Hinged Parallel Rule

This 6" ebony instrument has three blades, apparently cut from a single rectangle of wood, and is held together by intricate brass hinges. Surveyors, cartographers, navigators, and draftsmen began using parallel rules in the 18th century to easily draw parallel lines separated by various widths. These instruments were also used for reducing or enlarging scaled drawings.
According to the donor, the rule was brought to this continent by Alexander Matheson (1788–1866), an English officer who brought troops from the West Indies to fight against the Americans in the War of 1812. After the war, he helped build the Rideau Canal and settled near Perth, Ontario. His grandson, Alexander Matheson Richey (1826–1913), a lumberman who moved to Chicago, also used the instrument.
References: Maya Hambly, Drawing Instruments: 1580–1980 (London: Sotheby's Publications, 1988), 111; Ken W. Watson, "Smiths Falls Locks 28–31," Rideau Canal World Heritage Site, http://www.rideau-info.com/canal/history/locks/h28-31-smithsfalls.html; "The Town of Perth: The Settlement of Retired Military Heroes on 'the Scotch Line,'" Toronto Daily Mail (May 14, 1887), 6–7, 10; accession file.
Currently not on view
Object Name
parallel rule
date made
early 19th century
Physical Description
brass (overall material)
ebony (overall material)
overall: .2 cm x 15.2 cm x 3.6 cm; 3/32 in x 5 31/32 in x 1 13/32 in
place made
United Kingdom: England
ID Number
catalog number
accession number
Parallel Rules
Science & Mathematics
Measuring & Mapping
Drafting, Engineering
See more items in
Medicine and Science: Mathematics
Parallel Rules
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Ada B. Richey
Additional Media

Visitor Comments

Add a comment about this object

**Please read before submitting the form**

Have a comment or question about this object to share with the community? Please use the form below. Selected comments will appear on this page and may receive a museum response (but we can't promise). Please note that we generally cannot answer questions about the history, rarity, or value of your personal artifacts.

Have a question about anything else, or would you prefer a personal response? Please visit our FAQ or contact page.

Personal information will not be shared or result in unsolicited e-mail. See our privacy policy.

Enter the characters shown in the image.