Epact Scientific Instruments of Medieval and Renaissance Europe

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Protractor
Unsigned
Late 16th century; English
Brass; 90 mm in diameter

One side of the instrument is engraved on the rim with a scale of degrees divided to 10, to 5 and to 1 degree, numbered from 10 to 360 by 10 starting from north. The initials of the cardinal points are engraved 'N', 'E', 'S'. On the east side is a circular slot. The inner side of the slot is engraved on the rim with a sexagesimal scale, divided to 5, to 1, to 1/2 and to 1/4 (sexagesimal) degrees, numbered from 5 to 60 by 5. The opposite half of the protractor has a rectangular shape parallel to the east-west line. It is engraved with a scale divided to 1 and to 1/2, numbered from 9 to 1 by 1 from the centre to the outside of the protractor. Another rectangular slot is hollowed adjacent to the north-south line and two lugs help locating the centre of the protractor.

The other side of the protractor is engraved in a similar way but does not have the graduation in degrees on the rim. There are, however, faint traces of division. The inner circle of sexagesimal degrees is numbered by 5 from 65 to 120.

Ilaria Meliconi

Istituto e Museo di Storia della Scienza, Firenze
Inventory no. 613

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