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Perinola (top)
A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be rotation, spun on its vertical Axis of rotation, axis, balancing on the tip due to the gyroscopic effect. Once set in motion, a top will usually precession, wobble for a few seconds, spin upright for a while, then start to wobble again with increasing amplitude as it loses energy, and finally tip over and roll on its side. Tops exist in many variations and materials, chiefly wood, metal, and plastic, often with a metal tip. They may be set in motion by twirling a handle with the fingers, by pulling a rope coiled around the body, or by means of a built-in auger (spiral plunger). Such toys have been used since Classical antiquity, antiquity in solitary or competitive games, where each player tries to keep one's top spinning for as long as possible, or achieve some other goal. Some tops have faceted bodies with symbols or inscriptions, and are used like dice to inject random ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A Tough Gang Of Spinning Tops
A, or a, is the first letter and the first vowel of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''a'' (pronounced ), plural ''aes''. It is similar in shape to the Ancient Greek letter alpha, from which it derives. The uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lowercase version can be written in two forms: the double-storey a and single-storey ɑ. The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type. In English grammar, " a", and its variant " an", are indefinite articles. History The earliest certain ancestor of "A" is aleph (also written 'aleph), the first letter of the Phoenician alphabet, which consisted entirely of consonants (for that reason, it is also called an abjad to distinguish it fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeology
Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscapes. Archaeology can be considered both a social science and a branch of the humanities. It is usually considered an independent academic discipline, but may also be classified as part of anthropology (in North America – the four-field approach), history or geography. Archaeologists study human prehistory and history, from the development of the first stone tools at Lomekwi in East Africa 3.3 million years ago up until recent decades. Archaeology is distinct from palaeontology, which is the study of fossil remains. Archaeology is particularly important for learning about prehistoric societies, for which, by definition, there are no written records. Prehistory includes over 99% of the human past, from the Paleolithic until the adven ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Clerk Maxwell
James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and scientist responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and light as different manifestations of the same phenomenon. Maxwell's equations for electromagnetism have been called the " second great unification in physics" where the first one had been realised by Isaac Newton. With the publication of "A Dynamical Theory of the Electromagnetic Field" in 1865, Maxwell demonstrated that electric and magnetic fields travel through space as waves moving at the speed of light. He proposed that light is an undulation in the same medium that is the cause of electric and magnetic phenomena. (This article accompanied an 8 December 1864 presentation by Maxwell to the Royal Society. His statement that "light and magnetism are affections of the same substance" is at page 499.) The unification of light and electrical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James David Forbes
James David Forbes (1809–1868) was a Scottish physicist and glaciologist who worked extensively on the conduction of heat and seismology. Forbes was a resident of Edinburgh for most of his life, educated at its University and a professor there from 1833 until he became principal of the United College of St Andrews in 1859. He invented an inverted pendulum seismometer in 1842. Life and work Forbes was born on 20 April 1809 at 86 George Street in Edinburgh, the fourth son of Sir William Forbes, 7th Baronet, of Monymusk and Pitsligo (1773–1828) and Williamina Belches of Invermay. His brothers were the advocate and agriculturalist Sir John Stuart Hepburn Forbes of Fettercairn and Pitsligo and the banker Charles Forbes. He entered the University of Edinburgh in 1825, and soon afterwards began to contribute papers to the ''Edinburgh Philosophical Journal'' anonymously under the signature "Δ". At the age of nineteen he became a fellow of the Royal Society of Edinburgh, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potter's Wheel
In pottery, a potter's wheel is a machine used in the shaping (known as throwing) of clay into round ceramic ware. The wheel may also be used during the process of trimming excess clay from leather-hard dried ware that is stiff but malleable, and for applying incised decoration or rings of colour. Use of the potter's wheel became widespread throughout the Old World but was unknown in the Pre-Columbian New World, where pottery was handmade by methods that included coiling and beating. A potter's wheel may occasionally be referred to as a "potter's lathe". However, that term is better used for another kind of machine that is used for a different shaping process, turning, similar to that used for shaping of metal and wooden articles. The pottery wheel is an important component to create arts and craft products. The techniques of jiggering and jolleying can be seen as extensions of the potter's wheel: in jiggering, a shaped tool is slowly brought down onto the plastic clay body t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spindle Whorl
A spindle whorl is a disc or spherical object fitted onto the spindle to increase and maintain the speed of the spin. Historically, whorls have been made of materials like amber, antler, bone, ceramic, coral, glass, stone, metal (iron, lead, lead alloy), and wood (oak). Local sourced materials have been also used, such as chalk, limestone, mudstone, sandstone, slate, lydite and soapstone. Gallery File:Spindle Whorl (Sulsultin), 19th century, 05.588.7382.jpg, ''Spindle Whorl (Sulsultin)'', Chemainus, Coast Salish (Native American), 19th century, Brooklyn Museum File:Przęślik 0211.jpg, Whorl (12th or 13th century) found in Poland File:1017_-_Keramikos_Museum,_Athens_-_Spindle-whirls,_10th_century_BC_-_Photo_by_Giovanni_Dall'Orto,_Nov_12.jpg, Ancient Greek spindle whorls, 10th century BC, Kerameikos Archaeological Museum, Athens File:Muisca spindle whorl.jpg, Muisca spindle whorl (500AD – 1500AD). Archaeology Museum, Sogamoso, Colombia File:Object from the exhibition We call ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bow Drill
