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The Encyclopedia of Horology

Tool · Italian quadrant

Horary Quadrant by Girolamo della Volpaia

Partially verified

This brass horary quadrant, measuring 310 mm in radius, was produced by Girolamo della Volpaia in Florence in 1570. The instrument features a limb calibrated to 90 degrees, an Italian hours dial showing hours 9 to 24, a zodiacal calendar, and a shadow square incorporating a circular 'Tabula Solis motus'. On the back, an iron mounting system with a plate, screw, and wing nut allows for inclination, though this appears to be a later addition as it obscures parts of the engraved face. Two scrolled block sights are fixed along the edge for topographical operations. The piece serves as both a timekeeping and a measuring instrument, reflective of the work produced by the Della Volpaia family of instrument makers active during the 16th century.

The face of the brass horary quadrant by Girolamo della Volpaia, dated 1570.
The face of the brass horary quadrant by Girolamo della Volpaia, dated 1570. — Istituto e Museo di Storia della Scienza, Firenze. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.mhs.ox.ac.uk
Category
Tool · Italian quadrant
Maker / attribution
Girolamo della Volpaia
Reference
Not recorded
Catalogue / lot identifier
239
Source-reported date
1570
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

Face and Engraving

The face of the quadrant is constructed of brass and features a complex array of calibrated scales and diagrams. The outer limb is marked with a 90-degree scale, subdivided to 2 degrees. Adjacent to this are the halves of a zodiacal calendar, providing readings to 5 days and degrees. The primary functional area consists of an Italian hours dial for hours 9 through 24, distinguishing morning and afternoon hours through line styles.

Integrated into the design are a shadow square and a 'Tabula Solis motus'. The shadow square is numbered in groups of three up to twelve, with each section subdivided into fifteen. An inscription in Latin denotes the latitude for which the device is calibrated, specifically 43 degrees. This inscription wraps around the design and concludes with the signature of the artisan and the date of manufacture.

Evidence for this section
  • “The limb of the instrument carries a scale of 90? numbered by groups of five in a separate scale and subdivided to 2?' in a third.”
  • “Above this the left and centre of the instrument is filled with the diagram for an Italian hours dial”
  • “Within the shadow square is a circular table labelled 'TABVLA SOLIS MOTVS'”

Mounting and Mechanical Additions

To the reverse side of the brass quadrant is attached an iron mounting system. This component consists of a plate riveted to the main body, featuring a screw and wing nut mechanism that supports a semi-circular piece. A spiked adjustment allows the instrument to be pivoted through a 90-degree range, providing various inclinations as required for its operation.

Physical evidence suggests that this iron mounting was not part of the original design. The rivets used to secure the assembly to the back penetrate through to the front, breaking the existing engraving.

Evidence for this section
  • “To the back of the instrument an iron mounting is attached consisting of a plate riveted to the quadrant carrying, by a screw and a wing nut, a semi-circular support.”
  • “Since the rivets attaching the mounting assembly break the engraving on the face of the quadrant, the whole would appear to have been added after the quadrant itself had been completed.”

Origins and Signatures

The quadrant is signed by Girolamo della Volpaia, a maker of instruments identified as the son of Camillo della Volpaia. The family was noted for their output of measuring instruments in 16th-century Florence. The instrument itself is specifically calibrated for the geographic conditions of Central Italy, covering regions such as Tuscany, Umbria, and upper Lazio, which confirms its localized utility for 1570.

The piece is held in the collection of the Istituto e Museo di Storia della Scienza in Florence. The signature is placed directly on the face of the instrument, following the Latin inscription defining its topographical and chronometric capabilities. The object is officially catalogued under inventory number 239.

Evidence for this section
  • “It bears the signature of the artisan Girolamo della Volpaia , the son of Camillo”
  • “The instrument is calibrated for a latitude of 43?, corresponding to the band of Central Italy included, roughly, between Tuscany, Umbria and upper Lazio.”

Open research questions

  • What specific topographical measurements were intended for the shadow square on this quadrant?
  • Can the provenance of the iron mounting be further identified to a particular repair or modification period?

Source evidence

Recorded claims and source quotations for Horary Quadrant by Girolamo della Volpaia
FieldSource-reported valueSource quotation
MakerGirolamo della Volpaia“Signed by Girolamo della Volpaia”
Date1570“Dated 1570”
Radius310 mm“310 mm in radius”
Inventory Number239“Inventory number: 239”
Latitude Calibration43 degrees“The instrument is calibrated for a latitude of 43?”
InscriptionLatin text describing the function and latitude“LINEAE PERPETVAE ANTE MERIDIANAS HORAS INTERPVNGTAE VERO POMERIDIANAS INDICANT AD ALTITVDINIEM POLI GRADVVM XXXXIII”

Visible details

  • Features two scrolled block sights along the long edge.
  • Includes a circular Tabula Solis motus within a shadow square.
  • Morning hours are engraved as smooth lines and afternoon hours as dotted lines.
  • Iron mounting hardware on the reverse obscures parts of the face engraving.

Research qualifications

  • The provenance of the iron mounting assembly suggests it is a later addition.
  • The exact nature of the topographical operations supported by the shadow square is not specified beyond its presence.

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

Consulted source

Quadrant

Reviewed 2026-10-26 · Record 6097e7178c

Terms in this record

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

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