Dip Circle

Description
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.
Location
Currently not on view
Object Name
dip circle
Date made
ca 1860
maker
Wurdemann, William W.
Physical Description
metal (overall material)
Measurements
vertical circle: 6 1/2 in; 16.51 cm
Place Made
United States: District of Columbia, Washington
ID Number
PH*314633
catalog number
314633
accession number
208213
subject
Measuring & Mapping
Science & Mathematics
Science & Scientific Instruments
Science & Scientific Instruments
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
U.S. Coast & Geodetic Survey

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