Japan is an island country in East Asia. Located in the Pacific Ocean, it lies off the eastern coast of the Asian continent and stretches from the Sea of Okhotsk in the north to the East China Sea and the Philippine Sea in the south; the kanji that make up Japan's name mean "sun origin", it is called the "Land of the Rising Sun". Japan is a stratovolcanic archipelago consisting of about 6,852 islands; the four largest are Honshu, Hokkaido and Shikoku, which make up about ninety-seven percent of Japan's land area and are referred to as home islands. The country is divided into 47 prefectures in eight regions, with Hokkaido being the northernmost prefecture and Okinawa being the southernmost one; the population of 127 million is the world's tenth largest. 90.7 % of people live in cities. About 13.8 million people live in the capital of Japan. The Greater Tokyo Area is the most populous metropolitan area in the world with over 38 million people. Archaeological research indicates; the first written mention of Japan is in Chinese history texts from the 1st century AD.
Influence from other regions China, followed by periods of isolation from Western Europe, has characterized Japan's history. From the 12th century until 1868, Japan was ruled by successive feudal military shōguns who ruled in the name of the Emperor. Japan entered into a long period of isolation in the early 17th century, ended in 1853 when a United States fleet pressured Japan to open to the West. After nearly two decades of internal conflict and insurrection, the Imperial Court regained its political power in 1868 through the help of several clans from Chōshū and Satsuma – and the Empire of Japan was established. In the late 19th and early 20th centuries, victories in the First Sino-Japanese War, the Russo-Japanese War and World War I allowed Japan to expand its empire during a period of increasing militarism; the Second Sino-Japanese War of 1937 expanded into part of World War II in 1941, which came to an end in 1945 following the Japanese surrender. Since adopting its revised constitution on May 3, 1947, during the occupation led by SCAP, the sovereign state of Japan has maintained a unitary parliamentary constitutional monarchy with an Emperor and an elected legislature called the National Diet.
Japan is a member of the ASEAN Plus mechanism, UN, the OECD, the G7, the G8, the G20, is considered a great power. Its economy is the world's third-largest by nominal GDP and the fourth-largest by purchasing power parity, it is the world's fourth-largest exporter and fourth-largest importer. Japan benefits from a skilled and educated workforce. Although it has renounced its right to declare war, Japan maintains a modern military with the world's eighth-largest military budget, used for self-defense and peacekeeping roles. Japan is a developed country with a high standard of living and Human Development Index, its population enjoys the highest life expectancy and third lowest infant mortality rate in the world, but is experiencing issues due to an aging population and low birthrate. Japan is renowned for its historical and extensive cinema, influential music industry, video gaming, rich cuisine and its major contributions to science and modern technology; the Japanese word for Japan is 日本, pronounced Nihon or Nippon and means "the origin of the sun".
The character nichi means "sun" or "day". The compound therefore means "origin of the sun" and is the source of the popular Western epithet "Land of the Rising Sun"; the earliest record of the name Nihon appears in the Chinese historical records of the Tang dynasty, the Old Book of Tang. At the end of the seventh century, a delegation from Japan requested that Nihon be used as the name of their country; this name may have its origin in a letter sent in 607 and recorded in the official history of the Sui dynasty. Prince Shōtoku, the Regent of Japan, sent a mission to China with a letter in which he called himself "the Emperor of the Land where the Sun rises"; the message said: "Here, I, the emperor of the country where the sun rises, send a letter to the emperor of the country where the sun sets. How are you". Prior to the adoption of Nihon, other terms such as Yamato and Wakoku were used; the term Wa is a homophone of Wo 倭, used by the Chinese as a designation for the Japanese as early as the third century Three Kingdoms period.
