The commercialized measurement techniques for interfacial shear rheology include magnetic needle method, rotating ring method and rotating bicone method. The magnetic needle method, developed by Brooks et al., has the highest Boussinesq number of the commercialized methods. In this method, a thin magnetic needle is oscillated at the interface using a magnetic field.
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Developed by Peltier, this uses a form of magnetic compass to measure deflection by balancing the electrostatic force with a magnetic needle.
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Saeta can also mean "bud of a vine" or "hand of a clock" or "magnetic needle". Appleton's New Cuyás Dictionary, v.2 (NY 1928; Cumbre, México 16th ed. 1966), p. 488.
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During the Second World War, Bitter worked for the Naval Bureau of Ordnance. He often traveled to England to find ways to demagnetize British ships to protect them from a new type of German mine, which used a compass needle to trigger detonation. The mine, dropped from the air, would sink to the bottom of a river and remain there with its magnetic needle aligned to the Earth's magnetic field at that location. When a ship passed over it, the mass of the ship caused the magnetic needle to move slightly.
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In 1820, Hans Christian Orsted demonstrated that it was possible to deflect a magnetic needle by closing or opening an electric circuit nearby. A deluge of papers attempting explain the phenomenon was published. Ampère's law and the Biot- Savart law were quickly deduced. The science of electromagnetism was born.
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In 1819, Scoresby was elected a Fellow of the Royal Society of Edinburgh. His proposers were Robert Jameson. John Playfair and Sir G S Mackenzie. About the same time communicated a paper to the Royal Society of London: "On the Anomaly in the Variation of the Magnetic Needle".
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François Arago Arago's fame as an experimenter and discoverer rests mainly on his contributions to magnetism in the co-discovery with Léon Foucault of eddy currents, and still more to optics. He showed that a magnetic needle, made to oscillate over nonferrous surfaces, such as water, glass, copper, etc., falls more rapidly in the extent of its oscillations according as it is more or less approached to the surface. This discovery, which earned him the Copley Medal of the Royal Society in 1825, was followed by another, that a rotating plate of copper tends to communicate its motion to a magnetic needle suspended over it, which he called "magnetism of rotation"Annales de chimie et de physique (1824), vol.
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This is because the geographic north pole of the earth lies very close to the magnetic south pole of the earth. This south magnetic pole of the earth located at an angle of 17 degrees to the geographic north pole attracts the north pole of the magnetic needle and vice versa.
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175 A main contributor to this field was Shen Kuo (1031–1095), a polymath and statesman who was the first to describe the magnetic-needle compass used for navigation, as well as establishing the concept of true north. In optics, Shen Kuo independently developed a camera obscura.Joseph Needham, Volume 4, Part 1, 98.
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He wrote that steel needles were magnetized once they were rubbed with lodestone, and that they were put in floating position or in mountings; he described the suspended compass as the best form to be used, and noted that the magnetic needle of compasses pointed either south or north.Sivin (1995), III, 21.Elisseeff (2000), 296.
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The monument over Hans Christian Ørsted stands on the former Holck's Bastion. It was designed by Jens Adolf Jerichau and erected in 1876, when work on the park just started. The monument consists of a bronze statue of Ørsted mounted on a granite plinth. Ørsted is seen demonstrating the effect of an electric current on a magnetic needle.
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This magnetised rod (or magnetic needle) is then placed on a low friction surface to allow it to freely pivot to align itself with the magnetic field. It is then labeled so the user can distinguish the north-pointing from the south-pointing end; in modern convention the north end is typically marked in some way.
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In particular, Garzoni considers the behaviour of magnetized iron dust. The behaviour of iron placed in the sphere of action of more loadstones is salso investigated. In the subsequent experiments, Garzoni studies the external diffusion of magnetic virtue by displacing a magnetic needle within the sphere of action. At every point, the direction of the needle gives the direction of the magnetic virtue.
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A compass and map The Earth has a magnetic field which is approximately aligned with its axis of rotation. A magnetic compass is a device that uses this field to determine the cardinal directions. Magnetic compasses are widely used, but only moderately accurate. The north pole of the magnetic needle points towards the geographic north pole of the earth and vice versa.
