A bunker is a defensive military fortification designed to protect people and valued materials from falling bombs or other attacks. Bunkers are underground, in contrast to blockhouses which are above ground, they were used extensively in World War I, World War II, the Cold War for weapons facilities and control centers, storage facilities. Bunkers can be used as protection from tornadoes. Trench bunkers are small concrete structures dug into the ground. Many artillery installations for coastal artillery, have been protected by extensive bunker systems. Typical industrial bunkers include mining sites, food storage areas, dumps for materials, data storage, sometimes living quarters; when a house is purpose-built with a bunker, the normal location is a reinforced below-ground bathroom with fibre-reinforced plastic shells. Bunkers deflect the blast wave from nearby explosions to prevent ear and internal injuries to people sheltering in the bunker. Nuclear bunkers must cope with the underpressure that lasts for several seconds after the shock wave passes, block radiation.
A bunker's door must be at least as strong as the walls. In bunkers inhabited for prolonged periods, large amounts of ventilation or air conditioning must be provided. Bunkers can be destroyed with bunker-busting warheads; the word bunker originates as a Scots word for "bench, seat" recorded 1758, alongside shortened bunk "sleeping berth". The word has a Scandinavian origin: Old Swedish bunke means "boards used to protect the cargo of a ship". In the 19th century the word came to describe a coal store below decks in a ship, it was used for a sand-filled depression installed on a golf course as a hazard. In the First World War as the belligerents built underground shelters called dugouts in English, while the Germans used the term bunker: By the Second World War the term came to be used by the Germans to describe permanent structures both large; the military sense of the word was imported into English during World War II, at first in reference to German dug-outs. All the early references to its usage in the Oxford English Dictionary are to German fortifications.
However in the Far East the term was applied to the earth and log positions built by the Japanese, the term appearing in a 1943 instruction manual issued by the British Indian Army and gaining wide currency. By 1947 the word was familiar enough in English that Hugh Trevor-Roper in The Last Days of Hitler was describing Hitler's underground complex near the Reich Chancellery as "Hitler's own bunker" without quotes around the word bunker; this type of bunker is a small concrete structure dug into the ground, a part of a trench system. Such bunkers give the defending soldiers better protection than the open trench and include top protection against aerial attack, they provide shelter against the weather. Some bunkers may have open tops to allow weapons to be discharged with the muzzle pointing upwards. Many artillery installations for coastal artillery, have been protected by extensive bunker systems; these housed the crews serving the weapons, protected the ammunition against counter-battery fire, in numerous examples protected the guns themselves, though this was a trade-off reducing their fields of fire.
Artillery bunkers are some of the largest individual pre-Cold War bunkers. The walls of the'Batterie Todt' gun installation in northern France were up to 3.5 metres thick, an underground bunker was constructed for the V-3 cannon. Typical industrial bunkers include mining sites, food storage areas, dumps for materials, data storage, sometimes living quarters, they were built by nations like Germany during World War II to protect important industries from aerial bombardment. Industrial bunkers are built for control rooms of dangerous activities, such as tests of rocket engines or explosive experiments, they are built in order to perform dangerous experiments in them or to store radioactive or explosive goods. Such bunkers exist on non-military facilities; when a house is purpose-built with a bunker, the normal location is a reinforced below-ground bathroom with large cabinets. One common design approach uses fibre-reinforced plastic shells. Compressive protection may be provided by inexpensive earth arching.