Another form of Wa, Wei in Chinese) was used for an early state in Japan called Nakoku during the Han dynasty. However, the Japanese disliked some connotation of Wa 倭, it was therefore replaced with the substitute character Wa, meaning "togetherness, harmony"; the English word Japan derives from the historical Chinese pronunciation of 日本. The Old Mandarin or early Wu Chinese pronunciation of Japan was recorded by Marco Polo as Cipangu. In modern Shanghainese, a Wu dialect, the pronunciation of characters 日本; the old Malay word for Japan, Japun or Japang, was borrowed from a southern coastal Chinese dialect Fukienese or Ningpo – and this Malay word was encountered by Portuguese traders in Southeast Asia in the 16th century. These Early Portuguese traders brought the word
Bay City, Michigan
Bay City is a city in Bay County, located near the base of the Saginaw Bay on Lake Huron. As of the 2010 census, the city's population was 34,932, is the principal city of the Bay City Metropolitan Statistical Area, included in the Saginaw-Midland-Bay City Combined Statistical Area; the city, along with nearby Midland and Saginaw, form the Greater Tri-Cities region of Central Michigan, which has more been called the Great Lakes Bay Region. The city is geographically divided by the Saginaw River, travel between the east and west sides of the city is made possible by four modern bascule-type drawbridges: Liberty Bridge, Veterans Memorial Bridge, Independence Bridge, Lafayette Avenue Bridge, which allow large ships to travel down the river; the city is served by MBS International Airport, located in nearby Freeland, James Clements Municipal Airport. Leon Tromblé is regarded as the first settler within the limits of Bay County, in an area which would become Bay City. In 1831, he built a log cabin on the east bank of the Saginaw river.
Bay City was first established in 1837, was incorporated as a city in 1865. In 1834 John B. Trudell built a log-cabin near the present corner of Broadway. Trudell purchased land that extended from his residence north along the river to what became the location for the Industrial Brownhoist, making him the first permanent resident of what has become Bay County. Bay City became the largest community in the county and the location of the county seat of government. Most of the county's agencies and associations are located here; the city shares common borders with Essexville and the townships of Bangor, Hampton, Merritt and Portsmouth. Bay City was known as "Lower Saginaw," and fell within the boundaries of Saginaw County On June 4, 1846, the Hapton, or Hampton, Post Office opened to service Lower Saginaw; the community was placed in Bay County, when the county was organized in 1857. It was at this time; the Post Office changed its name to Bay City on March 22, 1858. While Saginaw had the first white settlement in this area in 1819, larger ships had difficulty navigating the shallower water near the Saginaw settlement.
Due to this fact, many of the early pioneers moved to Lower Saginaw as it became clear its deeper waters made it a better location for the growth of industry which relied on shipping. By 1860, Lower Saginaw had become a bustling community of about 2,000 people with several mills and many small businesses in operation. In 1865, the village of Bay City was incorporated as a city. Rapid economic growth took place during this time period, with lumbering and shipbuilding creating many jobs; the early industrialists in the area used the Saginaw River as a convenient means to float lumber to the mills and factories and as a consequence amass large fortunes. Many of the mansions built during this era are registered as historical landmarks by the state and federal government. In 1873, Charles C. Fitzhugh, Jr. a Bay City pioneer, his wife, purchased land and built a home on property bounded by Washington, Saginaw and Tenth Streets, which became the location for City Hall. Fitzhugh dealt on a large scale in wild lands and farms, being an agent for over 25,000 acres of land in Bay County.
During this time, Washington Avenue was developed with residential homes. Businesses were concentrated along Water Street near the Saginaw River; as time went on, businesses started to expand along Washington Avenue. In 1891, the Fitzhughs sold the land to the City of Bay City for $8,500 "to be used for the erection of a City Hall and offices and for no other purposes whatever." Until 1905, the City of Bay City was limited to the east bank of the Saginaw River. When West Bay City was annexed. During the latter half of the 19th century Bay City was the home of several now-closed industries including many sawmills and shipbuilders; the Defoe Shipbuilding Company, which ceased operations December 31, 1975 built destroyer escorts, guided missile destroyers, patrol craft for the United States Navy and the Royal Australian Navy. To maintain this strong Naval heritage, the Saginaw Valley Naval Ship Museum worked through the Naval Sea Systems Command to bring the USS Edson to Bay City as a museum ship.
