Dip Circle

This is one of eight dip circles that Edward Kahler made for the American expeditions sent to observe the transit of Venus across the face of the sun in 1874. It is marked "106." The vertical circle is graduated to 20 minutes. The horizontal circle is graduated to 30 minutes and read by vernier to single minutes. Both are silvered. The U.S. Naval Observatory transferred it to the Smithsonian in 1966.

Ref: Steve Dick, Sky and Ocean Joined (Cambridge, 2002), p. 250.

Currently not on view
Object Name
dip circle
Date made
ca 1874
Physical Description
wood (overall material)
metal (overall material)
vertical circle: 6 in; 15.24 cm
horizontal circle: 4 1/2 in; 11.43 cm
Place Made
United States: District of Columbia, Washington
ID Number
catalog number
accession number
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. Department of Defense, Dept. of the Navy, U.S. Naval Observatory

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