Stefano Buonsignori horary quadrant
Record status
Individual type · partial
Period
16th century
This 16th-century horary quadrant is constructed from lignum vitae and features a radius of 145 mm. It was crafted by the Olivetan friar and cosmographer Stefano Buonsignori.
The instrument serves multiple functions, including timekeeping, surveying, and astronomical calculation. Its face is calibrated for a latitude of 43° 30', corresponding to the city of Pisa, and displays an Italian hours dial marked with gold and white lines. The reverse side integrates a complex arrangement of a brass degree scale, a zodiacal calendar, and a lunar volvelle that tracks the phase, age, and zodiacal position of the moon.
Two block sights with pinnules are attached to the edge for altitude measurements. The instrument also contains an inset compass and is decorated with foliate patterns. It is currently held in the collection of the Istituto e Museo di Storia della Scienza in Florence.
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
- 16th century
- Type
- Italian quadrant
- Maker
- Stefano Buonsignori
- Latitude
- 43° 30'
- Material
- Lignum vitae
- Provenance
- Istituto e Museo di Storia della Scienza, Firenze
- Place recorded
- Florence
- Maker / attribution
- Stefano Buonsignori
Design
- Visible features
- • Inset magnetic compass on the reverse side • Two block sights with pinnules and scrolled backs • Surface decorated with flowing foliate patterns • Lunar volvelle with circular aperture
- Instrumental Face and Timekeeping
- The face of the quadrant is structured around a central Italian hours dial, calibrated specifically for a latitude of 43° 30'. The hours, ranging from 9 to 23, are indicated by distinct color-coded lines: gold lines for the morning hours and white lines for the afternoon. A zodiacal calendar is arranged on either side of this central diagram, positioned to align with specific calendar dates. Additionally, the face incorporates a shadow square divided into twelve units to assist in calculating heights and distances. The limb is graduated in a 90-degree scale, marked in groups of ten. Inscriptions on the face provide guidance for the user, clearly distinguishing between the morning and afternoon hour lines and specifying the latitude for which the quadrant is intended.
- Reverse and Astronomical Functions
- The reverse of the lignum vitae quadrant features an inset brass disc that functions as both a calendar and an astronomical calculator. It contains a degree scale covering four quadrants, surrounding a zodiacal calendar that is further subdivided by degree and date. A central lunar volvelle is mounted within this assembly. The volvelle provides information regarding the moon's age, its zodiacal sign, and its current phase, which is viewed through a circular aperture on the disc. The upper portion of the disc is engraved with an aspectarium, providing further astronomical data. This side of the instrument is also equipped with a magnetic compass and two block sights, which allow the user to perform traditional surveying tasks and solar altitude observations.
- Physical Construction and Provenance
- The quadrant measures 145 mm in radius and is fashioned from lignum vitae. Its maker, Stefano Buonsignori, was a known cosmographer to the court of Francesco I de' Medici and an Olivetan friar. The instrument exhibits decorative details, including symmetrically painted flowing foliate patterns on the reverse side, and recessed gold decoration on the sights. The object is part of the collection at the Istituto e Museo di Storia della Scienza in Florence, catalogued under inventory number 2499.
Identification
- Inventory number
- 2499
- 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: Latitude calibration is stated as 43° 30' for Pisa
- Research required: Primary material identified as lignum vitae