Plotting Scale Master, Signed John Shearson
date: label: date made
content: 18th century
notes: label: Description
content: This brass rule has three plotting scales, one with diagonal scales at both ends (graduated to 1/10" and 1/20") and two with diagonal scales at their right ends (graduated to 1/40" and 1/30"). The first plotting scale is 5" long and divided to 1/2", the second is 2-3/4" long and divided to 1/4", and the third is 3" long and divided to 1/3". A 12" scale of inches runs sequentially across the top of all three scales.
label: Description
content: A decorative pattern is engraved along the top and bottom edges of the instrument. Flat projecting pieces at the left and right ends may have been used to hold rules to be divided on the pattern of this rule. The back of the rule is marked: John Shearson. Since Shearson is not listed in the Webster Signature Database, it is uncertain whether he was the maker or previous owner of this rule. The rule may have been made in England in the 18th century. The Smithsonian acquired it in 1961.
label: Description
content: Reference: Adler Planetarium, <i>Webster Signature Database</i>, http://historydb.adlerplanetarium.org/signatures/; Gloria Clifton, <i>Directory of British Scientific Instrument Makers 1550–1851</i> (London: National Maritime Museum, 1995).
label: Location
content: Currently not on view
topic: label: Subject
content: Mathematics
label: Subject
content: Drafting, Engineering
setName: label: See more items in
content: Medicine and Science: Mathematics
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content: Science & Mathematics
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content: Scale Rules
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MA.319509
label: catalog number
content: 319509
label: accession number
content: 239015
objectType: label: Object Name
content: scale rule
label: Object Name
content: scale, plotting
physicalDescription: label: Physical Description
content: brass (overall material)
label: Measurements
content: overall: 41.6 cm x 3.6 cm x .2 cm; 16 3/8 in x 1 13/32 in x 3/32 in