Rare German military sector, late 17th or early 18th century

Rare German military sector, late 17th or early 18th century


A rare German mathematical/military sector in brass dating from the late 17th or early 18th century.


7 inches/18 cm


Late 17th or early 18th century

Country of manufacture


Categories: Scientific, Navigational instruments, Calculating, Drawing Instruments


Offered for sale is this substantial brass sector, 7 inches/18 cm in length (closed) and opening on a three-leaf hinge. The faces bear various doubled scales including Fortifica, Chorda, Cubica, and Metallo on one side and Arithmet, Geometr, and Polÿgon on the reverse. These scales were used for calculations in applied mathematics and engineering including gunnery, fortification design, surveying, navigation, plane and solid geometry, densities of ammunition materials, etc. A similar model was illustrated by mathematician Michael Scheffelt in his 1697 treatise Instrumentum proportionum:


This is an important piece considering the great rarity of early German sectors. Similar examples can be found in various museums including the London Science Museum, Adler Planetarium Chicago, Mathematisch-Physikalischer Salon in Dresden, British Museum and others, see links below:




Provenance: Private collection in Bremerhaven, Germany.

Condition: Very fine, some light scratches and tiny nicks as seen in the photos.

References: M. Scheffelt, Instrumentum proportionum, Ulm 1697; etesseract/calculation

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US Instrumentum

Instrumentum is based in the United States and specializes in high quality 17th and 18th century scientific instruments for architecture, mathematics and navigation. We have collected antique instruments for over 20 years with a focus on early and rare European architectural drafting sets, dividers, and rules. If you are interested in something particular please contact us at instrumentuminfo@gmail.com. Image galleries of our inventory can be viewed on Pinterest and Facebook at the following links:



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