Astrolabe Catalogue

 

Small image of astrolabe back with rules or alidades removed. Click to enlarge.
Date ca. 1650
Maker Muḥammad Mahdī
Place Persia
Material Brass
Inventory no. 41763
Acquisition Presented by J. A. Billmeir in 1957

Back



The back contains 17 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.
Cotangent 0 - 30, Feet Every 5 feet Circular, concentric Lower left quadrant of outer circular on back of instrument.
Cotangent 0 - 45, Fingers Every 5 fingers Circular, concentric Lower right quadrant of outer circular on back of instrument.
Sine/Cosine 1/60 of quadrant radius Not numbered  Angle Upper left quadrant (inside circular scales)
Equal hours 1 - 6, Times of day Every 1 hours Arc Upper left quadrant (inside circular scales)
Declination Zodiacal divisions, equal or unequal Not numbered  Arc Upper right quadrant (inside circular scales)
Altitude of noon sun Degrees of latitude Every altitude degrees Arc Upper right quadrant (inside circular scales)
Azimuth of Qibla Cities   Arc Upper right quadrant (inside circular scales)
Terms 0° Aries - 30° Pisces, Zodiacal divisions, equal or unequal At each term  Inner Circular, concentric half circle inside the outer circle (on mashriqi astrolabes) - covering LL and LR
Zodiacal signs Aries - Pisces, Zodiacal sign Not numbered  Inner Circular, concentric half circle inside the V circle (on mashriqi astrolabes) - covering LL and LR
Faces 0° Aries - 30° Pisces, Astrological face Not numbered  Inner Circular, concentric half circle inside the VI circle (on mashriqi astrolabes) - covering LL and LR
Faces 0° Aries - 30° Pisces, Astrological face Not numbered  Inner Circular, concentric half circle inside the VI circle (on mashriqi astrolabes) - covering LL and LR
Lunar Mansions 0° Aries - 30° Pisces, Lunar mansion Not numbered  Inner Circular, concentric half circle inside the VII circle (on mashriqi astrolabes) - covering LL and LR
Shadow square 0 - 7, Feet Every 1 feet Box Left hand vertical 'face' of the shadow square (in LL)
Shadow square 0 - 7, Feet Every 1 feet Box Left hand bottom face of the shadow square (in LL)
Shadow square 0 - 12, Fingers Every 1 fingers Box Right hand bottom face of the shadow square (in LR)
Shadow square 0 - 12, Fingers Every 1 fingers Box Right hand vertical face of the shadow square (in LR)
Triplicities 0 - 12, Zodiacal divisions, equal or unequal Every 1  Inner Box Box 'inside' the shadow square. Common site for triplicities, etc.
MHS Home | Contact Us | ©2006 Museum of the History of Science