The back contains 6 scales of the following types:
Type (click to view scale details) |
Range & Units | Numbered | Geometry | Location |
---|---|---|---|---|
Degree | 0 - 90, Degrees of arc | 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 | Days of year | days | Circular, eccentric | Circular scale second in from the outer scale - refers to the full circle. |
Solar cycle | Days of year | days | Inner Circular, concentric | First circle within shadow square. |
Shadow square | 0 - 12, Fingers | Every 2 fingers | Box | Right hand bottom face of the shadow square (in LR) |
Shadow square | 0 - 12, Fingers | Every 2 fingers | Box | Right hand vertical face of the shadow square (in LR) |
Transcription | Translation | Notes | Type |
---|---|---|---|
صنعه ٳبراهيم بن سعيد السهلي بمدينة طليطلة في شوال سنة تص الهجري | The work of Ibrāhīm ibn Saʿīd as-Sahlī in the city of Toledo in Shawwāl in A.H. 460. | Maker's signature |