Ivory Diptych Dial by Hans Troschel
Record status
Individual type · partial
Period
Early 17th century
This diptych dial is an ivory instrument measuring 90 x 55 mm, constructed in Nuremberg during the early 17th century. Signed by the instrument maker Hans Troschel, it functions as a horizontal string gnomon sundial adjustable for four different latitudes.
The interior lid features a table of geographical latitudes and a wind rose with a central pointer, alongside a compass inset into the base. The instrument incorporates a string gnomon that can be attached to various holes on the base corresponding to specific latitudes to indicate solar time. On the rear of the device, a lunar volvelle tracks moon phases, integrated with a scale for lunar and solar time conversion. The dial faces include diagrams for day length, zodiac symbols, and various hour scales, including markings for Italian and Babylonian hours.
The object is marked with the maker's signature and a six-pointed star mark.
Evidence at a glance
- Linked sources
- 1
- Photograph views
- 1
- Catalogue references
- 0
Counts describe this entry’s documentation, not authenticity, rarity or completeness. Photographs may show one specimen; check each caption and licence.
Technical characteristics
- Date
- Early 17th century
- Type
- Nuremberg diptych dial
- Maker
- Hans Troschel
- Dimensions
- 90 x 55 mm
- Maker's Mark
- Six-pointed star
- Place recorded
- Nuremberg
- Place of Origin
- Nuremberg
- Maker / attribution
- Hans Troschel
Design
- Visible features
- • Ivory casing with inset compass • String gnomon for variable latitude adjustment • Lunar volvelle featured on the rear of the instrument • Compass includes a magnetic declination mark for approximately 6 degrees East
- Dial Faces and Markings
- The interior faces of the dial are detailed with various scales and diagrams. Face Ia displays a thirty-two point wind rose surrounded by the inscription 'PERGE SECVRVS MONSTRO VIAM'. Face Ib presents a diagram depicting the length of the day, marked with zodiac symbols in red and hour lengths in black. This section also includes a detailed list of European cities paired with their respective latitudes, which serves as a reference for the latitude-dependent gnomon settings. Face IIa features the horizontal string-gnomon dial with four distinct hour rings to accommodate different latitude adjustments. Additionally, a pin gnomon dial is included for indicating Italian and Babylonian hours. Face IIb contains the lunar volvelle, surrounded by Gregorian and Julian epact scales, labeled 'DIES ?TATIS LUN? ET HOR? NOCTIS', providing comprehensive astronomical data beyond basic timekeeping.
- Signatures and Identification
- The instrument bears the clear signature of Hans Troschel, who is noted as an instrument maker from Nuremberg. His identity is confirmed by the textual signature located below the latitude list on Face Ib. The authenticity and manufacture of the piece are further indicated by a specific maker's mark consisting of a six-pointed star, which is repeated twice on the reverse side of the instrument. The object is held in the collection of the Istituto e Museo di Storia della Scienza in Firenze under inventory number 2462. The documentation identifies Troschel as a maker recognized for his work in ivory, and the stylistic and technical features of the dial are consistent with early 17th-century Nuremberg production standards.
- Construction and Functionality
- The instrument is a diptych dial crafted from ivory, comprising a hinged lid and base. The internal assembly includes a horizontal string gnomon, which provides time-keeping functionality when the string is anchored in selected holes corresponding to specified latitudes. The device is designed to be adjustable, allowing the user to determine the hour by reading the shadow projected onto the marked hour lines. Integrated into the design are multiple astronomical and geographical aids. The base houses an inset compass, which features a magnetic declination mark set for approximately 6 degrees East. The lid interior contains a wind rose with a hand-shaped pointer, while the reverse of the dial serves as a lunar volvelle, which displays the phases of the moon and enables conversions between solar and lunar time using a 2 x 12 hour scale.
Identification
- Inventory Number
- 2462
- Source note
- Facts transcribed from the linked source listing or collection record. Attribution and specifications are source-reported and have not been independently authenticated.
Catalogue references
No catalogue numbers recorded. Numbers are only published once transcribed from a verified edition of a standard catalogue — they are never inferred.
Research required
- Research required: Attribution to Hans Troschel is based on the signature on the face
- Research required: The magnetic declination mark is estimated at approximately 6 degrees East