Nidaros ordo

Sunday 23 August. Twelfth Sunday after Trinity. Anthem after Compline: Ave regina celorum.
Monday 24. SAINT BARTHOLOMEW, apostle, double. Sub tuum presidium.
Tuesday 25. St Audoen, bishop and confessor, three lessons. O florens rosa.
Wednesday 26. Feria IV. Rogamus te.
Thursday 27. St Hermes, martyr, three lessons. Ave stella matutina.
Friday 28. St Augustine, bishop and confessor, semidouble. Mundi domina.
Saturday 29. Beheading of John the Baptist, nine lessons. Commemoration of St Sabina, widow. Salve regina.

Audoen is Ouen, bishop of Rouen, and not the first saint from what is now Normandy that we've come across in the Nidaros calendar. Evidence perhaps that the liturgical reforms of William of Volpiano lie somewhere in the substrata of the Nidaros use.

St Hermes was an early Roman martyr (like Sabina). His feast was traditionally observed on the 28th. The thirteenth-century Ordo Nidrosiensis Ecclesie gives rather vague instructions about how to negotiate the clash of this feast with that of St Augustine of Hippo. By the time of the printed Breviary of 1519, the pragmatic decision had obviously been taken to transfer Hermes permanently to the 27th.