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While compass surveying, the magnetic needle is sometimes disturbed from its normal position under the influence of external attractive forces. Such a disturbing influence is called as local attraction.surveying volume 1 by Dr B.c Punmia and Ashok Kumar Jain. Chapter Compass Surveying The external forces are produced by sources of local attraction which may be current carrying wire (magnetic materials) or metal objects.
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He invented it for the purpose of finding the times of prayers. Arab navigators also introduced the 32-point compass rose during this time. In 1399, an Egyptian reports two different kinds of magnetic compass. One instrument is a “fish” made of willow wood or pumpkin, into which a magnetic needle is inserted and sealed with tar or wax to prevent the penetration of water.
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He had two tombs, one in Wo-erh-to in Yunnan and another memorial which contained his clothes in Xi'an in Shaanxi province. The author of "The Magnetic Needle of Islam", Ma Chu (1630–1710), was a descendant of Sayyid Ajall. The d'Ollone expedition during the Qing dynasty recorded that Imam Na Wa-Ch'ing was the leader of the family of descendants of Sayyid Ajall.( )( ) Ma repaired Sayyid Ajall's tomb.
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Cyclopaedia Circumferentor with Gunter's chain at Campus Martius Museum in Marietta, Ohio A circumferentor, or surveyor's compass, is an instrument used in surveying to measure horizontal angles. It was superseded by the theodolite in the early 19th century. A circumferentor consists of a circular brass box containing a magnetic needle, which moves freely over a brass circle, or compass divided into 360 degrees. The needle is protected by a glass covering.
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Needham, Volume 4, Part 2, 287–288 Much later the Chinese polymath scientist Shen Kuo (1031–1095 AD) was the first to describe the magnetic needle-compass, along with its usefulness for accurate navigation by discovering the concept of true north.Bowman, 599.Sivin, III, 22. In his Pingzhou Table Talks of 1119 AD the Song Dynasty maritime author Zhu Yu described the use of separate bulkhead compartments in the hulls of Chinese ships.
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It explores the role of sound and musical harmonics in the development and form of crystals, plants and animals. The paper shows how he tested many of his theories in his laboratory. "A New Suspension of the Magnetic Needle" describes a detector he built to measure the Earth's vertical current, and data he gathered using this detector. He also develops his hypothesis that a bar magnet has additional poles, East-West poles.
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"The Gravitational Wave,", Proceedings of the Scientific and Technical Congress of Radionics and Radiesthesia, London, May, 1950. "The Music of Crystals, Plants and Human Beings" , Radio Perception, September 1951 "A New Suspension of the Magnetic Needle", Radio Perception Vol XI, 80, June 1953 "Can there be any science behind Healing Hands?" The London Hospital Gazette, March 1967. "Milosc" from the "Summa Teologica" by St. Thomas Aquinas, translated into Polish with notes by Andrew Glazewski. Publ.
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His efforts were also overshadowed by Galileo Galilei's improvement of the telescope in 1609, following its introduction by Lippershey in the Netherlands in 1608. In the book, della Porta also mentioned an imaginary device known as a sympathetic telegraph. The device consisted of two circular boxes, similar to compasses, each with a magnetic needle, supposed to be magnetized by the same lodestone. Each box was to be labeled with the 26 letters, instead of the usual directions.
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Almost immediately, however, they run into an obstacle: the Giant of the Snows, a pipe-smoking, man-eating frost giant who has to be scared off with cannon fire. They come at last to the pole proper, where they find a huge magnetic needle. Stuck by magnetic attraction to the needle, which breaks under their weight and plunges them into the icy waters, they signal for help and are picked up by a passing airship. Penguins, seals, and Arctic birds wave goodbye.
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In order to navigate, Peral used a bronze magnetic needle installed in the ceiling of the turret. The design avoided any electrical interference. He also devised a periscope, a fixed tube on the turret; by using a series of prisms, it projected the outside world to within the submarine. The engine-cooling system consisted of forcing compressed air stored in the submarine over the engines, and though the original project had needed 430 accumulators, the final project installed 613 with a weight of .
