French-Style Sector

The arms of this brass instrument have straight edges, but the hinge is decorated with a straight and squiggly lines. One side has a double scale of chords that runs from 10 to 130; a double scale for "Les Solides" that runs from 1 to 60; and a double scale for the specific weights of four metals, marked with their symbols. Two holes are drilled on either side of the 80 mark on the scales of chords on the lower arm. The outer edge of the lower arm has a scale that runs from 4 to 24 and is labeled "pd des boulets" (for the weight of iron shot).
On the other side, the outer edge has a scale that runs from 4 to 24 and is labeled "Cbres des Pieces" (for the size of iron shot, given the diameter of the barrel and the weight of the shot). There are double scales of equal parts, running from 10 to 200; for architectural drawings, running from 10 to 60; and for inscribed regular polygons, from 12 sides to three sides. Compare to MA*321676 and 1985.0580.04.
According to the accession file, the donor collected this instrument in Mobile, Ala., around 1898 and sent it to the Smithsonian in 1936.
Currently not on view
Object Name
date made
18th century
Physical Description
brass (overall material)
overall: .3 cm x 17.5 cm x 3 cm; 1/8 in x 6 7/8 in x 1 3/16 in
place made
ID Number
catalog number
accession number
Science & Mathematics
Rule, Calculating
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of J. G. Sparkes
Additional Media

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