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Signed by Gillis Coignet
Dated 1560; Antwerp
Brass; 251 mm in diameter

The mater of this instrument is made up of three riveted layers of brass.

The face of the limb is exceptionally large with an outer calendar scale with the months named and divided to the single day with the 10th, 20th and last day numbered. Next is a zodiacal scale with the names and symbols of the signs, each divided into 30?, subdivided to 5? and to 1?, numbered by 10?. The first point of Aries corresponds to the 10th of March. The last division in the limb is in hours, each corresponding to 15 degrees on the zodiac scale, numbered I to XII.

Suspension is by a ring threaded through a small eyed-swivel, which turns in a plate riveted to the mater, perhaps replacing an earlier bracket.

The rete is reduced to the ecliptic band, with the east-west and meridian lines, both counterchanged, only in the inner part of the ecliptic. The ecliptic band itself is divided into 360?, with each zodiacal sign named and divided to 2?, numbered by 10?. The eight star pointers are of the flambent style and the stars are all named. The design of the rete comprises a circle tangent to the ecliptic and a semicircle interlocked with it.

The only plate is engraved on one side with a scale of 360?, divided to 10? and to 5?, numbered by 10? on the limb, and with a polar projection of the Northern Hemisphere, with engraved 'Tropicus capricorni', 'Tropicus cancri' and 'Aequinoctialis'. The circle of degrees starts with 0? at the Azores. The places named are: 'OCEAN OCCIDENTAL', 'OCEANVS ORIENTALIS', 'AFRICA', 'AMERICA', 'ASIA', 'EVROPA', 'Peru', 'Brasili', 'barbaria', 'c.ber', 'c.ginei', 's.cho', 'm.rub', 'arabia','nor, 'm ab.', 'mont.lunae', 's.laur.', 'calicut', 'barma', 'MALVCHE', 'mangay', 'canbay', 'mesico'.

On the other side the plate is engraved with an 'Horizontale catholicum', with east-west (indicated 'Horizon rectus') and meridian lines, with the cardinal points indicated 'ORIENS', 'OCCIDENS', 'MERIDIES' and 'SEPTEN'. The horizon lines are engraved every 2? and numbered by 10?, from [0] to 90? and the 'AEquinoctialis' is indicated. Only the XII hours are marked, twice.

The back of the mater is engraved on the limb with a roll-and-beads decoration, and graduated with a scale of degrees in four quadrants of 90? with 90? at the zenith, divided to 10?, subdivided to 5? and to 1?, numbered by 10?. A revolving plate is engraved with an orthographic projection of the sphere, similar to the Rojas type (called Geminus dial) with the longitude indicated by the zodiac symbols and the latitude indicated by hours numbered 1 to 12 in each direction. The poles are indicated by two pointers and are marked 'ELEVATIO POLI' and 'Polus anctarcticus', and the hours are marked 'Hore Pomeridiane' and 'Hore Antemeridiane'.

On top of the plate is a 'TRIGONUS' as described by Gemma Frisius in his Cosmographia. It is a triangle with one angle drawn out as 'index' and on the opposite side is a folded rectangular plate (as in a sight on an alidade) with the indication 'Linea Vmbrae' twice. On the inner part of this side is a sun effigy and the hypotenuse of the triangle is decorated. The sundial enables the user to find, in addition to the time, times of sunrise and sunset, and the duration of twilight.

The plate and trigonus fit between the mater and a diametral bar, inscribed 'HORIZON VEL LINEA ORTVS' and 'LINEA AVRORAE VEL CREPVSCVLINA', pierced in correspondence to the zodiac graduation of the smaller disc. At the bottom of the bar is the signature 'Aegidius cuiniet antuerpianus facieb. A. 1560'.

The one-arm rule is graduated with an unequal scale of latitudes from [0?] to 20? (indicated 'Latit. meridin.') and from [0?] to 70? (indicated 'Latitudo Septentrionalis'), divided to 10?, to 2?, numbered by 10?, and ends with a decorated point.

The pin is decorated and there is a ring of leather between the pin itself and the plate. The nut is in steps-form.

See R. T. Gunther, The Astrolabes of the World (2 vols, Oxford, 1932), vol 2, p. 378.

Ilaria Meliconi

Museum of the History of Science, Oxford
Inventory number 53211

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