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Different frequencies of oscillation give rise to the different forms of electromagnetic radiation, from radio waves at the lowest frequencies, to visible light at intermediate frequencies, to gamma rays at the highest frequencies. Ørsted was not the only person to examine the relationship between electricity and magnetism. In 1802, Gian Domenico Romagnosi, an Italian legal scholar, deflected a magnetic needle using a Voltaic pile. The factual setup of the experiment is not completely clear, so if current flowed across the needle or not.
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From 1821 to 1823, Seebeck performed a series of experiments trying to understand Ørsted's findings from 1820. During his experiments, he observed that a junction of dissimilar metals produces a deflexion on a magnetic needle (compass) when exposed to a temperature gradient. Because Ørsted had discovered that an electric current produces a deflexion on a compass transversal to the wire, Seebeck's results were interpreted as a thermoelectric effect. This is now called the Peltier–Seebeck effect and is the basis of thermocouples and thermopiles.
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Her extraordinary beauty led the seventeen-year-old Paraluman to be recommended by another sister of Corazón Noble, Norma, to film producer Luis Nolasco. Her first movie was Flores de Mayo (1940), and she initially used the screen name Mina de Gracía. She was rechristened "Paraluman" (archaic Tagalog for "muse" or "magnetic needle") by Fernando Poe, Sr., who signed her as a full-fledged star in X’otic Films' Paraluman (1941). This was followed by the actresses' roles in the films Bayani ng Bayan and Puting Dambana.
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The Magnetic Pavilion, 1900 The first magnetic observation was taken in 1680 by the first Astronomer Royal, John Flamsteed, using a magnetic needle from the Royal Society. The second and third Astronomers Royal, Edmond Halley and then James Bradley, also took some magnetic measurements during their tenure. In the 19th century George Airy established the Magnetical and Meteorological Department. The first Magnetic House was built next to the observatory but by 1900 a second, about 300–400 metres from the main observatory, was built to reduce magnetic interference.
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Pre modern Arabic sources refer to the compass using the term ṭāsa (lit. "bowl") for the floating compass, or ālat al-qiblah ("qibla instrument") for a device used for orienting towards Mecca. Friedrich Hirth suggested that Arab and Persian traders, who learned about the polarity of the magnetic needle from the Chinese, applied the compass for navigation before the Chinese did. However, Needham described this theory as "erroneous" and "it originates because of a mistraslation" of the term chia-ling found in Zhu Yu's book Pingchow Table Talks.
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Ma Yuan, featuring the oldest known depiction of a fishing reelNeedham, Volume 4, Part 2, 100. The Chinese of the Song dynasty were adept sailors who traveled to ports of call as far away as Fatimid Egypt. They were well equipped for their journeys abroad, in large seagoing vessels steered by stern-post rudders and guided by the directional compass. Even before Shen Kuo and Zhu Yu had described the mariner's magnetic needle compass, the earlier military treatise of the Wujing Zongyao in 1044 had also described a thermoremanence compass.
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Iwan Rhys Morus, Frankenstein's Children: Electricity, Exhibition, and Experiment in Early-Nineteenth-Century London, pp. 203-206, Princeton University Press, 2014 . Davy's telegraph was not protected by a patent at this stage, but one was granted in the following year, 1838, despite the objections of Cooke and Wheatstone. Davy invented a relay which used a magnetic needle which dipped into a mercury contact when an electric current passed through the surrounding coil. In recognition of this he was elected in 1885 as an honorary member of the Society of Telegraph Engineers and was informed of this by telegraph shortly before his death.
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This volume is devoted to problems relating to annuities, reversions, insurances, leases on lives, etc.. His Accountant, or a Method of Book-keeping, was published 1750, with a dedication to Macclesfield. In 1751 he edited Edmund Wingate's Arithmetic, which had previously been edited by John Kersey and then by George Shelley. Another work, An Account of the Methods used to describe Lines on Dr. Halley's Chart of the terraqueous Globe, showing the variation of the magnetic needle about the year 1756 in all the known seas, &c.; By Wm. Mountaine and James Dodson, about isogons, was published in 1758, after Dodson's death.
