Earth Inductor
date: label: Date made
content: 1912
name: label: maker
content: Carnegie Institution of Washington. Department of Terrestrial Magnetism
notes: label: Description
content: As scientists found that even the best dip circles gave unreliable results, they began using earth inductors to determine magnetic dip. In 1912, the Department of Terrestrial Magnetism of the Carnegie Institution of Washington developed a new earth inductor for use at sea. It had three key elements: an improved gimbal stand, a means for rotating the coil without disturbing the gimbal rings, and a sensitive galvanometer.
label: Description
content: This example marked "D.T.M. C.I.W. E.I. N° 3" is the third Carnegie marine earth inductor. When the Carnegie closed its program in terrestrial magnetism, it was lent to the U.S. Coast and Geodetic Survey. The U.S. Geological Survey acquired it in 1973 when it took over the geomagnetic program of the federal government, and transferred it to the Smithsonian in 1982.
label: Description
content: Ref: J. A. Fleming, "Description of the C.I.W. Marine Earth
label: Description
content: Inductor," <i>Terrestrial Magnetism</i> 18 (1912): 39-45.
label: Description
content: C. W. Hewlett, "Report on the C.I.W. Marine Earth Inductor," <i>Terrestrial Magnetism</i> 18 (1912): 46-48.
label: Location
content: Currently not on view
place: label: Place Made
content: United States: District of Columbia, Washington
topic: label: Subject
content: Science & Scientific Instruments
label: Subject
content: Science & Scientific Instruments
setName: label: See more items in
content: Medicine and Science: Physical Sciences
label: See more items in
content: Science & Mathematics
label: See more items in
content: Measuring & Mapping
creditLine: label: Credit Line
content: U.S. Department of the Interior, U.S. Geological Survey
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1982.0671.05
label: accession number
content: 1982.0671
label: catalog number
content: 1982.0671.05
objectType: label: Object Name
content: earth inductor
physicalDescription: label: Physical Description
content: metal (overall material)
label: Measurements
content: overall: 9 1/2 in; 24.13 cm
label: Measurements
content: overall in case: 12 11/16 in x 9 3/8 in x 8 7/8 in; 32.22625 cm x 23.8125 cm x 22.5425 cm