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Rudder Stock
A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, airship, or other vehicle that moves through a fluid medium (usually air or water). On an airplane, the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane. A rudder operates by redirecting the fluid past the hull or fuselage, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with hinges to the craft's stern, tail, or afterend. Often rudders are shaped to minimize hydrodynamic or aerodynamic drag. On simple watercraft, a tiller—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be turned by a helmsman. In larger vessels, cables, pushrods, or hydraulics may link rudders to steering wheels. In typical aircraft, the rudder is operated by pedals via mechanical linkages or hydraulics. History of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stern
The stern is the back or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite the bow, the foremost part of a ship. Originally, the term only referred to the aft port section of the ship, but eventually came to refer to the entire back of a vessel. The stern end of a ship is indicated with a white navigation light at night. Sterns on European and American wooden sailing ships began with two principal forms: the ''square'' or ''transom'' stern and the ''elliptical'', ''fantail'', or ''merchant'' stern, and were developed in that order. The hull sections of a sailing ship located before the stern were composed of a series of U-shaped rib-like frames set in a sloped or "cant" arrangement, with the last frame before the stern being called the ''fashion timber(s)'' or ''fashion piece(s)'', so called for "fashioning" the after part of the ship. This frame i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of The Han Dynasty
The Han dynasty (201 BCE220 CE) was the second imperial dynasty of China. It followed the Qin dynasty, which had unified the Warring States of China by conquest. It was founded by Liu Bang (Emperor Gaozu). The dynasty is divided into two periods: the Western Han (202 BCE9 CE) and the Eastern Han (25–220 CE), interrupted briefly by the Xin dynasty (9–23 CE) of Wang Mang. These appellations are derived from the locations of the capital cities Chang'an and Luoyang, respectively. The third and final capital of the dynasty was Xuchang, where the court moved in 196 CE during a period of political turmoil and civil war. The Han dynasty ruled in an era of Chinese cultural consolidation, political experimentation, relative economic prosperity and maturity, and great technological advances. There was unprecedented territorial expansion and exploration initiated by struggles with non-Chinese peoples, especially the nomadic Xiongnu of the Euras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Lefebvre Des Noëttes
Richard Lefebvre des Noëttes (1856–1936) was a French military officer and early historian of technology. After his early retirement from the French army in 1901, Lefebvre devoted his time to technological studies, then quite a new field, becoming a main proponent of the negative impact of slavery on technological progress in classical antiquity. Although dissenting voices emerged as early as the 1930s, his primitivist views of ancient traction technology met with considerable success in the 1950s and 1960s when authorities like the medievalist Lynn White and the sinologist Joseph Needham, but also many classicists, relied rather uncritically on his research. Based on a thorough reexamination of the pictorial evidence, much of it not available in Lefebvre's time, as well as experimental archaeology, modern scholars like Georges Raepsaet have refuted Lefebvre's findings, particularly his glaring underestimation of the capacities of ancient horse-drawn ploughs and carriages. H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Needham
Noel Joseph Terence Montgomery Needham (; 9 December 1900 – 24 March 1995) was a British biochemist, historian of science and sinologist known for his scientific research and writing on the history of Chinese science and technology, initiating publication of the multivolume '' Science and Civilisation in China''. A focus of his was what has come to be called the Needham Question of why and how China had ceded its leadership in science and technology to Western countries. He was elected a fellow of the Royal Society in 1941 and a fellow of the British Academy in 1971. In 1992, Queen Elizabeth II conferred on him the Order of the Companions of Honour, and the Royal Society noted he was the only living person to hold these three titles. Early life Needham's father, Joseph, was a doctor, and his mother, Alicia Adelaïde, née Montgomery (1863–1945), was a music composer from Oldcastle, County Meath, Ireland. His father, born in East London, then a poor section of town, ros ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxford Dictionary Of English Etymology
''The Oxford Dictionary of English Etymology'' is an etymological dictionary of the English language, published by Oxford University Press. The first editor of the dictionary was Charles Talbut Onions, who spent his last twenty years largely devoted to completing the first edition, published in 1966, which treated over 38,000 words and went to press just before his death. Editions * C. T. Onions, ed.; edited by C. T. Onions with the assistance of G. W. S. Friedrichsen and R. W. Burchfield (1966, reprinted 1983, 1992, 1994) Also published by OUP: *''The Concise Oxford Dictionary of English language'' **T. F. Hoad (1986) **T. F. Hoad (1993) *''An Etymological Dictionary of the English Language'' ** W. W. Skeat (1910; reprint 1963; now in the public domain) See also * ''Oxford English Dictionary'' References 1966 non-fiction books Etymological dictionaries English Etymology English etymology is the study of where English words came from. It may refer to: *History of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopædia Britannica
