Astrolabe Catalogue

 

Small image of astrolabe back with rules or alidades removed. Click to enlarge.
Date ca. 1400
Maker Jean Fusoris
Place Paris
Material Brass
Inventory no. 53801
Acquisition Presented by J. A. Billmeir in 1957

Back



The back contains 5 scales of the following types:
Type
(click to view scale details)
Range & Units Numbered Geometry Location
Degree 0 - 90, Degrees Every 10 degrees Circular, concentric The entire outer circle on the back of an astrolabe.
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
Calendar first day of month - last day of month, Days of year Every 10 days Circular, eccentric Circular scale second in from the outer scale - refers to the full circle.
Unequal hours 1 - 6, Days of year Every 1 days Arc The upper two quadrants of the back of the instrument
Shadow square 1 - 12, Fingers Every 4 fingers Box All four sides of the shadow square, commonly found in the lower half of the center of the instrument.
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