Objective Lens
date: label: date made
content: 1874
name: label: maker
content: Alvan Clark & Sons
notes: label: Description
content: Hoping to improve our understanding of the distance between the Earth and the Sun, the United States sponsored eight parties to observe the 1874 transit of Venus across the face of the sun, and equipped each with an identical set of apparatus made by Alvan Clark & Sons. For photographing the sun, each party had a horizontal telescope—known as a photoheliograph—with a lens of 5-inches aperture and nearly 40 feet focal length. This is one of those lenses. The “6. 1A / Pekin” inscription on the flange indicates that it was used in Peking, China, in 1874; Naval Observatory records indicate that it was used in Wellington, South Africa, 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), pp. 25-26.
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: 2005.3085.02
label: catalog number
content: 2005.3085.02
label: nonaccession number
content: 2005.3085
objectType: label: Object Name
content: lens, photoheliograph
physicalDescription: label: Measurements
content: overall: 1 3/4 in x 8 1/4 in; 4.445 cm x 20.955 cm
label: Measurements
content: overall: 1 1/2 in x 7 7/8 in; 3.81 cm x 20.0025 cm