Horary Quadrant by Giovanni Battista Giusti
Record status
Individual type · partial
Period
1565
This brass horary quadrant, measuring 203 mm in radius, was produced by Giovanni Battista Giusti in 1565. The instrument is a specialized tool used for measuring height and time, specifically calibrated for the latitude of Florence at 43° 40'.
The face features a complex layout including a 90-degree scale on the limb, a diagram for Italian hours, and a zodiacal calendar. It also incorporates a shadow square for topographical measurements and a circular solar table ('Tabula Solis') used to determine the entrance of the sun into zodiac signs. The instrument is signed by Giusti, who worked as an instrument maker in Florence during the 1560s, a period during which he was associated with the Medici metal workshop.
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
- 1565
- Type
- Italian quadrant
- Maker
- Giovanni Battista Giusti
- Latitude
- 43° 40'
- Material
- Brass
- Inscription
- QVADRANS HORARIVM AD LATITVDINEM GRADVVM XLIII XL MINVTORV{M)} LINEA PVMTOR{UM} POS{T} MERIDIES
- Place recorded
- Italy
- Maker / attribution
- Giovanni Battista Giusti
Design
- Visible features
- • The instrument features a 90-degree limb divided into two concentric arcs. • The front bears an engraved diagram for Italian hours from 9 to 23. • Two moulded sights with a fore pinnule are attached to the straight side. • A lead plug occupies the centre of the wind rose on the back.
- Historical Attribution
- The instrument is dated 1565 and bears the signature of Giovanni Battista Giusti. Giusti was active as an instrument maker in Florence during the 1560s. Research suggests he operated within the context of the Medici metal workshop, though this connection is cited as probable. The quadrant was specifically calibrated for the latitude of 43° 40', which corresponds to the location of Florence. The text on the face explicitly identifies the instrument as a horary quadrant for this specific latitude.
- Front Face Configuration
- The front face of the quadrant is densely engraved with multiple scales and diagrams for timekeeping and solar observation. The limb is divided into two concentric arcs; the outer arc contains unnumbered single degrees with dotted half-degree sub-divisions, while the inner arc provides numeric groupings of five. A third arc is positioned between these, marking the relative positions of the tropics and the equator. The central portion of the face contains a diagram for an Italian hours dial, scaled from 9 to 23. Morning hours are indicated by solid lines, while afternoon hours are depicted with dotted lines. Above this diagram, a shadow square of 12 surrounds a circular solar table, which provides the Italian hour of Noon for each month alongside its respective zodiacal sign.
- Reverse and Technical Features
- The reverse of the quadrant is engraved with an eight-point wind rose. The sectors are divided to 45 degrees, with numerical groupings of 5 degrees. The wind directions are named in the local tradition, including Ostro, Tramontano, and others. The center of the wind rose contains a lead plug, though there is speculation that a compass was intended for or originally occupied this space. For functionality as a surveying and measurement instrument, the side features two shaped, moulded sights with a fore pinnule. These components allow for the alignment of the quadrant to determine heights or topographical measurements using the shadow square engraved on the front.
Identification
- Inventory number
- 2524
- 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: The purpose of the lead plug at the center of the reverse wind rose is uncertain, as it may have replaced or originally been intended for a compass.
- Research required: The maker's association with the Medici metal workshop is described as probable rather than confirmed.