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The Wujing Zongyao part 1 volume 15 text stated: Later on in the Song dynasty the compass was used with maritime navigation. Several decades after the Wujing Zongyao was written, the scientist and statesman Shen Kuo (1031–1095 AD) wrote of the first truly magnetized compass needle in his book Dream Pool Essays (1088 AD). With a more efficient compass magnetized by lodestone, the thermoremanence compass fell out of use. The later maritime author Zhu Yu wrote of the magnetic needle compass as a means to navigate at sea in his Pingzhou Table Talks of 1119 AD.
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Soldier using a prismatic compass to get an azimuth A prismatic compass is a navigation and surveying instrument which is extensively used to find out the bearing of the traversing and included angles between them, waypoints (an endpoint of the lcourse) and direction. Compass surveying is a type of surveying in which the directions of surveying lines are determined with a magnetic compass, and the length of the surveying lines are measured with a tape or chain or laser range finder. The compass is generally used to run a traverse line. The compass calculates bearings of lines with respect to magnetic needle.
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John Lorimer (1732–1795) was an American surgeon, mathematician, politician and cartographer in the 18th Century. Lorimer served as a surgeon for the British army in North America between 1758 and 1784, participating in both the French and Indian War and the American Revolution. He was a fellow of the Royal College of Physicians of Edinburgh, and author of the book "A Concise Essay on Magnetism; with an Account of the Declination and Inclination of the Magnetic Needle; and an Attempt to ascertain the Cause of the Variation thereof," published in 1795.Portrait miniature of Doctor John Lorimer.
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A Hardy clock showed sidereal time and a Brequet clock showed mean time. All instruments were mounted on solid masonry piers. There was also a Fortin pendulum and two instruments for observing the dip and variation of the magnetic needle. Some £470 was spent on the building in 1832, when the house was extended by two small rooms. In 1835, the transit was replaced by a 3½ foot (1.06m) Jones' transit circle, after which the mural circle was predominantly used because Dunlop believed the Jones circle was too difficult for one person to operate (Rosen 2003: pp. 86–87).
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His design featured a metal compass capsule containing a magnetic needle with orienting marks mounted into a transparent protractor baseplate with a lubber line (later called a direction of travel indicator). By rotating the capsule to align the needle with the orienting marks, the course bearing could be read at the lubber line. Moreover, by aligning the baseplate with a course drawn on a map – ignoring the needle – the compass could also function as a protractor. Tillander took his design to fellow orienteers Björn, Alvid, and Alvar Kjellström, who were selling basic compasses, and the four men modified Tillander's design.
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Polymath geniuses—that is, people knowledgeable across an encyclopaedic range of topics—such as Shen Kuo (1031–1095) and Su Song (1020–1101) embodied the spirit of early empirical science and technology in the Song era. Shen is famous for discovering the concept of true north and magnetic declination towards the North Pole by calculating a more accurate measurement of the astronomical meridian, and fixing the calculated position of the pole star that had shifted over the centuries.Sivin, III, 22. This allowed sailors to navigate the seas more accurately with the magnetic needle compass, also first described by Shen.
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In 1772 was published in Dublin Hood's Tables of Difference of Latitude and Departure for Navigators, Land Surveyors. In it he recommended that in surveying the bearing of objects should be taken from the meridian of the place. The tables printed in the book are the natural sines of all the angles, in degrees and quarter degrees, to different radii, the latter ranging from 1 to 100, as being best adapted to Gunter's chain. Hood also gave an account of the diurnal variation of the magnetic needle and its correction, and a description of a new surveying instrument.