It was delivered to its temporary home in Essexville, Michigan on August 7, 2012. Another important part of the city's industrial history is Industrial Brownhoist, well known for its construction of large industrial cranes. On December 10, 1977 a deadly fire claimed the lives of 10 at the Wenonah Hotel in downtown Bay City; the Wenonah Hotel was located at the corner of Center Ave and Water Street, the current site of the Delta College Planetarium. Built in 1907, the 4 story Wenonah Hotel had been converted into apartments at the time of the fire. Strong winds and cold weather hampered the efforts of the fire department. There was some controversy over the cause of the fire and it remains the deadliest fire in Bay County history. In September 1990, the tankship MV Jupiter was unloading gasoline at the Total Petroleum Terminal. A passing cargo ship, MV Buffalo, moving at excessive speed, created a wake that caused Jupiter to break free of its berth. A fire and explosion ensued, one man drowned. There was considerable legal action taken resulting in an adjudication, subsequently appealed by the owners of Buffalo.
The findings of the Court of Appeals upheld the original decision, which assigned 50% of the responsibility to Buffalo, 25% to the dock operator and 25% to Jupiter. In January 2009
The Philippines the Republic of the Philippines, is an archipelagic country in Southeast Asia. Situated in the western Pacific Ocean, it consists of about 7,641 islands that are categorized broadly under three main geographical divisions from north to south: Luzon and Mindanao; the capital city of the Philippines is Manila and the most populous city is Quezon City, both part of Metro Manila. Bounded by the South China Sea on the west, the Philippine Sea on the east and the Celebes Sea on the southwest, the Philippines shares maritime borders with Taiwan to the north, Vietnam to the west, Palau to the east, Malaysia and Indonesia to the south; the Philippines' location on the Pacific Ring of Fire and close to the equator makes the Philippines prone to earthquakes and typhoons, but endows it with abundant natural resources and some of the world's greatest biodiversity. The Philippines has an area of 300,000 km2, according to the Philippines Statistical Authority and the WorldBank and, as of 2015, had a population of at least 100 million.
As of January 2018, it is the eighth-most populated country in Asia and the 12th most populated country in the world. 10 million additional Filipinos lived overseas, comprising one of the world's largest diasporas. Multiple ethnicities and cultures are found throughout the islands. In prehistoric times, Negritos were some of the archipelago's earliest inhabitants, they were followed by successive waves of Austronesian peoples. Exchanges with Malay, Indian and Chinese nations occurred. Various competing maritime states were established under the rule of datus, rajahs and lakans; the arrival of Ferdinand Magellan, a Portuguese explorer leading a fleet for the Spanish, in Homonhon, Eastern Samar in 1521 marked the beginning of Hispanic colonization. In 1543, Spanish explorer Ruy López de Villalobos named the archipelago Las Islas Filipinas in honor of Philip II of Spain. With the arrival of Miguel López de Legazpi from Mexico City, in 1565, the first Hispanic settlement in the archipelago was established.
The Philippines became part of the Spanish Empire for more than 300 years. This resulted in Catholicism becoming the dominant religion. During this time, Manila became the western hub of the trans-Pacific trade connecting Asia with Acapulco in the Americas using Manila galleons; as the 19th century gave way to the 20th, the Philippine Revolution followed, which spawned the short-lived First Philippine Republic, followed by the bloody Philippine–American War. The war, as well as the ensuing cholera epidemic, resulted in the deaths of thousands of combatants as well as tens of thousands of civilians. Aside from the period of Japanese occupation, the United States retained sovereignty over the islands until after World War II, when the Philippines was recognized as an independent nation. Since the unitary sovereign state has had a tumultuous experience with democracy, which included the overthrow of a dictatorship by a non-violent revolution; the Philippines is a founding member of the United Nations, World Trade Organization, Association of Southeast Asian Nations, the Asia-Pacific Economic Cooperation forum, the East Asia Summit.
