Holland Circle
name: label: maker
content: Steur, Jacob de
notes: label: Description
content: Jacob de Steur, who worked in Leyden in the second half of the 17th century, is known to have made several instrument of this sort. This one is particularly elegant, with images of dolphins at either side of the four fixed sights, and four dolphins on the alidade. The outer circle is graduated to 15 minutes. One half of the inner circle has a grad or gradient scale (graduated 0–100–0–100–0 in equal units) as used by military engineers. The other half has two irregular scales. One is a polygonal scale marked "anguli centri." It is numbered from 3 to 12, and is designed for laying out the exterior angles of forts with 3 to 12 sides. The other irregular scale is marked "mechanica." It bears the maker’s mark "Jacobus de Steur Fecit Leyde." The bottom drawer of the wooden box contains several auxiliary items: a sighting bar that can fit over the sights on the alidade; a pair of tall sight vanes that can fit over any of the shorter vanes; a head for a jacob's staff; two joints with screw bases (one fixed and the other universal); and a clinometer bob. There are spaces for two other accessories, now lost.
label: Location
content: Currently not on view
place: label: place made
content: Netherlands: South Holland, Leyden
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.317346
label: accession number
content: 230279
label: catalog number
content: 317346
objectType: label: Object Name
content: holland circle
physicalDescription: label: Measurements
content: overall: 11 in; 27.94 cm
label: Measurements
content: needle: 2 1/4 in; x 5.715 cm
label: Measurements
content: sighting bar: 11 in; 27.94 cm
label: Measurements
content: overall; case: 7 in x 13 in x 11 7/8 in; 17.78 cm x 33.02 cm x 30.1625 cm