- Museum number
This gilt brass quadrant has two long pivoted arms, one fixed and the other movable.
The OBVERSE is laid out as an HORARY QUADRANT labelled 'Horae Ante' / 'Post Meridiem' with hour lines 6 to 12 to 6. Further to the outside is a non-linear declination scale 0 to 90, labelled 'Declinatio Arc diurni et Nocturni Horarum 14 et Horarum 10'. Adjacent to this scale is a scale of solar declination labelled 'Zodiacus' extending over 23½°, marked with the symbols of the zodiacal signs, each pair with a degree scale 0 to 30. Along the arc is a transversal degree scale 0 to 90. Between this scale and the declination scale are inscribed the signature of the maker and date of production.
This side of the instrument is used for laying out sundials for a particular latitude. The latitudes are indicated on the 0 to 90 degree scale on the movable arm. The arm is moved over the horary quadrant, and where the appropriate latitude intersects with a particular hour line the corresponding angles can be read off on the transversal scale.
Both ARMS bear degree scales 0 to 90 closer to the centre and scales 0 to 60 further to the tips. The latter correspond to the transversal scale on the quadrant. The zodiacal scale indicates the solar declination as a function of the solar longitude.
The fixed arm has one hole, the movable arm has two holes close to the tips. It is likely that these holes were for sights or an arc with a fixing mechanism to keep the movable arm at a particular place.
The REVERSE of the quadrant is laid out as an horary quadrant with markings for morning and afternoon hours 6 to 12 to 6, labelled 'Horae Post' / 'Ante Meridiem'. Inside this quadrant is one quarter of a Rojas projection with hour lines 12 to 24 marked twice across the quadrant and once along the horizontal edge.
Along the arc is a degree scale 0 to 90, identical to the non-linear degree scales 0 to 90 on the arms. Between this scale and the horary quadrant markings is a scale of solar declination labelled 'Zodiacus' and extending over 23½°, marked with the symbols of the zodiacal signs, each pair with a degree scale 0 to 30.
The instrument is decorated overall with a geometrical pattern.
- Production date
Length: 298 millimetres (length of longer arm from center)
Length: 157 millimetres (length of shorter arm from center)
Length: 456 millimetres (overall length)
Length: 137 millimetres (radius)
Thickness: 5 millimetres
- Curator's comments
- The obverse of this unusual and very sophisticated instrument by one of the most renowned makers of the late 16th century bears markings which allow the construction of a horizontal sundial for any latitude, without calculation.
The reverse can be used to determine the maximum length of daylight for any latitude, at any time of year.
- Not on display
- Exhibition history
2016-2017 7 Oct-9 Jan, Berlin, Martin-Gropius-Bau, The British View: Germany – Memories of a Nation
G35 Germany Exhibition 16 Oct 2014 - 25 Jan 2015
1997-2007: ‘A Glimpse of a Universe-Scientific Instruments from Renaissance Germany’ (British Museum, Gallery 44)
Latest: 2 (Mar 2017)
3 (Jan 1996)
- Acquisition date
- Britain, Europe and Prehistory
- Registration number