This instrument, sometimes referred to as a 12–inch repeating circle, was made in the Instrument Division of the U. S. Coast Survey. It is marked "U. S. C. S. No. 100" and dates from before 1878, when the Coast Survey became the Coast and Geodetic Survey. The horizontal circle is graduated to 10 minutes, and read by opposite verniers and magnifiers to 6 seconds.
Ref: C. A. Schott, "Determination of the Astronomical Azimuth of a Direction," United States Coast Survey Annual Report (1866), Appendix No. 11.
Currently not on view
Object Name
theodolite (geodetic)
horizontal circle: 12 in; 30.48 cm
telescope aperture: 2 3/8 in; 6.0325 cm
telescope: 24 in; 60.96 cm
ID Number
accession number
catalog number
Measuring & Mapping
Surveying and Geodesy
See more items in
Medicine and Science: Physical Sciences
Surveying and Geodesy
Data Source
National Museum of American History, Kenneth E. Behring Center
United States Coast Survey. United States Coast Survey Annual Report

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