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*247913

Inscriptions:
"U.S.G.S. 185"

Dimensions:
base 20 inches long; telescope 10.25 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 two perpendicular level vials. 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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