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200-265 AD) invented the south- pointing chariot, a wheeled device employing a differential gear that allowed a fixed figurine to point always in the southern cardinal direction. The mariner's astrolabe was the chief tool of Celestial navigation in early modern maritime history. This scaled down version of the instrument used by astronomers served as a navigational aid to measure latitude at sea, and was employed by Portuguese sailors no later than 1481. The precise date of the discovery of the magnetic needle compass is undetermined, but the earliest attestation of the device for navigation was in the Dream Pool Essays by Shen Kuo (1088).
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The Conquest of the Pole () is a 1912 French silent film directed by and starring Georges Méliès. The film, loosely inspired by contemporary events and by Jules Verne's Voyages Extraordinaires, follows the comic misadventures of an international group of explorers on an expedition to the North Pole, where they encounter a man-eating frost giant and a dangerous magnetic needle. The film, one of Méliès's last cinematic works, was released by Pathé Frères to critical acclaim in France and England, but was a box-office failure and contributed to Méliès's mounting financial difficulties. It continues to be seen as one of his masterpieces and is sometimes named as his greatest work.
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Middleton returned to England in 1742, where he was presented with the Royal Society's Copley Medal, to whom he presented a paper entitled "The effects of cold; together with observations of the longitude, latitude, and declination of the magnetic needle, at Prince of Wales's fort, upon Churchill-River in Hudson's Bay, North America". Middleton was given command of , in May 1745, and commanded her until 1748, when peace was negotiated with Spain. Royal Navy officers were entitled to half-pay, when not employed, and Middleton spent the rest of his life on half-pay. He went back to the Hudson's Bay Company, and requested a command, there, without success.
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The monument consists of a bronze statue of Ørsted mounted on a granite plinth. Ørsted is seen demonstrating the effect of an electric current on a magnetic needle. With his hands he is connecting the wires from an electric battery, thereby making a magnet oscillate. At the foot of the statue sit the three Norns or goddesses of destiny in Norse mythology, Urðr (the past) who is noting the past, and Ørsted's name, on a tablet, Verðandi (the present), who with her distaff is spinning the thread of fate, and Skuld (the future), who is silently awaiting the fullness of time with a rune stick in her hand.
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In September 1820, Ampère's friend and eventual eulogist François Arago showed the members of the French Academy of Sciences the surprising discovery of Danish physicist Hans Christian Ørsted that a magnetic needle is deflected by an adjacent electric current. Ampère began developing a mathematical and physical theory to understand the relationship between electricity and magnetism. Furthering Ørsted's experimental work, Ampère showed that two parallel wires carrying electric currents attract or repel each other, depending on whether the currents flow in the same or opposite directions, respectively - this laid the foundation of electrodynamics. He also applied mathematics in generalizing physical laws from these experimental results.
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A sympathetic alphabet was a supposed form of communication used in the 17th century by Rosicrusians and Magnetisers.Charles MacKay, Extraordinary Popular Delusions and the Madness of Crowds Two parties would remove a section of skin from their arms or hands and mutually transplant it while still fresh. It was believed that the transplanted piece of flesh kept a close sympathy with the original limb so that its owner was still aware of any injury done to it. On the transplanted flesh was tattooed an alphabet whereby, by pricking the letters with a magnetic needle, the users believed they could communicate instantaneously across great distances.
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Diagram of a Ming dynasty mariner's compass A lodestone compass was used in China during the Han Dynasty between the 2nd century BCE and 1st century CE, where it was called the "south-governor" (sīnán ). The earliest reference to a magnetic device used for navigation is in a Song Dynasty book dated to 1040-1044, where there is a description of an iron "south-pointing fish" floating in a bowl of water, aligning itself to the south. The device is recommended as a means of orientation "in the obscurity of the night." The first suspended magnetic needle compass was written of by Shen Kuo in his book of 1088.
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Massa is mentioned for the first time in the Tabula Peutingeriana, a 2nd-4th century AD itinerary, with the name ad Tabernas frigidas, referring perhaps to a stage on the Via Aemilia Scauri consular road from Pisa to Luni. From the 15th to the 19th century, Massa was the capital of the independent Principate (later Duchy) of Massa and Carrara, ruled by the Malaspina and Cybo-Malaspina families. Massa is the first recorded town in Europe in which the magnetic needle compass was used in mines to map them and determine the extent of various mine owners' properties. In 1829 the states were inherited by Francis IV, Duke of Modena.
