This is a Kew pattern unifilar magnetometer that is marked ";Dover, Charlton Kent No. 145" and that belonged to the Survey Branch of the U.S. Navy Hydrographic Office. While the ";Dover, Charlton Kent" signature was used between 1859 and 1920, the serial number suggests that this example was made around 1900. The U.S. Coast and Geodetic Survey repaired, cleaned, adjusted, and calibrated this instrument around 1950, and transferred it to the Smithsonian in 1959.

Ref: J. E. H. Gordon, A Physical Treatise on Electricity and Magnetism (London, 1880), vol. I, pp. 166-177.

Currently not on view
Place Made
United Kingdom: England, London, Charlton
Physical Description
wood (overall material)
metal (overall material)
overall: 21 1/8 in x 11 1/4 in x 11 3/4 in; 53.721 cm x 28.575 cm x 29.845 cm
overall; tube: 50 in x 1 1/4 in; 127 cm x 3.175 cm
overall; box: 11 1/2 in x 21 1/4 in x 11 7/8 in; 29.21 cm x 53.975 cm x 30.1625 cm
ID Number
accession number
catalog number
Credit Line
U.S. Department of Commerce, 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