Astrolabe Catalogue

 

Small image of astrolabe back with rules or alidades removed. Click to enlarge.
Date ca. 1370
Place England (?)
Material Brass
Inventory no. 49359
Acquisition Presented by A. E. Gunther in 1986

Back


In addition to the scales catalogued, there is an incomplete semi-circular scale in the upper two quadrants. This was probably intended to be an epact or other calendrical scale.

The back contains 4 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 Circular scale immediately inside the outer scale - refers to the full circle
Altitude 0 - 90, Degrees Every 10 degrees Circular, concentric Upper right quadrant of outer circular on back of instrument.
Calendar first day of month - last day of month, Days of year Every 10 days Circular, concentric Circular scale second in from the outer scale - refers to the full circle.
Shadow square 0 - 12, Fingers Every 4 fingers Box Left hand vertical 'face' of the shadow square (in LL)
Shadow square 0 - 12, Fingers Every 4 fingers Box Left hand bottom face of the shadow square (in LL)
Shadow square 0 - 12, Fingers Every 4 fingers Box Right hand bottom face of the shadow square (in LR)
Shadow square 0 - 12, Fingers Every 4 fingers Box Right hand vertical face of the shadow square (in LR)
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