The overburden is designed to shield from radiation. To prevent the shelter from floating to the surface in high groundwater, some designs have a skirt held-down with the overburden, it may serve the purpose of a safe room. Munitions storage bunkers are designed to securely store explosive ordnance, contain any internal explosions; the most common configuration for high explosives storage is the igloo shaped bunker. They are built into a hillside in order to provide additional containment mass. A specialized version of the munitions bunker called a Gravel Gertie is designed to contain radioactive debris from an explosive accident while assembling or disassembling nuclear warheads, they are installed at all facilities in the United States and United Kingdom which do warhead assembly and disassembly, the largest being the Pantex plant in Amarillo, which has 12 Gravel Gerties. Bunkers deflect the blast wave from nearby explosions to prevent ear and internal injuri
USS Yorktown (CV-10)
USS Yorktown is one of 24 Essex-class aircraft carriers built during World War II for the United States Navy. She was named after the Battle of Yorktown of the American Revolutionary War, is the fourth U. S. Navy ship to bear the name. To have been named Bonhomme Richard, she was renamed Yorktown while still under construction to commemorate the loss of USS Yorktown during the Battle of Midway in June 1942. Yorktown was commissioned in April 1943, participated in several campaigns in the Pacific Theater of Operations, earning 11 battle stars and the Presidential Unit Citation. Decommissioned shortly after the end of the war, she was modernized and recommissioned in February 1953 as an attack carrier, served with distinction during the Korean War; the ship was modernized again with a canted deck becoming an antisubmarine carrier and served for many years in the Pacific, including duty in the Vietnam War, during which she earned five battle stars. Late in her career, the carrier served as a recovery ship for the Apollo 8 space mission, was used in the movie Tora!
Tora! Tora!, which recreated the Japanese attack on Pearl Harbor, in the science fiction film The Philadelphia Experiment. Yorktown was decommissioned in 1970 and in 1975 became a museum ship at Patriots Point, Mount Pleasant, South Carolina, where she was designated a National Historic Landmark. Work was begun on Bon Homme Richard when her keel was laid down on 1 December 1941 at Newport News, Virginia, by the Newport News Shipbuilding & Drydock Company, six days before the Attack on Pearl Harbor, she was renamed on 26 September 1942 as USS Yorktown CV10, launched on 21 January 1943, sponsored by Eleanor Roosevelt. Yorktown was commissioned on 15 April 1943, with Captain Joseph J. Clark in command. Yorktown remained in the Naval Station Norfolk area until 21 May, when she got underway for shakedown training in the vicinity of Trinidad, she began post-shakedown availability. The aircraft carrier completed repairs on 1 July and began air operations out of Norfolk until 6 July, when she exited Chesapeake Bay on her way to the Pacific Ocean.
She departed Balboa, Panama, on 12 July. The warship arrived in Pearl Harbor on 24 July and began a month of exercises in the Hawaiian Islands. On 22 August, she stood out of Pearl Harbor, bound for her first combat of the war, her task force, TF 15, arrived at the launching point about 128 miles from Marcus Island early on the morning of 31 August. She spent most of that day launching fighter and bomber strikes on Marcus Island before beginning the retirement to Hawaii that evening; the aircraft carrier remained there for two days. On 9 September, she stood out to sea, bound for the West Coast of the United States, she arrived in San Francisco on 13 September, loaded aircraft and supplies, returned to sea on 15 September. Four days the aircraft carrier reentered Pearl Harbor. Yorktown returned to sea to conduct combat operations on 29 September. Early on the morning of 5 October, she began two days of air strikes on Japanese installations on Wake Island. After retiring to the east for the night, she resumed those air raids early on the morning of 6 October and continued them through most of the day.
That evening, the task group began its retirement to Hawaii. Yorktown arrived at Oahu on 11 October and, for the next month, conducted air training operations out of Pearl Harbor. On 10 November, Yorktown departed Pearl Harbor in company with Task Force 38—the Fast Carrier Task Force, Pacific Fleet—to participate in her first major assault operation, the occupation of the Gilbert Islands. On 19 November, she arrived at the launch point near Jaluit and Mili Atoll and, early that morning, launched the first of a series of raids to suppress enemy airpower during the amphibious assaults on Tarawa and Makin; the next day, she sent raids back to the airfield at Jaluit. On 22 November, her air group concentrated upon planes at Mili once again. Before returning to Pearl Harbor, the aircraft carrier made passing raids on the installations at Wotje and Kwajalein Atolls on 4 December; the warship reentered Pearl Harbor on 9 December and began a month of air training operations in the Hawaiian Islands. On 16 January 1944, the warship exited Pearl Harbor once again to support an amphibious assault – Operation Flintlock, the Marshall Islands invasion.
