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Parallel Rule
Parallel rulers are a drafting instrument used by navigators to draw parallel lines on charts. The tool consists of two straight edges joined by two arms which allow them to move closer or further away while always remaining parallel to each other. History The parallel ruler was invented in about 1584 by Fabrizio Mordente, but it was not in common use until the 18th century. In the 19th century a retired sea captain, Captain William Andrew Field improved the design by adding a protractor-style scale to the upper edge of one rule, and compass points to the opposing edge, which made reading bearings easier. Examples exist of boxwood, ivory or ebony, usually with brass hinges. The instrument usually had two links, but longer models sometimes had three, and sometimes the links were scissored. Another variation is the "roller" model which included a cylindrical roller for ease of use. See also * Cras protractor Jean Émile Paul Cras (; 22 May 1879 – 14 September 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technical Drawing
Technical drawing, drafting or drawing, is the act and Academic discipline, discipline of composing Plan (drawing), drawings that Visual communication, visually communicate how something functions or is constructed. Technical drawing is essential for communicating ideas in Manufacturing, industry and engineering. To make the drawings easier to understand, people use familiar symbols, Perspective (graphical), perspectives, units of measurement, notation systems, visual styles, and page layout. Together, such Convention (norm), conventions constitute a visual language and help to ensure that the drawing is unambiguous and relatively easy to understand. Many of the symbols and principles of technical drawing are codified in an international standard called ISO 128. The need for precise communication in the preparation of a functional document distinguishes technical drawing from the expressive drawing of the visual arts. Artistic drawings are subjectively interpreted; their meanin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fabrizio Mordente
Fabrizio Mordente (Salerno, 1532 – ca 1608) was an Italian mathematician. He is best known for his invention of the " proportional eight-pointed compass" which has two arms with cursors that allow the solution of problems in measuring the circumference, area and angles of a circle. In 1567 he published a single sheet treatise in Venice showing illustrations of his device. Life and career Fabrizio Mordente was born in Salerno, Italy, and studied at the Università di Napoli. After completing his studies at the age of 20, he set out to see the world. He left Naples in 1552 and visited Crete, Cyprus, Egypt, Palestine and Mesopotamia. After reaching the Persian Gulf, he took a Portuguese ship to India. He stayed in Goa for three years and then continued his voyage around the Cape of Good Hope, eventually arriving in Lisbon. He went from there to Paris and visited other European cities before returning to Italy and visiting Venice, Florence and Rome. During this trip he drafted the in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Awards Of The Royal National Lifeboat Institution
A number of Royal National Lifeboat Institution awards have been established by the Royal National Lifeboat Institution (RNLI) since its creation in 1824. None are approved by the Crown, and are therefore unofficial awards. As such, they do not appear in the official British order of wear, although the principal lifesaving award, the ''Medal of the RNLI'', can be worn on the right breast in uniform by members of the British armed forces. RNLI awards The RNLI awards include: Medal of the RNLI The medal was established in 1824, the same year the RNLI was founded, to reward "humane and intrepid exertions in saving life from shipwrecks on our coasts, deemed sufficiently conspicuous to merit honourable distinction". The medal can be awarded for saving life at sea in gold, silver and, since 1917, in bronze. While awards are now only made to lifeboat crew who risk their lives in rescue attempts, a number of nineteenth century medals were bestowed on others who saved life from the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Humane Society
The Royal Humane Society is a British charity which promotes lifesaving intervention. It was founded in England in 1774 as the ''Society for the Recovery of Persons Apparently Drowned'', for the purpose of rendering first aid in cases of near drowning. History In 1773, physician William Hawes (physician), William Hawes (1736–1808) began publicising the power of artificial respiration and Tobacco smoke enema#Medical opinion, tobacco smoke enemas to resuscitate people who superficially appeared to have drowned. For a year he paid a reward out of his own pocket to any one bringing him a body rescued from the water within a reasonable time of immersion. Thomas Cogan, another English physician, who had become interested in the same subject during a stay at Amsterdam, where was instituted in 1767 a society for preservation of life from accidents in water, joined Hawes in his crusade. In the summer of 1774 Hawes and Cogan each brought fifteen friends to a meeting at the Chapter Coffee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protractor
