MS A 3: the Martyrology of Tallaght
The ten surviving leave containing the Martyrology of Tallaght were once part of the Book of Leinster. The prose text, which details the feast-days of saints arranged according to the day of the year on which they died, was ncompiled at Tallaght, County Dublin. This is the earliest surviving manuscript of the Martyrology which was first compiled in the early ninth century. There are 3-8 columns per page and c.60 lines per column.
Micheál Ó Cléirigh acquired these leaves from James Ussher, Church of Ireland archbishop of Armagh, possibly during his 1627 visit to Leinster. They were probably already separated from the Book of Leinster at that point. The manuscript was subsequently taken to Louvain before being returned to Dublin in 1872.