiting various enabling technologies radar, guided missiles and computing (initially electromechanical analogue computing from the 1930s on, as with equipment describ
Fiji the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean about 1,100 nautical miles northeast of New Zealand's North Island. Its closest neighbours are Vanuatu to the west, New Caledonia to the southwest, New Zealand's Kermadec Islands to the southeast, Tonga to the east, the Samoas and France's Wallis and Futuna to the northeast, Tuvalu to the north. Fiji consists of an archipelago of more than 330 islands—of which 110 are permanently inhabited—and more than 500 islets, amounting to a total land area of about 18,300 square kilometres; the most outlying island is Ono-i-Lau. The two major islands, Viti Levu and Vanua Levu, account for 87% of the total population of 898,760; the capital, Suva, on Viti Levu, serves as the country's principal cruise-ship port. About three-quarters of Fijians live on Viti Levu's coasts, either in Suva or in smaller urban centres such as Nadi—where tourism is the major local industry—or Lautoka, where the sugar-cane industry is paramount.
Due to its terrain, the interior of Viti Levu is sparsely inhabited. The majority of Fiji's islands formed through volcanic activity starting around 150 million years ago; some geothermal activity still occurs today, on the islands of Vanua Taveuni. The geothermal systems on Viti Levu are non-volcanic in origin, with low-temperature surface discharges. Sabeto Hot Springs near Nadi is a good example. Humans have lived in Fiji since the second millennium BC—first Austronesians and Melanesians, with some Polynesian influences. Europeans visited Fiji from the 17th century onwards, after a brief period as an independent kingdom, the British established the Colony of Fiji in 1874. Fiji operated as a Crown colony until 1970. A military government declared a Republic in 1987 following a series of coups d'état. In a coup in 2006, Commodore Frank Bainimarama seized power; when the High Court ruled the military leadership unlawful in 2009, President Ratu Josefa Iloilo, whom the military had retained as the nominal Head of State, formally abrogated the 1997 Constitution and re-appointed Bainimarama as interim Prime Minister.
In 2009, Ratu Epeli Nailatikau succeeded Iloilo as President. After years of delays, a democratic election took place on 17 September 2014. Bainimarama's FijiFirst party won 59.2% of the vote, international observers deemed the election credible. Fiji has one of the most developed economies in the Pacific thanks to its abundant forest and fish resources, its currency is the Fijian dollar, its main sources of foreign exchange are its tourist industry, remittances from Fijians working, bottled water exports. The Ministry of Local Government and Urban Development supervises Fiji's local government, which takes the form of city and town councils. Fiji's main island is known as Viti Levu and it is from this that the name "Fiji" is derived, though the common English pronunciation is based on that of their island neighbours in Tonga, its emergence can be described as follows: Fijians first impressed themselves on European consciousness through the writings of the members of the expeditions of Cook who met them in Tonga.
They were described as formidable warriors and ferocious cannibals, builders of the finest vessels in the Pacific, but not great sailors. They inspired awe amongst the Tongans, all their Manufactures bark cloth and clubs, were valued and much in demand, they called their home Viti, but the Tongans called it Fisi, it was by this foreign pronunciation, first promulgated by Captain James Cook, that these islands are now known. "Feejee", the Anglicised spelling of the Tongan pronunciation, was used in accounts and other writings until the late 19th century, by missionaries and other travellers visiting Fiji. Located in the central Pacific Ocean, Fiji's geography has made it both a destination and a crossroads for migrations for many centuries. According to oral tradition, the indigenous Fijians of today are descendants of the chief Lutunasobasoba and those who arrived with him on the Kaunitoni canoe. Landing at what is now Vuda, the settlers moved inland to the Nakauvadra mountains. Though this oral tradition has not been independently substantiated, the Fijian government promotes it, many tribes today claim to be descended from the children of Lutunasobasoba.