It hosts the headquarters of the Asian Development Bank. The Philippines is considered to be an emerging market and a newly industrialized country, which has an economy transitioning from being based on agriculture to one based more on services and manufacturing. Along with East Timor, the Philippines is one of Southeast Asia's predominantly Christian nations; the Philippines was named in honor of King Philip II of Spain. Spanish explorer Ruy López de Villalobos, during his expedition in 1542, named the islands of Leyte and Samar Felipinas after the then-Prince of Asturias; the name Las Islas Filipinas would be used to cover all the islands of the archipelago. Before that became commonplace, other names such as Islas del Poniente and Magellan's name for the islands San Lázaro were used by the Spanish to refer to the islands; the official name of the Philippines has changed several times in the course of its history. During the Philippine Revolution, the Malolos Congress proclaimed the establishment of the República Filipina or the Philippine Republic.
From the period of the Spanish–American War and the Philippine–American War until the Commonwealth period, American colonial authorities referred to the country as the Philippine Islands, a translation of the Spanish name. Since the end of World War II, the official name of the country has been the Republic of the Philippines. Philippines has gained currency as the common name since being the name used in Article VI of the 1898 Treaty of Paris, with or without the definite article. Discovery in 2018 of stone tools and fossils of butchered animal remains in Rizal, Kalinga has pushed back evidence of early hominins in the archipelago to as early as 709,000 years. However, the metatarsal of the Callao Man, reliably dated by uranium-series dating to 67,000 years ago remains the oldest human remnant found in the archipelago to date; this distinction belonged to the Tabon Man of Palawan, carbon-dated to around 26,500 years ago. Negritos were among the archipelago's earliest inhabitants, but their first settlement in the Philippines has not been reliably dated.
There are several opposing theories regarding the origins of ancient Filipinos. F. Landa Jocano theorizes. Wilhelm Solheim's Island Origin Theory postulates that the peopling of the archipelago transpired via trade networks originating in the Sundaland area around
Sonar is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels. Two types of technology share the name "sonar": passive sonar is listening for the sound made by vessels. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may be used in air for robot navigation, SODAR is used for atmospheric investigations; the term sonar is used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from low to high; the study of underwater sound is known as underwater hydroacoustics. The first recorded use of the technique was by Leonardo da Vinci in 1490 who used a tube inserted into the water to detect vessels by ear, it was developed during World War I to counter the growing threat of submarine warfare, with an operational passive sonar system in use by 1918.
Modern active sonar systems use an acoustic transponder to generate a sound wave, reflected back from target objects. Although some animals have used sound for communication and object detection for millions of years, use by humans in the water is recorded by Leonardo da Vinci in 1490: a tube inserted into the water was said to be used to detect vessels by placing an ear to the tube. In the late 19th century an underwater bell was used as an ancillary to lighthouses or light ships to provide warning of hazards; the use of sound to "echo-locate" underwater in the same way as bats use sound for aerial navigation seems to have been prompted by the Titanic disaster of 1912. The world's first patent for an underwater echo-ranging device was filed at the British Patent Office by English meteorologist Lewis Fry Richardson a month after the sinking of the Titanic, a German physicist Alexander Behm obtained a patent for an echo sounder in 1913; the Canadian engineer Reginald Fessenden, while working for the Submarine Signal Company in Boston, built an experimental system beginning in 1912, a system tested in Boston Harbor, in 1914 from the U.