Her task group, Task Group 58.1, arrived at its launching point early on the morning of 29 January, its carriers – Yorktown and Cowpens – began sending air strikes aloft at about 05:20 for attacks on Taroa airfield located on Maloelap Atoll. Throughout the day, her aircraft hit Maloelap in preparation for the assaults on Majuro and Kwajalein scheduled for 31 January. On 30 January and her sister carriers shifted targets to Kwajalein to begin softening up one of the targets; when the troops stormed ashore on 31 January, Yorktown aviators continued their strikes on Kwajalein in support of the troops attacking that atoll. The same employment occupied the Yorktown air group during the first three days in February. On 4 February, the task group retired to the fleet anchorage at secured Majuro Atoll. Over the next four months, Yorktown participated in a series of raids in which she ranged from the Marianas in the north to New Guinea in the south. After eight days at Majuro, she sortied with her task group on 12 February to conduct air strikes on the main Japanese anchorage at Truk Atoll.
Those successful raids occurred on 16–17 February. On 18 February, the carrier set a course for the Marianas
Tuvalu known as the Ellice Islands, is a Polynesian island country located in the Pacific Ocean, situated in Oceania, about midway between Hawaii and Australia. It lies east-northeast of the Santa Cruz Islands, southeast of Nauru, south of Kiribati, west of Tokelau, northwest of Samoa and Wallis and Futuna, north of Fiji, it comprises three reef islands and six true atolls spread out between the latitude of 5° to 10° south and longitude of 176° to 180°, west of the International Date Line. Tuvalu has a population of 10,640; the total land area of the islands of Tuvalu is 26 square kilometres. The first inhabitants of Tuvalu were Polynesians; the origins of the people of Tuvalu are addressed in the theories regarding migration into the Pacific that began about 3000 years ago. During pre-European-contact times there was frequent canoe voyaging between the islands as Polynesian navigation skills are recognised to have allowed deliberate journeys on double-hull sailing canoes or outrigger canoes.
The pattern of settlement, believed to have occurred is that the Polynesians spread out from Samoa and Tonga into the Tuvaluan atolls, with Tuvalu providing a stepping stone to further migration into the Polynesian outliers in Melanesia and Micronesia. In 1568, Spanish navigator Álvaro de Mendaña was the first European to sail through the archipelago, sighting the island of Nui during his expedition in search of Terra Australis; the island of Funafuti was named Ellice's Island in 1819. The Ellice Islands came into Great Britain's sphere of influence in the late 19th century, as the result of a treaty between Great Britain and Germany relating to the demarcation of the spheres of influence in the Pacific Ocean; each of the Ellice Islands was declared a British Protectorate by Captain Gibson of HMS Curacoa between 9 and 16 October 1892. The Ellice Islands were administered as a British protectorate by a Resident Commissioner from 1892 to 1916, as part of the British Western Pacific Territories, as part of the Gilbert and Ellice Islands colony from 1916 to 1976.
A referendum was held in December 1974 to determine whether the Gilbert Islands and Ellice Islands should each have their own administration. As a consequence of the referendum, the Gilbert and Ellice Islands colony ceased to exist on 1 January 1976, the separate British colonies of Kiribati and Tuvalu came into existence. Tuvalu became independent within the Commonwealth on 1 October 1978. On 5 September 2000, Tuvalu became the 189th member of the United Nations; the origins of the people of Tuvalu are addressed in the theories regarding migration into the Pacific that began about 3000 years ago. During pre-European-contact times there was frequent canoe voyaging between the nearer islands including Samoa and Tonga. Eight of the nine islands of Tuvalu were inhabited. Possible evidence of fire in the Caves of Nanumanga may indicate human occupation for thousands of years. An important creation myth of the islands of Tuvalu is the story of the te Pusi mo te Ali who created the islands of Tuvalu.