Pottery art from Fijian towns shows that Fiji was settled by Austronesian peoples before or around 3500 to 1000 BC, with Melanesians following around a thousand years although the question of Pacific migration still lingers. It is believed that the Lapita people or the ancestors of the Polynesians settled the islands first but not much is known of what became of them after the Melanesians arrived. Archeological evidence shows signs of settlement on Moturiki Island from 600 BC and as far back as 900 BC. Aspects of Fijian culture are similar to the Melanesian culture of the western Pacific but have a stronger connection to the older Polynesian cultures. Trade between Fiji and neighbouring archipelagos long before European contact is testified by the canoes made from native Fijian trees found in Tonga and Tongan words being part of the language of the Lau group of islands. Pots made in Fiji have been found in Samoa and the Marquesas Islands. In the 10th century, the Tu'i Tonga Empire was established in Tonga, Fiji came within its sphere of influence.
The Tongan influence brought Polynesian cu
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, a fluid is accelerated behind the blade. Propeller dynamics, like those of aircraft wings, can be modelled by Bernoulli's principle and Newton's third law. Most marine propellers are screw propellers with fixed helical blades rotating around a horizontal axis or propeller shaft; the principle employed in using a screw propeller is used in sculling. It is part of the skill of propelling a Venetian gondola but was used in a less refined way in other parts of Europe and elsewhere. For example, propelling a canoe with a single paddle using a "pitch stroke" or side slipping a canoe with a "scull" involves a similar technique. In China, called "lu", was used by the 3rd century AD. In sculling, a single blade is moved through an arc, from side to side taking care to keep presenting the blade to the water at the effective angle.
The innovation introduced with the screw propeller was the extension of that arc through more than 360° by attaching the blade to a rotating shaft. Propellers can have a single blade, but in practice there are nearly always more than one so as to balance the forces involved; the origin of the screw propeller starts with Archimedes, who used a screw to lift water for irrigation and bailing boats, so famously that it became known as Archimedes' screw. It was an application of spiral movement in space to a hollow segmented water-wheel used for irrigation by Egyptians for centuries. Leonardo da Vinci adopted the principle to drive his theoretical helicopter, sketches of which involved a large canvas screw overhead. In 1661, Toogood and Hays proposed using screws for waterjet propulsion, though not as a propeller. Robert Hooke in 1681 designed a horizontal watermill, remarkably similar to the Kirsten-Boeing vertical axis propeller designed two and a half centuries in 1928. In 1752, the Academie des Sciences in Paris granted Burnelli a prize for a design of a propeller-wheel.
At about the same time, the French mathematician Alexis-Jean-Pierre Paucton, suggested a water propulsion system based on the Archimedean screw. In 1771, steam-engine inventor James Watt in a private letter suggested using "spiral oars" to propel boats, although he did not use them with his steam engines, or implement the idea; the first practical and applied use of a propeller on a submarine dubbed Turtle, designed in New Haven, Connecticut, in 1775 by Yale student and inventor David Bushnell, with the help of the clock maker and brass foundryman Isaac Doolittle, with Bushnell's brother Ezra Bushnell and ship's carpenter and clock maker Phineas Pratt constructing the hull in Saybrook, Connecticut. On the night of September 6, 1776, Sergeant Ezra Lee piloted Turtle in an attack on HMS Eagle in New York Harbor. Turtle has the distinction of being the first submarine used in battle. Bushnell described the propeller in an October 1787 letter to Thomas Jefferson: "An oar formed upon the principle of the screw was fixed in the forepart of the vessel its axis entered the vessel and being turned one way rowed the vessel forward but being turned the other way rowed it backward.
