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An instrument which measures altitudes of celestial bodies, used for determining an accurate astronomical position, usually while ashore in survey work. Originally, the astrolabe consisted of a disk with an arm pivoted at the center, the whole instrument being hung by a ring at the top to establish the vertical.
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Related Terms |
PIVOTED WINDOW
A window having a section which is pivoted near the center so that the top of the section swings in and the bottom swings out.
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PEDESTAL
1. The support for a column. 2. A metal support carrying one end of a bridge truss or girder and transmitting any load to the top of a pier or abutment. 3. See blanking level. 4. A supporting part or the base of an upright structure, such as a radar antenna.
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PACHUCA TANK
Air-agitated, solidliquid mixing vessel in which the air is injected into the bottom of a center draft tube; air and solids rise through the tube, with solids exiting the top of the tube and falling through the bulk of the liquid.
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OVERSHOT WHEEL
A horizontal-shaft waterwheel with buckets around the circumference; the weight of water pouring into the buckets from the top rotates the wheel.
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OVERHEAD
Pertaining to fluid (gas or liquid) effluent from the top of a process vessel, such as a distillation column. See fixed cost.
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ORTHOTROPIC DECK
A bridge deck constructed typically of flat steel plate and longitudinal and transverse ribs; functions in carrying traffic and acting as top flanges of floor beams.
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MOS-CONTROLLED THYRISTOR
A type of thyristor in which there is a very thin metal oxide semiconductor (MOS) integrated circuit in the top surface of the high-power thyristor components, so that only a small gate current is needed.
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LIQUID-SEALED METER
A type of positive displacement meter for gas flows consisting of a cylindrical chamber that is more than half filled with water and divided into four rotating compartments formed by trailing vanes; gas entering through the center shaft into one compartment after another forces rotation that allows the gas then to exhaust out the top as it is displaced by the water. Also known as drum meter.
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LEVEL MEASUREMENT
The determination of the linear vertical distance between a reference point or datum plane and the surface of a liquid or the top of a pile of divided solid.
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IVORY POINT
A small pointer extending downward from the top of the cistern of a Fortin barometer; the level of the mercury in the cistern is adjusted so that it just comes in contact with the end of the pointer, thus setting the zero of the barometer scale.
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