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Improvements which made the dip circle a practical aid for polar navigation were made by Robert Were Fox FRS, who developed in the 1830s the first dip circle that could be used on board a moving ship. Another important improvement to the instrument was developed in the 1830s by the Dublin physicist Humphrey Lloyd, who devised a way of attaching a magnetic needle at right-angles to the dip needle in order to measure the intensity of force (by seeing the extent to which the right- angle needle deflected the dip-needle). By World War I the most advanced dip circles were being made. With the development of electronic systems dip circles became obsolete.
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Diagram of a Ming Dynasty mariner's compass In terms of global significance, Zhu Yu's book was the first book in history to mention the use of the mariner's magnetic-needle compass for navigation at sea.Sivin, III, 22. Although the compass needle was first described in detail by the Chinese scientist Shen Kuo (1031–1095) in his Dream Pool Essays of 1088 AD, he did not specifically outline its use for navigation at sea. The passage from Zhu Yu's Pingzhou Ketan relating to the use of the compass states: > According to government regulations concerning seagoing ships, the larger > ones can carry several hundred men, and the smaller ones may have more than > a hundred men on board.
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Gunpowder warfare at sea was also first known in China, with battles such as the Battle of Caishi and the Battle of Tangdao on the Yangtze River in 1161 AD during the Jin–Song wars. One of the most important books of medieval maritime literature was Zhu Yu's Pingzhou Table Talks of 1119 AD. Although the Chinese scientist Shen Kuo (1031–1095) was the first to describe the magnetic-needle compass, Zhu Yu's book was the first to specify its use for navigation at sea. Zhu Yu's book also described watertight bulkhead compartments in the hull of Chinese ships, which prevented sinking when heavily damaged in one compartment.Needham, Volume 4, Part 3, 463.
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Borri also made observations on the magnetic variation of the compass. According to Kircher (1641) he drew up the first chart for the Atlantic and Indian Oceans showing the spots where the magnetic needle makes the same angles with the meridian; if this is true, he should be regarded as the forerunner of Edmund Halley. Borrus gives the explanation to the chart in a manuscript that belongs to the Royal Academy at Lisbon. In another manuscript, now in Évora, Tratada da arte de navegar pelo Cristovao Bruno, which bears on the same subject, he makes suggestions, according to Allatius (1633), as to a new method for determining the longitude at sea and also concerning improvements in sea-charts.
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Essai de géométrie analytique, 1826 Jean-Baptiste Biot made many contributions to the scientific community in his lifetime – most notably in optics, magnetism, and astronomy. The Biot–Savart law in magnetism is named after Biot and his colleague Félix Savart for their work in 1820.A joint Biot-Savart paper "Note sur le magnétisme de la pile de Volta" was published in the Annales de chemie et de physique in 1820. In their experiment they showed a connection between electricity and magnetism by "starting with a long vertical wire and a magnetic needle some horizontal distance apart [and showing] that running a current through the wire caused the needle to move" (Parsley).
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Now let us look at the internal working of this meter. Voltage drop across an inductor is directly proportion to frequency of the source voltage, as we increase the frequency of the applied voltage the voltage drop across the inductor L1 increase that means the voltage impressed between the coil 1 is increased hence the current through the coil 1 increase while the current through the coil 2 decreases. Since the current through the coil 1 increases the magnetic field also increases and the magnetic needle attracts more towards the left side showing the increment in the frequency. Similar action will takes if decrease the frequency but in this the pointer will moves towards the left side. richardsradios.co.