S. Revenue Cutter Miami on the Grand Banks off Newfoundland. In that test, Fessenden echo ranging; the "Fessenden oscillator", operated at about 500 Hz frequency, was unable to determine the bearing of the iceberg due to the 3-metre wavelength and the small dimension of the transducer's radiating face. The ten Montreal-built British H-class submarines launched in 1915 were equipped with Fessenden oscillators. During World War I the need to detect; the British made early use of underwater listening devices called hydrophones, while the French physicist Paul Langevin, working with a Russian immigrant electrical engineer Constantin Chilowsky, worked on the development of active sound devices for detecting submarines in 1915. Although piezoelectric and magnetostrictive transducers superseded the electrostatic transducers they used, this work influenced future designs. Lightweight sound-sensitive plastic film and fibre optics have been used for hydrophones, while Terfenol-D and PMN have been developed for projectors.
In 1916, under the British Board of Invention and Research, Canadian physicist Robert William Boyle took on the active sound detection project with A. B. Wood, producing a prototype for testing in mid-1917; this work, for the Anti-Submarine Division of the British Naval Staff, was undertaken in utmost secrecy, used quartz piezoelectric crystals to produce the world's first practical underwater active sound detection apparatus. To maintain secrecy, no mention of sound experimentation or quartz was made – the word used to describe the early work was changed to "ASD"ics, the quartz material to "ASD"ivite: "ASD" for "Anti-Submarine Division", hence the British acronym ASDIC. In 1939, in response to a question from the Oxford English Dictionary, the Admiralty made up the story that it stood for "Allied Submarine Detection Investigation Committee", this is still believed, though no committee bearing this name has been found in the Admiralty archives. By 1918, Britain and France had built prototype active systems.
The British tested their ASDIC on HMS Antrim in 1920 and started production in 1922. The 6th Destroyer Flotilla had ASDIC-equipped vessels in 1923. An anti-submarine school HMS Osprey and a training flotilla of four vessels were established on Portland in 1924; the U. S. Sonar QB set arrived in 1931. By the outbreak of World War II, the Royal Navy had five sets for different surface ship classes, others for submarines, incorporated into a complete anti-submarine attack system; the effectiveness of early ASDIC was hampered by the use of the depth charge as an anti-submarine weapon. This required an attacking vessel to pass over a submerged contact before dropping charges over the stern, resulting in a loss of ASDIC contact in the moments leading up to attack; the hunter was firing blind, during which time a submarine commander could take evasive action. This situation was remedied by using several ships cooperating and by the adoption of "ahead-throwing weapons", such as Hedgehogs and Squids, which proj
3"/50 caliber gun
The 3″/50 caliber gun in United States naval gun terminology indicates the gun fired a projectile 3 inches in diameter, the barrel was 50 calibers long. Different guns of this caliber were used by the U. S. Navy and U. S. Coast Guard from 1890 through the 1990s on a variety of combatant and transport ship classes; the gun is still in use with the Spanish Navy on Serviola-class patrol boats. The US Navy's first 3″/50 caliber gun was an early model with a projectile velocity of 2,100 feet per second. Low-angle mountings for this gun had a range of 7000 yards at the maximum elevation of 15 degrees; the gun entered service around 1900 with the Bainbridge-class destroyers, was fitted to Connecticut-class battleships. By World War II these guns were found only on a few Coast Guard cutters and Defensively Equipped Merchant Ships. Low-angle 3″/50 caliber guns were mounted on ships built from the early 1900s through the early 1920s and were carried by submarines and merchant ships during the Second World War.
These guns fired the same 2,700 feet per second ammunition used by the following dual-purpose Marks, but with range limited by the maximum elevation of the mounting. These were built-up guns with a tube, partial-length jacket and vertical sliding breech block. Dual-purpose 3″/50 caliber guns first entered service in 1915 as a refit to USS Texas, were subsequently mounted on many types of ships as the need for anti-aircraft protection was recognized. During World War II, they were the primary gun armament on destroyer escorts, patrol frigates, submarine chasers, some fleet submarines, other auxiliary vessels, were used as a secondary dual-purpose battery on some other types of ships, including some older battleships, they replaced the original low-angle 4"/50 caliber guns on "flush-deck" Wickes and Clemson-class destroyers to provide better anti-aircraft protection. The gun was used on specialist destroyer conversions; these dual-purpose guns were "quick-firing", meaning that they used fixed ammunition, with powder case and projectile permanently attached, handled as a single unit weighing 34 pounds.