The stories as to the ancestors of the Tuvaluans vary from island to island. On Niutao and Vaitupu, the founding ancestor is described as being from Samoa, whereas on Nanumea, the founding ancestor is described as being from Tonga. Tuvalu was first sighted by Europeans on 16 January 1568, during the voyage of Álvaro de Mendaña from Spain, who sailed past Nui and charted it as Isla de Jesús because the previous day was the feast of the Holy Name. Mendaña was unable to land. During Mendaña's second voyage across the Pacific he passed Niulakita on 29 August 1595, which he named La Solitaria. Captain John Byron passed through the islands of Tuvalu in 1764, during his circumnavigation of the globe as captain of the Dolphin, he charted the atolls as Lagoon Islands. Keith S. Chambers and Doug Munro identified Niutao as the island that Francisco Mourelle de la Rúa sailed past on 5 May 1781, thus solving what Europeans had called The Mystery of Gran Cocal. Mourelle's map and journal named the island El Gran Cocal.
Longitude could only be reckoned crudely at the time, as accurate chronometers only became available in the late 18th century. The next European to visit was Arent Schuyler de Peyster, of New York, captain of the armed brigantine or privateer Rebecca, sailing under British colours, which passed through the southern Tuvaluan waters in May 1819; the name Ellice was applied to all nine islands after the work of English hydrographer Alexander George Findlay. In 1820, the Russian explorer Mikhail Lazarev visited Nukufetau as commander of the Mirny. Louis Isidore Duperrey, captain of La Coquille, sailed past Nanumanga in May 1824 during a circumnavigation of the earth. A Dutch expedition found Nui on the morning of 14 June 1825, named the main island as Nederlandsch Eiland. Whalers began roving the Pacific, although they visited Tuvalu only in
Rabaul is a township in East New Britain province, on the island of New Britain, in the country of Papua New Guinea. It lies about 60 kilometres to the east of the island of New Guinea. Rabaul was the provincial capital and most important settlement in the province until it was destroyed in 1994 by falling ash of a volcanic eruption in its harbor. During the eruption, ash was sent thousands of metres into the air and the subsequent rain of ash caused 80% of the buildings in Rabaul to collapse. After the eruption the capital was moved to Kokopo, about 20 kilometres away. Rabaul is continually threatened by volcanic activity because it is on the edge of Rabaul caldera, a flooded caldera of a large pyroclastic shield. Rabaul was planned and built around the harbor area known as Simpsonhafen during the German New Guinea administration which controlled the region between 1884 and formally through 1919. From 1910 Rabaul was the headquarters of German New Guinea until captured by the British Empire during the early days of World War I.
It became the capital of the Australian mandated Territory of New Guinea until 1937 when it was first destroyed by a volcano. During World War II it was captured by Japan in 1942, became its main base of military and naval activity in the South Pacific. Settlements and military installations around the edge of the caldera are collectively called Rabaul, although the old town of Rabaul was reduced to practical insignificance by the volcanic eruption in 1937; as a tourist destination, Rabaul is popular for its volcanoes, scuba diving and for snorkeling sites, spectacular harbour and other scenery, World War II history and fauna, the cultural life of the Tolai people. Before the 1994 eruption, Rabaul was a popular commercial and recreational boating destination. Tourism is a major industry in East New Britain generally. Rabaul's proximity to its volcanoes has always been a source of concern. In 1878 before it was established as a town, an eruption formed a volcano in the harbour. For older eruptions, see Rabaul caldera.
In 1910 the German colonial government during the administration of Governor Albert Hahl moved offices, the district court, a hospital and customs and postal facilities from Herbertshöhe to Simpsonhafen. That settlement was thus enlarged with official buildings and housing and renamed Rabaul, meaning mangrove in Kuanua as the new town was built on a reclaimed mangrove swamp. At the outset of World War I, at the behest of Great Britain, Australia — as one of the Dominions of the British Empire — defeated the German military garrison in Rabaul and occupied the territory with the volunteer Australian Naval and Military Expeditionary Force. Following Germany's defeat at the end of the war, the occupied territory was delegated in 1920 to Australia as a League of Nations Mandate. Rabaul became the capital of the Territory of New Guinea. Visits to and stays in Rabaul during this period were amply described in books by many authors, including Margaret Mead. Gunantambu, the famous house of “Queen” Emma Forsayth and her husband, contained furniture owned by Robert Louis Stevenson and left to her family in Samoa.
