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Jean-Charles De Borda
Jean-Charles, chevalier de Borda (4 May 1733 – 19 February 1799) was a French mathematician, physicist, and Navy officer. Biography Borda was born in the city of Dax to Jean‐Antoine de Borda and Jeanne‐Marie Thérèse de Lacroix. In 1756, Borda wrote ''Mémoire sur le mouvement des projectiles'', a product of his work as a military engineer. For that, he was elected to the French Academy of Sciences in 1764. Borda was a mariner and a scientist, spending time in the Caribbean testing out advances in chronometers. Between 1777 and 1778, he participated in the American Revolutionary War. In 1781, he was put in charge of several vessels in the French Navy. In 1782, he was captured by the English, and was returned to France shortly after. He returned as an engineer in the French Navy, making improvements to waterwheels and pumps. He was appointed as France's Inspector of Naval Shipbuilding in 1784, and with the assistance of the naval architect Jacques-Noël Sané in 17 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dax, Landes
Dax (; oc, Dacs; eu, Akize) is a Communes of France, commune in Nouvelle-Aquitaine, southwestern France, Subprefectures in France, sub-prefecture of the Landes (department), Landes Departments of France, department. It is known as a spa destination, specialising in mud treatment for rheumatism and similar ailments. Dax is also known for its tauromachy culture, especially during the August ferias, one of the most crowded festival events in France with 800,000 people attending over five days. It is also a market town, former bishopric and busy local centre, especially for the Chalosse area. Geography Dax lies on the river Adour, 30 km from the Atlantic Ocean and 42 km northwest of Bayonne. Dax station has rail connections to Paris, Hendaye, Tarbes, Bordeaux, Bayonne and Pau. History It was first established by the Romans, and its reputation is supposed to date from a visit by Julia, the daughter of the first E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quota Borda System
The Quota Borda system or quota preference score is a voting system that was devised by the British philosopher Michael Dummett and first published in 1984 in his book, ''Voting Procedures'', and again in his ''Principles of Electoral Reform''. If proportionality is required in a Borda count election, a quota element should be included into the counting procedure, which works best in multi-member constituencies of either 4 or 6 members. The threshold used is the Droop quota; in a single-seat constituency, the quota is an absolute majority, i.e., (50% + 1) of the valid vote; in a 2-seat constituency, it is (33% + 1); in a 3-seat, it's (25% + 1); and in a 4-seat, it is (20% + 1) of the valid vote. The four-seat selection goes as follows; Stage i) Any candidate gaining a quota of 1st preferences is elected. Stage ii) Any pair of candidates gaining 2 quotas is elected. (A pair of candidates, Ms J and Mr M, say, gains 2 quotas when that number of voters vote either 'J-1, M-2' or 'M- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Repeating Circle
Developed from the reflecting circle, the repeating circle is an instrument for geodetic surveying, invented by Etienne Lenoir in 1784, while an assistant of Jean-Charles de Borda, who later improved the instrument. It was notable as being the equal of the great theodolite created by the renowned instrument maker, Jesse Ramsden. It was used to measure the meridian arc from Dunkirk to Barcelona by Jean Baptiste Delambre and Pierre Méchain (see: meridian arc of Delambre and Méchain). Construction and operation The repeating circle is made of two telescopes mounted on a shared axis with scales to measure the angle between the two. The instrument combines multiple measurements to increase accuracy with the following procedure: At this stage, the angle on the instrument is double the angle of interest between the points. Repeating the procedure causes the instrument to show 4× the angle of interest, with further iterations increasing it to 6×, 8×, and so on. In this way, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tobias Mayer
Tobias Mayer (17 February 172320 February 1762) was a German astronomer famous for his studies of the Moon. He was born at Marbach, in Württemberg, and brought up at Esslingen in poor circumstances. A self-taught mathematician, he earned a living by teaching mathematics while still a youth. He had already published two original geometrical works when, in 1746, he entered J. B. Homann's cartographic establishment at Nuremberg. Here he introduced many improvements in mapmaking, and gained a scientific reputation which led (in 1751) to his election to the chair of economy and mathematics at the University of Göttingen. In 1754 he became superintendent of the observatory, where he worked until his death in 1762. Career Mayer's first important astronomical work was a careful investigation of the libration of the Moon (''Kosmographische Nachrichten'', Nuremberg, 1750), and his chart of the full moon (published in 1775) was unsurpassed for half a century. But his fame rests chiefl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflecting Instrument
Reflecting instruments are those that use mirrors to enhance their ability to make measurements. In particular, the use of mirrors permits one to observe two objects simultaneously while measuring the angular distance between the objects. While reflecting instruments are used in many professions, they are primarily associated with celestial navigation as the need to solve navigation problems, in particular the problem of the longitude, was the primary motivation in their development. Objectives of the instruments The purpose of reflecting instruments is to allow an observer to measure the altitude of a celestial object or measure the angular distance between two objects. The driving force behind the developments discussed here was the solution to the problem of finding one's longitude at sea. The solution to this problem was seen to require an accurate means of measuring angles and the accuracy was seen to rely on the observer's ability to measure this angle by simultaneously ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arc Measurement Of Delambre And Méchain