The is a general knowledge, general-knowledge English-language encyclopaedia. It has been published by Encyclopædia Britannica, Inc. since 1768, although the company has changed ownership seven times. The 2010 version of the 15th edition, which spans 32 volumes and 32,640 pages, was the last printed edition. Since 2016, it has been published exclusively as an online encyclopedia, online encyclopaedia. Printed for 244 years, the ''Britannica'' was the longest-running in-print encyclopaedia in the English language. It was first published between 1768 and 1771 in Edinburgh, Scotland, in three volumes. The encyclopaedia grew in size; the second edition was 10 volumes, and by its fourth edition (1801–1810), it had expanded to 20 volumes. Its rising stature as a scholarly work helped recruit eminent contributors, and the 9th (1875–1889) and Encyclopædia Britannica Eleventh Edition, 11th editions (1911) are landmark encyclopaedias for scholarship and literary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mediterranean
The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Europe, on the south by North Africa, and on the west almost by the Morocco–Spain border. The Mediterranean Sea covers an area of about , representing 0.7% of the global ocean surface, but its connection to the Atlantic via the Strait of Gibraltar—the narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates the Iberian Peninsula in Europe from Morocco in Africa—is only wide. Geological evidence indicates that around 5.9 million years ago, the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years during the Messinian salinity crisis before being refilled by the Zanclean flood about 5.3 million years ago. The sea was an important rout ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steering Oar
The steering oar or steering board is an over-sized oar or board, to control the direction of a ship or other watercraft prior to the invention of the rudder. It is normally attached to the starboard side in larger vessels, though in smaller ones it is rarely, if ever, attached. The steering oar was crucial in the invention of larger vessels in a time when the technology for rudders did not exist. Steering oars were the typical steering mechanism on larger Viking ship Viking ships were marine vessels of unique structure, used in Scandinavia throughout the Middle Ages. The boat-types were quite varied, depending on what the ship was intended for, but they were generally characterized as being slender and flexi ...s. References Sailboat components Sailing ship components {{Water-transport-stub, date=June 2018 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopædia Britannica 2006 Ultimate Reference Suite DVD
An encyclopedia is a reference work or compendium providing summaries of knowledge, either general or special, in a particular field or discipline. Encyclopedias are divided into articles or entries that are arranged alphabetically by article name or by thematic categories, or else are hyperlinked and searchable. Encyclopedia entries are longer and more detailed than those in most dictionaries. Generally speaking, encyclopedia articles focus on ''factual information'' concerning the subject named in the article's title; this is unlike dictionary entries, which focus on linguistic information about words, such as their etymology, meaning, pronunciation, use, and grammatical forms.Béjoint, Henri (2000)''Modern Lexicography'', pp. 30–31. Oxford University Press. Encyclopedias have existed for around 2,000 years and have evolved considerably during that time as regards language (written in a major international or a vernacular language), size (few or many volumes), intent ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pushrod
A valvetrain is a mechanical system that controls the operation of the intake and exhaust valves in an internal combustion engine. The intake valves control the flow of air/fuel mixture (or air alone for direct-injected engines) into the combustion chamber, while the exhaust valves control the flow of spent exhaust gases out of the combustion chamber once combustion is completed. Layout The valvetrain layout is largely dependent on the location of the camshaft. The common valvetrain configurations for piston engines, in order from oldest to newest, are: * Flathead engine: A single camshaft and the valves are located in the engine block below the cylinder or cylinder bank. * Overhead valve engine: A single camshaft remains in the block below the cylinder(s), however the valves are located in the cylinder head above the combustion chamber. * Overhead camshaft engine: Both the valves and one or more camshafts are located in the cylinder head above the cylinders or cylinder banks. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helmsman
A helmsman or helm (sometimes driver or steersman) is a person who steering, steers a ship, sailboat, submarine, other type of maritime vessel, airship, or spacecraft. The rank and seniority of the helmsman may vary: on small vessels such as fishing vessels and yachts, the functions of the helmsman are combined with that of the skipper (boating), skipper; on larger vessels, there is a separate officer of the watch who is responsible for the safe navigation of the ship and gives orders to the helmsman, who physically steers the ship in accordance with those orders. In the merchant navy, the person at the Ship's wheel, helm is usually an able seaman, particularly during ship arrivals, departures, and while maneuvering in restricted waters or other conditions requiring precise steering. An ordinary seaman is commonly restricted to steering in open waters. Moreover, military ships may have a Seaman (rank), seaman or quartermaster at the helm. A professional helmsman maintains a stea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