It was made to be turned by the hand or foot." The brass propeller, like all the brass and moving parts on Turtle, was crafted by the "ingenious mechanic" Issac Doolittle of New Haven. In 1785, Joseph Bramah in England proposed a propeller solution of a rod going through the underwater aft of a boat attached to a bladed propeller, though he never built it. In 1802, Edward Shorter proposed using a similar propeller attached to a rod angled down temporarily deployed from the deck above the waterline and thus requiring no water seal, intended only to assist becalmed sailing vessels, he tested it on the transport ship Doncaster in Gibraltar and at Malta, achieving a speed of 1.5 mph. The lawyer and inventor John Stevens in the United States, built a 25-foot boat with a rotary stem engine coupled to a four-bladed propeller, achieving a speed of 4 mph, but he abandoned propellers due to the inherent danger in using the high-pressure steam engines, instead built paddle-wheeled boats. By 1827, Czech-Austrian inventor Josef Ressel had invented a screw propeller which had multiple blades fastened around a conical base.
He had tested his propeller in February 1826 on a small ship, manually driven. He was successful in using his bronze screw propeller on an adapted steamboat, his ship, Civetta of 48 gross register tons, reached a speed of about 6 knots. This was the first ship driven by an Archimedes screw-type propeller. After a new steam engine had an accident his experiments were banned by the Austro-Hungarian police as dangerous. Josef Ressel was at the time a forestry inspector for the Austrian Empire, but before this he received an Austro-Hungarian patent for his propeller. He died in 1857; this new method of propulsion was an improvement over the paddlewheel as it was not so affected by either ship motions or changes in draft as the vessel burned coal. John Patch, a mariner in Yarmouth, Nova Scotia developed a two-bladed, fan-shaped propeller in 1832 and publicly demonstrated it in 1833, propelling a row boat across Yarmouth Harbour and a small coastal schooner at Saint John, New Brunswick, but his patent application in the United States was rejected until 1849 because he was not an American citizen.
His efficient design drew praise in American scientific circles but by
Terminal Island is a artificial island located in Los Angeles County, between the neighborhood of San Pedro in the city of Los Angeles, the city of Long Beach. Terminal Island is split between the Port of Los Angeles and Port of Long Beach. Land use on the island is industrial and port-related, as well as the Federal Correctional Institution, Terminal Island; the island was called Isla Raza de Buena Gente and Rattlesnake Island. It was renamed Terminal Island in 1891. In 1909, the newly reincorporated Southern California Edison Company decided to build a new steam station to provide reserve capacity and emergency power for the entire Edison system, to enable Edison to shut down some of its small, obsolete steam plants; the site chosen for the new plant was on a barren mudflat known as Rattlesnake Island, today's Terminal Island in Long Beach Harbor. Construction of Plant No. 1 began in 1910. The land area of Terminal Island has been supplemented from its original size. For instance, in the late 1920s, Deadman's Island in the main channel of the Port of Los Angeles was dynamited and dredged away, the resulting rubble was used to add 62 acres to the island's southern tip.
In 1930, the Ford Motor Company built a facility called Long Beach Assembly, having moved earlier operations from Downtown Los Angeles. The factory remained until 1958. In 1927, a civilian facility, Allen Field, was established on Terminal Island; the Naval Reserve established a training center at the field and took complete control, designating the field Naval Air Base San Pedro. In 1941 the Long Beach Naval Station became located adjacent to the airfield. In 1942 the Naval Reserve Training Facility was transferred, a year NAB San Pedro's status was downgraded to a Naval Air Station. Reeves Field as a Naval Air Station was disestablished in 1947, although the adjacent Long Beach Naval Station would continue to use Reeves Field as an auxiliary airfield until the late 1990s. A large industrial facility now covers the site of the former Naval Air Station; the island was home to about 3,500 first- and second-generation Japanese Americans prior to World War II in an area known as East San Pedro or Fish Island.
