Magnetometer

Object Details

U.S. Coast and Geodetic Survey

Description

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.

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.

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.

Ref: Edwin Smith, "Notes on Some Instruments Recently Made in the Instrument Division of the Coast and Geodetic Survey Office," Report of the Superintendent of the United States Coast and Geodetic Survey for the Year 1894, Appendix No. 8, p. 275.

L. A. Bauer, Maryland Geological Survey (Baltimore, 1897), p. 433.

Location

Currently not on view

Credit Line

U.S. Department of the Interior, U.S. Geological Survey

1892-1893

ID Number

1982.0671.08

accession number

1982.0671

catalog number

1982.0671.08

Object Name

magnetometer

Physical Description

metal (overall material)

Measurements

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

overall: 8 in x 28 in x 15 1/2 in; 20.32 cm x 71.12 cm x 39.37 cm

Place Made

United States: District of Columbia, Washington

See more items in

Medicine and Science: Physical Sciences

Science & Mathematics

Measuring & Mapping

National Museum of American History

Subject

Science & Scientific Instruments

Science & Scientific Instruments

Record ID

nmah_1029295

Metadata Usage (text)

CC0

GUID (Link to Original Record)

https://n2t.net/ark:/65665/ng49ca746a8-dadf-704b-e053-15f76fa0b4fa