Protractor and Parallel Rule
date: label: date made
content: late 18th century
notes: label: Description
content: This brass parallel rule has a semicircular protractor attached to the top blade. The protractor is divided to degrees and marked by tens from 10 to 90 to 10. A movable arm attached to the origin point of the protractor contains a vernier, which was intended to permit the measurement of angles to 5 minutes of accuracy. The hinges connecting the blades of the rule are straight. There is no maker’s mark.
label: Description
content: Mathematician James McKenna gave this measuring instrument to the Smithsonian. He reported that an ancestor used it at Bedford, Pa., before 1800. A name, scratched on one of the tools in the set of drawing instruments (310891) that accompanied this protractor, suggests that the ancestor was John A. Stuart, who surveyed a line in Bedford County on Wills Mountain that continues to bear his name.
label: Description
content: Compare this instrument to 1978.2110.06.
label: Description
content: Reference: Peggy A. Kidwell, "American Parallel Rules: Invention on the Fringes of Industry," <i>Rittenhouse</i> 10, no. 39 (1996): 90–96.
label: Location
content: Currently not on view
place: label: place made
content: United States
topic: label: Subject
content: Mathematics
label: Subject
content: Protractor
label: Subject
content: Surveying
setName: label: See more items in
content: Medicine and Science: Mathematics
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content: Science & Mathematics
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content: Protractors
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content: Parallel Rules
creditLine: label: Credit Line
content: Gift of James McKenna
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MA.310890
label: catalog number
content: 310890
label: accession number
content: 131549
objectType: label: Object Name
content: protractor and parallel rule
physicalDescription: label: Physical Description
content: brass (overall material)
label: Measurements
content: overall: 1.1 cm x 14.7 cm x 9.5 cm; 7/16 in x 5 25/32 in x 3 3/4 in