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 10 degrees | Circular, concentric | None |
| 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 | Days of year | Every 10 and the end of the month days | Circular, eccentric | Circular scale second in from the outer scale - refers to the full circle. |
| Shadow square | 0 - 12, None | Every 3 | Box | All four sides of the shadow square, commonly found in the lower half of the center of the instrument. |
| Unequal hours | 1 - 6, 1/12 of daylight | Every 1 hours | Arc | Upper left quadrant (inside circular scales) |
| Equal hours | 1 - 12, Times of day | Every 1 hours | Arc | Upper right quadrant (inside circular scales) |