Accession No
1761
Brief Description
Brass planispheric astrolabe, Persian, after Ali ibn Sadiq, 18th or 19th century, a possible forgery / fake
Origin
Persia (Islamic) [Iran?]
Maker
[copy of] Ali ibn Sadiq
Class
astronomy
Earliest Date
1700
Latest Date
1900
Inscription Date
Material
metal (brass)
Dimensions
diameter 91 mm
Special Collection
Holden-White collection
Provenance
On loan from The Fitzwilliam Museum, University of Cambridge.
Inscription
[signature appears to be a poor copy of that of the noted maker Ali ibn Sadiq, suggesting that this instrument is an imitation or later copy by a less skilled hand. It appears to read as:]
Ali bin Sa q u mi
Description Notes
Brass planispheric astrolabe. 3 plates. Rete for 26 named stars. On reverse, sinical quadrant, horary quadrant, shadow square, alidade.
This instrument matches fairly well the work of Ali ibn Sadiq (aka Alî ibn Sâdiq Qummî or Hâjjî 'Alî). However, inspection by Pouyan Rezvani on 21/03/2024 revealed that the signature is a poor imitation, and in general this instrument is of a lower quality than the roughly twenty known instruments by Ali ibn Sadiq, suggesting that it is a later copy of his work.
Condition fair ( some corrosion, one of the sights on the alidade is broken off, rim of one plate is incomplete and the rest is becoming detached, one plate has cracked along an engraved curve)
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:
The rete of this instrument has 26 named stars. There are 3 plates. On the reverse are a sinical quadrant, an horary quadrant, and a shadow square.
FM:39697
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