The mater consists of two pieces riveted together, one for the plate and one for the limb. The limb is numbered with hours 1 to 12 twice and is divided in four quadrants of 90? with 90? at the zenith, divided to 10? and to 1?, numbered by 10?.
Suspension is by means of throne, lined on the sides, shackle and two rings.
The rete is in silver, and is engraved with 36 flambent star pointers. They are all named and some of them have a number indicating the magnitude of the star. The east-west bar is counterchanged twice and the meridian bar, present only in the lower part of the rete, is also counterchanged twice. The ecliptic is divided into degrees by 2?, and the zodiacal signs are named. The ecliptic is linked to the Capricorn bar with two ties and some of the star pointers stand on a roll basis.
The two plates are engraved with both tropics and equator lines, east-west and meridian line, unequal hour lines and astrological houses, zenith lines and almucantars every 3?. The twilight line is marked 'AVRORA', or 'LINEAE AVRORA', or 'CREPVSCVLVM', the tropic of Capricorn 'TRO IIII' with or without the symbol of Capricorn, the equator with the symbols of Aries and Libra, the tropic of Cancer with the symbol of Cancer. The astrological houses are numbered I to XII and the unequal hours 1 to 12, the zenith lines are engraved and numbered by 10?. The plates are marked for latitudes 46?, 49?, 52? and 55?.
The back of the mater is engraved with a scale of 360? divided to 5?, to 1?, numbered by 10?, corresponding to a zodiac scale with the signs named and abbreviated. The zodiac scale is not numbered but the lines of the degrees have one, two or three transversal lines to mark the 10th, 20th and 30th degree of the sign respectively. Further to the centre is a calendar scale with the first point of Aries on the 11th of March, numbered with the same system of lines except for the last day which is numbered in Roman numerals. The month names are engraved in abbreviated form. Next to the centre, on the lower half is engraved a double shadow square marked 'VMBRA RECTA' and 'VERSA', divided to 1 and numbered by 3. On the top half of the mater, next to the centre, are engraved but not numbered, unequal hour lines.
The rule is single arm, lined on the sides and ending in a Gothic style.
The alidade, with two pin-hole sights, is counterchanged and decorated in Gothic manner. The pin has a double concentric decoration and the wedge is decorated with a small globe on the top.