- Museum number
This brass astrolabe is one of four instruments by the famous Nuremberg maker Georg Hartmann in the British Museum.
The RIM of the MATER is marked clockwise with the Latin names of the 12 winds as follows: 'AVSTER', 'LIBONOTVS', 'APHRICVS', 'FAVONIVS', 'CHORVS', 'CIRCIVS', 'SEPTENTRIO', 'AQVILO', 'CECIAS', 'SVBSOLANVS', 'VVLTVRNVS', 'EVROAVSTER'. Inside this are markings for the equal hours in Roman numerals, twice I to XII. Further inside is an altitude scale 90° to 0°, 0° to 90°, 90° to 0°, 0° to 90°.
The back plate and the throne appear to be brazed to the rim.
The THRONE has the characteristic Hartmann shape: two roses, a rosette, and two fir cones in a triangular layout supported by foliate scrolls.
The inside of the MATER is marked with circles for the tropics and the equator as well as east-west and meridian lines. There is a small '9' punched at the bottom of the meridian line.
The RETE is in the usual Hartmann shape which consists mainly of arcs of circles and split ends of the circle for the tropic of Capricorn. It has 27 pierced star pointers; the following stars are named: 'CAVDA CETI', 'ANDROMEDA', 'VENTER CETI', 'GORGO', 'NARIS CETI', 'OCVLVS [symbol of Taurus]', 'CAPRA', 'SI PES ORIONIS', 'CANIS MAIOR', 'PROCION', 'HIDRA', 'COR LEONIS', 'PATERA', 'CAVDA LEONIS', 'CORVVS', 'VRSA', 'SPICA VIRGINIS', 'ARCTVR', 'CORONA', 'YED', 'CAPVT SERPEN', 'LIRA', 'AQVILA', 'DELPHIN', 'HOLOR', 'HVME EQVI', 'PEGASVS'.
The ecliptic is marked with the usual Latin names of the zodiacal signs and is divided into 12 x 30°. The equinoctial bar is counterchanged six times: on both sides of the ecliptic, between the ecliptic and the tropic of Capricorn and between the ecliptic and the central disc.
The reverse of the rete is marked with 'IX' and '9' (both upside down) at the intersection of the tropic of Capricorn and the solstitial bar. The Arabic number is also to be found at the bottom of the plates and on the mater at the bottom opposite the throne.
The three PLATES are marked on both sides with circles for the tropics (marked 'CANCER' and 'CAPRICORNVS' and the equator (marked 'EQVATOR'); azimuths labelled every 10° and almucantars every 2°. They further bear markings for the unequal hours, numbered in Arabic clockwise 1 to 12, and the astrological houses in the manner of Regiomontanus, numbered in Roman numerals anticlockwise I to XII (additive form for 4, i.e., IIII). The numeral for the first hour line is on all plates mistakenly placed underneath the horizon curve; the correct first hour curve is mistakenly stamped as '2' and then overstamped with '1'. Each plate is marked on one side with a '9' and one (1a), two (2a), or three (3a) dots respectively according to the increasing latitudes. The plates are laid out and marked for the following latitudes ('LATITV', 'GRA'): 1a) XXXIX; 1b) XLII (the first four lines for the houses not numbered); 2a) XLV; 2b) XLVIII; 3a) LI; 3b) LIIII. The latitude is repeated in Arabic numerals on the small tongues which locate the plates in the mater.
The BACK bears the following scales (from the outside): 1) a circular altitude scale 90° to 0°, 0° to 90°, 90° to 0°, 0° to 90°; 2) a single degree scale with a regular division of the zodiacal signs 12 x 30° anticlockwise starting with Aries at the equinoctial line, numbered in Roman numerals by 5 and with the usual Latin names of the zodiacal signs; further inside is 3) a calendrical scale, marked with the usual Latin names of the months divided to the corresponding number of days, with the equinoxes at March 10½ and September 14.
The upper part of the space inside these circles is taken up by two hour quadrants with the hour lines numbered 1 to 12.
The vacant space bears a double-headed eagle displayed with hats instead of the usual crowns and without the heart-shaped shield which would make it the Imperial Eagle. The lower part consists of two shadow scales to the base 12, each marked 'VMBRA RECTA' and 'VMBRA VERSA'. Below the shadow scales are the maker's signature and the date. The vacant space inside the shadow scales is taken up by the arms of Nuremberg: a crowned harpy on the left side and a double-headed eagle couped palewise and three bends on the right side.
The counterchanged ALIDADE does not have any sighting vanes, although one arm appears to have rivets for fixing a vane.
The axis of the astrolabe consists of a rivet with a threaded nut pierced with two holes to be turned with a double pointed key.
- Production date
- 1537 (dated)
Diameter: 160 millimetres
Thickness: 6 millimetres
- Curator's comments
- The labelling of the different components with the same letter or number ('9' in this case) suggests that Hartmann had quite an extensive astrolabe production. The incorrect of the first unequal hour curve appears to be a common feature of Hartmann astrolabes dated 1537.
- Not on display
- Exhibition history
1997-2007: ‘A Glimpse of a Universe-Scientific Instruments from Renaissance Germany’ (British Museum, Gallery 44)
- Latest: 2 (Mar 2017)
- Acquisition date
- Britain, Europe and Prehistory
- Registration number