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Arago orally communicates the results of some experiments that he has conducted on the influence that metals and many other substances exert on a magnetic needle, which has the effect of rapidly reducing the amplitude of the oscillations without altering significantly their duration. He promises, on this subject, a detailed memoir.) but (after Faraday's explanation of 1832Philosospical magazine 1840) is now known as eddy current. Arago is also fairly entitled to be regarded as having proved the long-suspected connexion between the aurora borealis and the variations of the magnetic elements. In 1827 he was elected an associated member of the Royal Institute of the Netherlands, when that institute became the Royal Netherlands Academy of Arts and Sciences in 1851, he became foreign member.
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Needham p. 12-13 "...that the floating fish-shaped iron leaf spread outside China as a technique, we know from the description of Muhammad al' Awfi just two hundred years later" The earliest Arabic reference to a compass, in the form of magnetic needle in a bowl of water, comes from a work by Baylak al-Qibjāqī, written in 1282 while in Cairo.Kitāb Kanz al-tujjār fī maʿrifat al-aḥjār Al- Qibjāqī described a needle-and-bowl compass used for navigation on a voyage he took from Syria to Alexandria in 1242. Since the author describes having witnessed the use of a compass on a ship trip some forty years earlier, some scholars are inclined to antedate its first appearance in the Arab world accordingly.
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Christmas Lecture at the Royal Institution After the Dane Hans Christian Orsted demonstrated that it was possible to deflect a magnetic needle by closing or opening an electric circuit nearby, a deluge of papers attempting explain the phenomenon was published. Michael Faraday set himself to the task of clarifying the nature of electricity and magnetism by experiments. In doing so, he devised what could be described as the first electric motor (though it does not resemble a modern one), a transformer (now used to step up the voltage and step down the current or vice versa), and a dynamo (which contains the basics of all electric turbine generators). The practical value of Faraday's research on electricity and magnetism was nothing short of revolutionary.
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Changes in frequency cause an imbalance in the currents in the two coils, causing them, and the pointer, to move. Another type of frequency meter, Weston Frequency meter is not of the deflection type, is the resonant reed type, ordinarily used in ranges from 10 to 1,000 Hz, although special designs can operate at lower or higher frequencies. The main principle of working of weston type frequency meter is that "when an current flows through the two coils which are perpendicular to each other, due to these currents some magnetic fields will produce and thus the magnetic needle will deflects towards the stronger magnetic field showing the measurement of frequency on the meter". Construction of weston frequency is as compared to ferrodynamic type of frequency meter.
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"I am at the last contented that it should come forth in English," he wrote resignedly, "Not that I think it worthy either of my labour or the publique view, but to satisfy their importunity who not understand the Latin yet were at the charge to buy the instrument." It was a manual not for cloistered university fellows but for sailors and surveyors in real world. There is reason to believe that Gunter was the first to discover (in 1622 or 1625) that the magnetic needle does not retain the same declination in the same place at all times. By desire of James I he published in 1624 The Description and Use of His Majesties Dials in Whitehall Garden, the only one of his works which has not been reprinted.
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In May they agreed to join their forces, Wheatstone contributing the scientific, and Cooke the administrative talent. The deed of partnership was dated 19 November 1837. A joint patent was taken out for their inventions, including the five-needle telegraph of Wheatstone, and an alarm worked by a relay, in which the current, by dipping a needle into mercury, completed a local circuit, and released the detent of a clockwork. The five-needle telegraph, which was mainly, if not entirely, due to Wheatstone, was similar to that of Schilling, and based on the principle enunciated by André-Marie Ampère – that is to say, the current was sent into the line by completing the circuit of the battery with a make and break key, and at the other end it passed through a coil of wire surrounding a magnetic needle free to turn round its centre.
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The polymath Chinese scientist Shen Kuo (1031–1095 CE) was not only the first in history to describe the magnetic-needle compass, but also made a more accurate measurement of the distance between the pole star and true north that could be used for navigation. Shen achieved this by making nightly astronomical observations along with his colleague Wei Pu, using Shen's improved design of a wider sighting tube that could be fixed to observe the pole star indefinitely. Along with the pole star, Shen Kuo and Wei Pu also established a project of nightly astronomical observation over a period of five successive years, an intensive work that even would rival the later work of Tycho Brahe in Europe. Shen Kuo and Wei Pu charted the exact coordinates of the planets on a star map for this project and created theories of planetary motion, including retrograde motion.
