Keuffel & Esser Telescopic Alidade

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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 sold for $175. The Survey acquired this example in 1893. The signatures read “KEUFFEL & ESSER CO. NEW YORK CHICAGO 2447" and "U.S.C.&G.S. No. 91.”
Ref: Keuffel & Esser, Catalogue (New York, 1906), p. 408.
Currently not on view
Keuffel & Esser Co.
telescope: 10 in; 25.4 cm
objective; aperture: 1 in; 2.54 cm
overall in case: 5 5/8 in x 13 5/16 in x 8 5/16 in; 14.2875 cm x 33.81375 cm x 21.11375 cm
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Medicine and Science: Physical Sciences
Measuring & Mapping
Surveying and Geodesy
Data Source
National Museum of American History