Objective Lens
date: label: date made
content: 1874
name: label: maker
content: Alvan Clark & Sons
notes: label: Description
content: This is one of the eight long-focus objectives that Alvan Clark & Sons made for the U.S. expeditions sent to observe the 1874 Transit of Venus across the face of the Sun. It has a clear aperture of 5 inches, and a focal length of nearly 40 feet. In use, it was mounted horizontally, took sunlight from a heliostat mirror, and focused it onto a distant photographic plate. The 1874 apparatus was used again during the Transit of Venus of 1882.
label: Description
content: Ref: Simon Newcomb, ed., <i>Observations of the Transit of Venus, December 8-9, 1874</i> (Washington, D.C., 1880).
label: Location
content: Currently not on view
place: label: place made
content: United States: Massachusetts, Cambridgeport
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: 2005.0172.03
label: accession number
content: 2005.0172
label: catalog number
content: 2005.0172.03
objectType: label: Object Name
content: 5 inch lens in brass cell
physicalDescription: label: Measurements
content: overall: 1 1/2 in x 5 3/4 in; 3.81 cm x 14.605 cm
label: Measurements
content: overall: 1 1/2 in x 5 5/8 in; 3.81 cm x 14.2875 cm