The shells alone weighed about 13 pounds including an explosive bursting charge of 0.81 pounds for anti-aircraft rounds or 1.27 pounds for High Capacity rounds, the remainder of the weight being the steel casing. Maximum range was 14,600 yards at 45 degrees elevation and ceiling was 29,800 feet at 85 degrees elevation. Useful life expectancy was 4300 effective full charges per barrel; the 3"/50 caliber gun Marks 17 and 18 was first used as a submarine deck gun on R-class submarines launched in 1918-1919. At the time it was an improvement on the earlier 3"/23 caliber gun. After using larger guns on many other submarines, the 3"/50 caliber gun Mark 21 was specified as the standard deck gun on the Porpoise- through Gato-class submarines launched in 1935-1942; the small gun was chosen to remove the temptation to engage enemy escort vessels on the surface. The gun was mounted aft of the conning tower to reduce submerged drag, but early in World War II it was shifted to a forward position at the commanding officer's option.
Wartime experience showed. This need was met by transferring 4"/50 caliber guns from S-class submarines as they were shifted from combat to training roles beginning in late 1942; the 5"/25 caliber gun removed from battleships sunk or damaged in the attack on Pearl Harbor and manufactured in a submarine version, became standard. When multiple hits from Oerlikon 20 mm cannon and Bofors 40 mm guns were unable to prevent kamikaze strikes during the final year of the second world war. Post-war experimentation with an extended range variant was abandoned as shipboard surface-to-air missiles were developed; the United States Navy considered contemporary 5"/38 caliber guns and 5″/54 caliber guns more effective against surface targets. The 3″/50 caliber gun was a semiautomatic anti-aircraft weapon with a power driven automatic loader; these monobloc 3 ″ guns were fitted to both twin mountings. The single was to be exchanged for a twin 40 mm antiaircraft gun mount and the twin for a quadruple 40 mm mount.
This was performed on Essex-class aircraft carriers, Allen M. Sumner and Gearing-class destroyers and other ships circa 1946-50. Although intended as a one-for-one replacement for the 40 mm mounts, the final version of the new 3-inch mounts was heavier than expected, on most ships the mounts could be replaced only on a two-for-three basis; the mounts were of open-base-ring type. The right and left gun assemblies were identical in the twin mounts; the mounts used a common power drive that could train at a rate of 30 degree/second and elevate from 15 degrees to 85 degrees at a rate of 24 degree/second. The cannon was fed automatically from an on-mount magazine, replenished during action by two loaders on each side of the cannon. With proximity fuze and fire-control radar, a twin 3″/50 mount firing 50 rounds per minute per
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
Okinawa Prefecture is the southernmost prefecture of Japan. It encompasses two thirds of the Ryukyu Islands in a chain over 1,000 kilometres long; the Ryukyu Islands extend southwest from Kagoshima Prefecture in Kyushu to Taiwan. Naha, Okinawa's capital, is located in the southern part of Okinawa Island. Although Okinawa Prefecture comprises just 0.6 percent of Japan's total land mass, about 75 percent of all United States military personnel stationed in Japan are assigned to installations in the prefecture. About 26,000 U. S. troops are based in the prefecture. The oldest evidence of human existence on the Ryukyu islands is from the Stone Age and was discovered in Naha and Yaeyama; some human bone fragments from the Paleolithic era were unearthed from a site in Naha, but the artifact was lost in transportation before it was examined to be Paleolithic or not. Japanese Jōmon influences are dominant on the Okinawa Islands, although clay vessels on the Sakishima Islands have a commonality with those in Taiwan.