Destroyed in the 1937 volcano eruption, its remains became a tourist attraction after World War II and remained so until the 1994 further volcanic destruction of Rabaul. "Rabaul volcano is one of the most active and most dangerous volcanoes in Papua New Guinea." Having erupted and destroyed Rabaul in 1937, five years before the occupation by Japan, "Rabaul exploded violently in 1994 and devastated the.... Since the young cone Tavurvur located inside the caldera has been the site of near persistent activity in form of strombolian to vulcanian ash eruptions; the caldera has an elliptical form and is surrounded by a steep volcanic ridge several hundred meters high."Under the Australian administration, Rabaul developed into a regional base. In 1937, catastrophic volcanic eruptions destroyed the town after the two volcanoes and Vulcan, exploded. 507 people were killed, there was widespread damage. Following this, the Australian administration for the Territory of New Guinea decided to move the territorial headquarters to the safer location of Lae.
All long-term steps to re-establish the territorial headquarters at Rabaul were forestalled during World War II. By the time the Japanese attacked Pearl Harbor. So, by December 1941, women and children were evacuated. In January 1942 Rabaul was bombed, on 23 January the Battle of Rabaul began and Rabaul was captured shortly thereafter by thousands of Japanese naval landing forces. During their occupation the Japanese developed Rabaul into a much more powerful base than the Australians had planned after the 1937 volcanic eruptions, with long term consequences for the town in the post-war period; the Japanese army dug many kilometres of tunnels as shelter from Allied air attacks, such as the bombing of Rabaul. They expanded the facilities by constructing army barracks and support structures. By 1943 there were about 110,000 Japanese troops based in Rabaul. On 18 April 1943, the United States executed Operation Vengeance, in which Admiral Isoroku Yamamoto, the architect of the Japanese attack on Pearl Harbor, was shot down and killed by a United States P-38 Lightning over south Bougainville.
Yamamoto had taken off from Rabaul on an inspection tour, United States Navy cryptographers had intercepted and decrypted Japanese communications giving h
A battleship is a large armored warship with a main battery consisting of large caliber guns. During the late 19th and early 20th centuries the battleship was the most powerful type of warship, a fleet of battleships was considered vital for any nation that desired to maintain command of the sea; the term battleship came into formal use in the late 1880s to describe a type of ironclad warship, now referred to by historians as pre-dreadnought battleships. In 1906, the commissioning of HMS Dreadnought into the United Kingdom's Royal Navy heralded a revolution in battleship design. Subsequent battleship designs, influenced by HMS Dreadnought, were referred to as "dreadnoughts", though the term became obsolete as they became the only type of battleship in common use. Battleships were a symbol of naval dominance and national might, for decades the battleship was a major factor in both diplomacy and military strategy. A global arms race in battleship construction began in Europe in the 1890s and culminated at the decisive Battle of Tsushima in 1905, the outcome of which influenced the design of HMS Dreadnought.
The launch of Dreadnought in 1906 commenced a new naval arms race. Three major fleet actions between steel battleships took place: the decisive battles of the Yellow Sea and Tsushima during the Russo-Japanese War, the inconclusive Battle of Jutland during the First World War. Jutland was the largest naval battle and the only full-scale clash of battleships in the war, it was the last major battle fought by battleships in world history; the Naval Treaties of the 1920s and 1930s limited the number of battleships, though technical innovation in battleship design continued. Both the Allied and Axis powers built battleships during World War II, though the increasing importance of the aircraft carrier meant that the battleship played a less important role than had been expected; the value of the battleship has been questioned during their heyday. There were few of the decisive fleet battles that battleship proponents expected, used to justify the vast resources spent on building battlefleets. In spite of their huge firepower and protection, battleships were vulnerable to much smaller and inexpensive weapons: the torpedo and the naval mine, aircraft and the guided missile.
