The back contains 4 scales of the following types:
Type (click to view scale details) |
Range & Units | Numbered | Geometry | Location |
---|---|---|---|---|
Altitude | 0 - 90, Degrees of arc | Every 5 degrees | Circular, concentric | Upper right quadrant of outer circular on back of instrument. |
Altitude | 0 - 90, Degrees of arc | Every 5 degrees | Circular, concentric | Upper left quadrant of outer circular on back of instrument. |
Unequal hours | 1 - 6, 1/12 of daylight | Not numbered hours | Arc | half circle inside the VIII circle (on mashriqi astrolabes) - covering LL and LR |
Cotangent | 0 - 25, Fingers | Every 5 fingers | Circular, concentric | Lower right quadrant of outer circular on back of instrument. |
Shadow square | 0 - 12, Fingers | Every 6 fingers | Box | Lower right quadrant |