|Date||late 9th century|
|Maker||Khafīf, apprentice of ‘Alī ibn ‘Īsā|
|Acquisition||Presented by J. A. Billmeir in 1957|
The names are known of several of 'Alī ibn 'Īsā's apprentices and in turn of their apprentices, providing an approximate date for this astrolabe and establishing him as one of the pioneers of the craft of astrolabe making in the early centuries of Islam. He was living in the middle of the 9th century in the region approximating to modern Syria.
This astrolabe by his apprentice Khafīf is the oldest in the collection. It has the dagger-shaped star pointers typical of the earliest style of surviving astrolabes. Its plates cover latitudes 33° to 41°, appropriate to the region of Syria and (to the north) Armenia.
Like another early specimen in the collection (inventory number 48470), the astrolabe has early additions in Armenian. The shadow square has Armenian numbers and an inscription for 'shadow' on the diagonal, and there are latitude indications in Armenian on two of the three plates.
MaterThe mater and limb are of one-piece construction. The tab used to hold tympans in place is located at the bottom of the instrument, 180° from the throne.. Scales on the limb: degree scale. More information
BackThe back contains 4 scales of the following types: Altitude; Cotangent; Shadow square; Dastūr Circle. More information
Rete, Pin & WedgeThe rete contains 17 stars. The zodiac on the rete is labelled: الحمل , الثور , الجوزا , السرطان , الاسد , السنبله , الميزان , العقرب , القوس , الجدي , الدلو , السمكه .
The rete is attached using a pin & wedge. The head of the pin is decorated with radial lines.. More information
PlatesThere are 3 plates with latitudes ranging from 33°0' to 41°0' . More information
Rules & Alidades
|Pointer||Single-ended. The front is engraved with a decorative
|Alidade||Double-ended, counter-changed. The front is engraved
with the same decorative pattern found on the