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Hydroscope
A hydroscope is any of several instruments related to water: *One kind is an instrument for making observations below the surface of water, such as a long tube fitted with various lenses arranged so that objects lying at the bottom can be reflected upon a screen on the deck of the ship that carries it. These are built with a large tire tube that supports the screen and covered by an acrylic dome for protection. *Another kind detects subsurface water through nuclear magnetic resonance using the surface nuclear magnetic resonance technique. *An instrument (likely a hydrometer) described by Synesius in his ''Letter 15'' to Hypatia, written in 402 AD. There are references to such instruments as early as the fourth century. *Another ancient Greek instrument: a water clock A water clock or clepsydra (; ; ) is a timepiece by which time is measured by the regulated flow of liquid into (inflow type) or out from (outflow type) a vessel, and where the amount is then measured. Water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hygroscopic
Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance's molecules, adsorbing substances can become physically changed, e.g., changing in volume, boiling point, viscosity or some other physical characteristic or property of the substance. For example, a finely dispersed hygroscopic powder, such as a salt, may become clumpy over time due to collection of moisture from the surrounding environment. ''Deliquescent'' materials are sufficiently hygroscopic that they absorb so much water that they become liquid and form an aqueous solution. Etymology and pronunciation The word ''hygroscopy'' () uses combining forms of '' hygro-'' and '' -scopy''. Unlike any other ''-scopy'' word, it no longer refers to a viewing or imaging mode. It did begin that way, with the word ''hygroscope'' referring in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Nuclear Magnetic Resonance
Surface nuclear magnetic resonance (SNMR), also known as magnetic resonance Sounding (MRS), is a geophysical technique specially designed for hydrogeology. It is based on the principle of nuclear magnetic resonance (NMR) and measurements can be used to indirectly estimate the water content of saturated and unsaturated zones in the earth's subsurface. SNMR is used to estimate aquifer properties, including the quantity of water contained in the aquifer, porosity, and hydraulic conductivity. History The MRS technique was originally conceived in the 1960s by Russell H. Varian, one of the inventors of the proton magnetometer. SNMR is a product of a joint effort by many scientists and engineers who started developing this method in the USSR under the guidance of A.G. Semenov and continued this work all over the world.Semenov AG (1987) NMR Hydroscope for water prospecting.Proceedings of a Seminar on Geotomography, Indian Geophysical Union, Hyderabad, pp 66–67 Semenov's team used nuclea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, despite not providing food energy, food, energy or organic micronutrients. Its chemical formula, H2O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. "Water" is also the name of the liquid state of H2O at standard temperature and pressure. A number of natural states of water exist. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lens (optics)
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), usually arranged along a common axis. Lenses are made from materials such as glass or plastic, and are ground and polished or molded to a desired shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called lenses, such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses. Lenses are used in various imaging devices like telescopes, binoculars and cameras. They are also used as visual aids in glasses to correct defects of vision such as myopia and hypermetropia. History The word ''lens'' comes from '' lēns'', the Latin name of the lentil (a seed of a lent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrometer
A hydrometer or lactometer is an instrument used for measuring density or relative density of liquids based on the concept of buoyancy. They are typically calibrated and graduated with one or more scales such as specific gravity. A hydrometer usually consists of a sealed hollow glass tube with a wider bottom portion for buoyancy, a ballast such as lead or mercury for stability, and a narrow stem with graduations for measuring. The liquid to test is poured into a tall container, often a graduated cylinder, and the hydrometer is gently lowered into the liquid until it floats freely. The point at which the surface of the liquid touches the stem of the hydrometer correlates to relative density. Hydrometers can contain any number of scales along the stem corresponding to properties correlating to the density. Hydrometers are calibrated for different uses, such as a lactometer for measuring the density (creaminess) of milk, a saccharometer for measuring the density of sugar in a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synesius
Synesius (; el, Συνέσιος; c. 373 – c. 414), was a Greek bishop of Ptolemais in ancient Libya, a part of the Western Pentapolis of Cyrenaica after 410. He was born of wealthy parents at Balagrae (now Bayda, Libya) near Cyrene between 370 and 375. Life While still a youth (in 393), he went with his brother Euoptius to Alexandria, where he became an enthusiastic Neoplatonist and disciple of Hypatia. Between 395 and 399, he spent some time in Athens. In 398 he was chosen as an envoy to the imperial court in Constantinople by Cyrene and the whole Pentapolis. He went to the capital in occasion of the delivery of the ''aurum coronarium'' and his task was to obtain tax remissions for his country. In Constantinople he obtained the patronage of the powerful praetorian prefect Aurelianus. Synesius composed and addressed to Emperor Arcadius a speech entitled ''De regno'', full of topical advice as to the studies of a wise ruler, but also containing a bold statement that th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypatia
Hypatia, Koine pronunciation (born 350–370; died 415 AD) was a neoplatonist philosopher, astronomer, and mathematician, who lived in Alexandria, Egypt, then part of the Eastern Roman Empire. She was a prominent thinker in Alexandria where she taught philosophy and astronomy. Although preceded by Pandrosion, another Alexandrine female mathematician, she is the first female mathematician whose life is reasonably well recorded. Hypatia was renowned in her own lifetime as a great teacher and a wise counselor. She wrote a commentary on Diophantus's thirteen-volume ''Arithmetica'', which may survive in part, having been interpolated into Diophantus's original text, and another commentary on Apollonius of Perga's treatise on conic sections, which has not survived. Many modern scholars also believe that Hypatia may have edited the surviving text of Ptolemy's ''Almagest'', based on the title of her father Theon's commentary on Book III of the ''Almagest''. Hypatia constructed as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Clock
A water clock or clepsydra (; ; ) is a timepiece by which time is measured by the regulated flow of liquid into (inflow type) or out from (outflow type) a vessel, and where the amount is then measured. Water clocks are one of the oldest time-measuring instruments. The bowl-shaped outflow is the simplest form of a water clock and is known to have existed in Babylon, Egypt, and Persia around the 16th century BC. Other regions of the world, including India and China, also have early evidence of water clocks, but the earliest dates are less certain. Some authors, however, claim that water clocks appeared in China as early as 4000 BC. Water clocks were also used in ancient Greece and ancient Rome, described by technical writers such as Ctesibius and Vitruvius. Designs A water clock uses the flow of water to measure time. If viscosity is neglected, the physical principle required to study such clocks is Torricelli's law. There are two types of water clocks: inflow and out ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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