Astrolabe Catalogue

 

Small image of astrolabe back with rules or alidades removed. Click to enlarge.
Date 18th century
Place Persia (?)
Material Brass
Inventory no. 50180
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
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.
Declination 1 - 12, Zodiacal sign Not numbered  Arc Upper right quadrant (inside circular scales)
Sine/Cosine 0 - 60, 1/60 of quadrant radius Not numbered  Arc Upper left quadrant (inside circular scales)
Shadow square 1 - 7, Feet Every 1 feet Box Lower left quadrant
Shadow square 1 - 12, Fingers Every 1 fingers Box None
Cotangent 10 - 25, Feet Every 5 feet Circular, concentric Lower left quadrant of outer circular on back of instrument.
Cotangent 0 - 40, Fingers Every 5 fingers Circular, concentric Lower right quadrant of outer circular on back of instrument.
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