Personal Equation Machine
date: label: date made
content: 1875
notes: label: Description
content: The term “personal equation” came into use in the nineteenth century as scientists recognized that each observer has an inherent bias. Some anticipate an event before it occurs, while others report the event after it occurs. Personal equation machines were designed to measure biases of this sort. This example is probably one of the personal equation machines that was devised by John Robie Eastman (1836-1913), an astronomer who worked at the U.S. Naval Observatory for many years.
label: Description
content: Ref: Jimena Canales, <i>A Tenth of a Second: A History</i> (Chicago, 2009).
label: Description
content: “Observations with the Transit Circle,” in United States Naval Observatory, <i>Astronomical and Meteorological Observations Made During the Year 1875</i> (Washington, D.C., 1878). Appendix 1, pp. xxi-xxiv.
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
setName: label: See more items in
content: Medicine and Science: Physical Sciences
creditLine: label: Credit Line
content: U.S. Naval Observatory
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 2005.0172.02
label: accession number
content: 2005.0172
label: catalog number
content: 2005.0172.02
objectType: label: Object Name
content: personal equation apparatus
physicalDescription: label: Measurements
content: overall: 8 3/4 in x 14 in x 7 in; 22.225 cm x 35.56 cm x 17.78 cm
label: Measurements
content: overall: apparatus: 8 3/8 in x 7 1/2 in x 14 1/8 in; 21.2725 cm x 19.05 cm x 35.8775 cm
label: Measurements
content: overall: scope: 2 in x 7 7/8 in x 5 3/4 in; 5.08 cm x 20.0025 cm x 14.605 cm