Mott-Smith Gravimeter

Gravimeters (gravity meters) are extremely precise instruments that measure the earth’s gravity at a specific location. Gravimeters are often used by prospectors to locate subterranean deposits of valuable natural resources (mainly petroleum) as well as by geodesists to study the shape of the earth and its gravitational field. Differences in topography, latitude, or elevation—as well as differences in subterranean density—all affect the force of gravity. Commonly, gravimeters are composed of a weight hanging on a zero-length spring inside a metal housing to negate the influence of temperature and wind. Gravity is then measured by how much the weight stretches the spring.
Lewis Morton Mott-Smith (b. 1902), a professor of physics at Rice Institute in Houston, Texas, designed an astatic gravimeter that used an auxiliary quartz fiber as a labilizing spring. That meant that it could maintain a constant temperature within one-thousandth degrees centigrade under normal field conditions. Its basic features were covered by Mott-Smith's patent for a "torsion gravimeter" (#2,130,648), granted in 1938. A second patent (#2,304,191), granted in 1942, described a photoelectric indicating system for a gravimeter in which variations of intensity of the light source are eliminated by the use of a comparison light beam.
The Mott-Smith Corporation was formed in 1935. By 1938 there were some 18 Mott-Smith gravimeters in use. This example was probably made in the early 1940s. Robert M. Iverson donated it to the Smithsonian in 1966.
Ref: L. M. Mott-Smith, "Gravitational Surveying with the
Gravity-Meter," Geophysics 2 (1937): 21-33.
L. L. Nettleton, Geophysical Prospecting for Oil (New York: McGraw-Hill, 1940), pp 34-35.
Currently not on view
date made
ca 1940
overall: 15 in x 14 3/16 in x 17 5/16 in; 38.1 cm x 36.068 cm x 43.942 cm
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Work and Industry: Agriculture and Natural Resources
Measuring & Mapping
Data Source
National Museum of American History


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