parallel rulers
Parallel rulers are a drafting instrument used by navigators to draw parallel lines on charts. The tool consists of two straightedges joined by two arms which allow them to move closer or further away while always remaining parallel to each other. • Illustration — Parallel rule in plastic with aluminum arms lying on a cutting mat
parallel rulers
Clipper · CC BY-SA 3.0
- Field
- navigational instrument · ruler
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wikidata · Q2051620 · wikipedia · Parallel rulers
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History
History
The parallel ruler was invented at about 1584 by Fabrizio Mordente, as well as by Taqi al-Din who died in 1585. However it was not in common use (at least in Europe) until the 18th century. • Illustration — Captain Field's Improved Parallel Rule In the 19th century a retired sea captain, Captain William Andrew Field improved the design by adding a protractor-style scale to the upper edge of one rule, and compass points to the opposing edge, which made reading bearings easier. Examples exist of boxwood, ivory or ebony, usually with brass hinges. The instrument usually had two links, but longer models sometimes had three, and sometimes the links were scissored. Another variation is the "roller" model which included a cylindrical roller for ease of use.
Captain Field's Improved Parallel Rule, design c. 1854. Date for this model probably late 19th/early 20th century.
Rodhullandemu
Chart BA 4022 with parallel ruler and divider
BoH
Chronology
Dated record
Chronology
The full dated record · 2 entries
1584
parallel rulers first recorded.
1584
parallel rulers began in 1584.
Primary material
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reference work
- “Parallel rulers”, English Wikipedia, consulted as further reading
Reputable secondary · Wikipedia
authority record
- Wikidata, structured authority record Q2051620: parallel rulers
General reference · Wikidata
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Part of the biographical narrative on this page reuses licensed material. Its origin, revision and licence are recorded here.
The biographical narrative on this page is based on the Wikipedia article Parallel rulers, revision 1329245088 (EN edition), by its contributors. VALÉORINE has edited that text and built its own documentary record around it. The reused material is available under CC BY-SA 4.0, and this page's reuse of it is offered under the same licence. Everything else on this page — the chronology, the holdings, the evidence, the plates and the connections — is VALÉORINE's own record. Sources and licences.
Notes from the source article
Cited by Wikipedia
Notes from the source article
These works are cited by the source article, in its own numbering. They are recorded as its citations, not as sources VALÉORINE has verified.
- 1.Fazlıoğlu, İhsan. Biographical Encyclopedia of Astronomers. Springer, New York, NY. 2123–2126. 2014. 978-1-4419-9916-0.
- 2.Rootsweb, Captain Andrew Field
- 3.National Maritime Museum. Captain Field's Improved Parallel… (NAV0602). Astronomical and navigational instruments. 2009.
- 4.Parallel rules: Rolling and bar types. Mathematical Instruments - A private collection. 2009.
- 5.National Maritime Museum. Parallel rule (NAV0601). Astronomical and navigational instruments. 2009.
- 6.National Maritime Museum. Parallel rule (NAV0618). Astronomical and navigational instruments. 2009.
References
Citations
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General reference
The Encyclopedia exists whether or not anything is for sale. Corrections are recorded rather than overwritten, and every version of this record is kept. Published 14 August 2026.
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