Photoheliograph Lens

Description:

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.

Ref: Simon Newcomb, ed., Observations of the Transit of Venus, December 8-9, 1874 (Washington, D.C., 1880), pp. 25-26.

Date Made: 1874

Maker: Alvan Clark & Sons

Location: Currently not on view

Place Made: United States: Massachusetts, Cambridge

Subject: Science & Scientific Instruments

Subject:

See more items in: Medicine and Science: Physical Sciences

Exhibition:

Exhibition Location:

Credit Line: U.S. Naval Observatory

Data Source: National Museum of American History

Id Number: PH.327710Catalog Number: 327710Accession Number: 283654

Object Name: lens

Measurements: overall: 1 5/8 in x 6 in; 4.1275 cm x 15.24 cm

Guid: http://n2t.net/ark:/65665/ng49ca746a9-f115-704b-e053-15f76fa0b4fa

Record Id: nmah_1167215

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