A protractor is a measuring instrument, typically made of transparent plastic or glass, for measuring angles. Some protractors are simple half-discs or full circles. More advanced protractors, such as the bevel protractor, have one or two swinging arms, which can be used to help measure the angle. Typical Most protractors measure angles in degrees (°). Radian-scale protractors measure angles in radians. Most protractors are divided into 180 equal parts. Some precision protractors further divide degrees into arcminutes. They are used in mechanics, engineering and geometry. Bevel A bevel protractor is a graduated circular protractor with one pivoted arm; used for measuring or marking off angles. Sometimes Vernier scales are attached to give more precise readings. It has wide application in architectural and mechanical drawing, although its use is decreasing with the availability of modern drawing software or CAD. Universal bevel protractors are also used by toolmakers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compass
A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with magnetic north. Other methods may be used, including gyroscopes, magnetometers, and GPS receivers. Compasses often show angles in degrees: north corresponds to 0°, and the angles increase clockwise, so east is 90°, south is 180°, and west is 270°. These numbers allow the compass to show azimuths or bearings which are commonly stated in degrees. If local variation between magnetic north and true north is known, then direction of magnetic north also gives direction of true north. Among the Four Great Inventions, the magnetic compass was first invented as a device for divination as early as the Chinese Han Dynasty (since c. 206 BC),Li Shu-hua, p. 176 and later adopted for navigation by the Song Dynasty Chinese during the 11th centur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buxus
''Buxus'' is a genus of about seventy species in the family Buxaceae. Common names include box or boxwood. The boxes are native to western and southern Europe, southwest, southern and eastern Asia, Africa, Madagascar, northernmost South America, Central America, Mexico and the Caribbean, with the majority of species being tropical or subtropical; only the European and some Asian species are frost-tolerant. Centres of diversity occur in Cuba (about 30 species), China (17 species) and Madagascar (9 species). They are slow-growing evergreen shrubs and small trees, growing to 2–12 m (rarely 15 m) tall. The leaves are opposite, rounded to lanceolate, and leathery; they are small in most species, typically 1.5–5 cm long and 0.3–2.5 cm broad, but up to 11 cm long and 5 cm broad in ''B. macrocarpa''. The flowers are small and yellow-green, monoecious with both sexes present on a plant. The fruit is a small capsule 0.5–1.5 cm long (to 3 cm i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ivory
Ivory is a hard, white material from the tusks (traditionally from elephants) and teeth of animals, that consists mainly of dentine, one of the physical structures of teeth and tusks. The chemical structure of the teeth and tusks of mammals is the same, regardless of the species of origin, but ivory contains structures of mineralised collagen. The trade in certain teeth and tusks other than elephant is well established and widespread; therefore, "ivory" can correctly be used to describe any mammalian teeth or tusks of commercial interest which are large enough to be carved or scrimshawed. Besides natural ivory, ivory can also be produced synthetically, hence (unlike natural ivory) not requiring the retrieval of the material from animals. Tagua nuts can also be carved like ivory. The trade of finished goods of ivory products has its origins in the Indus Valley. Ivory is a main product that is seen in abundance and was used for trading in Harappan civilization. Finished ivory pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ebony
Ebony is a dense black/brown hardwood, coming from several species in the genus ''Diospyros'', which also contains the persimmons. Unlike most woods, ebony is dense enough to sink in water. It is finely textured and has a mirror finish when polished, making it valuable as an ornamental wood. The word ''ebony'' comes from the Ancient Egyptian ', through the Ancient Greek ('), into Latin and Middle English. Species Species of ebony include ''Diospyros ebenum'' (Ceylon ebony), native to southern India and Sri Lanka; '' D. crassiflora'' (Gabon ebony), native to western Africa; and '' D. celebica'' (Sulawesi ebony), native to Indonesia and prized for its luxuriant, multi-colored wood grain. Mauritius ebony, '' D. tessellaria'', was largely exploited by the Dutch in the 17th century. Some species in the genus yield an ebony with similar physical properties, but striped rather than the even black of ''D. ebenum''. Uses Ebony has a long history of use, and carved pieces have be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brass
Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other within the same crystal structure. Brass is similar to bronze, another copper alloy, that uses tin instead of zinc. Both bronze and brass may include small proportions of a range of other elements including arsenic (As), lead (Pb), phosphorus (P), aluminium (Al), manganese (Mn), and silicon (Si). Historically, the distinction between the two alloys has been less consistent and clear, and modern practice in museums and archaeology increasingly avoids both terms for historical objects in favor of the more general "copper alloy". Brass has long been a popular material for decoration due to its bright, gold-like appearance; being used for drawer pulls and doorknobs. It has also been widely used to make utensils because of its low melting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
