Dip Circle

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This is marked "Wm Würdemann, Washington, D.C." and "U.S.C.S. No. 10." It was designed by Julius Hilgard of the U.S. Coast Survey, constructed by Würdemann, and in use by 1860. The vertical circle is located outside the wood and glass box, silvered, graduated to 15 minutes, and read by opposite verniers with magnifiers to 30 seconds. It supports two telescopes which are used to take sights on small holes pierced through the ends of the needle. The horizontal circle is silvered, graduated to 30 minutes and read by vernier to single minutes.
Ref: "Results of Magnetical Observations Made at Eastport, Maine, Between 1860 and 1864, for the United States Coast Survey," Report of the Superintendent of the United States Coast Survey During the Year 1865, Appendix 18.
Currently not on view
Date made
ca 1860
Wurdemann, William W.
Place Made
United States: District of Columbia, Washington
Physical Description
metal (overall material)
vertical circle: 6 1/2 in; 16.51 cm
overall: 14 3/4 in x 12 13/16 in x 8 1/16 in; 37.465 cm x 32.54375 cm x 20.47875 cm
ID Number
catalog number
accession number
Credit Line
U.S. Coast & Geodetic Survey
Science & Scientific Instruments
Science & Scientific Instruments
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Medicine and Science: Physical Sciences
Measuring & Mapping
Science & Mathematics
Data Source
National Museum of American History