Following the attack on Pearl Harbor, all of the adult Issei males on Terminal Island were incarcerated by the FBI on February 9, 1942. After the signing of Executive Order 9066 on February 19, 1942, the rest of the inhabitants were given 48 hours to evacuate their homes, they were subsequently sent to internment camps, the entire neighborhood was razed. The Japanese community on Terminal Island was the first to be interned en masse; because of the relative geographical isolation of the island, the citizens developed their own culture and their own dialect. After World War II, the Terminal Islanders settled elsewhere. In 1971, they formed the Terminal Islanders Club, which has organized various events for its members. In 2002, the surviving second-generation citizens set up a memorial on Terminal Island to honor their parents. During World War II, Terminal Island was an important center for defense industries shipbuilding, it was therefore, one of the first places where African Americans tried to effect their integration into defense-related work on the West Coast.
In 1946, Howard Hughes moved his monstrous Spruce Goose airplane from his plant in Culver City to Terminal Island in preparation for its test flight. In its first and only flight, it took off from the island on November 2, 1947. Brotherhood Raceway Park, a 1⁄4 mile drag racing strip, opened in 1974 on former US Navy land, it operated, with many interruptions, until closing in 1995 to be replaced by a coal-handling facility. Preservation of vacant buildings earned the island a spot on the top 11 sites on the National Trust for Historic Preservation's 2012 Most Endangered Historic Places List. In mid-2013, the Los Angeles Board of Harbor Commissioners approved a preservation plan; the trust cited the site as one of ten historic sites saved in 2013. The west half of the island is part of the San Pedro area of the city of Los Angeles, while the rest is part of the city of Long Beach; the island has a land area of 11.56 km2, or 2,854 acres, had a population of 1,467 at the 2000 census. The Port of Los Angeles and the Port of Long Beach are the major landowners on the island, who in turn lease much of their land for container terminals and bulk terminals.
The island hosts canneries and United States Coast Guard facilities. The Federal Correctional Institution, Terminal Island, which began operating in 1938, hosts more than 900 low security federal prisoners; the Long Beach Naval Shipyard, decommissioned in 1997, occupied half of the island. Sea Launch maintains docking facilities on the mole, part of the naval station. Aerospace company SpaceX intends to build a factory on the island at Berth 240 to construct its planned BFR manned space transportation system intended for suborbital and interplanetary flight; the new SpaceX rocket, too large to be transported for long distances overland, will be shipped to the company's launch area in Florida by sea, via the Panama Canal. The 19 acres site was used for shipbuilding from 1918, was operated by the Bethlehem Shipbuilding Corporation and the Southwest Marine Shipyard; the location has been disused since 2005. While the new site is being prepared SpaceX has set up a temporary facility in a tent structure on a lot at 801 Reeves Avenue, leased from Sea-Logix.
The tent has been erected on the site of Navy Operations Support Command LA's former commiss
USS Mount Hood (AE-11)
USS Mount Hood was the lead ship of her class of ammunition ships for the United States Navy in World War II. She was the first ship named after a volcano in the Cascade Range in Oregon. On 10 November 1944, shortly after 18 men had departed for shore leave, the rest of the crew were killed when the ship exploded in Seeadler Harbor at Manus Island in Papua New Guinea; the ship was obliterated while sinking or damaging 22 smaller craft nearby. Marco Polo was a cargo ship built under a US Maritime Commission contract, by the North Carolina Shipbuilding Co. Wilmington, N. C.. The ship was renamed Mount Hood, 10 November 1943. Norfolk and the Norfolk Navy Yard. Harold A. Turner in command. Following an abbreviated fitting out and shakedown period in the Chesapeake Bay area, ammunition ship Mount Hood reported for duty to ComServFor, Atlantic Fleet, 5 August 1944. Assigned to carry cargo to the Pacific, she put into Norfolk. On 21 August, as a unit of Task Group 29.6, she transited the Panama Canal on the 27th, continued on, via Finschafen, New Guinea.
