Magnetometer
date: label: Date made
content: 1892-1893
name: label: maker
content: U.S. Coast and Geodetic Survey
notes: label: Description
content: Theodolite magnetometers were designed for observations in the field, and so are relatively light, compact, of simple construction, and easily handled. Their tri-leg base can hold either the magnetometer or the theodolite that is used for astronomical alignment. The U.S. Coast and Geodetic Survey designed this particular form in the early 1890s, basing it on the instrument that the Survey had been using since the early 1880s but adding several new features. One is the octagonal shape of the collimating magnets. Another is the black velvet screen that connects the telescope with the suspension box: this cuts off stray light,and eliminates the problems caused by the glass window in the earlier form.
label: Description
content: This example is marked "C. & G. S. NO. 18." The Survey produced it in 1892-1893 and made it available for L.A. Bauer's magnetic survey of Maryland at the end of the century. The base—marked "Bausch, Lomb, Saegmuller Co., ROCHESTER, N.Y. 2690"—must be a replacement, made after the formation of that firm in 1905.
label: Description
content: The U.S. Geological Survey acquired this magnetometer in 1973 when it assumed control of the geomagnetic program of the federal government, and it transferred it to the Smithsonian in 1982.
label: Description
content: Ref: Edwin Smith, "Notes on Some Instruments Recently Made in the Instrument Division of the Coast and Geodetic Survey Office," <i>Report of the Superintendent of the United States Coast and Geodetic Survey for the Year 1894</i>, Appendix No. 8, p. 275.
label: Description
content: L. A. Bauer, <i>Maryland Geological Survey</i> (Baltimore, 1897), p. 433.
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
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content: Science & Mathematics
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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: 1982.0671.08
label: accession number
content: 1982.0671
label: catalog number
content: 1982.0671.08
objectType: label: Object Name
content: magnetometer
physicalDescription: label: Physical Description
content: metal (overall material)
label: Measurements
content: overall: 22 1/4 in x 16 1/4 in x 7 1/2 in; 56.515 cm x 41.275 cm x 19.05 cm
label: Measurements
content: overall: 8 in x 28 in x 15 1/2 in; 20.32 cm x 71.12 cm x 39.37 cm