The growing range of naval engagements led to the aircraft carrier replacing the battleship as the leading capital ship during World War II, with the last battleship to be launched being HMS Vanguard in 1944. Four battleships were retained by the United States Navy until the end of the Cold War for fire support purposes and were last used in combat during the Gulf War in 1991; the last battleships were stricken from the U. S. Naval Vessel Register in the 2000s. A ship of the line was the dominant warship of its age, it was a large, unarmored wooden sailing ship which mounted a battery of up to 120 smoothbore guns and carronades. The ship of the line developed over centuries and, apart from growing in size, it changed little between the adoption of line of battle tactics in the early 17th century and the end of the sailing battleship's heyday in the 1830s. From 1794, the alternative term'line of battle ship' was contracted to'battle ship' or'battleship'; the sheer number of guns fired broadside meant a ship of the line could wreck any wooden enemy, holing her hull, knocking down masts, wrecking her rigging, killing her crew.
However, the effective range of the guns was as little as a few hundred yards, so the battle tactics of sailing ships depended in part on the wind. The first major change to the ship of the line concept was the introduction of steam power as an auxiliary propulsion system. Steam power was introduced to the navy in the first half of the 19th century for small craft and for frigates; the French Navy introduced steam to the line of battle with the 90-gun Napoléon in 1850—the first true steam battleship. Napoléon was armed as a conventional ship-of-the-line, but her steam engines could give her a speed of 12 knots, regardless of the wind condition; this was a decisive advantage in a naval engagement. The introduction of steam accelerated the growth in size of battleships. France and the United Kingdom were the only countries to develop fleets of wooden steam screw battleships although several other navies operated small numbers of screw battleships, including Russia, the Ottoman Empire, Naples and Austria.
The adoption of steam power was only one of a number of technological advances which revolutionized warship design in the 19th century. The ship of the line was overtaken by the ironclad: powered by steam, protected by metal armor, armed with guns firing high-explosive shells. Guns that fired explosive or incendiary shells were a major threat to wooden ships, these weapons became widespread after the introduction of 8-inch shell guns as part of the standard armament of French and American line-of-battle ships in 1841. In the Crimean War, six line-of-battle ships and two frigates of the Russian Black Sea Fleet destroyed seven Turkish frigates and three corvettes with explosive shells at the Battle of Sinop in 1853. In the war, French ironclad floating batteries used similar weapons against the defenses at the Battle of Kinburn. Wooden-hulled ships stood up comparatively well to shells, as shown in the 1866 Battle of Lissa, where the modern Austrian steam two-decker SMS Kaiser ranged across a confused battlefield, rammed an Italian ironclad and took 80 hits from Italian ironclads, many of which were shells, but including at least one 300-pound shot at point-blank range.
Despite losing her bowsprit and her foremast, bei
5"/38 caliber gun
The Mark 12 5"/38 caliber gun was a United States naval gun. The gun was installed into Single Purpose and Dual Purpose mounts used by the US Navy. On these 5" mounts, Single Purpose means that the mount is limited to 35° elevation with no provision for AA shell fuze setters, is designed to fire at surface targets only. Dual Purpose means that it is designed to be effective against both surface and aircraft targets because it can elevate to 85° and has on mount AA shell fuze setters; the 38 caliber barrel was a mid-length compromise between the previous United States standard 5"/51 low-angle gun and 5"/25 anti-aircraft gun. United States naval gun terminology indicates the gun fired a projectile 5 inches in diameter, the barrel was 38 calibers long, making the 5"/38 dual purpose midway in barrel length between the 5"/51 surface-to-surface and the 5"/25 anti-aircraft guns; the increased barrel length provided improved performance in both anti-aircraft and anti-surface roles compared to the 5"/25 gun.
