417 of 520
Sorted by:
Instrument type

Attributed to Giovanni Battista Giusti
Dated 1556; Italian
Ebony; 167 mm in radius

The face of the quadrant is divided on the limb with a scale of 90? reading to 1? by numbered groups of five. Above this, the left and centre of the instrument are filled with the diagram for an Italian hours dial (9 to 24 without subdivisions) for 43? 45', the morning hours being indicated by silver lines, the afternoon hours by gold lines. On each side of the diagram the two halves of a zodiacal calendar are marked, and the meridian line is also named to the right of the diagram. The remaining space at the right of the instrument carries the inscription 'QVADRANS HORARVM AD LAT{ITUDINEM} GRA{DUUM} XLIII. MIN{UTA} XLV'. Above the hour diagram is a shadow square of twelve divided to single units and numbered in three groups of four. To the left of the shadow square is the inscription 'LINE? ARGENTEA AN/TE MERID AUR POST' ('Silver lines morning, gold afternoon'). At the apex/centre of the instrument is a silver attachment ring for the thread cursor rotatable around a male head executed in relief against a ring of sun rays.

The reverse of the instrument is entirely filled with a circular diagram of nine rings containing, reading from the outer circle towards the centre, the number of the solar cycle for twenty eight years, the dominical letter, the leap year letter from 1556, the golden number, the epact, a zodiacal calendar with the date of the sun's entry into each sign (reading across three rings), and the date of the Roman indication(?). The centre of the circle is filled by the date repeated in Roman numerals, and the two lower corners of the instrument are filled with symmetrical scrolled foliate decoration painted in gold. Two sighting blocks with scrolled backs are set on the longer side of the instrument, the back sight with pinnule, the fore sign with level line. Between the two sights is the inscription 'COSIMO M.R.P. FLO. DVC. II' which may perhaps be expanded in translation as 'Cosimo Medici, [IInd] Duke of the State of Florence'.

In the 1954 Catalogo, authorship of this instrument was tentatively ascribed to Gian Baptista Giusti ('Questo strumento sembra di fabbrica del Giusti'). Although there are general resemblances between the lettering of this instrument and that of signed examples of Giusti's work, the difference of the materials, wood and brass, between this instrument and comparable pieces by Giusti, and the different size of the punches used, make certainty in such an ascription difficult . Where punches of the same size have been used however none of the individually characteristic Giusti punches such as the 'S' with exaggerated diagonal but not parallel serifs to the right, the 'F' with heavy diagonal serifs to the upper right, or the broad, sometimes composite 'N', appear on the Cosimo quadrant which in general has the lettering rather more carefully spaced and executed (some remains of guide lines can be seen), than is normal on Giusti's work. A number of other differences such as use of the unusual division of the shadow square into three numbered groups 4, 8, 12 rather than 3, 6, 9, 12 and the spelling 'HORARVM' rather than the form 'HORARIVM' found on other quadrants by Giusti, argue against ascription of this instrument to him.

Provenance: Cosimo I, second Duke of Florence as inscribed on the instrument who was later to become Ist Grand-Duke of Tuscany. This ownership inscription, which is certainly contemporary with the other inscriptions on the instrument, is confirmed by the entry in the inventory of Cosimo and Francesca Medici's goods in 1574 (Arch. Di Stato di Firenze Guard. Med. M. 87, f9r) 'Quadrante uno debano in sua busta di cuoio nero e dentro scritto per lettere 1556' although the case referred to has since disappeared.

Anthony J. Turner

Istituto e Museo di Storia della Scienza, Firenze
Inventory no. 2521

© Istituto e Museo di Storia della Scienza, Firenze. All rights reserved. Information and images provided here may not be reproduced in any form or by any means without the prior written permission of the museum.

Basic URL:

|| Introduction || Essay || Museums || Bibliography || Conventions || Credits || Privacy || Help ||
|Catalogue entries |Handlist || Makers || Places || Articles || Glossary || Search || Home ||