Astrolabe Catalogue

 

Small image of astrolabe back with rules or alidades removed. Click to enlarge.
Date 1350/1 (A.H. 751)
Place Persia (?)
Material Silver
Inventory no. 41106
Acquisition Purchased from Malcolm Gardner in 1955

Back


Many of the scales on the back of this instrument defy easy interpretation. Although they visually resemble scales typically found on the backs of Islamic astrolabes, the symbols used and their arrangement are unusual. The two inner-most scales in the lower half of the instrument remain a mystery.

The back contains 9 scales of the following types:
Type
(click to view scale details)		 Range & Units Numbered Geometry Location
Altitude 0 - 90, Degrees of arc Every 5 degrees Circular, concentric Upper right quadrant of outer circular on back of instrument.
Altitude 0 - 90, Degrees of arc Every 5 degrees Circular, concentric Upper left quadrant of outer circular on back of instrument.
Sine/Cosine 0 - 60, 1/60 of quadrant radius Not numberered  Angle Upper left quadrant (inside circular scales)
Shadow square None Not numberered  Box Upper right quadrant (inside circular scales)
Terms None Not numberered  Inner Box Upper right quadrant (inside circular scales)
Cotangent 0 - 45, None Every 5  Circular, concentric Lower left quadrant of outer circular on back of instrument.
Cotangent 0 - 30, None Every 5  Circular, concentric Lower right quadrant of outer circular on back of instrument.
Zodiacal signs Aries - Pisces, Zodiacal divisions, equal or unequal Not numberered  Inner Circular, concentric half circle inside the outer circle (on mashriqi astrolabes) - covering LL and LR
Faces 0° Aries - 30° Pisces, Astrological face Not numberered  Inner Circular, concentric half circle inside the V circle (on mashriqi astrolabes) - covering LL and LR
Lunar Mansions 0° Aries - 30° Pisces, Lunar mansion Not numberered  Inner Circular, concentric half circle inside the VI circle (on mashriqi astrolabes) - covering LL and LR
The back is inscribed:
Transcription Translation Notes Type
في سعد الهجري ذنل In good fortune, 751 Hijra The date on this could be 711 Miscellaneous
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