Signed by Robert Dudley
Dated 1597; English
Brass; 370 mm in radius
The limb of the quadrant is engraved with a scale of degrees, divided to 5, to 1, to 1/4 degree by alternate shading, numbered from 5 ot 90 by 5. Further to the apex are two tables with the solar cycle 'CICLVS SOLIS' and the dominical letter 'LITERA D<OMI>NICALIS', the Epact 'EPACTA' and the Lunar cycle 'CICLVS LVNAE'. Further to the apex is a zodiac scale divided to the day by alternate shading, numbered from 5 to 30 by 5, and with the names and symbols of the zodiacal signs engraved. On the right of the scale is the signature 'Sir Robert Duddeley was the Inventer of this Instrument Ano 1597'. On one of the square edges are two tables. The first one is used to find the date of Easter 'Tabula Pascalis' and the other lists years 'An Do' and 'REVOLVTIONES CICLI LVNAE' and 'REVOLVTIONES CICLI SOLIS' for years from 1539 to 1868.
On the centre of the quadrant are hour lines numbered from 1 to 6 to 12 and an unequal scale of sun's latitude, divided to 5 degrees by alternate shading, not numbered, with the names and symbols of the zodiacal signs engraved. The tropics and equator are engraved 'TROPIC CANCRI', 'TROPIC CAPRICOR' and 'LINEA AEQVINOCTIALIS'. Close to the apex are unequal hour lines numbered from 1 to 12 and engraved 'HORE PLANETARVM', and two double concentric circles with in the centre the date 'IX 1597'.
The back of the quadrant is engraved on the limb with a scale of degrees similar to the front. The rest of the quadrant is engraved with a shadow square divided to 5 and to 1, numbered from 1 to 60. The inner side of the shadow square is numbered continuously on all the four edges from 1 to 32 at the apex and is divided to 1/8. The shadow square is inscribed 'VMBRAE RECTAE' and 'VMBRAE VERSAE'. Inside the shadow square is a wind rose with 32 directions numbered, north indicated by a fleur-de-lis. The four cardinal points are engraved 'Septemtrio', 'Ortus', 'Auster', 'Occasus'. The wind rose is divided into 256 parts by alternate shading. In the centre of the wind rose are engraved in the four quadrants '4', '4', '4', '1'. Around the wind rose is a calendar scale, divided to the day by alternate shading and numbered from 10 to the last day of the month as appropriate, by 10. The names of the months are engraved in Latin. Around the calendar scale is a zodiac scale, divide to 5 and to 1 degree by alternate shading, numbered from 5 to 30 by 5. The names and symbols of the zodiacal signs are engraved. The first point of Aries corresponds to March 10.
In the centre of the quadrant is a hole, possibly for fixing an alidade.
Istituto e Museo di Storia della Scienza, Firenze
Inventory no. 3365
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