Dip Circle

This instrument is marked "Froment B Paris." Since Paul Gustave Froment (1815-1865) worked for H. P. Gambey before opening his own shop in Paris in 1841, it is not surprising that this dip circle resembles a Gambey instrument. The vertical circle is silvered and graduated to 10 minutes; the horizontal circle is silvered, graduated to 30 minutes, and read by vernier to single minutes. The U.S. Naval Observatory transferred it to the Smithsonian in 1966.

Ref: Paolo Brenni, "Paul Gustave Froment," Bulletin of the Scientific Instrument Society 45 (1995): 19-24.

Currently not on view
Object Name
dip circle
Physical Description
metal (overall material)
vertical circle: 10 in; x 25.4 cm
horizontal circle: 7 in; 17.78 cm
Place Made
France: Île-de-France, Paris
ID Number
accession number
catalog 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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