Personal Equation Machine
date: label: date made
content: 1911
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 events before they occur, while others report events somewhat later. This personal equation machine was designed by Frank Bowers Littell, an astronomer at the U.S. Naval Observatory. Using an artificial star that moved back and forth across the line of sight, it measured the personal equations of astronomers who would use the 9-inch transit circle at the U.S. Naval Observatory.
label: Description
content: Ref: Jimena Canales, <i>A Tenth of a Second: A History</i> (Chicago, 2009).
label: Description
content: F. B. Littell, “Personal Equation Apparatus for Nine-inch Transit Circle, Naval Observatory.” See <i>Science</i> 35 (1912): 711-712.
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: PH.327718
label: catalog number
content: 327718
label: accession number
content: 283654
objectType: label: Object Name
content: Personal Equation Machine
physicalDescription: label: Measurements
content: overall: machine: 8 1/2 in x 9 1/2 in x 16 in; 21.59 cm x 24.13 cm x 40.64 cm
label: Measurements
content: overall: attachment: 3 3/4 in x 6 1/8 in x 4 1/4 in; 9.525 cm x 15.5575 cm x 10.795 cm