open-sight alidade

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• Theodolite — A theodolite (IPA en|θiːˈɒdəlаɪt) is an instrument for measuring both horizontal and vertical angles, as used in triangulation networks. It is a key tool in surveying and engineering work, particularly on inaccessible grounds, but theodolites… …   Wikipedia

• Ceiling projector — The ceiling projector or cloud searchlight is used to measure the height of the base of clouds (called the ceiling) above the ground. It is used in conjunction with an alidade, usually positioned 1000 ft (304.8 m) away and wherever possible set… …   Wikipedia

• surveying — /seuhr vay ing/, n. 1. the science or scientific method of making surveys of land. 2. the occupation of one who makes land surveys. 3. the act of one who surveys: The surveying required nearly two days. [1425 75; late ME: act of examining… …   Universalium

• Ordnance QF 18 pounder — Australian gun crew in action in the Ypres sector, 28 September 1917 Type Field gun Place& …   Wikipedia

• Alhazen — For the Moon crater, see Alhazen (crater). For the asteroid, see 59239 Alhazen. Alhazen Alhazen (Ibn al Haytham) …   Wikipedia

• Graphometer — or semicircle is a surveying instrument used for angle measurements. It consists of a semicircular divided into 180 degrees and sometimes subdivided into minutes. The limb is subtended by the diameter with two sights at its ends. In the middle of …   Wikipedia

• Sextant — This article is about the sextant as used for navigation. For the astronomer s sextant, see Sextant (astronomical). : For the history and development of the sextant see Reflecting instruments A sextant is an instrument generally used to measure… …   Wikipedia

• Triangulation — In trigonometry and geometry, triangulation is the process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline, rather than measuring distances to the point directly. The point can… …   Wikipedia