The outer side of the upper leaf has a pierced lunar volvelle with the names of the phases engraved in Latin and a half moon engraved on the brass plate. At the top a framed inscription reads 'IN ORBICVLO ROTVNDO AEQVIPARAT SE HORA NOCTVRNA CVM PROXIMO NVMERO'.The inner face of the upper leaf has a pin gnomon dial marking the length of the day and the declination of the sun with symbols of the zodiacal signs, all marked in green, and holes for adjusting the latitude to 42?, 45?, 48?, 51?, 55? indicated by the inscription 'AD ELEVATIO POLI' in black. In a double circle is 'ILLA CVSPIS INDICATCAT [sic] INCREMENTVM ET DECREMENTVM DIEI ET DVODECIM SIGNA' in red. At the bottom is written in green 'IMPONE FILVM FORAMINI QVOD LOCI TVI POLVM INDICAT ET HORA HABEBITVR IN CIRCVLO QVI EODEM NUMERO [deletion] POLARI INSCRIBITVR' ('place the string in the slot which corresponds to the latitude of your place and you will have the hour in the circle which has inscribed that number').
The inner part of the lower leaf has a metal compass and a string gnomon dial for the latitudes mentioned above, with common hours marked from 4 to 12 to 8 and dots for the half hours. Around the border is the inscription 'COMPASSI SVNT POLIREGIONVM ET CIVITATVM CIRCVLI HVIVS'.
On the border of the outer part of the lower leaf the inscription 'QVIS QVIS VVLT HORAM SOLIS COGNOSCERE VERAM FERRO COMPASSVM REMOVET ILLE SVVM' ('he who wants to know the true hour of the sun takes away his compass from iron'). At the top centre is the signature 'HANS TVCHER' with his mark, the date '15 89' and the quality mark 'n' for Nuremberg.
See P. Gouk, The Ivory Sundials of Nuremberg 1500-1700 (Cambridge, 1988).
Ilaria Meliconi