Accession No
1171
Brief Description
sector, by Claude Langlois, French, 2/4 18th Century
Origin
France; Paris; Aux Galleries du Louvre
Maker
Langlois, Claude
Class
calculating; mathematics
Earliest Date
1725
Latest Date
1750
Inscription Date
Material
metal (brass)
Dimensions
length 173mm; breadth 31mm; thickness 4mm
Special Collection
Provenance
Transferred from the Museum of Archaeology and Ethnography, University of Cambridge (now Museum of Archaeology and Anthropology).
Inscription
‘Langlois aux Galleries
du Louvre AParis ‘ (on obverse)
Description Notes
Six inch brass sector with decorated hinge and internal scroll piece. Obverse carries double scales: ‘les Cordes’ divided [0] - 180 numbered by 10 to 130, 10 - 150 divided to 1; 150 - 170 divided to 5; ‘les Solides’ divided 1 - [64] numbered by 10 subdivided to 1; ‘les Metaux’ by symbol. On the fully opened limbs single scale of ‘diametre et poids des boulets’ numbered 1/4, 1/2, 3/4, 1, 2, 3 ... 10, 12, 14 ... 20, 24, 27, 30, 33, 36, 40, 48, 50, 55, 60, 64. Reverse carries double scales: ‘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 the fully opened limbs single scale of ‘Calibre des pieces’ numbered 1/4, 1/2, 3/4, 1, 2, 3 ... 10, 12, 14 ... 20, 24, 27, 30, 33, 36, 40, 48, 50, 55, 60, 64.
Condition fair (tarnished); 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:39517
Images (Click to view full size):
