Capt. Field's Improved Hinged Parallel Rule
date: label: date made
content: 1919
notes: label: Description
content: This 21" German silver hinged parallel rule has two small knobs for positioning the instrument. Brass pins secure the hinges. The top blade is marked: U. S. C. & G. S. NO. 323. A fleur-de-lis or letter H appears above the mark. The edges of the top blade are marked as a rectangular protractor, and the edges of the bottom blade are marked for nautical compass points.
label: Description
content: Capt. William Andrew Field (about 1796–1871) of Britain added the protractor and compass scales to hinged parallel rules in 1854. This made it easier for ship navigators to move the rule without losing track of the ship's course. According to the accession file, the U.S. Coast & Geodetic Survey acquired this rule on July 23, 1919, and last issued it on March 18, 1920. Compare to MA.309661 and MA.309662.
label: Description
content: References: "Field's Parallel Rule," <i>The Nautical Magazine and Naval Chronicle</i> 23, no. 5 (May 1854): 280; Peggy A. Kidwell, "American Parallel Rules: Invention on the Fringes of Industry," <i>Rittenhouse</i> 10, no. 39 (1996): 90–96; National Maritime Museum, "Captain Field's Improved Parallel Rule," Object ID NAV0602, http://collections.rmg.co.uk/collections/objects/42814.html.
label: Location
content: Currently not on view
topic: label: Subject
content: Mathematics
label: Subject
content: Protractor
label: Subject
content: Navigation
setName: label: See more items in
content: Medicine and Science: Mathematics
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content: Science & Mathematics
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content: Measuring & Mapping
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content: Parallel Rules
creditLine: label: Credit Line
content: Transfer from U.S. Department of Commerce, Coast & Geodetic Survey
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MA.309663
label: catalog number
content: 309663
label: accession number
content: 106954
objectType: label: Object Name
content: parallel rule
physicalDescription: label: Physical Description
content: german silver (overall material)
label: Measurements
content: overall: 1.1 cm x 53.6 cm x 7.3 cm; 7/16 in x 21 3/32 in x 2 7/8 in