However, except for the barrel length and the use of semi-fixed ammunition, the 5"/38 gun was derived from the 5"/25 gun. Both weapons had power ramming; the 5"/38 entered service on USS Farragut, commissioned in 1934. The base ring mount, which improved the effective rate of fire, entered service on USS Gridley, commissioned in 1937. Among naval historians, the 5"/38 gun is considered the best intermediate-caliber, dual purpose naval gun of World War II as it was under the control of the advanced Mark 37 Gun Fire Control System which provided accurate and timely firing against surface and air targets; this advanced system required nearly 1000 rounds of ammunition expenditure per aircraft kill. However, the planes were killed by shell fragments and not direct hits; this would result in large walls of shell fragments being put up to take out one or several planes or in anticipation of an unseen plane, this being justifiable as one plane was capable of significant destruction. The comparatively high rate of fire for a gun of its caliber earned it an enviable reputation as an anti-aircraft weapon, in which role it was employed by United States Navy vessels.
Base ring mounts. On pedestal and other mounts lacking integral hoists, 12 to 15 rounds per minute was the rate of fire. Useful life expectancy was 4600 effective full charges per barrel; the 5"/38 cal gun was mounted on a large number of US Navy ships in the World War II era. It was backfitted to many of the World War I-era battleships during their wartime refits replacing 5"/25 guns that were fitted in the 1930s, it has left active US Navy service, but it is still on mothballed ships of the United States Navy reserve fleets. It is used by a number of nations who bought or were given US Navy surplus ships. Millions of rounds of ammunition were produced for these guns, with over 720,000 rounds still remaining in Navy storage depots in the mid-1980s because of the large number of Reserve Fleet ships with 5"/38 cal guns on board; each mount carries one or two Mk 12 5"/38cal Gun Assemblies. The gun assembly shown is used in single mounts, it is the right gun in twin mounts, it is loaded from the left side.
The left gun in twin mounts is the mirror image of the right gun, it is loaded from the right side. The Mk12 gun assembly weighs 3,990 lb; the Mark 12 Gun Assembly was introduced in 1934, where it was first used in single pedestal mounts on the Farragut-class destroyers, but by the time of World War II they had been installed in single and twin mounts on nearly every major warship and auxiliary in the US fleet. The major Mk12 Gun Assembly characteristics are::158 Semi-automatic During recoil, some of the recoil energy is stored in the counter-recoil system; that stored. The firing pin is cocked, the breech is opened, the spent propellant case is ejected, the bore is cleared of debris with an air blast. Hand loaded a powder-man are stationed at each gun assembly, their job is to move the round, consisting of a projectile and a propellant case, from the hoists to the rammer tray projecting from the gun's breech, start the ram cycle. Power rammed This gun used a 7.5 hp electric-hydraulic power rammer, designed to ram a 93 lb, 47.5 in long round into the chamber at any gun elevation in less than one second.:172 The rammer's control box, hydraulic fluid tank and AC motor are bolted to the top of the slide.
The hydraulically driven rammer spade, called the power spade in that picture, is at the back of the rammer tray. If the multiple names of the "spade" are confusing, look at this footnote. Vertical sliding-wedge breech block, it contains the firing pin assembly. Hydraulic recoil Two hydraulic pistons in the housing absorb the major shock of recoil as the housing moves back inside the slide, they buffer the end of counter-recoil for a soft return to battery. Pneumatic counter-recoil At the end of recoil, the counter-recoil system moves the housing forward again until it is back "in battery," and holds it there at any gun elevation. A chamber in the housing is filled with compressed air. At the rear of this chamber is a 3.5 in cylindrical hole with a c
The Panama Canal is an artificial 82 km waterway in Panama that connects the Atlantic Ocean with the Pacific Ocean. The canal is a conduit for maritime trade. Canal locks are at each end to lift ships up to Gatun Lake, an artificial lake created to reduce the amount of excavation work required for the canal, 26 m above sea level, lower the ships at the other end; the original locks are 34 m wide. A third, wider lane of locks was constructed between September 2007 and May 2016; the expanded canal began commercial operation on June 26, 2016. The new locks allow transit of larger, post-Panamax ships, capable of handling more cargo. France began work on the canal in 1881, but stopped due to engineering problems and a high worker mortality rate; the United States took over the project in 1904 and opened the canal on August 15, 1914. One of the largest and most difficult engineering projects undertaken, the Panama Canal shortcut reduced the time for ships to travel between the Atlantic and Pacific Oceans, enabling them to avoid the lengthy, hazardous Cape Horn route around the southernmost tip of South America via the Drake Passage or Strait of Magellan.