Mount Hood arrived in Manus Island of the Admiralty Islands, on 22 September. Assigned to ComSoWesPac, she commenced dispensing ammunition and explosives to ships preparing for the Philippine offensive. At 08:30, 10 November 1944, a party consisting of communications officer, Lt. Lester H. Wallace, 13 men left the ship and headed for shore. At 08:55, while walking on the beach, they saw a flash from the harbor, followed by two quick explosions. Scrambling into their boat, they headed back to the ship, only to turn around again shortly thereafter as "There was nothing but debris all around..." Mount Hood, anchored in about 35 feet of water, had exploded with an estimated 3,800 tons of ordnance material on board. The initial explosion caused flame and smoke to shoot up from amidships to more than masthead height. Within seconds, the bulk of her cargo detonated with a more intense explosion. Mushrooming smoke rose to 7,000 feet, obscuring the ship and the surrounding area for a radius of 500 yards.
Mount Hood's former position was revealed by a trench in the ocean floor 1,000 feet long, 200 feet wide, 30 to 40 feet deep. The largest remaining piece of the hull was found in the trench and measured no bigger than 16 by 10 feet. No other remains of Mount Hood were found except fragments of metal which had struck other ships in the harbor and a few tattered pages of a signal notebook found floating in the water several hundred yards away. No human remains were recovered of the 350 men aboard Mount Hood or small boats loading alongside at the time of the explosion; the only other survivors from the Mount Hood crew were a junior officer and five enlisted men who had left the ship a short time before the explosion. Two of the crew were being transferred to the base brig for trial by court martial. Charges against the prisoners were dropped following the explosion; the concussion and metal fragments hurled from the ship caused casualties and damage to ships and small craft within 2,000 yards. The repair ship Mindanao, broadside-on to the blast, was the most damaged.
All personnel topside on Mindanao were killed outright, dozens of men were killed or wounded below decks as numerous heavy fragments from Mount Hood penetrated the side plating. Eighty-two of Mindanao's crew died; the damage to other vessels required more than 100,000 man-hours to repair, while 22 small boats and landing craft were sunk, destroyed, or damaged beyond repair. A board convened to examine evidence relating to the disaster was unable to ascertain the exact cause. After only a little over four months' service, Mount Hood was struck from the Naval Register on 11 December 1944; the following ships were damaged by the explosion of Mount Hood: In addition to the above ships, nine medium landing craft and a pontoon barge moored alongside Mount Hood were destroyed, 13 small boats or landing craft were sunk or damaged beyond repair. Port Chicago disaster List of accidents and incidents involving transport or storage of ammunition This article incorporates text from the public domain Dictionary of American Naval Fighting Ships.
The entry can be found here. Gile, Chester A.. "The Mount Hood Explosion". Proceedings. United States Naval Institute. Photo gallery of Mount Hood at NavSource Naval History AE Sailors Association Selected documents relating to the loss of USS Mount Hood photos from history.navy.mil Roll of Honor Navy Board of Investigation Official Report
A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder; this pushing force is transformed, into rotational force for work. The term "steam engine" is applied only to reciprocating engines as just described, not to the steam turbine. Steam engines are external combustion engines, where the working fluid is separated from the combustion products; the ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine. Steam-driven devices were known as early as the aeliopile in the first century AD, with a few other uses recorded in the 16th and 17th century. Thomas Savery's dewatering pump used steam pressure operating directly on water.
The first commercially-successful engine that could transmit continuous power to a machine was developed in 1712 by Thomas Newcomen. James Watt made a critical improvement by removing spent steam to a separate vessel for condensation improving the amount of work obtained per unit of fuel consumed. By the 19th century, stationary steam engines powered the factories of the Industrial Revolution. Steam engines replaced sail for ships, steam locomotives operated on the railways. Reciprocating piston type steam engines were the dominant source of power until the early 20th century, when advances in the design of electric motors and internal combustion engines resulted in the replacement of reciprocating steam engines in commercial usage. Steam turbines replaced reciprocating engines in power generation, due to lower cost, higher operating speed, higher efficiency; the first recorded rudimentary steam-powered "engine" was the aeolipile described by Hero of Alexandria, a mathematician and engineer in Roman Egypt in the first century AD.
