alidade

n. tool used in topographic surveying; indicator on a plane table

The Alhidade, alidade or alidad was originally a part of many different scientific or astronomical instruments. With changes in technology, the name is now applied to complete instruments such as the plane table alidade.An alidade is a device that allows one to sight a distant object and use the line of sight to perform a task. This task can be, for example, to draw a line on a plane table in the direction of the object or to measure the angle to the object from some reference point. Angles measured can be horizontal, vertical or on any chosen plane.
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Noun
1. surveying instrument consisting of the upper movable part of a theodolite including the telescope and its attachments
(synonym) alidad
(hypernym) surveying instrument, surveyor's instrument
(part-holonym) theodolite, transit
2. surveying instrument used with a plane table for drawing lines of sight on a distant object and for measuring angles
(synonym) alidad
(hypernym) surveying instrument, surveyor's instrument

n. alidade

n. alidade