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Dip Circle
{{Refimprove, date=November 2011 Dip circles (also ''dip needles'') are used to measure the angle between the horizon and the Earth's magnetic field (the dip angle). They were used in surveying, mining and prospecting as well as for the demonstration and study of magnetism. Georg Hartmann first discovered dip angle in 1544, when he noticed the needle on a compass dipped towards the north hemisphere. Rather than explore this phenomenon, Hartmann sought ways to eliminate it. However, Robert Norman around 1576 investigated dip angle further and in 1581 described in print a device to measure this phenomenon.Norman, Robert; Borough, William. (1581). ''The newe attractiue, containyng a short discourse of the magnes or lodestone, and amongst other his vertues, of a newe discouered secret and subtill propertie, concernyng the declinyng of the needle, touched therewith vnder the plaine of the horizon. Now first founde out by Robert Norman. Herevnto are annexed certaine necessarie rule ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Norman
Robert Norman was a 16th-century-English mariner, compass builder, and hydrographer who discovered magnetic inclination, the deviation of the Earth's magnetic field from the vertical. Work Robert Norman is noted for ''The Newe Attractive'', a pamphlet published in 1581Published in London by Ballard. See describing the lodestone (magnet) and practical aspects of navigation. More importantly, it included Norman's measurement of magnetic dip, the incline at an angle from the horizon by a compass needle discovered by Georg Hartmann in 1544. This effect is caused by the Earth's magnetic field not running parallel to the planet's surface. Norman demonstrated magnetic dip by creating a compass needle that pivoted on a horizontal axis. The needle tilted at a steep angle relative to the horizon line. Magnetic inclination and local variations were known before Robert Norman, but his pamphlet had a greater influence than the earlier work. The crater Norman on the Moon is named ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fighting occurring throughout Europe, the Middle East, Africa, the Pacific, and parts of Asia. An estimated 9 million soldiers were killed in combat, plus another 23 million wounded, while 5 million civilians died as a result of military action, hunger, and disease. Millions more died in genocides within the Ottoman Empire and in the 1918 influenza pandemic, which was exacerbated by the movement of combatants during the war. Prior to 1914, the European great powers were divided between the Triple Entente (comprising France, Russia, and Britain) and the Triple Alliance (containing Germany, Austria-Hungary, and Italy). Tensions in the Balkans came to a head on 28 June 1914, following the assassination of Archduke Franz Ferdi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Force
In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newton (N). Force is represented by the symbol (formerly ). The original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. If the mass of the object is constant, this law implies that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object. Concepts related to force include: thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque, which pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humphrey Lloyd (physicist)
Humphrey Lloyd FRS FRSE MRIA (1800–1881) was an Irish physicist. He was Erasmus Smith's Professor of Natural and Experimental Philosophy at Trinity College Dublin (1831-1843) and much later Provost (1867–1881). Lloyd is known for experimentally verifying conical refraction, a theoretical prediction made by William Rowan Hamilton about the way light is bent when travelling through a biaxial crystal. He was a Fellow of the Royal Society, and President of both the British Association and the Royal Irish Academy. Early life The eldest son of the Rev. Bartholomew Lloyd, and his wife, Eleanor McLaughlin, he was born in Dublin on 16 April 1800. His father had also served as Erasmus Smith's Professor of Natural and Experimental Philosophy and Provost of TCD. After early education at Mr. White's school in Dublin, he entered Trinity College Dublin in 1815, first out of 63 competitors in the entrance examination. He was elected a Scholar in 1818, and graduated B.A. in 1819, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dublin
Dublin (; , or ) is the capital and largest city of Ireland. On a bay at the mouth of the River Liffey, it is in the province of Leinster, bordered on the south by the Dublin Mountains, a part of the Wicklow Mountains range. At the 2016 census it had a population of 1,173,179, while the preliminary results of the 2022 census recorded that County Dublin as a whole had a population of 1,450,701, and that the population of the Greater Dublin Area was over 2 million, or roughly 40% of the Republic of Ireland's total population. A settlement was established in the area by the Gaels during or before the 7th century, followed by the Vikings. As the Kingdom of Dublin grew, it became Ireland's principal settlement by the 12th century Anglo-Norman invasion of Ireland. The city expanded rapidly from the 17th century and was briefly the second largest in the British Empire and sixth largest in Western Europe after the Acts of Union in 1800. Following independence in 1922, Dubli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Were Fox The Younger
Robert Were Fox FRS (26 April 1789 – 25 July 1877) was a British geologist, natural philosopher and inventor. He is known mainly for his work on the temperature of the earth and his construction of a compass to measure magnetic dip at sea. Life and family Fox was born on 26 April 1789 at Falmouth, England, the eldest son of Robert Were Fox (1754–1818) and his wife, Elizabeth Tregelles. He had nine siblings. The Fox family were members of the Religious Society of Friends (Quakers), and were descended from members who had long settled in Cornwall, although they were not related to George Fox who had introduced the community into the county. In 1814, Fox the Younger married Maria Barclay (1785–1858), daughter of Robert and Rachel Barclay of Bury Hill, near Dorking, Surrey. Maria's sister, Lucy, married Fox's cousin, George Croker Fox (1784–1850). Robert Were Fox the Younger and his wife had three children, Anna Maria (1816–1897), Barclay (1817–1855) and Carolin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into ''static friction'' ("stiction") between non-moving surfaces, and ''kinetic friction'' between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities (see Figure 1). *Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other. *Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces. *Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body. *Internal friction is the force resisting motion between the elements making up a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's North Pole. Owing to Earth's axial tilt of 23.439281°, winter in the Northern Hemisphere lasts from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer lasts from the June solstice through to the September equinox (typically on 23 September UTC). The dates vary each year due to the difference between the calendar year and the astronomical year. Within the Northern Hemisphere, oceanic currents can change the weather patterns that affect many factors within the north coast. Such events include El Niño–Southern Oscillation. Trade winds blow from east to west just above the equator. The winds pull surface water with them, creating currents, which flow westward due to the Corio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizon
The horizon is the apparent line that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This line divides all viewing directions based on whether it intersects the relevant body's surface or not. The ''true horizon'' is a theoretical line, which can only be observed to any degree of accuracy when it lies along a relatively smooth surface such as that of Earth's oceans. At many locations, this line is obscured by terrain, and on Earth it can also be obscured by life forms such as trees and/or human constructs such as buildings. The resulting intersection of such obstructions with the sky is called the ''visible horizon''. On Earth, when looking at a sea from a shore, the part of the sea closest to the horizon is called the offing. Pronounced, "Hor-I-zon". The true horizon surrounds the observer and it is typically assumed to be a circle, drawn on the surface of a perfectly spherica ... [...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 ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