In the following centuries, the few steam-powered "engines" known were, like the aeolipile experimental devices used by inventors to demonstrate the properties of steam. A rudimentary steam turbine device was described by Taqi al-Din in Ottoman Egypt in 1551 and by Giovanni Branca in Italy in 1629. Jerónimo de Ayanz y Beaumont received patents in 1606 for 50 steam powered inventions, including a water pump for draining inundated mines. Denis Papin, a Huguenot refugee, did some useful work on the steam digester in 1679, first used a piston to raise weights in 1690; the first commercial steam-powered device was a water pump, developed in 1698 by Thomas Savery. It used condensing steam to create a vacuum which raised water from below and used steam pressure to raise it higher. Small engines were effective, they were prone to boiler explosions. Savery's engine was used in mines, pumping stations and supplying water to water wheels that powered textile machinery. Savery engine was of low cost. Bento de Moura Portugal introduced an improvement of Savery's construction "to render it capable of working itself", as described by John Smeaton in the Philosophical Transactions published in 1751.
It continued to be manufactured until the late 18th century. One engine was still known to be operating in 1820; the first commercially-successful engine that could transmit continuous power to a machine, was the atmospheric engine, invented by Thomas Newcomen around 1712. It improved on Savery's steam pump. Newcomen's engine was inefficient, used for pumping water, it worked by creating a partial vacuum by condensing steam under a piston within a cylinder. It was employed for draining mine workings at depths hitherto impossible, for providing reusable water for driving waterwheels at factories sited away from a suitable "head". Water that passed over the wheel was pumped up into a storage reservoir above the wheel. In 1720 Jacob Leupold described a two-cylinder high-pressure steam engine; the invention was published in his major work "Theatri Machinarum Hydraulicarum". The engine used two heavy pistons to provide motion to a water pump; each piston was returned to its original position by gravity.
The two pistons shared a common four way rotary valve connected directly to a steam boiler. The next major step occurred when James Watt developed an improved version of Newcomen's engine, with a separate condenser. Boulton and Watt's early engines used half as much coal as John Smeaton's improved version of Newcomen's. Newcomen's and Watt's early engines were "atmospheric", they were powered by air pressure pushing a piston into the partial vacuum generated by condensing steam, instead of the pressure of expanding steam. The engine cylinders had to be large because the only usable force acting on them was atmospheric pressure. Watt developed his engine further, modifying it to provide a rotary motion suitable for driving machinery; this enabled factories to be sited away from rivers, accelerated the pace of the Industrial Revolution. The meaning of high pressure, together with an actual value above ambient, depends on the era in which the term was used. For early use of the term Van Reimsdijk refers to steam being at a sufficiently high pressure that it could be exhausted to atmosphere without reliance on a vacuum to enable it to perform useful work.
Ewing states that Watt's condensing engines were known, at the time, as low pressure compared to high pressure, non-condensing engines of the same period. Watt's patent prevented others from making high pres
Canis Major is a constellation in the southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, is counted among the 88 modern constellations, its name is Latin for "greater dog" in contrast to Canis Minor, the "lesser dog". The Milky Way passes through Canis Major and several open clusters lie within its borders, most notably M41. Canis Major contains Sirius, the brightest star in the night sky, known as the "dog star", it is bright because of its proximity to the Solar System. In contrast, the other bright stars of the constellation are stars of great distance and high luminosity. At magnitude 1.5, Epsilon Canis Majoris is the second-brightest star of the constellation and the brightest source of extreme ultraviolet radiation in the night sky. Next in brightness are the yellow-white supergiant Delta at 1.8, the blue-white giant Beta at 2.0, blue-white supergiants Eta at 2.4 and Omicron1 at 3.0, white spectroscopic binary Zeta at 3.0. The red hypergiant VY Canis Majoris is one of the largest stars known, while the neutron star RX J0720.4-3125 has a radius of a mere 5 km.
