Accession No
1172
Brief Description
sector by Clerget, 1/2 18th Century
Origin
France; Paris
Maker
Clerget
Class
calculating; mathematics
Earliest Date
1700
Latest Date
1750
Inscription Date
Material
metal (brass)
Dimensions
length 174mm; breadth 31mm; thickness 4mm
Special Collection
Provenance
Transferred from the Museum of Archaeology and Ethnography, University of Cambridge (now Museum of Archaeology and Anthropology) in 09/1953.
Inscription
‘Clerget AParis
au Butterfield’ (obverse)
Description Notes
6-inch brass sector with decorated hinge and internal scroll piece.
Obverse carries double scales of: ‘les Cordes’ divided [0] - 180˚, numbered by 10˚ (except 160 and 170), 0 - 150˚ subdivided to 1˚, 150˚ - 170˚ subdivided to 5˚; ‘les Solides’ divided 1 - [65], numbered by 10, subdivided to 1; ‘les Metaux’ marked by symbol. On fully opened limbs unequal scale of ‘poids des boulets’, divided 1/4 - 64, numbered 1/4, 1/2, 3/4, 1, 2, 4, 6, 8, 10, 14, 18, 20, 24, 30, 36, 40, 48, 50, 55, 60, 64.
Reverse carries double scales of: ‘Les Parties Egales’ divided [0] - 200, numbered by 10, subdivided to 1; ‘les Plans’ divided 1 - 64, numbered by 10, subdivided to 1; ‘les Poligones’ divided 12 - 3, numbered by 1. On fully opened limbs, unequal scale of ‘calibre des pieces’, divided 1/4 - 64, numbered 1/4, 1/2, 3/4, 1, 2, 4, 6, 8, 10, 14, 18, 20, 24, 30, 36, 40, 48, 50, 55, 60, 64.
Two pins to secure limbs together.
Condition good; 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:39548
Images (Click to view full size):
