Accession No
0606
Brief Description
sector by Duhamel Fils, 2/2 18th C
Origin
Paris; France
Maker
Duhamel Fils
Class
calculating; mathematics
Earliest Date
1750
Latest Date
1800
Inscription Date
Material
metal (brass)
Dimensions
length closed 173mm; breadth 31mm; thickness 4mm
Special Collection
Provenance
Inscription
‘Duhamel Fils
AParis’ (obverse)
Description Notes
Brass sector with decorated hinge with internal scroll-piece.
Obverse: double scales of ‘Les Cordes’, divided [0] - [200], numbered by 10 (to 130), subdivided to 1 (to 140). Double scales of ‘Les Solides’, divided [1] - [64], numbered 5, 10, 20...60, subdivided to 1. Double scales of ‘Les Metaux’, divided by symbol. On the fully opened limbs, a single scale of ‘Poids des Boules’, divided 1/4 - 64, numbered 1/4, 1/2, 3/4, 1, 2...8, 10, 14, 18, 20, 24, 30, 36, 40, 48, 50, 55, 60, 64.
Reverse: double scales of ‘Les Parties Egalles’, divided [0] - 200, numbered by 10, subdivided to 1. Double scales of ‘Les Plans’, divided [1] - [64], numbered by 10, subdivided to 1. Double scales of ‘Les Poligones’, divided 12 - 4, numbered by 1. On the fully opened limbs, a single scale of ‘Calibre des pieces’, divided 1/4 - 64, numbered 1/4, 1/2, 3/4, 1, 2...8, 10, 14, 18,20, 24, 30, 36, 40, 48, 50, 55, 60, 64.
Condition fair; complete.
References
Events
Description
Sector
Sectors were used for calculation by navigators, surveyors, gunners and draftsmen (and, famously, by Galileo) from the about the mid 16th century to the mid 19th century. During the 16th century, they were used as general mathematical tools, but the introduction of logarithms drastically expanded their application. Usually made of brass, wood or ivory, they look like a jointed rule with scales engraved on either side.
Sectors use the principle of similar triangles (that the ratio of lengths of two sides of similar triangles will always be the same) with scales of proportion for calculating mathematical functions such as finding the line of equal parts, inscribing a rectangular polygon inside a circle of a given radius and protracting angles. This made them useful for similar calculations to a slide rule.
18/10/2002
Created by: Saffron Clackson on 18/10/2002
FM:43072
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