Astrolabe Catalogue

 

Small image of astrolabe back with rules or alidades removed. Click to enlarge.
Date ca. 1400
Place Europe
Material Brass
Inventory no. 52869
Acquisition Presented by J. A. Billmeir in 1957

Back


The script on the back of the instrument suggests that it was engraved at a later date. Unlike the rete and the womb, which were engraved in a Lombardic capital script, the back was engraved in Roman capitals.

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 5 degrees Circular, concentric The entire outer circle on the back of an astrolabe.
Zodiacal signs 0 - 30, Zodiacal divisions, equal or unequal Every 5  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 5 and end of the month days Circular, eccentric Circular scale second in from the outer scale - refers to the full circle.
Unequal hours 1 - 6, 1/12 of daylight Every 1 hours Arc The upper two quadrants of the back of the instrument
Shadow square 1 - 12, Fingers Every 4 fingers Box The lower two quadrants of the back of the instrument
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