Rolling Navigation Ruler, 19th century
notes: label: Description
content: This brass rolling ruler is engraved with measurements on all four sides. There are rollers on either side of the ruler, connected by an axle. The object is well worn with a dent on one corner, and it is screwed together. There are inches on one side of the ruler, on the remaining three sides the hash marks are slanted in ascending and descending increments of ten towards the center of the ruler ending in 90 making degree angles. The names “Cary London” and “R.F. Crawford R.N.” are stamped on the tool. William Cary was an instrument maker in London in the late 19th and early 20th centuries. “R.F. Crawford” was the owner of the instrument; the “R.N.” represents Royal Navy.
label: Description
content: This navigational instrument was used to plot courses on nautical charts and could be rolled across a chart without changing its orientation. The different sides were used for angle or scale corrections on the meridians or curved lines on a globe connecting the poles.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Maritime
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content: Maritime Objects
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content: Measuring & Mapping
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: TR.320635
label: catalog number
content: 320635
label: accession number
content: 242721
objectType: label: Object Name
content: parallel rule
label: Object Name
content: rolling ruler
label: Other Terms
content: parallel rule; Maritime
physicalDescription: label: Measurements
content: overall: 15 1/2 in x 2 1/2 in; 39.37 cm x 6.35 cm