In ancient Mesopotamia, named KAK. SI. DI by the Babylonians, was seen as an arrow aiming towards Orion, while the southern stars of Canis Major and a part of Puppis were viewed as a bow, named BAN in the Three Stars Each tablets, dating to around 1100 BC. In the compendium of Babylonian astronomy and astrology titled MUL. APIN, the arrow, was linked with the warrior Ninurta, the bow with Ishtar, daughter of Enlil. Ninurta was linked to the deity Marduk, said to have slain the ocean goddess Tiamat with a great bow, worshipped as the principal deity in Babylon; the Ancient Greeks replaced the arrow depiction with that of a dog. In Greek Mythology, Canis Major represented a gift from Zeus to Europa, it was considered to represent one of Orion's hunting dogs, pursuing Lepus the Hare or helping Orion fight Taurus the Bull. The ancient Greeks refer only to one dog, but by Roman times, Canis Minor appears as Orion's second dog. Alternative names include Canis Sequens and Canis Alter. Canis Syrius was the name used in the 1521 Alfonsine tables.
The Roman myth refers to Canis Major as Custos Europae, the dog guarding Europa but failing to prevent her abduction by Jupiter in the form of a bull, as Janitor Lethaeus, "the watchdog". In medieval Arab astronomy, the constellation became al-Kalb al-Akbar, "the Greater Dog", transcribed as Alcheleb Alachbar by 17th century writer Edmund Chilmead. Islamic scholar Abū Rayḥān al-Bīrūnī referred to Orion as Kalb al-Jabbār, "the Dog of the Giant". Among the Merazig of Tunisia, shepherds note six constellations that mark the passage of the dry, hot season. One of them, called Merzem, includes the stars of Canis Major and Canis Minor and is the herald of two weeks of hot weather. In Chinese astronomy, the modern constellation of Canis Major is located in the Vermilion Bird, where the stars were classified in several separate asterisms of stars; the Military Market was a circular pattern of stars containing Nu3, Beta, Xi1 and Xi2, some stars from Lepus. The Wild Cockerel was at the centre of the Military Market, although it is uncertain which stars depicted what.
Schlegel reported that the stars Omicron and Pi Canis Majoris might have been them, while Beta or Nu2 have been proposed. Sirius was the Celestial Wolf, denoting invasion and plunder. Southeast of the Wolf was the asterism Húshǐ, the celestial Bow and Arrow, interpreted as containing Delta, Epsilon and Kappa Canis Majoris and Delta Velorum. Alternatively, the arrow was depicted by Omicron2 and Eta and aiming at Sirius, while the bow comprised Kappa, Sigma, Delta and 164 Canis Majoris, Pi and Omicron Puppis. Both the Māori people and the people of the Tuamotus recognized the figure of Canis Major as a distinct entity, though it was sometimes absorbed into other constellations. Te Huinga-o-Rehua called Te Putahi-nui-o-Rehua and Te Kahui-Takurua, was a Māori constellation that included both Canis Minor and Canis Major, along with some surrounding stars. Related was Taumata-o-Rehua called Pukawanui, the Mirror of Rehua, formed from an undefined group of stars in Canis Major, they called Sirius Rehua and Takarua, corresponding to two of the names for the constellation, though Rehua was a name applied to other stars in various Māori groups and other Polynesian cosmologies.
The Tuamotu people called Canis Major Muihanga-hetika-o-Takurua, "the abiding assemblage of Takarua". The Tharumba people of the Shoalhaven River saw three stars of Canis Major as Wunbula and his two wives Murrumbool and Moodtha, he spears them and all three are placed in the sky as the constellation Munowra. To the Boorong people of Victoria, Sigma Canis Majoris was Unurgunite, its flanking stars Delta and Epsilon were his two wives; the moon sought to lure the further wife away, but Unurgunite assaulted him and he has been wandering the sky since. Canis Major is a constellation in the Southern Hemisphere's summer sky, bordered by Mo