Astrolabe Catalogue

 

Small image of astrolabe back with rules or alidades removed. Click to enlarge.
Date ca. 1260
Place Spain
Material Brass
Inventory no. 37878
Acquisition Presented by Lewis Evans in 1924

Back



The back contains 5 scales of the following types:
Type
(click to view scale details)
Range & Units Numbered Geometry Location
Zodiacal signs 0 - 30, Zodiacal divisions, equal or unequal Every 10  Circular, concentric The entire outer circle on the back of an astrolabe.
Calendar Days of year  days Circular, eccentric Circular scale immediately inside the outer scale - refers to the full circle
Unequal hours 1 - 12, 1/12 of daylight Every 1 hours Arc Upper left quadrant (inside circular scales)
Unequal hours 1 - 12, 1/12 of daylight Every 1 hours Arc Upper right quadrant (inside circular scales)
Shadow square 1 - 12, Fingers Every 4 fingers Box Left hand vertical 'face' of the shadow square (in LL)
Shadow square 1 - 12, Fingers Every 4 fingers Box Right hand vertical face of the shadow square (in LR)
Shadow square 1 - 12, Fingers Every 4 fingers Box Left hand bottom face of the shadow square (in LL)
Shadow square 1 - 12, Fingers Every 4 fingers Box Right hand bottom face of the shadow square (in LR)
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