The first mention of the word Ryukyu was written in the Book of Sui. Okinawa was the Japanese word identifying the islands, first seen in the biography of Jianzhen, written in 779. Agricultural societies begun in the 8th century developed until the 12th century. Since the islands are located at the eastern perimeter of the East China Sea close to Japan and South-East Asia, the Ryukyu Kingdom became a prosperous trading nation. During this period, many Gusukus, similar to castles, were constructed; the Ryukyu Kingdom entered into the Imperial Chinese tributary system under the Ming dynasty beginning in the 15th century, which established economic relations between the two nations. In 1609, the Shimazu clan, which controlled the region, now Kagoshima Prefecture, invaded the Ryukyu Kingdom; the Ryukyu Kingdom was obliged to agree to form a suzerain-vassal relationship with the Satsuma and the Tokugawa shogunate, while maintaining its previous role within the Chinese tributary system. The Satsuma clan earned considerable profits from trade with China during a period in which foreign trade was restricted by the shogunate.
Although Satsuma maintained strong influence over the islands, the Ryukyu Kingdom maintained a considerable degree of domestic political freedom for over two hundred years. Four years after the 1868 Meiji Restoration, the Japanese government, through military incursions annexed the kingdom and renamed it Ryukyu han. At the time, the Qing Empire asserted a nominal suzerainty over the islands of the Ryukyu Kingdom, since the Ryūkyū Kingdom was a member state of the Chinese tributary system. Ryukyu han became Okinawa Prefecture of Japan in 1879 though all other hans had become prefectures of Japan in 1872. In 1912, Okinawans first obtained the right to vote for representatives to the National Diet, established in 1890. Near the end of World War II, in 1945, the US Army and Marine Corps invaded Okinawa with 185,000 troops. A third of the civilian population died; the dead, of all nationalities, are commemorated at the Cornerstone of Peace. After the end of World War II, the Ryukyu independence movement developed, while Okinawa was under United States Military Government of the Ryukyu Islands administration for 27 years.
During this "trusteeship rule", the United States established numerous military bases on the Ryukyu islands. During the Korean War, B-29 Superfortresses flew bombing missions over Korea from Kadena Air Base on Okinawa; the military buildup on the island during the Cold War increased a division between local inhabitants and the American military. Under the 1952 Treaty of Mutual Cooperation and Security between the United States and Japan, the United States Forces Japan have maintained a large military presence. Since 1960, the U. S. and Japan have maintained an agreement that allows the U. S. to secretly bring nuclear weapons into Japanese ports. The Japanese tended to oppose the introduction of nuclear arms into Japanese territory by the government's assertion of Japan's non-nuclear policy and a statement of the Three Non-Nuclear Principles. Most of the weapons were alleged to be stored in ammunition bunkers at Kadena Air Base. Between 1954 and 1972, 19 different types of nuclear weapons were deployed in Okinawa, but with fewer than around 1,000 warheads at any one time.
Between 1965 and 1972, Okinawa was a key staging point for the United States in its military operations directed towards North Vietnam. Along with Guam, it presented a geographically strategic launch pad for covert bombing missions over Cambodia and Laos. Anti-Vietnam War sentiment became linked politically to the movement for reversion of Okinawa to Japan. In 1965, the US military bases, earlier viewed as paternal post war protection, were seen as aggressive; the Vietnam War highlighted the differences between the United States and Okinawa, but showed a commonality between the islands and mainland Japan. As controversy grew regarding the alleged placement of nuclear weapons on Okinawa, fears intensified over the escalation of the Vietnam War. Okinawa was perceived, by some inside Japan, as a potential target for China, should the communist government feel threatened by the United States. American military secrecy blocked any local reporting on what was occurring at bases such as Kadena Air Base.
As information leaked out, images of air strikes were published, the local population began to fear the potential for retaliation. Political leaders such as Oda Makoto