Epact Scientific Instruments of Medieval and Renaissance Europe

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Quadrant
Signed by Giovanni Battista Giusti
Dated 1568; Florence
Brass; 226 mm in radius

This quadrant is calibrated for the latitude of 43? 40', corresponding to Florence. One face is engraved with the hour lines. The hour was indicated with the aid of a plumb-line which allowed the height of the sun at a particular moment to be calculated by indicating the degrees engraved on the limb of the quadrant. The same face bears a magic square ('4 9 2' / '3 5 7' / '8 1 6' totalling 15 in all directions) and the 'Rota medii motus et quantitas diei', which allows the length of the day to be calculated.

The maker, Giovanni Battista Giusti, worked in Florence in the 1560s, probably in the Medicean metal workshop.

Istituto e Museo di Storia della Scienza, Firenze
Inventory no. 2520

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