Photoheliograph 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 “Kerguelen” inscription on the cell indicates that this lens was used at the observing station on a Kerguelan island in the southern Indian Ocean.
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, Cambridge
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.327710
label: catalog number
content: 327710
label: accession number
content: 283654
objectType: label: Object Name
content: lens
physicalDescription: label: Measurements
content: overall: 1 5/8 in x 6 in; 4.1275 cm x 15.24 cm