On one side this brass rule has an unnumbered scale of chords and architect's scales for making drawings at proportions of 1/5", 1/4", 1/3", 1/2", and 1" to the foot. The other side has 8" plotting scales with diagonal scales at each end. One plotting scale is divided to 1" and numbered by ones from 1 to 8, and the other is divided to 1/2" and numbered by ones from 1 to 16. A badly worn leather sleeve may not be original to the instrument. Compare to 1980.0676.01.
The Smithsonian's Division of Ethnology received this rule in 1951 and believed it to be of American manufacture.
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