Italian-Style Sector

This copper-colored metal instrument has scrolling at the ends of both arms. The hinge is decorated with a floral pattern and is held together with a screw shaped like a flower. On one side, the sector has four unlabeled double scales. From the fold line out, these appear to be a scale of equal parts, running from 20 to [2]50 with the interval from 20 to 30 shorter than the rest of the intervals; a scale of unequal parts, running from 1 to 50; a scale for the quadrature of circle sections, running from 1 to 40; and a scale for the specific weights of metals, which is marked O, P, A, R, F, S, M, and P. Around the hinge reads: IN LEVITATE GRAVIS ("in lightness, seriousness"). The arms are engraved with two stars, floral designs, a bee, a bird, a hand holding dividers, a globe, and a carpentry square.
The other side has four unlabeled double scales. The innermost scale runs from 3 to 15 and is presumably for tetragonic lines, although the numbers increase from the hinge out on this instrument but decrease from the hinge out on most sectors. The second scale runs from 13 to 3 and is probably for the sides of inscribed regular polygons. The "3" on the top arm is incorrectly engraved on the first scale. The third is evenly divided and runs from 18 to 1. The fourth scale is on the same line as the third scale. It is unevenly divided and runs from 17 to 1. The letter D is engraved below the fourth scale. Around the hinge reads: HISQVO[illegible] FINEM ("having end"). The arms are engraved with clouds, a sailing ship, castle towers above and below water, a bird, a dragon, and an inscription in Hebrew. According to Bernard Goldstein, who examined photograph P-64-112E of the object on 21 March 1973, the Hebrew inscription reads, "Keep your tongue from evil and your lips from saying deceits."
The Smithsonian received this sector from New York University in 1963. It has similarities to the arrangement of scales typical of the Italian style of the instrument, but it is also quite different from surviving instruments known to have been made in Italy, France, or England in the 17th and 18th centuries. For another unusual mathematical instrument that may not be authentic, see MA*316861.
Reference: Anthony Turner, "Sector," in Instruments of Science: An Historical Encyclopedia, ed. Robert Bud and Deborah Jean Warner (New York and London: Garland Publishing, 1998), 526–528.
Currently not on view
Object Name
Physical Description
metal (overall material)
overall: .4 cm x 26.8 cm x 4.8 cm; 5/32 in x 10 9/16 in x 1 7/8 in
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 New York University
Additional Media

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