Graphometer
name: label: maker
content: Delure
notes: label: Description
content: A graphometer consists of a graduated semicircle with a pair of sight vanes at either end, and a movable alidade with another pair of sights at either end. The form was introduced in Philippe Danfrie, <i>Déclaration de l’usage du graphomètre</i> (Paris, 1597), and was always popular in France. Many graphometers have an inset magnetic compass. Most are made of brass, but some American ones are made of wood. Some 19th-century examples had telescopes rather than open sights. Graphometers were also known as semi circles or semicircumferentors.
label: Description
content: Samuel P. Langley, the third Secretary of the Smithsonian, bought this graphometer for the U.S. National Museum in 1902. The semicircle is graduated to single degrees, numbered clockwise and counterclockwise, and read by diagonal scales at either end of the alidade to 10 minutes. The "Delure A Paris" inscription indicates that it was made in the early 18th century.
label: Description
content: Ref: J. A. Bennett, <i>The Divided Circle</i> (Oxford, 1987), pp. 49–50.
label: Location
content: Currently not on view
place: label: place made
content: France: Île-de-France, Paris
setName: label: See more items in
content: Medicine and Science: Physical Sciences
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content: Surveying and Geodesy
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content: Measuring & Mapping
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.219497
label: catalog number
content: 219497
label: accession number
content: 40529
objectType: label: Object Name
content: Graphometer
physicalDescription: label: Measurements
content: overall: 9 1/2 in; 24.13 cm
label: Measurements
content: needle: 1 1/2 in; 3.81 cm
label: Measurements
content: overall: 6 3/4 in x 9 3/4 in x 6 3/4 in; 17.145 cm x 24.765 cm x 17.145 cm