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Edmond Halley's hypothesis The following lines from Act 3, Scene 2 of Shakespeare's play A Midsummer Night's Dream, written in London in 1595/6, suggest that the idea may have been known in Western Europe 100 years before it took on a more scientific form: Hermia: 'I'll believe as soon / This whole earth may be bored and that the moon / May through the centre creep and so displease / Her brother's noontide with Antipodes.' Edmond Halley in 1692Halley, Edmond, An Account of the cause of the Change of the Variation of the Magnetic Needle; with an Hypothesis of the Structure of the Internal Parts of the Earth, Philosophical Transactions of Royal Society of London, No. 195, 1692, pp 563–578 conjectured that the Earth might consist of a hollow shell about thick, two inner concentric shells and an innermost core. Atmospheres separate these shells, and each shell has its own magnetic poles. The spheres rotate at different speeds.
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Professor Loomis, however, went on > to collect facts about other auroras, and to make inductions from the whole > of the material thus brought together. He showed that there was good reason > for believing that not only was this display represented by a corresponding > one in the Southern Hemisphere, but that all remarkable displays in either > hemisphere are accompanied by corresponding ones in the other. He showed > also that all the principal phenomena of electricity were developed during > the auroral display of 1859; that light was developed in passing from one > conductor to another, that heat in poor conductors, that the peculiar > electric shock to the animal system, the excitement of magnetism in irons, > the deflection of the magnetic needle, the decomposition of chemical > solutions, each and all were produced during the auroral storm, and > evidently by its agency. There were also in America effects upon the > telegraph that were entirely consistent with the assumption previously made > by Walker for England, that currents of electricity moved from northeast to > southwest across the country.
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Shen Kuo (; 1031–1095) or Shen Gua, courtesy name Cunzhong (存中) and pseudonym Mengqi (now usually given as Mengxi) Weng (夢溪翁),Yao (2003), 544. was a Chinese polymathic scientist and statesman of the Song dynasty (960–1279). Excelling in many fields of study and statecraft, he was a mathematician, astronomer, meteorologist, geologist, entomologist, anatomist, climatologist, zoologist, botanist, pharmacologist, medical scientist, agronomist, archaeologist, ethnographer, cartographer, geographer, geophysicist, mineralogist, encyclopedist, military general, diplomat, hydraulic engineer, inventor, economist, academy chancellor, finance minister, governmental state inspector, philosopher, art critic, poet, and musician. He was the head official for the Bureau of Astronomy in the Song court, as well as an Assistant Minister of Imperial Hospitality.Needham (1986), Volume 4, Part 2, 33. At court his political allegiance was to the Reformist faction known as the New Policies Group, headed by Chancellor Wang Anshi (1021–1085). In his Dream Pool Essays or Dream Torrent Essays (; Mengxi Bitan) of 1088, Shen was the first to describe the magnetic needle compass, which would be used for navigation (first described in Europe by Alexander Neckam in 1187).Bowman (2000), 599.
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Of these some are on the aurora borealis, which he studied closely for many years. In 1823 he published in the Edinburgh Philosophical Journal a more accurate description of the aurora than had previously appeared; and in the 'Philosophical Transactions' for 1829 he confirmed his views by new observations—showing that the arrangement and progress of its arches and streamers are exactly definite in relation to the lines of the earth's magnetism, and that there exist such close relations between the streamers and arches as to prove that they are in fact the same phenomenon. He also inferred, from his own observations, that the elevation of the aurora is far less than had been generally supposed, being confined to altitudes not extending far beyond the region of the clouds; and in a paper in the 'Philosophical Transactions' for 1830, besides detailing new proofs of its intimate connection with the magnetic needle, he showed that it was produced by the development of electricity by the condensation of watery vapour. In the volume for 1839 he gave a geometrical measurement of an aurora, one of the first attempted, which made its height less than a mile, and showed its dependency upon the altitude of the clouds.
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