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The Encyclopedia of Horology

Tool · Italian horizontal dial

Horizontal Dial by Girolamo della Volpaia

Partially verified

This horizontal sundial, crafted from gilt brass, measures 125 x 110 mm and is signed by the Florentine instrument maker Girolamo della Volpaia. The instrument is dated 1576 and features a pin gnomon mounted on a flat, engraved brass plate. The plate consists of three straight edges and one decoratively shaped edge featuring a suspension hole. The dial is calibrated to track Italian hours from 10 to 23. Inscriptions designate the tropics and the equator, specifically marked as 'TROPICVS CANCRI', 'TROPICVS CAPRICORNI', and 'AEQVINOCTIALIS LINEAE', accompanied by astrological symbols for Cancer, Capricorn, Libra, and Aries. A small compass is integrated into the plate, surrounded by a 32-point wind rose.

The horizontal dial by Girolamo della Volpaia, 1576, featuring the pin gnomon, hour lines, and integrated compass.
The horizontal dial by Girolamo della Volpaia, 1576, featuring the pin gnomon, hour lines, and integrated compass. — British Museum, London. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.mhs.ox.ac.uk
Category
Tool · Italian horizontal dial
Maker / attribution
Girolamo della Volpaia
Reference
Not recorded
Catalogue / lot identifier
MLA 1894, 12-11.2
Source-reported date
1576
Source-reported place
Italy

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

Dial Plate Construction

The horizontal dial is constructed from a gilt brass plate. It features three straight edges, while the fourth edge is designed with an irregular, decorative profile incorporating a suspension hole. The plate surface serves as the medium for all timekeeping calculations and navigational markings.

The engraving includes specific lines for the Tropic of Cancer, Tropic of Capricorn, and the equator, labeled in Latin. Symbols representing the zodiac signs of Cancer, Capricorn, Libra, and Aries are positioned alongside these lines, providing astronomical reference points for the user.

Evidence for this section
  • “This horizontal dial is engraved on a brass plate with three straight edges and the fourth of irregular, decorative shape, where a suspension hole is pierced.”
  • “the tropics and equator are inscribed 'TROPICVS CANCRI', 'TROPICVS CAPRICORNI', and 'AEQVINOCTIALIS LINEAE'.”

Signatures and Inscriptions

The dial bears the formal signature of Girolamo della Volpaia at the top of the plate. The text is presented in Latin characters, attributing the work to the Florentine maker and providing the date of manufacture. Additional textual information is contained within a scrollwork design.

The scrollwork includes specific details regarding the latitude for which the instrument was calibrated. The presence of these marks establishes the association with Rome and confirms the specific technical parameters of the instrument's design as intended by the maker.

Evidence for this section
  • “On the top of the plate is the signature 'HYERONIMVS VVLPARIAE FLORENTINVS ? FA ? A ? D ? M ? D ? LXXVI'”
  • “in scrollwork 'T[expunged]ADLATITVDINEM GRADVVM XXXXII ADDVS ROME'”

Navigation and Orientation

A small compass is mounted directly onto the surface of the brass plate below the dial face. This component is designed to aid in the orientation of the instrument, allowing the user to align the dial correctly for accurate timekeeping.

The compass is situated within a surrounding wind rose featuring 32 distinct directions. Eight of these directions are marked with the initials of wind names in Italian, providing further assistance for navigation and geographical orientation during the use of the dial.

Evidence for this section
  • “Below the dial is a small compass mounted above the dial surface, marked for magnetic deviation and with cardinal points.”
  • “It is surrounded on the plate by a wind rose with 32 directions”

Open research questions

  • What is the significance of the expunged letter in the scrollwork inscription regarding the latitude setting?
  • How does the specific layout of the wind rose initials correspond to 16th-century Italian cartographic traditions?

Source evidence

Recorded claims and source quotations for Horizontal Dial by Girolamo della Volpaia
FieldSource-reported valueSource quotation
MakerGirolamo della Volpaia“Signed by Girolamo della Volpaia”
Date1576“Dated 1576”
Dimensions125 x 110 mm“125 x 110 mm”
MaterialsGilt brass“Gilt brass”
Inventory NumberMLA 1894, 12-11.2“Registration no. MLA 1894, 12-11.2”
OriginFlorence“Florence”
Dial markingsItalian hours from 10 to 23“indicates Italian hours from 10 to 23”

Visible details

  • Small compass mounted on the dial plate
  • Gilt brass surface with hand-engraved inscriptions
  • Irregular decorative edge with suspension hole
  • Wind rose with 32 directions

Research qualifications

  • The exact function of the suspension hole in relation to its primary use as a horizontal dial is not detailed
  • The specific nature of the magnetic deviation calibration on the compass is not documented

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

Consulted source

Horizontal Dial

Reviewed 2026-10-26 · Record b8b937515b

Terms in this record

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

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