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The Encyclopedia of Horology

Clock · Diptych sundial

Diptych sundial for latitude 47 degrees

Partially verified

This ivory diptych sundial was made by Hanns Troschel in Nuremberg between 1623 and 1628 for use at latitude 47 degrees, as recorded by the Science Museum Group. The instrument incorporates both vertical and horizontal dials, astronomical and astrological markings, a circular compass well, and scales for Italian and Babylonian hours. The interior base of the upright leaf bears the maker's signature 'HANNS TROSCHEL'. According to museum documentation, the object was equipped with a lunar volvelle, wind rose, and pin gnomon, while the wind vane, compass needle, and cover glass are missing.

Ivory diptych sundial for latitude 47 degrees by Hanns Troschel, Nuremberg, 1623-1628
Ivory diptych sundial for latitude 47 degrees by Hanns Troschel, Nuremberg, 1623-1628 — Science Museum Group. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
collection.sciencemuseumgroup.org.uk
Category
Clock · Diptych sundial
Maker / attribution
Hanns Troschel
Reference
Not recorded
Catalogue / lot identifier
1992-194
Source-reported date
1623-1628
Country
Germany

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Identity and Attributed Provenance

Catalogued under object number 1992-194 by the Science Museum Group, this instrument is recorded as an ivory diptych sundial designed for latitude 47 degrees. Production is attributed to maker Hanns Troschel in Nuremberg between 1623 and 1628.

The maker attribution corresponds directly with physical markings visible on the piece. Across the base of the upright leaf, the inscription 'HANNS TROSCHEL' appears engraved in red-filled capital letters.

Evidence for this section
  • “Ivory diptych sundial for latitude 47 degrees by Hanns Troschel”
  • “Made: 1623-1628 in Nuremberg”
  • “The maker's name 'HANNS TROSCHEL' is engraved in red-filled capital letters across the base of the upright leaf.”

Dial Construction and Observable Markings

The object consists of a hinged ivory diptych open at roughly a right angle, displaying engraved hour lines and astrological symbols filled with dark and red pigment.

A central circular compass well is hollowed into the horizontal leaf, marked with cardinal points 'SEP', 'MERI', 'ORI', and 'OCCI'. Additionally, a circular through-hole is visible towards the base of the upright leaf.

Evidence for this section
  • “Hinged ivory diptych open at roughly a right angle, displaying engraved hour lines and astrological symbols filled with dark and red pigment.”
  • “A central circular compass well is hollowed into the horizontal leaf, marked with cardinal points 'SEP', 'MERI', 'ORI', and 'OCCI'.”
  • “A circular through-hole is visible towards the base of the upright leaf.”

Documented Features and Missing Elements

Museum cataloguing records that the object was made with vertical and horizontal dial scales, a pin gnomon for Italian and Babylonian hours, a lunar volvelle, and a wind rose (transcribed in the record as 'wind pose').

The museum documentation specifically notes that the wind vane, compass needle, and cover glass are missing.

Evidence for this section
  • “with vertical and horizontal dial, pin gnomon for Italian & Babylonian hours, lunar volvelle and wind pose.”
  • “Wind vane, compass needle and cover glass missing.”

Open research questions

  • What markings or volvelles are engraved on the exterior faces of the leaves not visible in the primary photograph?
  • What are the physical dimensions and weight of diptych 1992-194?
  • What specific function was served by the through-hole near the base of the upright leaf?

Source evidence

Recorded claims and source quotations for Diptych sundial for latitude 47 degrees
FieldSource-reported valueSource quotation
MakerHanns Troschel“maker: Hanns Troschel”
Date1623-1628“Made: 1623-1628 in Nuremberg”
Object Number1992-194“Object Number: 1992-194”
Material and TypeIvory diptych sundial“Ivory diptych sundial for latitude 47 degrees by Hanns Troschel”
Missing partsWind vane, compass needle, and cover glass missing“Wind vane, compass needle and cover glass missing.”
Museum CategoryTime Measurement“Category: Time Measurement”
Design Latitude47 degrees“Diptych sundial for latitude 47 degrees”
Object Typesundial“type: sundial”

Visible details

  • Hinged ivory diptych open at roughly a right angle, displaying engraved hour lines and astrological symbols filled with dark and red pigment.
  • The maker's name 'HANNS TROSCHEL' is engraved in red-filled capital letters across the base of the upright leaf.
  • A central circular compass well is hollowed into the horizontal leaf, marked with cardinal points 'SEP', 'MERI', 'ORI', and 'OCCI'.
  • A circular through-hole is visible towards the base of the upright leaf.

Research qualifications

  • Exterior sides, including the lunar volvelle, are not visible in this photograph.
  • The source reports the compass needle, cover glass, and wind vane are missing.

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

Diptych sundial for latitude 47 degrees | Science Museum Group Collection

Reviewed 2026-10-21 · Record 79e78056dc

Terms in this record

Glossary explanations for terms named in this object’s record.