Parallel rulers
Parallel rulersare adraftinginstrument used by navigators to draw parallel lines on charts. The tool consists of two straight edges joined by two arms which allow them to move closer or further away while always remaining parallel to each other.
History[edit]
The parallel ruler was invented at about 1584 byFabrizio Mordente,[citation needed]as well as byTaqi al-Dinwho died in 1585.[1]However it was not in common use (at least in Europe) until the 18th century.[2]
In the 19th century a retired sea captain, Captain William Andrew Field[Note 1]improved the design by adding aprotractor-style scale to the upper edge of one rule, andcompasspoints to the opposing edge, which made reading bearings easier.[2]Examples exist ofboxwood,ivoryorebony,usually withbrasshinges.[2][4]The instrument usually had two links, but longer models sometimes had three,[5]and sometimes the links werescissored.[6]Another variation is the "roller" model which included a cylindrical roller for ease of use.[5]
See also[edit]
Notes[edit]
- ^Captain William Andrew Field (c. 1796–1871).[3]In February 1833 he rescued 14 sailors from the Sicilian brig Felicita, which was wrecked on rocks at the entrance to Sandy Haven in Milford Haven for which he received theRNLI Silver Medaland a medal from theRoyal Humane Society.[3]
References[edit]
- ^Fazlıoğlu, İhsan (2014). "Taqī al-Dīn Abū Bakr Muḥammad ibn Zayn al-Dīn Maҁrūf al-Dimashqī al-Ḥanafī".Biographical Encyclopedia of Astronomers.Springer, New York, NY. pp. 2123–2126.doi:10.1007/978-1-4419-9917-7_1360.ISBN978-1-4419-9916-0.
- ^abc"Captain Field's Improved Parallel… (NAV0602)".Astronomical and navigational instruments.National Maritime Museum.2009. Archived fromthe originalon 2011-08-02.Retrieved2009-06-23.
- ^abRootsweb, Captain Andrew Field
- ^"Parallel rule (NAV0601)".Astronomical and navigational instruments.National Maritime Museum.2009. Archived fromthe originalon 2011-06-09.Retrieved2009-06-23.
- ^abRiches, D. M. (2009) [2001]."Parallel rules: Rolling and bar types".Mathematical Instruments - A private collection.Archivedfrom the original on 2021-07-22.Retrieved2009-06-23.
- ^"Parallel rule (NAV0618)".Astronomical and navigational instruments.National Maritime Museum.2009. Archived fromthe originalon 2011-06-09.Retrieved2009-06-23.
External links[edit]
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