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Definition Surveying Theodolite

A precision telescopic instrument used in topographic and geodetic surveying or precise alignment operations. Generally, the optical systems for reading the horizontal and vertical circles are fully inclosed. The reading of the circles is made through optical micrometers. Some optical systems are so designed that readings of diametrically opposite points of the circles are mechanically averaged. The instruments are leveled by three leveling screws. Internal illumination may be provided for reading the circles and viewing the reticle crosslines. Excludes transit and transit, pocket.