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Drafting instrument used to draw parallel lines
Parallel rulers
are a
drafting
instrument 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
[
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]
The parallel ruler was invented at about 1584 by
Fabrizio Mordente
,
[
citation needed
]
as well as by
Taqi al-Din
who 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 a
protractor
-style scale to the upper edge of one rule, and
compass
points to the opposing edge, which made reading bearings easier.
[2]
Examples exist of
boxwood
,
ivory
or
ebony
, usually with
brass
hinges.
[2]
[4]
The instrument usually had two links, but longer models sometimes had three,
[5]
and sometimes the links were
scissored
.
[6]
Another variation is the "roller" model which included a cylindrical roller for ease of use.
[5]
See also
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]
Notes
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]
- ^
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 the
RNLI Silver Medal
and a medal from the
Royal Humane Society
.
[3]
References
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External links
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]