Accession No
3382
Brief Description
model of Galileo’s sector with explanatory material, by the Florence Museum of the History of Science, Italian, 1980
Origin
Italy; Florence
Maker
Museum of the History of Science, Florence
Class
calculating; mathematics; demonstration; ephemera
Earliest Date
1980
Latest Date
1980
Inscription Date
30-5-1980
Material
paper (card and two others); metal (brass)
Dimensions
length 295mm; breadth 183mm
Special Collection
Provenance
Donated, 01/1985. Purchased by donor from Museum of the History of Science, Florence. Made for sale in the Museum of the History of Science, Florence.
Inscription
‘LE OPERAZIONI DEL COMPASSO GEOMETRICO ET MILITARE DI GALILEO GALILEI’ (front cover of booklet)
Description Notes
Model of Galileo’s sector accompanied by Italian instruction booklet explaining its use. The sector is made of card and stowed in a pocket on the inside cover of the instruction booklet.
References
Events
Description
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, edited by Allison Ksiazkiewicz on 18/10/2002
FM:40806
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