The lid is laid out as a nocturnal with a volvelle rotating over a fixed disc and a hinged index arm rotating over both.
The scales on the disc and the volvelle correspond to each other as follows: the disc is inscribed with a calendrical scale with the abbreviated names of the months in Latin (MARTY for March) and the corresponding number of days, numbered by 10 and divided to 2. The nocturnal can be set for the right time of the year with the help of a small pointer on the volvelle, marked 'A'. An inscription on the volvelle gives the instruction 'DER ZAYGER A SOL AVF DEN TAG DES MONATS GERVCKT WERDEN'. A second inscription on the volvelle instructs the user how to align the index with the pointer stars in the Great Bear: 'DER ZAYGER B SOL AVF DIE ZWAY HINDERE REDER DES GROSEN WAGEN GERVCKT WERDEN'. The index itself, consisting of a hinged arm, is marked in the centre 'STELA POLARIS DUBH', and with stars on the foldable part. The tip of the pointer is broken off and there is no 'B'.
The outside ring of the volvelle is marked as an hour scale 3 to 12 to 9 with small pins on the outside, numbered by 1 and divided to 15 minutes. This hour scale is continued for latitudes ('POLVS H') 44, 47, 50, 53 on the fixed disc and can be seen through two apertures in the volvelle.
The inside of the lid contains a lunar volvelle for converting solar time into lunar time and vice versa. Three scales are marked as follows: 1) an hour scale twice I to XII, marked by 1 and divided to 15 minutes; 2) the age of the moon 0 to 291/2, numbered by 1; 3) a second hour scale on the volvelle 3 to 12 to 9, numbered by 1 and divided to 15 minutes. The scale is labelled 'INDEX DIERVM AETATIS LVNAE'. An aperture in the volvelle reveals the phases of the moon on the disc underneath. The centre of the volvelle is marked with an aspectarium.
Hinged between the lid and the bottom of the box is an equatorial dial consisting of a double hour ring and a foldable pin gnomon. The outer, movable ring bears an hour scale 1 to 24, numbered by 1 and divided to 30 minutes. The inner, fixed ring is marked twice 1 to 12, numbered by 1 and divided to 30 minutes. By turning the outer ring against the inner ring common hours can be converted into Italian or Babylonian hours. The signature of the maker and the date 'MELCHIOR REICHLE VECIT ANNO 1568' are given on the reverse of the ring.
The dial can be set to the appropriate latitude with the help of a foldable degree arc hinged to the bottom. The scale runs from 16 to 90, numbered by 10 and divided to 2. The other side is marked 'ELEVATIO POLI'.
The bottom plate has the eight main directions and the corresponding weather in German and Latin as follows: 'NORD - SCHON - SEPTENTRIO, NORDOST - SCHON KALT, OST - SCHON - ORIENS, SVDOST HALBSCHON, SVD - GWILCK - MERIDIES, SVDWEST - REGEN, WEST - TRIEB - OCCIDENS, NORDWEST - SCHNESCHAVR'. In the centre, around an inset magnetic compass, is a degree scale for the magnetic variation, marked 'DECLINATIO MANGNET' 0 to 90, 0 to 90. The compass is marked 'SE' and 'ME' for North and South and a deviation of 10?W of N.
The underside has a circular list of 30 places with their latitudes as follows: 'Vtinis 45, Verona 45, Venetiae 45, Tessalonica 40, Tubinga G 49, Turonia 47, Treveris 50, Tarentum 40, Tridentum 44, Taurinum 44, Toletum H 41, Salvedia Tu 51, Salisburg 46, Spira 50, Sebenicum 43, Praga 30, Monacha 48, Ingoldsta 48, Breslae 51, Antwerph 52, Augusta 48, Vilna Litu 54, Vurtember 52, Vienna Au 45, Vienna G 45, Vlma 48, Volaterae 43, Villitrum 41, Vrbinum 43'.
The outside of the box is decorated with foliate scrollwork.
The instrument was presented by A.W. Franks in 1865 and is described in F. A. B. Ward, A Catalogue of European Scientific Instruments in the Department of Medieval and Later Antiquities of the British Museum (London, 1981), p. 122 ff., no. 354.