Dod Protractor and Parallel Rule
- Description
- This brass semicircular protractor is divided by single degrees and marked by tens from 10° to 90° to 10°. It is attached with metal screws to a set of brass parallel rules. Brass S-shaped hinges connect the rules to each other. The bottom left screw on the parallel rules does not attach to the bottom piece. A rectangular brass arm is screwed to the center of the protractor. A thin brass piece screwed to the arm is marked with a small arrow for pointing to the angle markings. The protractor is stored in a wooden case, which also contains a pair of metal dividers (5-1/4" long).
- The base of the protractor is signed: L. Dod, Newark. Lebbeus Dod (1739–1816) manufactured mathematical instruments in New Jersey and is credited with inventing the "parallel rule protractor." He served as a captain of artillery during the Revolutionary War, mainly by making muskets. His three sons, Stephen (1770–1855), Abner (1772–1847), and Daniel (1778–1823), were also noted instrument and clock makers. The family was most associated with Mendham, N.J. (where a historic marker on N.J. Route 24 indicates Dod's house), but Dod is known to have also lived at various times in Newark.
- ID number MA*310890 is a similar protractor and parallel rule.
- References: Bethuel Lewis Dodd and John Robertson Burnet, "Biographical Sketch of Lebbeus Dod," in Genealogies of the Male Descendants of Daniel Dod . . . 1646–1863 (Newark, N.J., 1864), 144–147; Alexander Farnham, "More Information About New Jersey Toolmakers," The Tool Shed, no. 120 (February 2002), http://www.craftsofnj.org/Newjerseytools/Alex%20Farnham%20more%20Jeraey%20Tools/Alex%20Farnham.htm; Deborah J. Warner, “Surveyor's Compass,” National Museum of American History Physical Sciences Collection: Surveying and Geodesy, http://americanhistory.si.edu/collections/surveying/object.cfm?recordnumber=747113; Peggy A. Kidwell, "American Parallel Rules: Invention on the Fringes of Industry," Rittenhouse 10, no. 39 (1996): 90–96.
- Object Name
- protractor
- date made
- late 1700s
- maker
- Dod, Lebbeus
- Physical Description
- leather (overall material)
- wood (overall material)
- brass (overall material)
- Measurements
- overall: 2.9 cm x 33.5 cm x 14 cm; 1 5/32 in x 13 3/16 in x 5 1/2 in
- place made
- United States: New Jersey, Newark
- ID Number
- 1978.2110.06
- accession number
- 1978.2110
- catalog number
- 336732
- subject
- Science & Mathematics
- Protractors
- Mathematics
- Protractor
- Parallel Rule
- Dividers
- Drawing Instruments
- See more items in
- Medicine and Science: Mathematics
- Protractors
- Exhibition
- 1W, Life in America Exhibit;
- Data Source
- National Museum of American History, Kenneth E. Behring Center
- Credit Line
- Gift of Ruth A. Ming
- Additional Media
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