Accession No
1759
Brief Description
Islamic planispheric astrolabe of the 14th century, North African, by Husain b. Ali, 1309 / 1310
Origin
North Africa [attributed]; Moorish Islamic
Maker
Husain b. Ali
Class
astronomy
Earliest Date
1309
Latest Date
1310
Inscription Date
10
Material
metal (brass)
Dimensions
diameter 144 mm
Special Collection
Holden-White collection
Provenance
On loan from The Fitzwilliam Museum, University of Cambridge.
Inscription
Husain b. Ali
Description Notes
Islamic planispheric astrolabe of the 14th century, North African, by Husain b. Ali [Believed to be North African Moor], 1309 / 1310.
Brass planispheric astrolabe. 4 plates. Rete for 21 named stars. On reverse, shadow square, alidade. Dated on throne 709 AH = 1309/1310
Fair condition, some scratching.
Script on mater and plates match, and is typical of C14th script. Rete is likely a later replacement (its design follows C10th style, but the script is more typical of C17th or later. XRF suggests might be reasonably modern, C17th or C18th, maybe later.)
[NOTE: On 14/07/2015 XRF analysis was conducted on this instrument. Results and analysis are given in the ‘Notes’ field.]
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:
This astrolabe, the oldest in the Whipple collections, is thought to be North African in origin.
The rete shows 21 named stars. On the reverse is a shadow square.
FM:39704
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