Smithsonian - National Museum of American History, Behring Center

 
Physical Sciences Collection - Surveying and Geodesy

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Telescopic Alidade - click to enlarge

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Telescopic Alidade

Catalogue number:
PH*247914

Inscriptions:
"U.S.G.S. No 11"

Dimensions:
base 26 inches long; telescope 11.5 inches long

Discussion:
This alidade has a telescope with a level mounted above, and a vertical circle that is silvered, graduated to 30 minutes, and read by vernier to single minutes. The base has six large circular holes, and a circular level vial. The United States Geological Survey transferred this instrument to the Smithsonian in 1907, describing it as a "preliminary type" of alidade devised for the Survey about 1890.

Further Information:

Alidade

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