Sundials in the Middle Ages

In the Middle Ages, the design of the sundial was reduced even further. The gnomon was still horizontal, but the scale was now placed on a flat wall facing towards the south: a simple semicircle, divided up into twelve regular sections, the canonical hours, which, depending on the time of year, were of different lengths.

The day began at sunrise, as is reflected by the daily monastic routines:

- Immediately after sunrise, the monks gathered for Prime (prima = first)
- Terce was held between sunrise and noon. Those who did not have any work to do kept  themselves busy reading religious books (tertia = third).
- Noon mass was held at Sext (sexta = sixth).
- In the middle between noon and sunset, the bells called to None (nona = ninth).
- The day ended after sunset. The monks attended Compline, the final prayer of the day (completus = complete).