The back contains 7 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 and end of the month days | Circular, concentric | Circular scale second in from the outer scale - refers to the full circle. |
| Perpetual calendar | 1 - 28, Days of year | Every 1 days | Circular, concentric | Circular scale third in from the outer scale - refers to the full circle. |
| Shadow square | 0 - 12, Fingers | Every 2 fingers | Box | Left hand vertical 'face' of the shadow square (in LL) |
| Shadow square | 0 - 12, Fingers | Every 2 fingers | Box | Right hand vertical face of the shadow square (in LR) |
| Shadow square | 0 - 12, Fingers | Every 2 fingers | Box | Left hand bottom face of the shadow square (in LL) |
| Shadow square | 0 - 12, Fingers | Every 2 fingers | Box | Right hand bottom face of the shadow square (in LR) |
| Cotangent | Fingers | The numbers are too worn to read fingers | Circular, concentric | Lower left quadrant of outer circular on back of instrument. |
| Cotangent | Fingers | The numbers are too worn to read fingers | Circular, concentric | Lower right quadrant of outer circular on back of instrument. |