Astrolabe Catalogue

 

Small image of astrolabe back with rules or alidades removed. Click to enlarge.
Date 1081/2
Maker Muḥammad ibn Sa‘īd as-Ṣabbān
Place Guadalajara
Material Brass
Inventory no. 52473
Acquisition Presented by J. A. Billmeir in 1957

Back



The back contains 7 scales of the following types:
Type
(click to view scale details)
Range & Units Numbered Geometry Location
Degree 0 - 90, Degrees of arc Every 5 degrees Circular, concentric outermost scale on the front of the limb
Lunar Mansions 0° Aries - 30° Pisces, Lunar mansion Not numbered  Circular, concentric Circular scale immediately inside the outer scale - refers to the full circle
Zodiacal signs 0 - 30, Zodiacal divisions, equal or unequal Every 5  Circular, concentric Circular scale second in from the outer scale - refers to the full circle.
Calendar Days of year Every 5 days days Circular, concentric Circular scale third in from the outer scale - refers to the full circle.
Perpetual calendar None   Circular, concentric Upper left quadrant (inside circular scales)
Perpetual calendar None   Circular, concentric Upper right quadrant (inside circular scales)
Perpetual calendar None   Circular, concentric Lower left quadrant
Shadow square 1 - 12, Fingers Every 2 fingers Box Right hand bottom face of the shadow square (in LR)
Shadow square 1 - 12, Fingers Every 2 fingers Box Right hand vertical face of the shadow square (in LR)
The back is inscribed:
Transcription Translation Notes Type
مما أحكم صنعته محمد بن سعيد الصبان في مدينة الفرج حرسها الله في سنة تعد الهجرية Among the objects skilfully made by Muḥammad ibn Saʿīd as-Ṣabbān in Guadalajara (Madīnat al-Faraj) in A.H. 474. Maker's signature
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