Micrometer
date: label: date made
content: early 20th century
name: label: maker
content: Troughton and Simms
notes: label: Description
content: Micrometer designed for measuring astronomical photographs. The “Troughton & Simms, London” inscription indicates that it was made before 1922 when Troughton & Simms merged with T. Cooke & Sons to form Cooke, Troughton & Simms. The eyepiece is marked “Carl Zeiss, Jena”.
label: Description
content: This example was at use in the Ladd Observatory established at Brown University, in Providence, Rhode Island, by 1891.
label: Description
content: The Royal Observatory, Greenwich, acquired a similar micrometer in 1903, and used it measure photographs of the minor planet Eros relative to the fixed stars. Those photographs had been taken during the opposition of Eros in 1900-1901, with the hope of obtaining a more accurate determination of the solar parallax.
label: Description
content: Ref: <i>Observations of the Planet Eros 1900-1901 for Determination of the Solar Parallax</i> (Edinburgh, 1908), frontispiece and p. xii.
label: Location
content: Currently not on view
place: label: place made
content: United Kingdom: England, London
topic: label: Subject
content: Science & Scientific Instruments
setName: label: See more items in
content: Medicine and Science: Physical Sciences
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.315380
label: catalog number
content: 315380
label: accession number
content: 218984
objectType: label: Object Name
content: micrometer