Accession No
4552
Brief Description
astrological astrolabe, possibly Germanic, early 16th Century
Origin
Maker
Class
astronomy
Earliest Date
1500
Latest Date
1550
Inscription Date
Material
metal (copper, gold)
Dimensions
169mm height with the ring held vertical, 144mm height to the top of the throne, 124mm width/diameter, 12mm depth
Special Collection
Provenance
Purchased by Philips Trevor & Son Ltd., London, on 12/07/1996. Acquired with assistance from MGC/Science Museum Prism Grant Fund.
Inscription
Description Notes
Astrological astrolabe, possibly Germanic, early 16th century.
A single cast copper plate, gilded, with integral throne. A brass wire ring and shackle pierce the throne. The front is engraved with an outer ring of 24 hours (twice 12) and a concentric ring of 360 degrees, divided to one degree. Within are lines giving the unequal planetary hours and the astrological Houses. The centre is marked 48 for the latitude. Rotating over the front is an ecliptic circle, divided and labelled for the twelve Zodiac signs, and in degrees to two degrees. Over the ecliptic rotates a rule, unmarked. The rotating parts re secured by a split pin. The back is engraved with an outer ring of degrees, 0-90-0-90-0, divided to one degree; a Zodiac ring, labelled with the signs and in degrees; a calendar scale, marked in days of the month. In the centre is a shadow square, and above it two quadrants for time-telling; planetary and equal hours. Over this rotates the alidade, with sights at either end, each pierced twice. One arm is engraved with a declination scale of Zodiac signs for use with the equal hour quadrant.
Gilt shows wear, particularly on the front, and there is some pitting.
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 on to 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:
A single plate astrological astrolabe, made of gilded copper, and with a projection for 48° latitude (place***). The rete has no star pointers.
On the reverse are a planetary quadrant and an equal-hours quadrant.
FM:39501
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