Gravity Pendulums (3)
date: label: date made
content: 1891
name: label: Associated Name
content: U.S. Coast & Geodetic Survey
notes: label: Description
content: These are some of the earliest examples of the pendulums that Thomas C. Mendenhall designed soon after he became superintendent of the U.S. Coast and Geodetic Survey. One is marked "U.S.C. & G.S. A1"; the second "U.S.C. & G.S. A2"; and the third "U.S.C.& G.S. A3." Each is also stamped with the date "1891." The dummy pendulum (presumably marked "A0") is missing.
label: Description
content: Each pendulum is made of a copper-aluminum alloy, with a flat stem supporting a lenticular bob. Each has a period of swing of nearly ½ second, so that a coincidence between the pendulum and a chronometer would occur every 5 or 6 minutes. These pendulums are similar to those designed by von Sterneck of Austria in the late 1880s, and widely used in Europe. Mendenhall, however, reversed the mode of support, putting the plane surface on the pendulum, and the knife edge on the corresponding stand. This design, he claimed, made the pendulums less liable to accidental injury.
label: Description
content: The Coast and Geodetic Survey produced many sets of Mendenhall apparatus, and used them until the 1930s. It transferred this example to the Smithsonian in 1955.
label: Description
content: Ref: Victor Lenzen and Robert Multhauf, "Development of Gravity Pendulums in the 19th Century," <i>United States National Museum Bulletin</i> 240 (1965): 301-348.
label: Description
content: C. H. Swick, <i>Modern Methods of Measuring the Intensity of Gravity </i>(Washington, D.C.: United States Coast and Geodetic Survey, 1921).
label: Description
content: T. C. Mendenhall, "Determination of Gravity with the New Half-Second Pendulum," <i>Report of the Superintendent of the U.S. Coast and Geodetic Survey for 1890-91</i>, part 2, pp. 503-564.
label: Location
content: Currently not on view
place: label: place made
content: United States: District of Columbia, Washington
setName: label: See more items in
content: Medicine and Science: Physical Sciences
label: See more items in
content: Measuring & Mapping
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.314639
label: accession number
content: 208213
label: catalog number
content: 314639
objectType: label: Object Name
content: gravity pendulums (Mendenhall 1/2 second)
physicalDescription: label: Measurements
content: overall: 12 in; 30.48 cm
label: Measurements
content: overall: 6 5/8 in x 19 in x 9 3/4 in; 16.8275 cm x 48.26 cm x 24.765 cm