Abbot Periodometer
date: label: date made
content: 1932
name: label: maker
content: Smithsonian Institution
notes: label: Description
content: By the 1920s, the Smithsonian Astrophysical Observatory had established three observatories to monitor the influx of solar radiation at the surface of the earth. To find periodic fluctuations in the annual insolation, Smithsonian Secretary Charles Greeley Abbot designed this instrument. Given a suspected period determined by eye, an operator could use the periodometer to compute the mean value of the insolation for each point of the cycle and the shape of the variation over this period. This variation could then be subtracted from the observations, revealing further periodicities.
label: Description
content: The instrument consists of two large interconnected brass drums that rotate on a common shaft that is mounted on a wooden base. there is a cover. The mechanism is described in detail in the references.
label: Description
content: The device was built by Andrew Kremer at the Smithsonian Astrophysical Observatory, with the two large barrels supplied to order by the Gaertner Scientific Corporation of Chicago. A grant of $1000 from the Research Corporation of New York provided funding. The machine was operated for many years by Gladys T. Bond of the SAO.
label: Description
content: Later astrophysicists questioned whether the periodicities detected by Abbot and his colleagues corresponded to changes in the solar constant or arose from other causes.
label: Description
content: References: C. G. Abbot, “The Periodometer: An Instrument for Finding and Evaluating Periodicities in Long Series of Observations,” <I>Smithsonian Miscellaneous Collections</I>, vol. 87 #4 (1932).
label: Description
content: “Evaluating Periodicities by Machinery,” <I>Nature</I>, vo. 129 (7 May 1932), pp. 684.
label: Description
content: C. G. Abbot and Mrs. A. M. Bond, “Periodicity in Solar Variation,” <I>Proceedings of the National Academy of Sciences</I>, vol. 19 (1933), pp. 361-370.
label: Description
content: "Abbot's Weather Machine Praised," Washington Post, February 14, 1932.
label: Description
content: DeVorkin, D., "Defending a Dream: Charles Greeley Abbot’s Years at the Smithsonian," Journal for the History of Astronomy. 1990;21(1):121-136.
label: Description
content: “Mrs. Gladys T. Bond, 55, Smithsonian Employee,” <I>Washington Post</I>, December 20, 1951.
label: Description
content: Sterne, Theodore, "On Periodicities in Measures of the Solar Constant," <I>Proceedings of the National Academy of Sciences</I>, vol. 25 (1939), pp. 559-564 .
label: Description
content: Sterne, Theodore, “On Possible Changes in the Solar "Constant," <I>The Observatory</I>, vol. 63 (1940), pp. 183-185.
label: Location
content: Currently not on view
place: label: place made
content: United States: District of Columbia, Washington
topic: label: Subject
content: Mathematics
setName: label: See more items in
content: Medicine and Science: Mathematics
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content: Calculating Machines
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content: Science & Mathematics
creditLine: label: Credit Line
content: Transfer from Smithsonian Institution Instrument Room
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MA.314627
label: accession number
content: 208046
label: catalog number
content: 314627
objectType: label: Object Name
content: Calculating Machine
label: Object Name
content: computing device, analog
physicalDescription: label: Measurements
content: overall: 19 in x 37 in x 19 in; 48.26 cm x 93.98 cm x 48.26 cm