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A marine sextant accessory consisting of a tubular sighting vane, the function of which is to keep the line of vision parallel to the frame of the instrument when observing horizontal sextant angles.
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A marine sextant accessory consisting of a tubular sighting vane, the function of which is to keep the line of vision parallel to the frame of the instrument when observing horizontal sextant angles.
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Related Terms |
PLI
A unit of line density (mass per unit length) equal to 1 pound per inch, or approximately 17.8580 kilograms per meter.
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PITCH ATTITUDE
The attitude of an aircraft, rocket, or other flying vehicle, referred to the relationship between the longitudinal body axis and a chosen reference line or plane as seen from the side.
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PIPELINE
A line of pipe connected to valves and other control devices, for conducting fluids, gases, or finely divided solids.
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PIERHEAD LINE
The line in navigable waters beyond which construction is prohibited; open-pier construction may extend outward from the bulkhead line to the pierhead line.
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PICTURE ELEMENT
1. That portion, in facsimile, of the subject copy which is seen by the scanner at any instant; it can be considered a square area having dimensions equal to the width of the scanning line. 2. In television, any segment of a scanning line, the dimension of which along the line is exactly equal to the nominal line width; the area which is being explored at any instant in the scanning process. Also known as critical area; elemental area; pixel; recording spot; scanning spot.
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PHOTOELECTRICLOOPCONTROL
[CONTSYS] Aphotoelectric control system used as a position regulator for a loop of material passing from one stripprocessing line to another that may travel at a different speed. Also known as loop control.
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PENDULUM LEVEL
A leveling instrument in which the line of sight is automatically kept horizontal by a built-in pendulum device (such as a horizontal arm and a plumb line at right angles to the arm).
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PANCAKE AUGER
An auger having one spiral web, 12 to 15 inches (30 to 38 centimeters) in diameter, attached to the bottom end of a slender central shaft; used as removable deadman to which a drill rig or guy line is anchored.
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OFFSET LINE
A secondary line established close to and roughly parallel with the primary survey line to which it is referenced by measured offsets.
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OFF-LINE
1. A condition existing when the drive rod of the drill swivel head is not centered and parallel with the borehole being drilled. 2. A borehole that has deviated from its intended course. 3. A condition existing wherein any linear excavation (shaft, drift, borehole) deviates from a previously determined or intended survey line or course. 4. State in which an equipment or subsystem is in standby, maintenance, or mode of operation other than online.
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