The back contains 6 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. |
| 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 days | Circular, concentric | 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 3 fingers | Box | Left hand vertical 'face' of the shadow square (in LL) |
| Shadow square | 1 - 12, Fingers | Every 3 fingers | Box | Right hand vertical face of the shadow square (in LR) |
| Shadow square | 1 - 12, Fingers | Every 3 fingers | Box | Left hand bottom face of the shadow square (in LL) |
| Shadow square | 1 - 12, Fingers | Every 3 fingers | Box | Right hand bottom face of the shadow square (in LR) |