MS St. Gallen, Stiftsbibliothek, 225 was probably compiled in 773. It contains 21 hitherto unexplored pages dealing with natural science and computistics: three tables (Easter table, Easter Sundays, lunar age), two schematic chapters (horologium and Julian calendar with multiplication-tables), eight computistical argumenta (dealing with the bissextile day, the annus mundi, the annus domini, the indiction, the concurrentes, common and embolismic lunar years, the annus passionis, the seasons), and two inserted chapters on ecclesiastical feastdays and Greek names. This material shows parallels with the Cologne textbook on time-reckoning of 805, as well as the encyclopaedia on time-reckoning from Aachen of 809; yet, this manuscript does not contain a cohesive work, but only disconnected computistical bits. It is evidently influenced by Irish computistical thought, but it also transmits Roman traditions through its lunar calculations, which were later promoted by Alcuin in the Carolingian kingdom. A pseudo-calculation of Irish-Frankish origin is mentioned in the context of the bissextile day. Likewise, a table listing all possible Easter Sundays depending on the weekday of the Easter full moon also derives from Irish-Frankish Easter calculations. This calculation, using certain regulars for March and April, is explained in the Calculatio Albini of 776, which is an adaptation of Irish material, presumably by Alcuin.