Colombia and the United States controlled the territory surrounding the canal during construction. The US continued to control the canal and surrounding Panama Canal Zone until the 1977 Torrijos–Carter Treaties provided for handover to Panama. After a period of joint American–Panamanian control, in 1999, the canal was taken over by the Panamanian government, it is now operated by the government-owned Panama Canal Authority. Annual traffic has risen from about 1,000 ships in 1914, when the canal opened, to 14,702 vessels in 2008, for a total of 333.7 million Panama Canal/Universal Measurement System tons. By 2012, more than 815,000 vessels had passed through the canal, it takes 11.38 hours to pass through the Panama Canal. The American Society of Civil Engineers has ranked the Panama Canal one of the seven wonders of the modern world; the earliest mention of a canal across the Isthmus of Panama occurred in 1534, when Charles V, Holy Roman Emperor and King of Spain, ordered a survey for a route through the Americas that would ease the voyage for ships traveling between Spain and Peru.
Such a route would have given the Spanish a military advantage over the Portuguese. In 1668, the English physician and philosopher Sir Thomas Browne speculated in his encyclopaedic endeavour Pseudodoxia Epidemica - "some Isthmus have been eat through by the Sea, others cut by the spade: And if policy would permit, that of Panama in America were most worthy the attempt: it being but few miles over, would open a shorter cut unto the East Indies and China". In 1788, American Thomas Jefferson Minister to France, suggested that the Spanish should build the canal since it would be a less treacherous route for ships than going around the southern tip of South America, that tropical ocean currents would widen the canal thereafter. During an expedition from 1788 to 1793, Alessandro Malaspina outlined plans for its construction. Given the strategic location of Panama and the potential offered by its narrow isthmus separating two great oceans, other trade links in the area were attempted over the years.
The ill-fated Darien scheme was launched by the Kingdom of Scotland in 1698 to set up an overland trade route. Inhospitable conditions thwarted the effort and it was abandoned in April 1700. Numerous canals were built in other countries in the late early 19th centuries; the success of the Erie Canal in the United States in the 1820s and the collapse of the Spanish Empire in Latin America led to a surge of American interest in building an inter-oceanic canal. Beginning in 1826, US officials began negotiations with Gran Colombia, hoping to gain a concession for the building of a canal. Jealous of their newly obtained independence and fearing that they would be dominated by an American presence, the president Simón Bolívar and New Granada officials declined American offers; the new nation was politically unstable, Panama rebelled several times during the 19th century. Another effort was made in 1843. According to the New York Daily Tribune, August 24, 1843, a contract was entered into by Barings of London and the Republic of New Granada for the construction of a canal across the Isthmus of Darien.
They referred to it as the Atlantic and Pacific Canal, it was a wholly British endeavor. It was expected to be completed in five years. At nearly the same time, other ideas were floated, including a canal across Mexico's Isthmus of Tehuantepec. Nothing came of that plan, either. In 1846, the Mallarino–Bidlack Treaty, negotiated between the US and New Granada, granted the United States transit rights and the right to intervene militarily in the isthmus. In 1848, the discovery of gold in California, on the West Coast of the United States, created great interest in a crossing between the Atlantic and Pacific oceans. William H. Aspinwall, the man who won the federal subsidy for the building and operating the Pacific mail steamships at around the same time, benefited from this discovery. Aspinwall's route included steamship legs from New York City to Panama and from Panama to California, with an overland portage through Panama; the route between California and Panama was soon traveled, as it provided one of the fastest links between San Francisco and the East Coast cities, about 40 days' transit in total.
Nearly all the gold, shipped out of California went by the fast Panama route. Several new and larger paddle steamers were soon plying