New York , NY
Photograph - Photograph
Kite and balloon theodolite in use at Weather Bureau, Military and Naval Aerological Stations. Circa 1919. A theodolite is an optical instrument used to measure angles in surveying, meteorology, and navigation. In meteorology, it is used to track the motion of a weather balloon by measuring its elevation and azimuth angle. The earliest theodolite consisted of a small mounted telescope that rotated horizontally and vertically; modern versions are sophisticated computerized devices, capable of tracking weather balloons, airplanes, and other moving objects, at distances of up to 20,000 m (65,600 ft).
March 7th, 2013
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