Protractor and Parallel Rule
Protractor and Parallel Rule
Usage conditions apply
- Description
- 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.
- 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.
- Compare this instrument to 1978.2110.06.
- Reference: Peggy A. Kidwell, "American Parallel Rules: Invention on the Fringes of Industry," Rittenhouse 10, no. 39 (1996): 90–96.
- Location
- Currently not on view
- Object Name
- protractor and parallel rule
- date made
- late 18th century
- place made
- United States
- Physical Description
- brass (overall material)
- Measurements
- 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
- ID Number
- MA.310890
- catalog number
- 310890
- accession number
- 131549
- Credit Line
- Gift of James McKenna
- subject
- Mathematics
- Protractor
- Surveying
- See more items in
- Medicine and Science: Mathematics
- Protractors
- Science & Mathematics
- Parallel Rules
- Data Source
- National Museum of American History
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