A bow drill is a simple hand-operated type of tool, consisting of a rod (the ''spindle'' or ''drill shaft'') that is set in rapid rotary motion by means of a cord wrapped around it, kept taut by a bow which is pushed back and forth with one hand. This tool of prehistoric origin has been used both as a drill, to make holes on solid materials such as wood, stone, bone, or teeth, and as a fire drill to start a fire. The spindle can be held in a fixed frame, or by a hand-held block (the ''hand piece'' or ''thimble'') with a hole into which the top of the shaft is inserted. Some lubricant should be used to reduce friction between these two parts. A popular campcraft book of 1920 attributed this invention to the Inuit. In Mehrgarh (Pakistan) it has been dated between the 4th-5th millennium BCE. The string of the bow is wrapped once around the spindle, so that it is tight enough not to slip during operation. In the variation called the Egyptian bow drill, the cord is wound aro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rattleback
A rattleback is a semi-ellipsoidal top which will rotate on its axis in a preferred direction. If spun in the opposite direction, it becomes unstable, "rattles" to a stop and reverses its spin to the preferred direction. This spin-reversal appears to violate the law of the conservation of angular momentum. Moreover, for most rattlebacks the motion will happen when the rattleback is spun in one direction, but not when spun in the other. Some exceptional rattlebacks will reverse when spun in either direction. This makes the rattleback a physical curiosity that has excited human imagination since prehistoric times. A rattleback may also be known as a "anagyre", "(rebellious) celt", "Celtic stone", "druid stone", "rattlerock", "Robinson Reverser", "spin bar", "wobble stone" (or "wobblestone") and by product names including "ARK", "Bizzaro Swirl", "Space Pet" and "Space Toy". History Archeologists who investigated ancient Celtic and Egyptian sites in the 19th century found celts whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Celt (tool)
In archaeology, a celt is a long, thin, prehistoric, stone or bronze tool similar to an adze, hoe, or axe. A shoe-last celt was a polished stone tool used during the early European Neolithic for felling trees and woodworking. Etymology The term "celt" seems to have come about from a copyist's error in many medieval manuscript copies of Job 19:24 in the Latin Vulgate Bible, which became enshrined in the authoritative Sixto-Clementine printed edition of 1592. Where all earlier versions (the Codex Amiatinus, for example) have ''vel certe'' (the Latin for 'but surely'), the Sixto-Clementine has ''vel celte''. The Hebrew has לעד (''lā‘aḏ'') at this point, which means 'forever'. The editors of the Oxford English Dictionary " nclineto the belief that ''celtis'' was a phantom word," simply a misspelling of ''certe''. However, some scholars over the years have treated ''celtis'' as a real Latin word. From the context of Job 19:24 ("Oh, that my words were inscribed with an i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samara (fruit)
A samara (, ) is a winged achene, a type of fruit in which a flattened wing of fibrous, papery tissue develops from the ovary wall. A samara is a simple dry fruit, and is indehiscent (not opening along a seam). The shape of a samara enables the wind to carry the seed farther away from the tree than regular seeds would go, and is thus a form of anemochory. In some cases the seed is in the centre of the wing, as in the elms (genus ''Ulmus''), the hoptree (''Ptelea trifoliata''), and the bushwillows (genus ''Combretum''). In other cases the seed is on one side, with the wing extending to the other side, making the seed autorotate as it falls, as in the maples (genus '' Acer'') and ash trees (genus ''Fraxinus''). There are also single-wing samara such as mahogany (genus Swietenia) which have a shape that enables fluttering. Some species that normally produce paired samaras, such as ''Acer pseudoplatanus'', can also produce them in groups of three or four. File:TripleSycamoreS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maple
''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http://www.mobot.org/MOBOT/research/APweb/. There are approximately 132 species, most of which are native to Asia, with a number also appearing in Europe, northern Africa, and North America. Only one species, ''Acer laurinum'', extends to the Southern Hemisphere.Gibbs, D. & Chen, Y. (2009The Red List of Maples Botanic Gardens Conservation International (BGCI) The type species of the genus is the sycamore maple, '' Acer pseudoplatanus'', the most common maple species in Europe.van Gelderen, C. J. & van Gelderen, D. M. (1999). ''Maples for Gardens: A Color Encyclopedia'' Maples usually have easily recognizable palmate leaves ('' Acer negundo'' is an exception) and distinctive winged fruits. The closest relatives of the maples are the horse c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Role-playing Game
A role-playing game (sometimes spelled roleplaying game, RPG) is a game in which players assume the roles of player character, characters in a fictional Setting (narrative), setting. Players take responsibility for acting out these roles within a narrative, either through literal acting or through a process of structured decision-making regarding character development. Actions taken within many games succeed or fail according to a formal role-playing game system, system of rules and guidelines. There are several forms of role-playing games. The original form, sometimes called the tabletop role-playing game (TRPG), is conducted through discussion, whereas in live action role-playing game, live action role-playing (LARP), players physically perform their characters' actions.(Tychsen et al. 2006:255) "LARPs can be viewed as forming a distinct category of RPG because of two unique features: (a) The players physically embody their characters, and (b) the game takes place in a physica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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