Accession No
1263
Brief Description
planispheric astrolabe, with rete, six plates, alidade, rule and horse, Italian [attributed], late 15th Century, with some parts likely modern
Origin
Italy [attributed]
Maker
Class
astronomy
Earliest Date
1450
Latest Date
1500
Inscription Date
Material
metal (brass)
Dimensions
mater diameter 104 mm
Special Collection
Provenance
Inscription
DEPU. MONA. SAN. BENE. DE. PADO. MAN. DIO. (rim of mater)
Description Notes
Planispheric astrolabe of brass, with rete, six plates, alidade, rule and horse, [Italian, late 15th century, with some parts likely modern]. Object has been lacquered. Rete, alidade, rule, pin and horse are all likely modern (see results of XRF analysis).
Rete has eighteen star pointers, with sixteen labelled: AQUILA VOLAN, CAPUT HERCULI, CASIOPEI ALGOL, URSA MA within ecliptic ring; CAUDA CETI, MENKAR, ALDEBARAN, RIGIL, CANIS MAIOR, ALHABOR, COR LEONIS, ALA CORVI DEXTRA, SPICA, CAPUT ANDROMACE, COR SCORPII, CANIS MINOR outside ecliptic. The zodiac is marked on the ecliptic by the astrological symbols, with each sign divided down to 2 degrees, and labelled in tens. On the reverse are labelled zodiacal and calendar scales, divided to single degrees, and labelled in fives. PISSCIS, SAGITARIUS, CAPRICORNIUS are non-classical spellings. The 1st point of Aries falls on the 11th of March. Within the calendar scale are a shadow square (calibrated from 0 to 12 to 0 twice, labelled in twos) and a pair of unequal hour quadrants (calibrated 1 to 6).
Three latitude plates are inscribed on each side, and labelled for latitudes: 13 & 17, 28 & 31, 43 & 45. Three more are marked on one side only with incomplete almucantars and azimuthal lines, and are unlabelled.
[NOTE: On 06/12/2013 XRF analysis was conducted on this instrument. Results and analysis are given in the ‘Notes’ field and in the OHF.]
References
Events
Description
An astrolabe is a model of the heavens with the earth placed at the centre. A section of the heavens is projected onto the astrolabe. The co-ordinates of stars and planets are depicted on a grid called the rete. The earth is represented by latitude plates of which there are more than one. This is because the movement of the stars depends upon the latitude of the place from where the observation is made. Cambridge has a latitude of 52°, Rome 42°, Madrid 41°, and Paris 49°. Each latitude plate has circles and lines engraved on them which include the tropic of Cancer and Capricorn, the equator and a twilight line. The rete and latitude plates are housed within the mather which has a raised edge called the limb. On European astrolabes the limb is engraved with a degree scale showing 0° to 360° and / or a scale of 24 equal hours.
On the back of the astrolabe are engraved several scales including a calendar scale and a shadow square. On Islamic astrolabes extra scales and tables are engraved for finding the direction of Mecca (for times of prayer). At the back of the astrolabe is also the alidade (see diagram above). The alidade has sights through which an astronomer would take simple observations of the sun or of a particular star, to find the time of day or night. The sights can also be used for finding the heights of buildings, trees or hills.
From display label:
Probably made in Italy, this astrolabe is labelled on the rim of the mater with "DEPU. MONA. SAN. BENE. DE PADO. MAN. DIO", possibly indicating the maker and place of manufacture.
FM:39707
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