Universal Quadrant by Tobias Volckmer

Technical characteristics

Date

1608

Type

Quadrant

Maker

Tobias Volckmer

Material

Gilt brass

Dimensions

360 x 360 mm

Place recorded

Germany

Compass diameter

65 mm

Signature detail

Auctorae Tobia Volckmero Brunsvicensi

Maker / attribution

Tobias Volckmer

Latitude calibration

48 degrees

Design

Visible features

• Removable compass with wind rose and sundial cover • Two independent alidades with sliding pointers • Gilt brass construction with elaborate floral engraving • Small removable feet for vertical positioning

Construction and Design

The instrument is a square-shaped, gilt brass device designed for universal application in mathematical, astronomical, and military tasks. It stands on small, removable feet that facilitate a vertical operating position. The primary surface is heavily engraved with various scales, including linear scales divided into twelve parts and a complex system of nonius circles intersected by oblique lines to ensure precision. The overall dimensions are 360 x 360 mm, with decorative engraving occupying the corners of the quadrant. A prominent feature is the 65 mm diameter removable compass, which includes a wind rose divided into 360 degrees and 24 hours. The compass cover functions as an independent sundial with a folding gnomon and features a lunar nocturnal dial on the underside. Two pivoted alidades with removable sights and sliding pointers extend from the upper right corner to facilitate precise angular measurement. The grid structure on the main face allows for the measurement of trigonometric functions by intersecting horizontal and vertical lines with the circumference of the quadrant. The bounding radii of the grid are divided into 90 equal parts, which are further grouped into units of five for readability.

Functional Capabilities

The quadrant serves as a multi-functional tool capable of planetary and chronological calculations. Face b of the instrument presents an altimetric scale with markings for Umbra recta, Umbra versa, and Umbra media. Additionally, it contains two separate horary quadrants of the Stoffler type: one for unequal or planetary hours, and the other for equal or common hours. These scales are delimited by zodiacal signs and equinoctial lines, reflecting both horary use and astrological influences. The device also includes a 'scala iaciendi' and a 'calendarium et locus solis' for tracking seasonal changes and the solar position. For astronomical work, a plumb-line is integrated with the graduated alidade, which features two sliding pointers. This combination allows the user to calculate the influence of planets on zodiacal signs and define seasonal progressions with high accuracy, further enhanced by the nonius divisions of 10' on the angular scale.

Provenance and Signature

The maker's signature is located on the sides of the pivot supporting the alidade. The inscription identifies Tobias Volckmer of Brunswick, goldsmith to the House of Saxony, and confirms the date of production as 1608. The instrument is part of the collection held at the Istituto e Museo di Storia della Scienza in Florence, bearing inventory numbers 2465 and 1495. Historical records indicate that the instrument was transported from Germany to Italy by Prince Mattias de' Medici in 1635. The instrument is documented as being part of a larger set that originally included a Jacob's staff and a tripod, although the primary focus here is the quadrant itself.

Identification

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.