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Dip Circle
Dip circles (also known as ''dip needles or inclination compasses'') are used to measure the angle between the horizon and the Earth's magnetic field (the Magnetic dip, dip angle). They were used in surveying, mining and prospecting as well as for the demonstration and study of magnetism. Uses Dip circles typically consist of a magnetised needle swinging freely vertically within a case. The needle will dip to follow the lines of Earth's magnetic field. As the dip angle varies by latitude (0° at the equator and 90° at the poles), a dip circle can be used to determine latitude when compared against a chart of dip angles. As the variation is not constant, this is not an exact measurement. Dip circles can also be used in locate ore, and they were the first scientific instrument to be used for this purpose. They were used to find magnetite in Sweden in the Middle Ages, and have been used extensively in iron mining. They were still in use in the 1930s, but modern Magnetometer, ma ... [...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 by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar System as Earth's North Pole. Due to Earth's axial tilt of 23.439281°, there is a seasonal variation in the lengths of the day and night. There is also a seasonal variation in temperatures, which lags the variation in day and night. Conventionally, winter in the Northern Hemisphere is taken as the period from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer is taken as the period 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 Year#Astronomical years, astronomical year. Within the Northern Hemisphere, oceanic currents can change the weather patterns that aff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting took place mainly in European theatre of World War I, Europe and the Middle Eastern theatre of World War I, Middle East, as well as in parts of African theatre of World War I, Africa and the Asian and Pacific theatre of World War I, Asia-Pacific, and in Europe was characterised by trench warfare; the widespread use of Artillery of World War I, artillery, machine guns, and Chemical weapons in World War I, chemical weapons (gas); and the introductions of Tanks in World War I, tanks and Aviation in World War I, aircraft. World War I was one of the List of wars by death toll, deadliest conflicts in history, resulting in an estimated World War I casualties, 10 million military dead and more than 20 million wounded, plus some 10 million civilian de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Force
In physics, a force is an influence that can cause an Physical object, object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the Magnitude (mathematics), magnitude and Direction (geometry, geography), direction of a force are both important, force is a Euclidean vector, vector quantity. The SI unit of force is the newton (unit), newton (N), and force is often represented by the symbol . Force plays an important role in classical mechanics. The concept of force is central to all three of Newton's laws of motion. Types of forces often encountered in classical mechanics include Elasticity (physics), elastic, frictional, Normal force, contact or "normal" forces, and gravity, gravitational. The rotational version of force is torque, which produces angular acceleration, changes in the rotational speed of an object. In an extended body, each part applies forces on the adjacent pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humphrey Lloyd (physicist)
Humphrey Lloyd PRIA (16 April 1800 – 17 January 1881) was an Irish physicist and academic who served as the 30th Provost of Trinity College Dublin from 1867 to 1881. He was Erasmus Smith's Professor of Natural and Experimental Philosophy at Trinity College Dublin from 1831 to 1843. 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. Humphrey carried out the Lloyd's mirror optic experiments, and was a member of numerous societies in Europe and North America. He also published works relating to religion and the religious identities of Ireland. Early life The eldest son of the Very 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 Profe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dublin
Dublin is the capital and largest city of Republic of Ireland, Ireland. Situated on Dublin Bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, and is bordered on the south by the Dublin Mountains, part of the Wicklow Mountains range. Dublin is the largest city by population on the island of Ireland; at the 2022 census of Ireland, 2022 census, the city council area had a population of 592,713, while the city including suburbs had a population of 1,263,219, County Dublin had a population of 1,501,500. Various definitions of a metropolitan Greater Dublin Area exist. 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 Europ ... [...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 Caroli ... [...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. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of the processes involved is called tribology, and has a history of more than 2000 years. Friction can have dramatic consequences, as illustrated by the use of friction created by rubbing pieces of wood together to start a fire. Another important consequence of many types of friction can be wear, which may lead to performance degradation or damage to components. It is known that frictional energy losses account for about 20% of the total energy expenditure of the world. As briefly discussed later, there are many different contributors to the retarding force in friction, ranging from asperity deformation to the generation of charges and changes in local structure. When two bodies in contact move relative to each other, due to these variou ... [...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 nam ... [...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 North magnetic pole, 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 bearing (angle), bearings which are commonly stated in degrees. If local magnetic declination, 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 history of science and technology in China, Chinese Han dynasty (since c. 206 BC),#Li, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizon
The horizon is the apparent curve 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 curve 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 sph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