The arc measurement of Delambre and Méchain was a geodetic survey carried out by Jean-Baptiste Delambre and Pierre Méchain in 1792–1798 to measure an arc section of the Paris meridian between Dunkirk and Barcelona. This arc measurement served as the basis for the original definition of the metre. In 1791, the French Academy of Sciences chose to define the metre as one ten-millionth of the distance from the equator to the North or South Pole. This replaced the earlier definition based on the period of a pendulum, because the force of Earth's gravity varies slightly over the surface of the Earth, which affects the period of a pendulum. To establish a universally accepted foundation for the definition of the metre, more accurate measurements of a meridian were needed. The French Academy of Sciences commissioned an expedition led by Jean Baptiste Joseph Delambre and Pierre Méchain, lasting from 1792 to 1799, which attempted to accurately measure the distance between a belfry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metric System
The metric system is a system of measurement that succeeded the Decimal, decimalised system based on the metre that had been introduced in French Revolution, France in the 1790s. The historical development of these systems culminated in the definition of the International System of Units (SI) in the mid-20th century, under the oversight of an international standards body. Adopting the metric system is known as ''metrication''. The historical evolution of metric systems has resulted in the recognition of several principles. Each of the fundamental dimensions of nature is expressed by a single base unit (measurement), base unit of measure. The definition of base units has increasingly been realisation (metrology), realised from natural principles, rather than by copies of physical artefacts. For quantities derived from the fundamental base units of the system, units SI derived unit, derived from the base units are used—e.g., the square metre is the derived unit for area, a qu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewis And Clark Expedition
The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select group of U.S. Army and civilian volunteers under the command of Captain Meriwether Lewis and his close friend Second Lieutenant William Clark. Clark and 30 members set out from Camp Dubois, Illinois, on May 14, 1804, met Lewis and ten other members of the group in St. Charles, Missouri, then went up the Missouri River. The expedition crossed the Continental Divide of the Americas near the Lemhi Pass, eventually coming to the Columbia River, and the Pacific Ocean in 1805. The return voyage began on March 23, 1806, at Fort Clatsop, Oregon, and ended on September 23 of the same year. President Thomas Jefferson commissioned the expedition shortly after the Louisiana Purchase in 1803 to explore and to map the newly acquired territory, to find a pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Position Fixing
Geopositioning, also known as geotracking, geolocalization, geolocating, geolocation, or geoposition fixing, is the process of determining or estimating the geographic position of an object. Geopositioning yields a set of geographic coordinates (such as latitude and longitude) in a given map datum; positions may also be expressed as a bearing and range from a known landmark. In turn, positions can determine a meaningful location, such as a street address. Specific instances include: animal geotracking, the process of inferring the location of animals; positioning system, the mechanisms for the determination of geographic positions in general; internet geolocation, geolocating a device connected to the internet; and mobile phone tracking. Background Geopositioning uses various visual and electronic methods including position lines and position circles, celestial navigation, radio navigation, and the use of satellite navigation systems. The calculation requires measurements or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Navigation
Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navigation, marine navigation, aeronautic navigation, and space navigation. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks. All navigational techniques involve locating the navigator's position compared to known locations or patterns. Navigation, in a broader sense, can refer to any skill or study that involves the determination of position and direction. In this sense, navigation includes orienteering and pedestrian navigation. History In the European medieval period, navigation was considered part of the set of '' seven mechanical arts'', none of which were used for long voyages across open ocean. Polynesian navigation is probably the earliest form of open-ocean navigation; it was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Longitude
Longitude (, ) is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians are semicircular lines running from pole to pole that connect points with the same longitude. The prime meridian defines 0° longitude; by convention the International Reference Meridian for the Earth passes near the Royal Observatory in Greenwich, England on the island of Great Britain. Positive longitudes are east of the prime meridian, and negative ones are west. Because of the Earth's rotation, there is a close connection between longitude and time measurement. Scientifically precise local time varies with longitude: a difference of 15° longitude corresponds to a one-hour difference in local time, due to the differing position in relation to the Sun. Comparing local time to an absolute measure of time allows ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
