Dialling Quadrant by Erasmus Habermel
Record status
Individual type · partial
Period
1592
This 1592 dialling quadrant was manufactured in Prague by Erasmus Habermel and is composed of gilt brass with a diameter of 138 mm. It functions as a complex mathematical tool for calculating sundial construction and daylight duration.
The instrument features two pivoted arms—one fixed and one movable—mounted to a quadrant plate. The obverse side contains scales for horary lines, solar declination, and transversal degree markings to facilitate the calculation of horizontal sundials for varying latitudes. The reverse displays horary scales alongside a Rojas projection, which assists in determining maximum daylight duration throughout the year. The surface is decorated with a geometrical pattern.
The piece is currently held in the British Museum collection, having been presented by A.W. Franks in 1867, and is documented in scholarly catalogues regarding European scientific instruments.
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
- 1592
- Type
- Central European dialling quadrant
- Maker
- Erasmus Habermel
- Diameter
- 138 mm
- Location
- Prague
- Material
- Gilt brass
- Literature
- F. A. B. Ward, A Catalogue of European Scientific Instruments in the Department of Medieval and Later Antiquities of the British Museum (London, 1981), p. 94, no. 273
- Place recorded
- Prague
- Maker / attribution
- Erasmus Habermel
Design
- Visible features
- • Quadrant plate features a transversal degree scale 0 to 90 • Surface displays engraved zodiacal scales and hour line markings • Overall construction is of gilt brass with a diameter of 138 mm
- Reverse Functionality
- The reverse of the instrument is designed to determine the maximum daylight duration for any location and time of year. It features a similar horary quadrant layout but includes one quarter of a Rojas projection. This projection contains hour lines numbered 12 to 24, which are marked twice across the quadrant and once along the horizontal edge, with alternating shading for half-hour and quarter-hour divisions. Operational use involves setting the movable arm against the zodiacal scale to account for the time of year. By identifying the intersection of the correct latitude on the arm with the hour curves, the duration of daylight is indicated. The arms on this side also possess identical non-linear degree scales for precision adjustments.
- Provenance and Identification
- The instrument is signed by Erasmus Habermel and dated 1592. The piece is part of the collection at the British Museum, identified by the registration number MLA 1867,7-5.25. It entered the collection as a gift from A.W. Franks in 1867. The quadrant has been formally catalogued in scholarly research regarding the history of scientific instruments. Specifically, it appears in the 1981 catalogue compiled by F. A. B. Ward, which documents the collection of European scientific instruments held within the Department of Medieval and Later Antiquities.
- Design and Obverse Functionality
- The obverse of the quadrant is engineered to aid in the creation of horizontal sundials for any given latitude without the need for manual calculation. The surface is engraved with a series of scales including an horary quadrant marked with hour lines ranging from 6 to 12 to 6, subdivided into quarter-hour increments. A declination arc and a zodiacal scale are integrated into the design, the latter extending over 23.5 degrees and marked with zodiacal symbols. The two pivoted arms attached to the quadrant plate play a critical role in its operation. By moving the arm over the horary quadrant and aligning the appropriate latitude with a specific hour line, the user can determine angles using the transversal scale. The 0 to 60 scale on the arms corresponds directly to the transversal scale on the instrument plate.
Identification
- Inventory number
- MLA 1867,7-5.25
- 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 exact function of the holes on the arms remains speculative, possibly for sights or an arc fixing mechanism
- Research required: The specific purpose of the geometrical surface decoration is not detailed in the source