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*309665

Inscriptions:
"KEUFFEL & ESSER CO. NEW YORK CHICAGO 2447; U.S.C.&G.S. No. 91"

Dimensions:
telescope 10 inches long, objective 1 inch aperture

Discussion:

This alidade has an inverting telescope, striding level, vertical arc reading 30 degrees each way, and separate trough compass. It is part of a complete plane-table outfit that Keuffel & Esser described "as made for the U.S. Coast and Geodetic Survey" and that sold for $175. The Survey acquired this example in 1893

Ref: Keuffel & Esser, Catalogue (New York, 1906), p. 408.

Further Information:

Alidade
Keuffel & Esser

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