Astrolabe Catalogue

The back contains 9 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, concentric	Circular scale second in from the outer scale - refers to the full circle.
Saints' Days	Days of year	days	Circular, concentric	Circular scale third in from the outer scale - refers to the full circle.
Unequal hours	1 - 12, 1/12 of daylight	Every 1 hours	Arc	The upper two quadrants of the back of the instrument
Shadow square	1 - 60, None	Every 10	Box	Left hand vertical 'face' of the shadow square (in LL)
Shadow square	1 - 60, None	Every 10	Box	Right hand vertical face of the shadow square (in LR)
Shadow square	1 - 60, None	Every 10	Box	Left hand bottom face of the shadow square (in LL)
Shadow square	1 - 60, None	Every 10	Box	Right hand bottom face of the shadow square (in LR)
Planetary hours	1 - 12, None	Every 1	Inner Box	None
Shadow square	1 - 12, Fingers	Every 3 fingers	Box	All four sides of the shadow square, commonly found in the lower half of the center of the instrument.

The back is inscribed:

Transcription	Translation	Notes	Type
Erasmus Habermel fe:	Erasmus Habermel made this	This inscription is found below the ornament underneath the shadow square	Maker's signature